The following is a collection of research reports and peer-reviewed publications for work supported by the AquaFish Innovation Lab. Prior to 2008, the research presented in these papers was supported by previous awards under the Pond Dynamics / Aquaculture Collaborative Research Support Program (CRSP) and the Aquaculture CRSP.

The titles below are linked to the full article information, including the abstract. The full research report or journal article should be obtained through the journal in which it was published or by contacting the author.

The collected abstracts of previous CRSP work can also be downloaded as PDF documents:

2018

NOP18-396 (English)

Impact of aquaculture feed technology on fish income and poverty in Kenya
Journal Article
2018

NOP18-393 (English)

Agricultural extension services are critical to the development of crops, livestock and fish farming in order to bring about social change. Fish farming, though introduced over 50 years ago through research and extension, remains at a slow pace of growth. There is a consensus in academic and policy literature about the potential benefits of fish farming, particularly nutrition and income generation. So why has extension not been more successful in improving the status of fish farming? Most explanations focus on supply side issues highlighting lack of inputs, particularly fingerlings and feeds with little consideration given to how the extension services themselves are organized in view of fish farming under general agriculture. Equally absent in the discourse are the perspectives on the motivations and experiences of individual fish farmers. Drawing from the Actor Oriented Perspective, this paper examines the organization and current status of extension service provision in aquaculture based on perspectives of policy makers, extension workers and fish farmers. Interviews were conducted with 246 fish farmers, eight extension workers and 11 key informants from government institutions. Secondary sources of information included various government documents on agriculture. Results revealed slow growth of aquaculture due to institutional and social factors regarding alignment of extension service provision to the needs of fish farmers. Reforms instituted over the past decades in search of better ways to avail farmers with improved farming knowledge have had minimal success. Less than 50% of fish farmers received extension visits from district extension staff with moderate difference (p<0.05) between frequency of extension visits in central and northern regions. Bias of extension service provision towards production related technical and information aspects above building and strengthening social capital of fish farmers was noted. Extension interventions should be socially negotiated and adapted in view of aspirations and limitations of fish farmers.

Aquaculture Development and Uganda’s Agricultural Extension System : The Case of Fish Farmers in Central and Northern Regions
Journal Article
2018
NOP 18-400 (English)

NOP 18-400 (English)

Seasonal patterns in production and demand are common in many agricultural markets. Charting these patterns provides information that complements fundamental and technical analyses. It is in this spirit that this paper seeks to examine price seasonality in the catfish value chain in Uganda. The analysis draws on monthly prices taken from secondary source recorded data and uses moving average index to chart price patterns. The results reveal distinct seasonal patterns in the farm-gate, ex-vessel, retail, and wholesale market channels. Across market channels, the results for farm-gate versus ex-vessel prices reveal that farm-gate prices are more affected by seasonal effects compared to ex-vessel prices. On the contrary, both price series in the retail versus wholesale market channels show a declining trend, with the wholesale price series showing stronger variability compared to the retail price series.

Price Seasonality in the Catfish Value Chain in Uganda
Journal Article
2018
Hien, H. V., N. T. K. Quyen, T. M. Phu, T. T. T. Hien, and P. M. Duc. 2018. Survey of fish consumption by women and children in An Giang province. Journal of Vietnam Agricultural Science and Technology 86(1):106 - 112.
NOP 18-392 (English)

NOP 18-392 (English)

The aim of this study is to assess amount of food and energy provided within 24 hours for women and children and to analyze the role of food fish for daily consumption. The study was conducted from January to November 2017 in An Giang province by interviewing 300 women and 300 children in the dry and wet seasons. The study found that women’s daily dietary intake in dry and wet seasons was 750.3 g/day (1,411.8 kcal) and 780.6 g/day (1,403.5 kcal), respectively. For children, daily food intake in dry and wet seasons was 683.1 g/day (764.7 kcal) and 616.5 g/day (983.7 kcal), respectively. Food fish consumption by women accounted for 18.1-18.8% in quantity (10.9 - 12.8% in energy). For children, food fish products constituted 9.5 - 9.8% in quantity (6.8 - 9.3% in energy).

Survey of fish consumption by women and children in An Giang province
Journal Article
2018

NOP 18-395 (English)

A survey of 131 households culturing snakehead with three scales production as following: 30 households with small scale (SS) 300 - 700 m2 ; 70 households with medium scale (MS) 700 - 1,500 m2 and 31 households with large scale (LS) > 1,500 - 8,000 m2 was carried out in the main snakehead culture areas in three provinces of An Giang, Dong Thap and Tra Vinh from January to December 2017. The study aimed to analyze production efficiency of snakehead culture to find out the optimal scale for recommend of sustainable culturing scale in the Mekong Delta. The technical analysis showed that the stocking density of small scale (SS) (55.1 ind/m2 ) was higher than that of medium scale (MS) (51.3 ind/m2 ) and large scale (LS) (51.9 ind/m2 ); survival rate of SS (63.1%) was lower than MS (64.5%) and higher than LS (57.5%); yield of SS (15.6 kg/m2 ) was lower than MS (16.2 kg/m2 ) and LS (16.9 kg/m2). In terms of economic efficiency: Direct cost of SS (485.2 thousand VND/m2) was lower than that of MS (502.5 thousand VND/ m2 ) and LS (525.6 thousand VND/m2 ); the production cost of SS (30.9 thousand VND/kg) was lower than that of MS (31 thousand VND/kg) and LS (31.2 thousand VND/kg); profit ratio of SS (4,3%) was higher that that of MS (1,4%) and lower than that of LS (5,8%). Feed cost accounts for the largest proportion (78.4-81.8%) of total cost at all farming scales. In summary, based on technical and economic aspects and actual conditions of production scale, SS is suitable for the sustainable development of snakehead fish in household culture in the Mekong Delta.

Analysis of efficiency of snakeahead (<i>Channa striata</i>) model culturing in earthen pond in the Mekong Delta
Journal Article
2018

NOP 18-397 (English)

Prior to 2006, the predominant method for culturing snakehead in Vietnam and Cambodia was to collect wild juveniles from natural sources like the Mekong River and Tonle Sap. Particularly in Cambodia, aquaculture farmers, who were also fishermen, would collect their own fingerling snakehead. They would then also collect “small fish” (also known as low-value fish or trash fish) from natural sources, chop them up and feed them to the snakehead in culture. A conflict existed between users of these fish: the aquaculture/fishing people and the remainder of the Cambodian population who rely on small fish (Fig. 1) for a variety of products, including fish sauce and prahok, that provide protein to the Cambodian people throughout the year. As a result, and to protect the nutrition of the Cambodian people, aquaculture of snakehead was banned in the country in 2004.

Alternative Feeding Strategies and Feed Ingredients for Snakehead Farming in Cambodia and Vietnam
Magazine Article
2018
Hien, T. T. T., N. T. C. Duyen, T. L. C. Tu, N. V. Khanh, and T. M. Phu. 2018. Dietary methionine and lysine requirement of snakehead (Channa striata) fingerlings. International Journal of Scientific and Research Publications 8(8):795 - 805.
NOP 18-401 (English)

NOP 18-401 (English)

This study was aimed determine the dietary methionine (Met) and lysine (Lys) requirement for snakehead fingerlings (2-4 g fish-1). Basal diets in two experiments contained approximately isonitrogenous 42% and isoenergetic 20.3 KJ g-1. In the first experiment on Met requirement, L-Met was added to the basal diets including six treatments containing from 7.3 to 14.8 g Met kg-1 diet (17.5 to 35.3 g Met kg-1 protein) interval increasing of 1.5 g kg-1 diet. In the second experiment determining Lys requirement, L-Lys HCL was added to basal diets including seven treatments containing from 12.6 to 36.6 g Lys kg-1 diet (30.1 to 87.2 g Lys kg-1 protein), interval increasing of about 4 g kg-1 diet. The experiements were randomly designed with four replications for each treatment. The first experiment indicated that optimal weight gain, special growth rate, protein efficiency ratio was found in the diet containing 28.2 g Met kg-1 protein and there were significant differences in those parameters between diet treatment containing 24.8 g Met kg-1 protein and other diets containing lower Met levels. The hepatosomatic index and protein content in whole-body fish were significantly affected by dietary Met levels. Feed conversion ratio (FCR) was significantly improved with the increase of dietary Met level in diet to 28.2 g kg-1 protein (P<0.05). Results of the second experiment showed that optimal growth rate and protein efficiency ratio were found in diet containing 73.1 g Lys kg-1 protein and there were significant differences in those parameters between diet treatment containing 73.1 g Lys kg-1 protein and other diets containing lower Lys levels. The hepatosomatic index, protein and fat content in whole-body fish were significantly affected by dietary Lys levels. The FCR was significantly improved by increasing dietary Lys concentration to approximately 77.9 g Lys kg-1 protein. Fish survival rate were not significant differences among treatments in both experiments. Broken-line analysis on the basis of optimal growth rate showed that the dietary Met requirement was 11.9 g Met kg-1 diet (28.4 g kg-1 protein) and the dietary Lys requirement of snakehead was 30.7 g Lys kg-1 diet (73.1 g kg-1 protein).

Dietary methionine and lysine requirement of snakehead (<i>Channa striata</i>) fingerlings
Journal Article
2018

NOP 18-389 (English)

Although carp polyculture is well established throughout southern Asia, its overall efficiency in providing sufficient nutrients and financial profit remains variable. Site-specific adjustments are needed to improve efficiencies of polyculture under local circumstances. We evaluated variations of carp polyculture systems in two separate trials: one on a research station (on-station), and one in farmers’ ponds (on-farm). The on-station experiment included four treatments: TF (carp + 100% feed), TFS (carp + SIS (small indigenous species) +100% feed), TFSP (carp + SIS + 50% feed + bamboo substrate) and TSP (carp + SIS+ bamboo substrate with no feed), each done with three replicates. Silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), rohu (Labeo rohita), and mrigal (Cirrhinus mrigala) were stocked at a ratio of 4:1:4:3:5:5 and a rate of 15,000 fish/ha. Additionally, 2 SIS, dedhuwa (Esomus danricus) and pothi (Puntius sophore), were stocked at 1:1 and a combined density of 50,000 fish/ha. Carps were fed daily at 5% of body weight (BW) for 60 days, then 2% BW for 150 days, using a supplemental feed composed of dough (mustard oil cake and rice bran (1:1)), or using grass (for grass carp). Total carp yield and FCR were highest in TFSP ponds. Gross margin was also higher in treatments enhanced with periphyton (TFSP and TSP). Overall, TFSP was determined the best on-station result, based on total production of fish and profit. The two treatments with the highest net fish yield, TF and TFSP, were introduced to 37 women farmers in Chitwan and Nawalparasi districts for on-farm trials. After 8 months of culture, total fish weight and gross margin were 24.0% and 51.2% higher, respectively, in TFSP ponds than in TF ponds. Reduced feed application with increased periphyton enhancement dramatically improved profit while maintaining fish yields similar to those of traditional polyculture systems with full feeding.

Production of periphyton to enhance yield in polyculture ponds with carps and small indigenous species
Journal Article
2018

NOP18-394 (English)

We document for the first time the early ontogeny of Centropomus poeyi based on captive raised material representing 0-19 days posthatch (dph). The achievement of early developmental landmarks (i.e., yolk-sac depletion, flexion, development of fins) and changes in pigmentation are described (1.4 mm NL-10.6 mm SL; 0-19 dph) and documented for a subset of individuals using high quality photographs. The ontogeny of the viscerocranium is also described (2.4 mm NL-10.6 mm SL; 6-19 dph). Development in C. poeyi occurs over a short period with attainment of the juvenile stage (i.e., full complement of fin rays present in each fin) occurring by 6.9 mm SL. The ontogeny of external pigmentation in C. poeyi is marked by two trends throughout growth: (1) a decrease in pigmentation dorsally; and (2) an increase in pigmentation ventrally along the midline. Development of the viscerocranium begins with the appearance of the maxilla and dentary in individuals of 2.4 mm NL, coinciding with the depletion of the yolk-sac. By 10.6 mm SL all bones of the viscerocranium are present and teeth are present on all teeth-bearing bones of the adult. Aspects of early development in C. poeyi are compared with the congeners C. undecimalis and C. parallelus.

Larval development of the Mexican Snook , <i>Centropomus poeyi</i> ( Teleostei : Centropomidae )
Journal Article
2018
Lam, M. T., P. M. Duc, and T. T. T. Hien. 2018. Effects of Vitamin C on growth and immune parameters of snakehead culture in hapa. Journal of Vietnam Agricultural Science and Technology 89(4):109 - 114.
NOP 18-398 (English)

NOP 18-398 (English)

The experiment was carried out to evaluate the appropriate supplementation method and dose of vitamin C supplemented in feed in order to stimulate on growth and healthy parameters of snakehead (Channa striata). The study was conducted in 5 months, including 2 experiments. The first experiment consisted of 4 treatments of feed A supplemented with different vitamin C of 0, 500, 750 and 1000 mg/kg of feed during processing. The second experiment also included 4 treatments of feed B mixed with the same level of vitamin C as with feed A by traditional method. The results showed that the inclusion of vitamin C in pellet feed before extrusion was recorded better growth performance, survival rate and fish health compared to addition of vitamin C by traditional method in daily. Addition of vitamin C in diet for snakehead in commercial pellet feed at a level of 500 mg/kg of feed enhanced fish growth performance, survival rate, fish health and increasing profit.

Effects of Vitamin C on growth and immune parameters of snakehead culture in hapa
Journal Article
2018

NOP 18-391 (English)

The proximate composition of local feed ingredient is limited by unbalanced dietary amino acid contents, thereby increasing de-amination and ammonia levels in water. This study formulated experimental diets and balanced the Essential Amino Acids (EAA) to enhance the feed nutritive value for culture of Oreochromis niloticus. Four diets comprising methionine+lysine and lysine supplemented at 5.1 g kg-1, 2.7 g kg-1 to non- EEAs supplemented and commercial diets at the University of Eldoret Fish Farm were tested. Growth performance was conducted in hapas suspended in earthen pond 150 m2 in a randomized design for 105 days. There were significant variations in temperature (24 to 26°C), Dissolved oxygen (4.8 to 6.2 mg L-1) and pH (7.2-7.6) but within optimal range for tilapia. The diets provided about 17.17 MJ kg-1 with 22.9% digestible Crude Protein and 8.03% ash content. Lysine supplemented Diet 2 induced highest mean final weight of 156.05±1.74 g, 2.4 Specific Growth Rate, 1.42 Feed Conversion Ratio and 2.68 Protein Efficiency Ratio. A high profit index (2.286±0.07) at low incidence cost (0.437±0.05) was observed in Diet 2.The study reports reduced production cost by supplementing plant proteins with limiting amino acids hence increasing nutritive value of aquafeeds.

EFFECTS OF LYSINE AND METHIONINE SUPPLEMENTATION AND COST EFFECTIVENESS IN PRODUCTION OF NILE TILAPIA (<i>Oreochromis niloticus</i>) IN WESTERN KENYA
Journal Article
2018

NOP 18-390 (English)

Aquaponics is an environmentally friendly production system involving reuse of waste and nutrients in production of fish and vegetables. Currently aquaponic system is the only solution for fish and plants production but one unique challenge is the maintaining of micro and macro-nutrient and the pH balance in the system. The study was conducted at the University of Eldoret for 119 days. A complete randomized design was used. The supplementation rates in fish diets constituted 30g, 20g, 10g and 0g Fe kg-1 respectively. Nile tilapia fry with a mean weight of 0.475 ± 0.025g and nine spinach (height 3 ± 0.131cm, 2 leaves) were stocked in 12 aquaria in an aquaponic system. 30g Fe kg-1 treatment exhibited higher minerals content than other treatments with Phosphorus 67.51 ± 2.42 mgL-1, Zinc 9.06 8± 0.45 mgL-1, Iron 5.2 ± 0.218 mgL-1, Manganese 7.655 ± 0.344 mgL-1, Total Nitrogen 11.248 ± 0.141mgL-1 and Sodium 7.218 ± 0.028 mgL-1. There was improved water quality at 30g Fe kg-1 compared to other treatments. These results revealed that 30g Fe kg-1 iron amino acid chelate supplementation had better nutritional attributes as feedstuff for spinach growth than the three other dietary treatments. The study recommends the incorporation of 30g Fe kg-1 iron amino acid chelate in on-farm formulated diets for aquaponic system where complete diets are not easily accessible for small scale farmers.

Effect of Iron Amino Acid Chelate Supplemented Fish Feeds on Nutrients Composition of Spinach (</i>Spinacia oleracea</i>) in an Aquaponic System in Kenya
Journal Article
2018
Rono, K. et al. 2018. GROWTH PERFORMANCE OF SPINACH (Spinacia oleracea) ON DIETS SUPPLEMENTED WITH IRON-AMINO ACID COMPLEX IN AN AQUAPONIC. International Journal of Research Science and Management 5(7):117 - 127.
NOP 18-399 (English)

NOP 18-399 (English)

Aquaponic is an environmental-friendly production system involving reuse of waste and nutrients in production of fish and vegetables. Currently the system experiences unbalance in pH and nutrients deficiency in plants. This study investigated the effect of iron amino acid chelate supplement in fish feeds on growth performance of spinach (Spinacia oleracea) in aquaponic system. The experimental research was conducted at the University of Eldoret from August-December 2016. A complete randomized design was used in triplicate treatments. The supplementation quantity in fish diets constituted 30 Fe kg-1, 20 Fe kg-1 10 Fe kg-1 and 0 Fe kg-1 of iron amino acid chelate respectively. At 30 Fe kg-1 treatments spinach indicated a significant growth at (p < 0.05) than other treatments with final mean height (52.44 ± 0.798cm) and 19.33 leaves. The least growth of spinach was at 0 Fe kg-1 treatments with final mean (25.36 ± 0.72 cm, 9.704) height and leaves respectively. 30 Fe kg-1 exhibited highest nutrients and improved water quality as compared to other treatments. The results revealed that 30 Fe kg-1 iron amino acid chelate supplementation had significant nutritional attributes as feedstuff in aquaponic system for spinach growth than other dietary treatment tested.

GROWTH PERFORMANCE OF SPINACH (<i>Spinacia oleracea</i>) ON DIETS SUPPLEMENTED WITH IRON-AMINO ACID COMPLEX IN AN AQUAPONIC
Journal Article
2018

2017

NOP 17-384 (English)

The fish fauna in the Yangtze-based riparian ecosystem has been imperiled largely due to genetic degradation of populations. Regular genetic monitoring of the fish populations is required for an effective management and conservation. The genetic structure of Dojo loach, Misgurnus anguillicaudatus was investigated in twelve populations originating from the Yangtze River basin by using thirteen microsatellite loci. The number of alleles per locus varied between 2 and 8 with an average of 4.6 alleles per locus. Overall, low-to-moderate level of genetic diversity was observed in the loach populations. Significant deviations from Hardy-Wienberg equilibrium were observed in about 50% of the total locus-population combination tests. The AMOVA indicated that most of the variance existed among the individuals (90.50%) rather than among populations within groups (9.03%). Significant differentiation was found among the samples from scattered habitats with different connections to the Yangtze River (P<0.05). The clustering of sample populations in UPGMA dendrogram followed their geographic distribution except for Zigui and Xiaogan which clustered against their geographical origin. The factors involved in genetic differentiation and shaping the existing patterns of population structure of the loach were discussed so as to provide guidelines for conservation strategies and management programs.

Microsatellite Markers Reveal Genetic Differentiation of Chinese Dojo Loach <i>Misgurnus anguillicaudatus</i> in the Yangtze River Basin
Journal Article
2017

NOP 17-380 (English)

Five isolipidic experimental diets (32% crude protein) were formulated to contain 3% fish oil (FO) and virgin coconut oil (3 VCO) as sole lipids or blends of FO + VCO in ratios of 75:25% (0.75 VCO), 50:50% (1.5 VCO) and 25:75% (2.25 VCO). Triplicate groups of O. niloticus were fed one of five diets to apparent satiation, twice daily for 8 weeks. It was observed that fish fed diet 3 VCO exhibited the best performance with respect to feed intake (492.1 g), final weight (214.60 g) and weight gain (154.90 g). Significant effects of dietary fatty acid profile were reflected in fish fed the diets in whole body, muscle and liver C12:0 and C14:0. However, eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic (DHA, 22:6n-3) were significantly different (P ≥ 0.05) compared to their respective diets while liver n-3: n-6 ratio significantly increased and recorded low levels in whole body and muscle. Statistically, least values of mortality were recorded as VCO levels were elevated when fish were subjected to Streptococcus iniae infection while plasma metabolite indicators among treatments were not altered. The inclusion of VCO at 3% in the diet gave excellent performance, indicating that it could wholly replace FO and as such represents a better alternative lipid source for feeding O. niloticus.

Evaluation of blended virgin coconut oil and fish oil on growth performance and resistance to <i>Streptococcus iniae</i> challenge of Nile tilapia (<i>Oreochromis niloticus</i>)
Journal Article
2017

NOP 17-372 (English)

This paper examines price volatility in the African catfish (Clarias gariepinus) supply chain in Uganda. The volatility process in the catfish markets was analyzed based on monthly price data from January 2006 to August 2013. A GARCH model is used to estimate the volatility parameters. Empirical results revealed that the value of the first-order autoregressive term and the value of the first-order moving average term were significant for both aquaculture and wild harvest catfish supply chains. The observed long persistence of volatility in both supply channels suggests a fundamental level of uncertainty and risk in the catfish subsector over the studied period.

Assessment of Price Volatility in the Fisheries Sector in Uganda
Journal Article
2017

17-A01(English)

Stabilization of prices of essential agricultural commodities continues to remain an area of major concern for policy makers; given that price instability affects both producers and consumers, and has macroeconomic implications. This paper examines farm-gate price behavior in the African catfish markets in Uganda, and develops a forecasting model that adjusts for the seasonal fluctuations in the price series. The analysis utilizes monthly catfish real price series for the period January 2006 to December 2013. The model provides good in-sample and out-of-sample forecasts for the eight-year time period. The out-sample predictions based on SARIMA (1, 1, 1) (0, 1, 1)12 model suggest that the stochastic seasonal fluctuations depicted in the price series are successfully modeled, and that catfish real prices follow an upward trend. The findings can assist policy makers and major stakeholders to gain insight into more appropriate economic and sectorial policies that can lead to the development of reliable market information systems and up-to-date data on catfish supply, demand and stocks.

Forecasting Farm-Gate Catfish Prices in Uganda Using SARIMA Model
Journal Article
2017

NOP 17-383 (English)

While gender disparities are decreasing in some areas of academia, studies have shown that gender inequities in scholarly literature still persist. A review of more than eight million papers across disciplines found that men predominate in the first and last author positions and women are underrepresented in single-authored papers.

The present study applies the vetted methodology of assigning authorship gender in peer-reviewed literature, according to the U.S. Social Security Database of names, to the broad discipline of aquaculture in peer-reviewed journals in the complete JSTOR database archive, and compares these results to authorship by gender in the International Aquaculture Curated Database (IACD). The International Aquaculture Curated Database (IACD) is a compilation of over 500 peer-reviewed publications supported by four international aquaculture programs developed by Oregon State University researchers. Preliminary findings reveal that the percentage of women authors was similar to that for the JSTOR aquaculture journals subsample (13.8 %) and the journals in the IACD (15.7 %). Women, therefore, are not well represented in either database. The next steps for this work include comparing and contrasting the proportion of women authors in aquaculture journals to women working in the aquaculture discipline and to women graduates in the discipline. Learning how gender authorship has changed in the aquaculture discipline is a critical component for promoting gender equity in the academic discipline and broader field of aquaculture.

Towards Assessing Gender Authorship in Aquaculture Publications
Journal Article
2017

NOP 17-371 (English)

Leptin is a pleiotropic hormone that plays a critical role in regulating appetite, energy metabolism, growth, stress, and immune function across vertebrate groups. In mammals, it has been classically described as an adipostat, relaying information regarding energy status to the brain. While retaining poor sequence conservation with mammalian leptins, teleostean leptins elicit a number of similar regulatory properties, although current evidence suggests that it does not function as an adipostat in this group of vertebrates. Teleostean leptin also exhibits functionally divergent properties however, possibly playing a role in glucoregulation similar to what is observed in lizards. Further, leptin has recently been implicated as a mediator of immune function and the endocrine stress response in teleosts. Here, we provide a review of leptin physiology in vertebrates, with a particular focus on its actions and regulatory properties in the context of stress and the regulation of energy homeostasis.

Assessing the Functional Role of Leptin in Energy Homeostasis and the Stress Response in Vertebrates
Journal Article
2017

NOP 16-361 (English)

Leptin is an important cytokine for regulating energy homeostasis, however, relatively little is known about its function and control in teleost fishes or other ectotherms, particularly with regard to interactions with the growth hormone (GH)/insulin-like growth factors (IGFs) growth regulatory axis. Here we assessed the regulation of LepA, the dominant paralog in tilapia (Oreochromis mossambicus) and other teleosts under altered nutritional state, and evaluated how LepA might alter pituitary growth hormone (GH) and hepatic insulin-like growth factors (IGFs) that are known to be disparately regulated by metabolic state. Circulating LepA, and lepa-and lepr- gene expression increased after 3-weeks fasting and declined to control levels 10 days following refeeding. This pattern of leptin regulation by metabolic state is similar to that previously observed for pituitary GH and opposite that of hepatic GHR and/or IGF dynamics in tilapia and other fishes. We therefore evaluated if LepA might differentially regulate pituitary GH, and hepatic GH receptors (GHRs) and IGFs. Recombinant tilapia LepA (rtLepA) increased hepatic gene expression of igf-1, igf-2, ghr-1, and ghr-2 from isolated hepatocytes following 24 h incubation. Intraperitoneal rtLepA injection, on the other hand, stimulated hepatic igf-1, but had little effect on hepatic igf-2, ghr1, or ghr2 mRNA abundance. LepA suppressed GH accumulation and gh mRNA in pituitaries in vitro, but had no effect on GH release. We next sought to test if abolition of pituitary GH via hypophysectomy (Hx) affects the expression of hepatic lepa and lepr. Hypophysectomy significantly increases hepatic lepa mRNA abundance, while GH replacement in Hx fish restores lepa mRNA levels to that of sham controls. Leptin receptor (lepr) mRNA was unchanged by Hx. In in vitro hepatocyte incubations, GH inhibits lepa and lepr mRNA expression at low concentrations, while higher concentration stimulates lepa expression. Taken together, these findings indicate LepA gene expression and secretion increases with fasting, consistent with the hormones function in promoting energy expenditure during catabolic stress. It would also appear that LepA might play an important role in stimulating GHR and IGFs to potentially spare declines in these factors during catabolism. Evidence also suggests for the first time in teleosts that GH may exert important regulatory effects on hepatic LepA production, insofar as physiological levels (0.05–1 nM) suppress lepa mRNA accumulation. Leptin A, may in turn exert negative feedback effects on basal GH mRNA abundance, but not secretion.

Control of leptin by metabolic state and its regulatory interactions with pituitary growth hormone and hepatic growth hormone receptors and insulin like growth factors in the tilapia (<i>Oreochromis mossambicus</i>)
Journal Article
2017

NOP 17-388 (English)

This study was conducted to determine suitable faecal collection methods applied for digestibility studies of different protein ingredients for snakehead fish (Channa striata). The study included three experiments: in the first experiment, faecal collection was done every 2 hours within 24-hour period by settling technique; in the second experiment, different feces collection were applied such as settling, stripping and dissection; and in the last experiment, ADC of dry matter, protein, and energy of fish meal, soy bean meal, meat bone meal, and blood meal was evaluated as feed ingredients for snakehead. The results showed the suitable time for collecting snakehead feces was 8 hours; faecal collection by settlement method was more suitable than dissection and stripping methods for snakehead digestibility study; and the best ADC of dry mater was found in fish meal (85.8%), then deflated soybean meal (69.7%), blood meal (69.0%) and meat bone meal (52.3%). Similar results on ADC protein and ADC energy of these ingredient used as feed for snakehead were confirmed.

Assessment of faecal collection methods for determination of digestibilities of snakehead fish (<i>Channa striata</i>) with protein feed ingredients sources
Journal Article
2017

NOP17-A03 (English)

The aim of this study is to describe activities of some digestive enzymes of snakehead larvae from day 1 to day 35 after hatching, feeding with two different diets. In the first treatment, larvae were fed with live feed including Moina sp. and marine trash fish; in the second treatment, larvae were still fed with live feed, but live feed was gradually replacement by formulated diet from day 17 onwards. Larvae were sampled at 1; 3; 5; 7; 9; 12; 15; 18; 21; 25; 30 and 35 days after hatching (DAH), before feeding in the morning. The result showed that, amylase enzymes activity fluctuated during the research period and reached 3.68±0.17 mU/mg protein in live feed treatment and 5.77±0.14 mU/mg protein in formulated diet treatment at 35 DAH. Proteolytic enzymes were detected at low level as early as hatching and remained constant until 12 DAH. Trypsin activity increased significantly at 21 DAH. The highest pepsin activity was 1.44±0.26 mU/mg protein, recorded at 25 DAH, and the highest trypsin and chymotrypsin activities were 333±19.9 mU/mg protein and 1,773±62.3 mU/mg protein respectively, at 35 DAH. Pepsin and trypsin activities of larvae feeding with live feed were significantly higher than those fed formulated diet. However, the higher α-amylase activity was found in larvae fed formulated diet treatment.

Digestive enzyme activities of snakehead (<i>Channa striata</i>) larvae from early hatching to 35 days with different diets
Journal Article
2017
Frimpong, E. A., and G. Anane-Taabeah. 2017. Social and economic performance of tilapia farming in Ghana. Pp. 49 - 90 in Social and economic performance of tilapia farming in Africa, Social and economic performance of tilapia farming in Africa, edited by J. Cai, Quagrainie, K.K., and Hishamunda, N. Rome, Italy: FAO Fisheries and Aquaculture. Retrieved (http://www.fao.org/documents/card/en/c/14262acc-fc20-4fa6-b03c-5bb03e0568d5/).
NOP 17-373 (English)

NOP 17-373 (English)

This report presents an overview of the social and economic performance of tilapia farming in Ghana from a value-chain perspective. The content is based primarily on the synthesis of the relevant literature on fisheries and aquaculture in Ghana, and the information gathered by the authors from interviews and interactions with key leaders of the sector in Ghana from 2009 to 2015. In addition, information is also included from postings on Ghana to the Sustainable Aquaculture Research Networks in sub-Saharan Africa (SARNISSA) listserv, unpublished material from the authors’ recently completed and ongoing research involving more than 500 fish farmers, processors and traders, government administrators and field officers, and researchers in Ghana, and the reanalysis of information from a combination of all these sources. The social and economic analysis uses the framework of Trienekens (2011), and draws heavily on almost a dozen recently completed value chain and related studies and reviews of the aquaculture and fisheries sectors of Ghana (Asmah, 2008; Abban et al., 2009; Cobbina, 2010; Ofori et al., 2010; Antwi-Asare and Abbey, 2011; Hamenoo, 2011; Nunoo et al., 2012; Simpson, 2012; Anane-Taabeah, Quagrainie and Amisah, 2015). [Note that this is the first paragraph of the introduction].

Social and economic performance of tilapia farming in Ghana
Book Chapter
2017

NOP 17-387 (English)

Mud crab (Scylla serrata (Forsskål 1775)) fattening and culture is an emerging industry in Bangladesh that directly benefits households in the coastal region of Bangladesh. Currently, 37.8 % of crab fattening and culturing facilities are owned and operated by women whose households are generally poor. The study was conducted to promote the integration of tilapia (Oreochromis niloticus (Linnaeus 1758)) into mud crab culture, thus diversifying the crops and potentially improving household income and nutrition. First, a baseline survey of 150 mud crab farmers in the Satkhira, Khulna, and Bagerhat regions was conducted, focusing on household food consumption, dietary nutrition and earned incomes, plus household demographic and socio-economic information. The survey revealed that the majority of mud crab farmers are poorly educated (5 years average schooling) and consumed low dietary nutrients, particularly from animal protein sources. Second, tilapias were integrated into mud crab culture by 45 farmers, 15 from each surveyed region. 5 farmers from each region continued with the traditional mud crab fattening procedures and 10 were instructed in methods of mud crab and tilapia stocking and culture, using mixed sex tilapia for continuous breeding. 5 of the 10 farmers sold their tilapia to market while the other 5 kept the tilapia for direct household consumption. In both groups small tilapia were fed to mud crabs to reduce reliance on wild-caught trash fish as feed. Including tilapia in mud crab fattening and culture increased growth and production of mud crabs, albeit not to a level that differed significantly from the group where mud crab alone were produced. Adding tilapia into mud crab culture increased the nutrient-rich foods available for the farmer's households. A follow up survey found that the women and their household members improved their incomes and consumption of high quality protein. Overall, the integration of tilapia provides a more sustainable method for growing mud crab while also enhancing the livelihoods of farmers.

Improving the Livelihood for Marginalized Women's Households in Southwest Bangladesh through Aquaculture
Journal Article
2017

NOP17-A02 (English)

Cypermethrin, the synthetic pyrethroid commonly used as a pesticide, contaminates the aquatic ecosystem as a toxic pollutant from agricultural and domestic washouts. An experiment was conducted to carry out an empirical study to investigate the sub-lethal effects of LC50 value of a pyrethroid pesticide, cypermethrin 10EC on histological changes of kidney in Tengra, Mystus tengara at wet laboratory of the Faculty of Fisheries, Bangladesh Agricultural University (BAU), Mymensingh. The LC50 value of cypermethrin 10EC was calculated by probit analysis and LC50 value for 96 hours was found 0.133 ppm. The experiment was conducted with four treatments, each with three replications. Treatment one (T1) was used as control (0 ppm) and three concentrations, such as 0.026 ppm (20% of 96 h LC50), 0.052 ppm (40% of 96 h LC50) and 0.104 ppm (80% of 96 h LC50) were used as Treatment two (T2), Treatment three (T3) and Treatment four (T4), respectively. For histological study kidney of studied fish were collected from control and experimental group at 7, 14 and 28 days interval up to the end of experiment of 28 days. The physical reactions observed in the treated fish were erratic swimming, discolorations of the skin, loss of reflex, hyperactivities, motionless state and these effects increased with increasing concentration of the toxicants and duration of exposure. The changes observed in the kidney tissues were vacuolation, necrosis, ruptured kidney tubules, Cellular degeneration and karyolysis were recorded. Cypermethrin 10 EC has adverse effects on the organs of fish, so it should not be used indiscriminately in agriculture and aquaculture.

Toxic effects of agro-pesticide cypermethrin on histological changes of kidney in Tengra, Mystus tengara
Journal Article
2017

NOP 16-360 (English)

Soya bean meal-based formulated feeds have recently become available for snakehead culture in Vietnam. This study was conducted to determine the appropriate replacement of fish meal (FM) protein by another soya product, soya protein concentrate (SPC), in snakehead (Channa striata) diets. Five iso-nitrogenous (45% crude protein) and iso-caloric (19 KJ g−1) practical diets were formulated to replace 0% (control), 40%, 60%, 80% and 100% of protein FM by protein SPC (100% FM, 40% SPC, 60% SPC, 80% SPC and 100% SPC respectively). A digestibility experiment was also conducted with the same formulated diets with addition of 1% chromic oxide. Fish fed 100% FM and 40% SPC diets had significantly better growth and survival compared with other treatments. Feed intake, feed conversion ratio, protein efficiency ratio and net protein utilization, trypsin and chymotrypsin activities of experimental fish fed 100% FM and 40% SPC diets were significantly higher than those fed other diets. The apparent digestibility coefficient (ADC) of the diet and diet components, ADCdiet, ADCprotein and ADClipid, of fish fed diet 40% SPC and 100% FM treatment were significantly higher than those of other treatments. The cost/kg fish produced in diets 100% FM and 40% SPC was much lower compared with other treatments. Dietary inclusion levels of SPC in diet above 40% significantly affected fish survival, growth, digestibility and trypsin and chymotrypsin activities, although fish chemical composition was not greatly affected.

Effects of replacing fish meal with soya protein concentrate on growth, feed efficiency and digestibility in diets for snakehead, <i>Channa striata</i>
Journal Article
2017

NOP 17-377 (English)

The culture of snakehead fish (Channa striata and Channa micropeltes) in Vietnam is limited, and snakehead culture has been banned in Cambodia, because traditional practices include capture of fingerlings from the wild as seed, as well as capture of small-size (also known as trash fish or low-value) fish. As hatchery breeding technology has improved, we investigated the optimal weaning practices for these two species. Both laboratory experiments and farm trials were conducted. For C. striata, the optimal weaning procedure is to begin at 17 days after hatch (dah) and wean the fish at 10% replacement of live feed with formulated feed per day. However, for C. micropeltes, the optimal procedure is to wait until 40 dah to begin weaning and then to wean the fish with a 10% replacement of live feed with formulated feed every 3 days. These results should enable farmers to domesticate snakehead culture in Vietnam and Cambodia and eliminate reliance on fish captured from the wild as both seed and feed.

Weaning methods using formulated feeds for snakehead (<i>Channa striata</i> and <i>Channa micropeltes</i>) larvae
Journal Article
2017
Hyuha, T. S., W. Ekere, H. S. Egna, and J. J. Molnar. 2017. Social and economic performance of tilapia farming in Uganda. Pp. 127 - 144 in Social and economic performance of tilapia farming in Africa, Social and economic performance of tilapia farming in Africa, edited by J. Cai, Quagrainie, K.K., and Hishamunda, N. Rome, Italy: FAO Fisheries and Aquaculture. Retrieved (http://www.fao.org/documents/card/en/c/14262acc-fc20-4fa6-b03c-5bb03e0568d5/).
NOP 17-375 (English)

NOP 17-375 (English)

Uganda is a landlocked country in Eastern Africa bordering Kenya to the east, the United Republic of Tanzania to the south, Rwanda to the southwest, the Democratic Republic of the Congo to the west and South Sudan to the north. It has a surface area of 241,038 km2 with about 18 percent covered by open waters and 3 percent by swamps. This offers enormous potential for aquaculture and fisheries development, as the sector contributed about 12 percent of agricultural GDP and 2.5 percent of GDP and provided a livelihood to 3.5 million people, who make up 4 percent of the population (Mulonde, 2013; MAAIF, 2012). Uganda has five major inland lakes out of about 165 lakes, which, together with the Nile River, are responsible for most of the capture fisheries production. The lakes, namely Lake Victoria, Lake Albert, Lake Kyoga, Lake Edward and Lake George, contribute 80 percent to Uganda’s capture fisheries production. Lake Victoria accounts for about 58 percent of the total catch for the important export species, Nile perch and Nile tilapia. Main rivers in Uganda include the Victoria Nile, Albert Nile, Achwa River (called Aswa in South Sudan) and Kazinga Channel (Keizire, 2006).

Social and economic performance of tilapia farming in Uganda
Book Chapter
2017

NOP 17-379 (English)

Sahar (Tor putitora), also known as mahseer, is an important fish species of the torrential waters of the Himalayas. It is a popular, economically important, and high-value indigenous species. Sahar is a game and food fish that is widely distributed in rivers, streams, and lakes (Rai et al. 1997). The price of sahar in the Nepalese market is almost double that of commonly cultivated carps and tilapia. Sahar is captured from lakes and rivers but commercial cultivation has yet to begin in Nepal. This species is declining in its natural habitat mainly because of urbanization, poaching, overfishing, and ecological alterations of physical, chemical, and biological conditions in the natural environment (Bista et al. 2007). Hence, there is a need for conservation of this species. In recent years, successful artificial breeding at some research stations has led to additional enthusiasm towards developing sahar for commercial cultivation, as well as rehabilitation in natural waters (Rai et al. 2006). Attempts to culture and conserve sahar were initiated in Nepal, with major efforts to develop culture technology and propagate the species (Gurung et al. 2002, Joshi et al. 2002). This has led to better knowledge of spawning biology, ecology, behavior, and preliminary growth performance in captive conditions. Enhanced growth in tropical and subtropical ponds and recent breeding success in hatcheries has raised new hope for the prospects of sahar aquaculture in Nepal (Shrestha et al. 2005, Bista et al. 2001, 2007, Rai 2008). In addition to the culture of fish to adult size for consumption, these new developments can contribute to rearing individuals that can be stocked into natural waters to replenish populations there. Its omnivorous and predatory feeding habits make sahar a good candidate to co-culture with mixed-sex tilapia to control tilapia recruits and provide better size at harvest and yield of tilapia (Shrestha et al. 2011). Inclusion of sahar in polyculture of mixed-sex tilapia with carps has enhanced overall fish production in these ponds. Sahar is an intermittent spawner. It can spawn year-round in Nepal, except during January, under culture conditions. In natural waters, sahar typically migrate a long distance from large rivers to streams for spawning during the monsoon season when rivers and streams are at peak flows. The Fisheries Research Center (FRC) in Pokhara is the key center that produces sahar fry in limited quantity. Demand for sahar fry has increased for restocking rivers and lakes and for aquaculture production. Lack of fry availability is a major bottleneck for commercial production and conservation. The objectives of the study described in this article were to test sahar breeding in the warmer climate of Chitwan, develop protocols for sahar reproduction and mass-scale seed production there, establish nursing and rearing management practices for sahar fry, and make sahar fry available for culture and restocking.

Successful Breeding of Sahar <i>Tor putitora</i> in Sub-tropical Nepal
Magazine Article
2017

NOP 16-365 (English)

Water analysis kits are useful for practical aquaculture only if they provide equivalent decision making as compared to standard water analysis methods. This study used weighted Cohen's kappa statistics to compare management decisions made by farmers who used water analysis kits (e.g., Seneye slide kit, Tetra EasyStrips, API test strips, Seachem Ammonia Alert, Salifert Profi test kit, and Hach dissolved oxygen (DO) and alkalinity kit) and decisions made by those who used standard methods. The decisions made by farmers were similar for water analysis kits and standard methods, except for Tetra and API test strips, when measuring nitrate concentrations. The highest conformity between the two methods (kappa ‹value = 1.0, P < 0.0001) was obtained with the Hach and Salifert Profi test kits (for measuring DO) and the API test strip (for measuring total hardness). The rapid, simple measurements by the kits appear suitable for use by farmers if they are properly maintained and manufacturer's instructions are followed.

Assessing the Reliability of Water-Test Kits for Use in Pond Aquaculture
Journal Article
2017

NOP 16-364 (English)

The productive fisheries of the Lower Mekong Basin of Cambodia and Vietnam are essential to the food security and nutrition of 60 million people. Yet these fisheries, both culture and capture, are susceptible to the impacts of climate change. This article reports on a study undertaken to examine the vulnerability, as perceived by snakehead (Channa striata) fish farmers in Vietnam and fishers in Cambodia, to the impacts from climate change. Perceived impacts on various actors in the value chain are identified, as well as adaptation strategies currently being utilized and planned for the future. Recommendations are suggested to contribute to assisting snakehead farmers and fishers in adapting and preparing for the impacts of climate change.

Impacts of climate change on snakehead fish value chains in the Lower Mekong Basin of Cambodia and Vietnam
Journal Article
2017

NOP 17-370 (English)

A number of leafy vegetables, their protein concentrates and hydrolasates are under evaluation as alternative protein ingredients to fish meal (FM) in aquafeeds. This study evaluated the nutritional characteristics and suitability of replacing FM with the amaranth (Amaranthus hybridus) leaf protein concentrates (ALPC) as a protein ingredient in the diet of Nile tilapia (Oreochromis niloticus). Experimental diets were formulated, where 100%, 75%, 50%, 40%, 20% and 0% FM protein was substituted by protein from ALPC. The six dietary treatments were tested in triplicate in static flow-through tanks. The substitution effects were compared in terms of fish growth performance, nutrient utilization, whole body composition and apparent nutrient digestibility. After 160 days of feeding, the growth, nutrient utilization and Feed Conversion Ratio (FCR) in fish fed diets containing 100%, 75%, 50%, 40% and 20% FM were better (P < 0.05) than those fed diet with 0% FM. The Apparent nutrient digestibility was high for protein, lipid and energy and differed significantly among the dietary treatments (P < 0.05). Protein digestibility in fish was highest in feed formulated with 100%, 75%, 50% and 40% FM, which were significantly (P < 0.05) higher than at 25% and 0% FM. Lipid digestibility was comparable for all the diets except fish fed 0% FM. Digestible carbohydrates and dry matter were similar for all dietary treatments (P < 0.05). We demonstrate that it is possible to replace up to 80% of fish meal with ALPC without compromising the performance O. niloticus. These results demonstrate that although it is possible to replace large part of fish meal with ALPC, it is not possible to eliminate it in Nile tilapia diet as alternative protein ingredient.

Characterization of the nutritional quality of amaranth leaf protein concentrates and suitability of fish meal replacement in Nile tilapia feeds
Journal Article
2017
Ngugi, C. C., B. Nyandat, J. O. Manyala, and B. Wagude. 2017. Social and economic performance of tilapia farming in Kenya. Pp. 91 - 111 in Social and economic performance of tilapia farming in Africa, Social and economic performance of tilapia farming in Africa, edited by J. Cai, Quagrainie, K.K., and Hishamunda, N. Rome, Italy: FAO Fisheries and Aquaculture. Retrieved (http://www.fao.org/documents/card/en/c/14262acc-fc20-4fa6-b03c-5bb03e0568d5/).
NOP 17-374 (English)

NOP 17-374 (English)

Aquaculture makes an important contribution to livelihoods, economic development and food security in Africa (Quagrainie, Amisah and Ngugi, 2009). The effective start of aquaculture in most of sub- Saharan Africa was, in the 1950s, under the impetus of the various colonial administrations. The Abuja Declaration on sustainable fisheries and aquaculture called for increased fish production, focusing more on aquaculture promotion and development (Kaliba et al., 2007). It is increasingly recognized that promoting aquaculture as a business could yield adequate and solid benefits from the sector, and thereby leading to its sustainable development. Similar to many countries in Africa, aquaculture production in Kenya has been low and stagnated over the past decade (Hetch, 2006). The slow progress of aquaculture growth in sub-Saharan Africa has been attributed to institutional, biotechnical and economic factors (Hecht, 2006). Rural fish farming in Kenya dates back to the 1940s and was popularized in the 1960s by the Kenya Government through the “Eat More Fish Campaign”. The number of small-scale farmers increased and peaked at about 20,000 in 1985, with annual production of slightly over 1,000 tonnes (Aloo and Ngugi, 2005). [Note that this is the first three paragraphs of the introduction.]

Social and economic performance of tilapia farming in Kenya
Book Chapter
2017

NOP 16-356 (English)

Essential oils (EOs) are used in the food industry because of their biological activity. We evaluated the effects of administration of essential oil (EO) extracted from bitter lemon (Citrus limon) fruit peels on the growth performance, biochemical, haemato-immunological parameters and possible disease resistance in fingerlings (4 weeks old) Labeo victorianus challenged with Aeromonas hydrophila. Fish were divided into five groups and fed diets supplemented with C. limon fruit peels EO extract at 1%, 2%, 5% and 8% [as fed basis] and treatment compared with control group fed diet without C. limon fruit peels EO extract. The experiment was executed in triplicate. Concentration of plasma cortisol, glucose, triglyceride and cholesterol decreased while that of total protein and albumin increased as dietary inclusion of the EO extract of C. limon fruit peels was increased from 2% to 5%. Meanwhile haemato-immunological parameters including red blood cell (RBC), white blood cell (WBC) counts, haematocrit (Htc), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC) and neutrophiles increased with increasing dietary inclusion from 1% to 5% inclusion of C. limon fruit peels EO extract. Serum immunoglobulins, lysozyme activity and respiratory burst increased with increasing dietary levels up to 5% inclusion of EO extract of C. limon fruit peels. We demonstrate that formulation of feeds by incorporating upto 5% the EO extract from C. limon fruit peels significantly improved biochemical, haematological and immunological response in juvenile fish resulting to lower mortality than the untreated groups and appear to be effective antibacterial against A. hydrophila.

Effects of dietary levels of essential oil (EO) extract from bitter lemon fruit peels on growth, biochemical, haemato-immunological parameters and disease resistance in Juvenile <i>Labeo victorianus</i> fingerlings challenged with <i>Aeromonas hydrop</i>
Journal Article
2017

NOP 17-381 (English)

Jar incubation system is a well established artificial incubation system for intensive fry production of Nile tilapia. However, this system needs special hatchery structure and huge amount of water for circulation of eggs. The present study aimed to explore a simple, economic and water efficient alternative incubation system appropriate for small-scale hatchery operators. Two incubation systems, i.e. atkin incubation system and aquarium incubation system were compared with jar incubation systems in terms of water use, hatching rate and subsequent survival of larvae. Results showed that the amount of water used was significantly higher in atkin (127.0 ± 3.1 m3) and jar (36.8 ± 4.9 m3) incubation systems compared to aquarium (0.05 ± 0.0 m3) incubation system. The hatching percentage was significantly higher in jar incubation system (95.5 ± 0.6%) compared to aquarium (65.2 ± 7.7%) and atkin (57.8 ± 2.2%) incubation systems. Hatching tended to occur slightly earlier in the jar incubator than other systems. After 7 days of rearing, the mean larval survival rate was highest in jar incubation (96.9 ± 0.5%), intermediate in aquarium incubation (90.9 ± 3.4%) and lowest in atkin incubation (81.0 ± 3.1) system (P < 0.05). The dissolved oxygen was significantly higher in aquarium (6.1 ± 0.0 mg/L) than jar (3.0 ± 0.0 mg/L) and atkin (3.0 ± 0.1 mg/L) incubation systems. Further experiments indicated that about 5,000 eggs can be successfully hatched with a hatching rate of 95% and reared to swim-up fry in in 50 L size glass aquarium with water exchange twice daily. This system is best suited for incubation of late stage eggs and rearing of newly hatched larvae up to free swimming stage. The results indicate that aquarium incubation can be used as an alternative of jar incubation system for Nile tilapia eggs, especially in water scarce areas.

Alternative artificial incubation system for intensive fry production of Nile tilapia (<i>Oreochromis niloticus</i>)
Journal Article
2017

NOP 17-376 (English)

The small-scale aquaculture (SSA) sector is recognized as making an important contribution to food security, poverty alleviation, and socioeconomic development. A value chain analysis can uncover insights into the linkages and trust within a value chain and constraints and challenges that face the sector. This paper examines the linkages and trust between SSA producers and traders in Asia in order to better understand the constraints and opportunities faced by small-scale producers. The perspective revealed by the value chain analysis provides response strategies that can enhance the sustainability and competitiveness of the entire value chain and the actors that comprise it.

Linkages and Trust in the Value Chain for Small-scale Aquaculture in Asia
Journal Article
2017

NOP 17-382 (English)

Coastal Bangladesh has the most commercially important species of mud crabs Scylla spp., from the family Portunidae (Macintosh et al. 2002). They dig and inhabit burrows in mangrove swamps and shallow, soft-bottom intertidal water bodies (Quinitio et al. 2008). Mud crabs spend most of their life in estuaries and coastal environments that have mud or detritus, debris of leaves, branches, roots and enough shelter materials or places to hide to avoid cannibalism or to molt. Mud crabs are also known commonly as green crabs or mangrove crabs (Sha and Quddus 1982). Mud crabs are omnivorous or scavengers, feeding on dead animal and plant matter. The 734-km long coastline of Bangladesh, with the world’s largest mangrove forest, is a hotspot for diverse aquatic organisms, including mud crabs, providing suitable breeding, feeding and nursery grounds.

Mud Crab Aquaculture and Fisheries in Coastal Bangladesh
Magazine Article
2017

NOP 17-385 (English)

An on-farm trial of carp polyculture was carried out with participation of women farmers from Sundardeep Women Fish Farmer's Cooperative (15 women farmers) in Chitwan District and Mishrit Fish Farmer's Cooperative (22 women farmers) in Nawalparasi District to field-test the enhancing effect of periphyton on use of feed and fish production. The trial was conducted for 8 months from April to December 2015. Women farmers stocked six carp species and two small indigenous species (SIS) to ponds. Women farmers were divided into two groups. One group fed their fish with dough of rice bran and mustard oil cake, while the other group installed bamboo substrates in their ponds and fed their fish with half the amount of the feed used by the first group. Women farmers netted and weighed fish monthly to check fish growth and calculate ration. Women farmers were provided with a book to record fish harvested for consumption or sale and fish mortality. Final harvest was done after 8 months of culture. The netted fish were counted, weighed, and returned to the pond as the farmers wanted to keep fish for their biggest festival "Maghi" in mid-January. In aggregate, 84 % of farmers consumed fish at home, and 41 % of farmers sold carps. The trial showed that culturing carps with SIS with 50 % feeding amount and with bamboo substrates in ponds resulted in a 22 % higher fish production as compared to the culture of carps with normal feeding. More interestingly, the gross margin of the half-fed periphyton enhanced carp polyculture was almost two times as much as that of the normal fed polyculture system. Women farmers also benefited socially as well as economically from the interactions within the cooperatives, which increased their self-confidence and developed leadership skills in some members.

Involving Women in Field-Testing of Periphyton Enhanced Aquaculture System for Nutrition Security
Journal Article
2017

NOP 17-386 (English)

Small-scale aquaculture is one of the options for improving household family nutrition and also supplements income for rural poor. Family nutrition depends on women as they prepare, cook and provide food for the family in most of the Nepalese communities. This short communication deals about the use of foot hill riverbed for aquaculture involving women in order to improve family nutrition and supplement income of an ethnic community. 90 household ponds were constructed on both sides of river flood plain in foothills of Nepal. Womens' groups participated in monthly technical training sessions along with fish farming activities. Ponds were stocked with grass carp (Ctenopharyngodon idella (Valenciennes 1844)), common carp (Cyprinus carpio (Linnaeus 1758)) and Nile tilapia (Oreochromis niloticus (Linnaeus 1758)). Local river species were allowed to enter and grow in ponds. Pond dikes were used for vegetable farming, grass cultivation, and pig farming. Though pond fish farming added extra work, ethnic women were able to produce significant amounts of fish, fruits and vegetables that supported family nutrition and was also a source of income.

Women in Riverbed Aquaculture for Livelihoods in Foothills of Nepal
Journal Article
2017

NOP 17-378 (English)

Aquaculture development commentary supports the formation of fish farmer associations or producer organizations as avenues for cultivating small- and medium-scale commercial farmers. However, little is known about the types of associations that facilitate commercialization. This research presents four qualitative case studies, based on semi-structured interviews, profiling existing associations of commercial fish farmers in Uganda. We conclude that the umbrella organizations under which local fish farmer associations vertically align themselves have important implications for fish farmer production. Aquaculture-specific umbrella organizations contribute to the success of local member association’s more than general umbrella organizations do. Successful fish farmer associations accept government assistance only when it directly improves their fish farm operations. Other farmer groups seemed to wait for direct subsidization. Training fish farmers, providing quality information, cost sharing, and advocating for the aquaculture sector, not donor seeking, are the top priorities in productive fish farmer associations.

Understanding the Role of Fish Farmer Associations as Intermediaries for the Commercialization of Aquaculture in Uganda
Journal Article
2017

2016

NOP 15-352 (English)

Freshwater aquaculture plays an important role in the economy of Bangladesh, providing food, income, livelihoods and export earnings. However, freshwater aquaculture in the Mymensingh area of north-central Bangladesh has been accompanied by recent concerns over climate change. Field survey revealed that different climatic variables including flood, drought, rainfall variation and temperature fluctuation have had adverse effects on pond-fish culture. These climatic variables have detrimental effects on the ecosystem of ponds and thus affect survival, growth and production of fish. Changes in climatic variables have adverse effects on fish reproduction, grow-out operation, parasite infestation and disease occurrence. Considering vulnerability to the effects of climate change on pond-fish culture, we propose adaptation strategies that need to be introduced to cope with the challenges.

Does climate change matter for freshwater aquaculture in Bangladesh?
Journal Article
2016

NOP 16-362 (English)

Fish farming households' demand for improved fish feed from the private market in Kenya is potentially influenced by the government's feed subsidy program. This article applies the double-hurdle model to a cross-section of fish farms to analyze demand for improved fish feed from private markets, and whether the government feed subsidy program has an effect on private demand for improved feed. The results indicate that households' decisions to participate in the improved feed market are affected by the quantity of improved feed received from the government. Once the participation decision has been made, we find evidence of crowding-in of the private improved feed sector; that is, the government's allocations of subsidized feed appear to increase private sector demand. In addition, the price of improved feed negatively affects the quantity purchased as expected. Education, extension contacts, and ease of marketing matured fish increase household propensity to purchase improved feed commercially. Policies that help reduce the price of improved feed such as reduction in tariffs on imported feeds and feed ingredients will foster demand for the feed, as will policies that facilitate marketing of fish at reasonable prices by households.

Demand for improved fish feed in the presence of a subsidy: a double hurdle application in Kenya
Journal Article
2016

NOP 15-351 (English)

The study assessed the value chain of farmed tilapia in Ghana. A survey conducted in 2012 provided data on key actors, flow of products and information, costs and margins, and relationship among actors. The study showed that all key actors in the value chain: input suppliers; fish farmers; traders; and food services had positive margins except fish farmers. Input suppliers accrued most of the margins generated along the chain. The performance of chain actors was assessed using a factor evaluation matrix, which showed that product offering may be the strength at each stage of the value chain. The efficiency and profitability of tilapia value chain in Ghana can be improved by having well-defined payment transaction with customers, persistent relationships with customers, and good information management such as keeping good records on costs and revenues. Fish farming could be more profitable if farmers reduced their variable costs, priced their fish using a cost plus or percentage markup approach, and adopted target marketing.

Assessment of farmed tilapia value chain in Ghana
Journal Article
2016
Chow, M., L. A. Cramer, and H. S. Egna. 2016. Gender Dimensions in Disaster Management: Implications for Coastal Aquaculture and Fishing Communities in the Philippines. Pp. 159 - 172 in Responses to Disasters and Climate Change: Understanding Vulnerability and Fostering Resilience, Responses to Disasters and Climate Change: Understanding Vulnerability and Fostering Resilience, edited by M. Companion and Chaiken, M.S. Boca Raton, FL: Taylor & Francis. Retrieved (https://www.crcpress.com/Responses-to-Disasters-and-Climate-Change-Understanding-Vulnerability-and/Companion-Chaiken/p/book/9781498760966).
NOP 16-368 (English)

NOP 16-368 (English)

Women are critical to aquaculture and small-scale fisheries sectors, despite the lack of recognition and access to resources. In the Phillipines, the status of women has improved over the last few decades. However, gender issues during disasters still emerge. In 2009, the Asia-Pacific Economic Cooperation (APEC) published a study that indicated a high level of awareness of the importance of gender integration for disaster risk reduction (DRR) in the Philippines, yet gaps remain during disaster plan implementation. This research builds on that study by assessing gender integration in disaster management in fishing and aquaculture communities since recent DRR legislation (2010) and two major typhoons (2013 and 2014). Results reveal that important steps are being taken to integrate gender at the disaster risk reduction and management (DRRM) programmatic level, yet gaps remain at the community level. Addressing these shortcomings and underlying perceptions of gender in disaster management will foster more resilient fishing and aquaculture communities in the Philippines and nations worldwide.

Gender Dimensions in Disaster Management: Implications for Coastal Aquaculture and Fishing Communities in the Philippines
Book Chapter
2016

NOP 16-358 (English)

This study used a choice experiment to analyze the preferences of consumers for the attributes of tilapia (price, mode of production, product form, and size), a major aquaculture product in Tanzania. The results showed that consumers were willing to pay a price 665.020 Tanzanian shillings (TZS) lower for farmed tilapia than for wild tilapia; a price TZS 833.210 and TZS 1799.110 higher for medium-size and large-size tilapia respectively than for small-size tilapia; and a price TZS 1214.090 higher for fresh tilapia than for smoked tilapia. Consumers’ willingness to pay less for farmed tilapia than for wild tilapia is mainly attributed to issues related to taste and availability. It was also found that consumers were heterogeneous in their preferences for all the tilapia attributes (mode of production, size, and form) considered in this study.

Consumer preferences for farmed tilapia in Tanzania: A choice experiment analysis
Journal Article
2016

NOP16-A05 (English)

Aquaculture, the farming of aquatic animals and plants, and other seafood businesses continue to grow rapidly around the world. However, many of these businesses fail due to the lack of sufficient attention to marketing. The Seafood and Aquaculture Marketing Handbook provides the reader with a comprehensive, yet user-friendly presentation of key concepts and tools necessary for aquaculture and seafood businesses to evaluate and adapt to changing market conditions. Markets for aquaculture and seafood products are diverse, dynamic, and complex. The Seafood and Aquaculture Marketing Handbook presents fundamental principles of marketing, specific discussion of aquaculture and seafood market channels and supply chains from around the world, and builds towards a step-by-step approach to strategic market planning for successful aquaculture and seafood businesses. This book is an essential reference for all aquaculture and seafood businesses as well as students of aquaculture. The volume contains a series of synopses of specific markets, an extensive annotated bibliography, and webliography for additional sources of information. Written by authors with vast experience in international marketing of aquaculture and seafood products, this volume is a valuable source of guidance for those seeking to identify profitable markets for their aquaculture and seafood products.

Seafood and Aquaculture Marketing Handbook, 2nd Edition
Book
2016

NOP 16-A06 (English)

When it comes to nutritional value, fish are hard to beat. They are rich in high-quality protein and contain assorted vitamins and minerals, such as iodine and selenium, which are important to human health. Fish also happen to be the best source of omega-3 fatty acids, making it a popular food choice around the world; billions of people include fish in their diets. According to the Food and Agriculture Organization, about half of the fish that’s consumed in the world is produced by aquaculture—the farming of aquatic life—making this activity a valuable source of nutrition as well as income. In Nepal, where 41 percent of children under 5 suffer from stunting, families can increase their consumption of nutrient-rich fish by raising them at home. It can also provide a source of income to women, who often manage their households but lack opportunities to improve their livelihoods. [Note: This is the first three paragraphs from the publication]

Fish Fill Ponds, Plates, and Pocketbooks in Nepal
Magazine Article
2016

NOP 16-363 (English)

Several regional fisheries and marine conservation organizations in the Coral Triangle (CT) and Southeast Asia have indicated their support for an ecosystem approach to fisheries management (EAFM). It is also likely that science and technology (S&T) innovations will play a role in the region for the purposes of filling gaps in fisheries data, enhancing the coordination of fisheries management efforts, and implementing and operationalizing an EAFM. Here, we outline the methodology and results of an expert-opinion survey designed to elucidate and prioritize the implementation of these S&T innovations. As a first step and case study, the survey presented here was conducted on U.S. government experts. The U.S. market is one of the world's largest importers of seafood, and therefore, in the framework of this study, is considered to be a stakeholder in the seafood supply chain that originates in the CT and Southeast Asia region. Results are discussed in terms of the data needs and principles of an EAFM, as well as current trends and contexts of the CT and Southeast Asia region. Next steps and recommendations are also provided on how S&T innovations can be implemented to enhance the cooperation and coordination of regional marine resource management efforts.

The mobilization of science and technology fisheries innovations towards an ecosystem approach to fisheries management in the Coral Triangle and Southeast Asia
Journal Article
2016

NOP 16-357 (English)

Growth Performance and Immune Response of Snakehead, <i>Channa striata</i> (Bloch 1793) Fed Soy Diets with Supplementation of Mannan Oligosaccharides
Journal Article
2016

NOP 16-359 (English)

Traditional snakehead culture in Southeast Asia relies on use of small-size (trash) fish as food, an unsustainable practice. Following development of weaning methods and testing of formulated feed (FF) in laboratory experiments, we conducted feeding trials of FF vs. trash fish (TF) in experimental ponds at Can Tho University (CTU), followed by similar trials on commercial farms in two provinces in Vietnam. CTU pond trials consisted of five treatments (in triplicate), in which TF was replaced by FF in increasing percentages: 0 (control), 25, 50, 75, and 100% replacement of TF by FF (i.e., three treatments had mixed TF/FF diets). Although survival was significantly reduced in the 100% replacement treatment, and growth was significantly reduced in the 75% and 100% replacement treatments, the cost per kg of fish produced was 28-35% less in those high-replacement treatments compared to the 0% replacement treatment. On-farm trials were then conducted at two farms in An Giang and Dong Thap provinces for 6 months with snakehead fed TF only or FF only. At both farms, survival (73-80%) was not significantly different, but growth was significantly better on FF diet at both; however, FF-fed fish at the An Giang farm showed significantly higher levels of abnormal development. Overall production was about twice as high at the An Giang farm as at Dong Thap, but significantly greater production by FF-fed fish vs. TF-fed fish was only seen at Dong Thap. Sensory evaluation by a tasting panel found no difference in product quality between FF-fed fish, TF-fed fish, and a commercial sample bought in the market. Economic analysis indicated that profits were higher for FF-fed fish from both farms, although production costs and sales varied greatly, reflecting market differences in the two provinces.

Replacement of freshwater small-size fish by formulated feed in snakehead (<i>Channa striata</i>) aquaculture: Experimental and commercial-scale pond trials, with economic analysis
Journal Article
2016

NOP 16-369 (English)

Present study determines the causes and seasonal variation of red bloom in fishponds of Eastern, Western and Central regions of Nepal. Monthly monitoring of water quality and phytoplankton was carried out for one year. Water parameters such as NH3-N, total phosphorus, total Kjeldahl nitrogen (TKN), total dissolved solids (TDS) and conductivity were significantly higher (p<0.05) in red bloom fishponds than non-red bloom fishponds. The total density of euglenophytes in red-bloom fishponds was significantly higher (P<0.05) (1970±260 cells L-1) than non-red bloom fishponds (410±30 cells L-1). Euglenophyte density varied seasonally and significantly lower in spring season (1250±220 cells L-1) than autumn (1950±390 cells L-1), winter (2180±370 cells L-1), and summer (2490±480 cells L-1) in red bloom fishponds. High nutrients might favor the growth of euglenophytes (Euglena sanguinea) causing red bloom fish ponds of Nepal.

Water quality and red bloom algae of fish ponds in three different regions of Nepal
Journal Article
2016

NOP 16-A03 (English)

Aquaculture productivity in Uganda is less limited by technical or genetic barriers, compared to a lack of implementation of best practices for producing fish in earthen ponds and cages. Most small-scale fish farmers in Africa have limited access to reliable information about improved farming methods. Access to appropriate information, inputs, and technical support are significant determinants of agricultural productivity and business success. With corresponding innovation in existing social and institutional arrangements, mobile phones have potential to increase the income of small-scale fish farmers (Verheye 2000). As mobile phones converge with notebook and tablet devices, opportunities will proliferate. Affordability will remain an issue, but cell phone capability and market penetration will grow. Little is known about the use of mobile phones and the needs and interests of fish farmers in Uganda. The emergence of Information and Communication Technologies (ICT) has implications for social and economic development throughout the world (Ogunsola 2005). As with other economic sectors, effective agricultural development requires access to information. Information and Communication Technologies aid in transmission of knowledge that can be used by producers to improve their enterprise. ICT-based services such as information, advice, inputs, finance, and other resources can enhance a farmer's participation in commercial value chains. Despite growth of ICT, many Africans still lack the basic communication infrastructure necessary to access information and make timely decisions. Much of the information provided by extension workers is sometimes out of date, irrelevant and not applicable to small farmers' needs, leaving farmers with very little information to improve productivity. Information and Communication Technologies enables extension workers to gather, store, retrieve and disseminate a broad range of information needed by farmers; ICT can help bridge the gap between extension workers and

The Role of Mobile Phones in Facilitating Aquaculture Development in Uganda
Magazine Article
2016

NOP 16-366 (English)

Intensification of aquaculture may result in more fish culture waste being discharged into adjacent rivers and streams. Due to composition of such wastes, ecological conditions in water bodies may be adversely affected. We determined the ecological consequences of freshwater land-based Tilapia farms on headwater streams using macroinvertebrate community attributes and functional feeding response in an upstream tributaries of a highland stream in Kenya. Nine aquaculture sites adjacent to tributaries of three headwater streams with different fish production volumes were sampled and monitored for macroinvertebrate abundance, richness, composition of Ephemeroptera, Plecoptera and Trichoptera, Oligochaetes and Chironomids (percentage Oligochaetes and Chironomids), species diversity as well as the functional feeding group responses. The total abundance of benthic macroinvertebrate consistently increased near discharge points and immediately downstream of the effluent outlets near the aquaculture farms. We observed positive correlations between macroinvertebrate attributes (except Ephemeroptera, Plecoptera and Trichoptera) with fish production at aquaculture facilities adjacent to the tributaries of the headwater streams. The proportion of Oligochaetes and Chironomids (percentage Oligochaetes and Chironomids) increased while that of Ephemeroptera, Plecoptera and Trichoptera at discharge points and downstream of the farms decreased. Also, relative abundance of scrapers and shredders decreased significantly, while significant increase of abundance was observed for deposit feeders, filter feeders and parasites with low predator population at discharge and downstream points. These consistent patterns indicated changes in ecosystem integrity and functioning, due to aquaculture effluents with particulate organic matter from fish food-derived wastes becoming a central source of energy in river benthic food webs.

Monitoring the Effects of Aquaculture Effluents on Benthic Macroinvertebrate Populations and Functional Feeding Responses in a Tropical Highland Headwater Stream (Kenya)
Journal Article
2016

NOP 16-A04 (English)

The productive Mekong fisheries are essential to the food security and nutrition of the 60 million people of the Lower Mekong Basin (LMB). Fish, from capture and culture, are a significant source of income and food security in Cambodia and Vietnam. Annual freshwater fish consumption in Cambodia and Vietnam ranges up to 40 kg/person, among the top three countries in the world. Fish contributes 81 percent of protein intake in Cambodia and 70 percent in Vietnam. In Cambodia, inland capture fisheries remain of primary importance in the fisheries sector, while aquaculture is more important in Vietnam. Snakehead is a popular and highly valued food fish in both countries, and are consumed in fresh and processed forms in the Lower Mekong Basin (Sinh et al. 2014). There are two species of snakehead murrel Channa striata and the giant snakehead Channa micropeltes. The combination of high fish biodiversity, high productivity, high exploitation rate, long distance migrations, and fish trade make protecting these fisheries and aquaculture of great importance. However, they are highly vulnerable to climate and non-climate (specifically water development such as hydropower dam development) related drivers of change. These include increased temperatures, changes in rainfall patterns; changes in the hydrological regime (water levels, duration of flooding, timing of flooding); changes in runoff or sediment load/movement; and increased instances of extreme weather events (storms, floods and droughts) (Keskinen et al. 2010, Hoanh et al. 2010, Vastila et al. 2010, Lauri et al. 2012). These drivers of change will be felt throughout the fish value chain and will pose significant challenges for fisheries and aquaculture production, food security and the nutrition and health of people, especially poor households, household income, livelihoods, markets and trade, and gender issues in the LMB of Cambodia and Vietnam. However, a complete understanding of the impacts of each individual driver and combination of drivers is only just beginning. Adaptation is needed urgently to address these impacts. It will be important to identify a suite of potential adaptation options for the various biophysical and technical conditions of capture and culture fisheries in the LMB. A study was undertaken in 2014 to examine the vulnerability, impacts and adaptation strategies to climate change as perceived by snakehead murrel value chain actors in the snakehead capture fisheries value chain but not the aquaculture value chain in Cambodia because of a ban on snakehead aquaculture that was only lifted by the government in April 2016. The important actors in the value chain of cultured snakehead in Vietnam were seed producers, farmers, traders and processors (Fig. 1). The important actors in the value chain of captured snakehead in Cambodia were fishers, traders and processors (Fig. 2).

Assessing the impacts of climate change on snakehead fish value chains in the Lower Mekong Basin of Cambodia and Vietnam
Magazine Article
2016

NOP 16-367 (English)

Small-scale aquaculture in Africa is limited by cost of protein ingredient in fish feeds, which requires continuous research in ways of improving protein ingredients. We evaluated the suitability of replacing fishmeal with rice bran alone or rice bran in combination with atyid shrimp (Caridina nilotica) on growth performance and economic benefits of Nile tilapia (Oreochromis niloticus) cultured in cages suspended of statistic ponds. The best growth performance and feed conversion ratio (FCR) occurred in fish fed fishmeal followed by those fed a combination of rice bran and C. nilotica, while rice bran alone resulted in lowest fish growth performance. The best economic benefit was obtained from fish fed a combination of rice bran and C. nilotica. We therefore demonstrate that it is possible to replace expensive fishmeal in the diet of O. niloticus using combination of cheaper rice bran and C. nilotica without compromising economic benefits for the small-scale aquaculturists.

Growth, yields and economic benefit of Nile tilapia (<i>Oreochromis niloticus</i>) fed diets formulated from local ingredients in cages
Journal Article
2016

NOP 16-354 (English)

The quality and safety of dried snakehead fish (Channa striata) on the local markets in Vietnam could not be controlled recently. Therefore improvement of this former processing is necessary concerned and conducted in order to obtain high quality of dried fish products as well as long-term storage to meet the diversified consumer taste. The study aims not only to assess the properties of dried snakehead fish (with sucrose addition) based on supplementing wine (30%) and glycerol into fish muscle but also to enhance the quality of dried fish products. Total plate count, chemical indices, and organoleptic evaluation were recorded to exam the changes of dried snakehead fish corresponding to 1, 2 and 3% (w/w) of wine (30%) addition. Then, the effects of adding glycerol (0, 1, 2, 3%, w/w) on dried snakehead fish with 2% of wine (w/w) were surveyed over a period of four weeks. As compared to the other treatments, addition of 2% (w/w) of glycerol and 2% (w/w) of wine (30%) to dried fish illustrated the highest sensory properties and the lowest parameters of total plate count, moisture content, water activity, peroxide value, total volatile base nitrogen in four weeks. In addition, these analyzed parameters were within acceptable limits. Therefore, the quality and safety of dried snakehead fish were obtained during storage time. The proximate composition of raw snakehead fish and dried products were also studied. The results showed that moisture, protein, lipid, ash and sodium chloride content of raw snakehead fish were 78.1, 18, 2.5, 1.14, 0.73% respectively, whereas those of dried products with wine and glycerol addition were 29.4, 58.9, 5.54, 5.49, 4.56%.

Quality Enhancement of Dried Snakehead Fish (<i>Channa striata</i>) by Supplementing Wine and Glycerol
Journal Article
2016

NOP 16-A02 (English)

This study was carried out from February to December 2014 by interviewing 75 farmers who operate snakehead seed production in An Giang, Dong Thap and Hau Giang provinces, Vietnam. The results showed that the total area for production was 629.01 ± 756.77 m2, whereas the volume for nursing was 582.10 ± 119.81 m3 for pond system and 1,019.56 ± 736.66 m3 for combining pond – hapa system). Each hatchery used 44.26 ± 22.63 pairs of broodstock/breeding cycle and produced whole year. The quantity of seed per cycle of pond system was a half of that figure of other system while seed productivity per m3 was much lower. Snakehead seed was mainly sold to seed traders in the Delta (82.3%). With average production cost of 47.81 ± 16.23 thousand Vietnam dong (VND)/m3, each farm in pond system could reach the total net profit of 49.83 ± 18.74 thousand VND/m3, equivalent to 328 million VND/year. These corresponding numbers of pond – hapa system were 106.98 ± 86.25; 196.12 ± 87.45 thousand VND/m3, equal to 1.75 billion VND/year. Factors of climate change affecting snakehead seed production involved rainfall change, droughts, water and air temperature increase, salinity intrusion which caused diseases easier (36%), affected seed production in general (31%), bad water quality (10%), .... To reduce the impacts of climate change to production, the farmer in snakehead seed production often changed selling market, suspended production of seeds, used better broodstocks by choosing them more carefully and a number of other measures. This study is one of very few studies, which have investigated the impact of climate change on snakehead seed production. The paper's primary contribution is finding that which and how climate phenomenon has effected on seed production as well as suggesting some adaptive methods for them.

Technical-economic efficiencies of snakehead seed production under impacts of climate change in the Mekong Delta, Vietnam
Journal Article
2016

NOP 16-A01 (English)

As demand for fish meal as a primary protein source in aquaculture feeds has continued to increase, aquaculturists have sought a replacement with similar nutritional profile and more consistent economic value. Two feeding trials were designed to evaluate the effect of replacing fish meal with soybean meal and soy protein concentrate in summer flounder (Paralychthis dentatus) diets on fish growth and survival to challenge with the pathogenic bacterium Vibrio harveyi. Fish fed for 12 weeks with a diet in which 60% of the fish meal was replaced with a 1:1 ratio (w/w) of soybean meal and soy protein concentrate (SBM/SPC) increased to a significantly greater mass than fish fed either a fish meal (FM) diet or a 60% replacement diet with soybean meal (SBM; p < 0.05). Survival following bacterial challenge was significantly lower in fish fed the FM diet than fish fed the SBM or SBM/SPC diets (p < 0.05). In the second feeding trial, 60% of the fish meal was replaced in six diets by either soybean meal, soy protein concentrate, or varying ratios of the two. The highest body weights at the end of the trial were observed in the fish fed the FM and 60% SPC replacement diets compared to the other groups (p < 0.05). Fish fed a 12% SBM/48% SPC replacement diet had the highest survival to bacterial challenge, significantly higher (p ≤ 0.001) than fish in other groups except the fish fed the 24% SBM/36% SPC diet. Fish fed 40% SBM/20% SPC and 60% SPC showed the lowest survival to bacterial challenge. These results show that: 1) growth of summer flounder fed a diet in which 60% of the fish meal was replaced with soy protein concentrate was similar to the growth seen in fish fed fish meal diets; 2) addition of increasing amounts of soybean meal in the replacement diet led to a decrease in growth compared to diets with fish meal. However, replacement of 60% of the fish meal with a mix of soybean meal and soy protein concentrate containing 12 or 24% of soybean meal led to increased survival of fish to bacterial challenge. Further identification of the products in soybean meal leading to increased survival of summer flounder could lead to the development of replacement diets for summer flounder that provide increased survival to disease challenge without compromising growth. 

Incorporation of soybean products in summer flounder (<i>Paralichthys dentatus</i>) feeds: Effects on growth and survival to bacterial challenge
Journal Article
2016

NOP 16-355 (English)

Leptin is an anorexigenic peptide hormone that circulates as an indicator of adiposity in mammals, and functions to maintain energy homeostasis by balancing feeding and energy expenditure. In fish, leptin tends to be predominantly expressed in the liver, another important energy storing tissue, rather than in fat depots as it is in mammals. The liver also produces the majority of circulating insulin-like growth factors (IGFs), which comprise the mitogenic component of the growth hormone (GH)-IGF endocrine growth axis. Based on similar regulatory patterns of leptin and IGFs that we have documented in previous studies on hybrid striped bass (HSB: Morone saxatilis × Morone chrysops), and considering the co-localization of these peptides in the liver, we hypothesized that leptin might regulate the endocrine growth axis in a manner that helps coordinate somatic growth with energy availability. Using a HSB hepatocyte culture system to simulate autocrine or paracrine exposure that might occur within the liver, this study examines the potential for leptin to modulate metabolism and growth through regulation of IGF gene expression directly, or indirectly through the regulation of GH receptors (GHR), which mediate GH-induced IGF expression. First, we verified that GH (50 nM) has a classical stimulatory effect on IGF-1 and additionally show it stimulates IGF-2 transcription in hepatocytes. Leptin (5 and/or 50 nM) directly stimulated in vitro GHR2 gene expression within 8 h of exposure, and both GHR1 and GHR2 as well as IGF-1 and IGF-2 gene expression after 24 h. Cells were then co-incubated with submaximal concentrations of leptin and GH (25 nM each) to test if they had a synergistic effect on IGF gene expression, possibly through increased GH sensitivity following GHR upregulation by leptin. In combination, however, the treatments only had an additive effect on stimulating IGF-1 mRNA despite their capacity to increase GHR mRNA abundance. This suggests that leptin's stimulatory effect on GHRs may be limited to enhancing transcription or mRNA stability rather than inducing full translation of functional receptors, at least within a 24-h time frame. Finally, leptin was injected IP (100 ng/g and 1 μg/g BW) to test the in vivo regulation of hepatic IGF-1 and GHR1 gene expression. The 100 ng/g BW leptin dose significantly upregulated in vivo IGF-1 mRNA levels relative to controls after 24 h of fasting, but neither dosage was effective at regulating GHR1 gene expression. These studies suggest that stimulation of growth axis component transcripts by leptin may be an important mechanism for coordinating somatic growth with nutritional state in these and perhaps other fish or vertebrates, and represent the first evidence of leptin regulating GHRs in vertebrates.

Leptin stimulates hepatic growth hormone receptor and insulin-like growth factor gene expression in a teleost fish, the hybrid striped bass
Journal Article
2016

2015

NOP 15-349 (English)

In Bangladesh, tiger shrimp (Penaeus monodon) is commercially known as "white gold", because of its export value. However, the production of "white gold" under shrimp alternate rice and shrimp-only farming systems in coastal Bangladesh has been accompanied by recent concerns over climate change. Field survey reveals that different climatic variables including coastal flooding, cyclone, sea-level rise, salinity, drought, rainfall, and sea surface temperature have had adverse effects on shrimp culture as well as socioeconomic conditions of farming households. There is also overwhelming evidence that changes in climatic variables has detrimental effects on the ecosystem of shrimp farms, and thus, severe effects on survival, growth, and production of shrimp. Considering extreme vulnerability to the effects of climate change on shrimp farming, we propose that community based adaptation strategies and integrated coastal zone management are needed to cope with the challenges.

Threatening "white gold": Impacts of climate change on shrimp farming in coastal Bangladesh
Journal Article
2015

NOP 15-A02 (English)

The practice of prawn (Macrobrachium rosenbergii) farming is widespread in coastal Bangladesh due to favorable biophysical resources. However, export-oriented prawn farming is particularly vulnerable to climate change in coastal Bangladesh. This study identified different climatic variables, including salinity, coastal flooding, cyclone, sea-level rise, water temperature, drought, and rainfall have profound effects on prawn farming in the Bagerhat area of southwest Bangladesh. Considering extreme vulnerability to the effects of climate change on prawn production, one of the adaptation strategies is to translocate prawn culture from coastal to inland (i.e., Bagerhat–Gopalganj) that appear less vulnerable to climate change. Although the prospects for prawn–carp polyculture and integrated prawn–fish–rice farming are positive in Gopalganj, a number of challenges were identified for the expansion of prawn culture. We suggest that institutional support would help to adopt prawn production.

Coastal to inland: Expansion of prawn farming for adaptation to climate change in Bangladesh
Journal Article
2015

NOP 15-342 (English)

Best management practices (BMPs) are the most cost-effective means of mitigating negative impacts of pond aquaculture on the environment. The impacts of BMPs and other innovations on fish farm profits have been studied widely. This study estimates impacts of BMP adoption on social welfare. We employed the economic surplus model to determine net present value (NPV) of adopting the more expensive but less polluting commercial floating fish feed in the pond culture of Nile tilapia (Oreochromis niloticus) in Ghana. We also conducted a sensitivity analysis to determine which variables had the greatest influence on mean NPV. Our results indicate an NPV of US $11 million from the adoption of commercial floating feed in pond farming alone in Ghana. The variables with the biggest impacts on NPV were level of change in tilapia yield, and level of change in production costs, with the adoption of the new feed type. We conclude that adoption of yield-enhancing BMPs and innovations in Ghana will result in significant social welfare benefits. We recommend that credit programs and other financial packages be set up by governments or nongovernmental organizations to help farmers meet the increased cost of fish feed and to accelerate diffusion of commercial fish feed in pond farming.

Impact of the adoption of BMPs on social welfare: A case study of commercial floating feeds for pond culture of tilapia in Ghana
Journal Article
2015

NOP 15-343 (English)

Aquaculture presents a unique challenge to the modeling of fish growth, because the main objective is to accelerate growth for profit. Growth patterns of captive fish in well-fed conditions will diverge from that found in wild fish. For a fish-farming enterprise, overestimating growth will lead to expectations for revenue and profit that will not be realized. Underestimating growth will lead to planning for later harvest than is optimal and the unnecessary additional cost of feeding.We evaluated the performance of four candidate models—Gompertz, logistic, quadratic, and von Bertalanffy—in predicting the growth of Nile Tilapia (Oreochromis niloticus). Each model was fitted to 20 weight-at-age data sets collected from five demonstration farms in Ghana over a 5-month period.We used the Akaike information criterion adjusted for small sample size and model weights to assess model fit. We also assessed predictive performance by comparing predicted to actual growth observed over the last month of the experiment. The logistic growth model performed best for both model fitting and prediction. For a 1-month period approximately between day 121 and day 152 all but the logistic model over predicted growth with corresponding SEs as follows: Gompertz (14.9 ± 3.8 g, mean ± SE), von Bertalanffy (21.0 ± 3.9 g), and quadratic (34.0 ± 3.6 g). The logistic model (–0.5±3.8) did not significantly over- or underpredict growth, and is recommended for predicting future growth of Nile Tilapia under pond culture conditions in applications such as the construction of enterprise budgets to assess profitability of tilapia farms. The default fitting of the von Bertalanffy growth model to farmed tilapia data is not supported by this study.

Using Model-Based Inference to Select a Predictive Growth Curve for Farmed Tilapia
Journal Article
2015

NOP 15-A13 (English)

Cambodia has plans to expand freshwater aquaculture, including in reservoirs (Fisheries Administration, 2011). Lakes and reservoirs represent commonly owned or used water bodies and are therefore subject to the “tragedy of the commons”, in which too many users can destroy the quality of the resource (Hardin, 1968). It is not unusual in Southeast Asia to see reservoirs in which aquaculture has grown beyond reasonable limits, with subsequent declines in water quality (e.g. the Cirata and Jatiluhur reservoirs in Indonesia, with tens of thousands of fish cages). [1st paragraph of introduction]

Aquaculture carrying capacity of Stung Chinit Reservoir: A pilot project
Newspaper Article
2015

NOP 15-A09 (English)

In life cycle analysis of aquaculture, there is a danger of the entire array of embodied resources and impacts being assigned to the production facility. Producers have no control over the inefficiencies or impacts associated with feed production, but can help lessen resource use through good management practices. Improving feed conversion not only reduces resource use and impacts, but also lowers the amounts of nitrogen and phosphorus discharged to the environment. Better feed conversion also lowers production costs.

Embodied Resource Use In Feed-Based Aquaculture
Magazine Article
2015
NOP 15-A10 (English)

NOP 15-A10 (English)

Although relatively expensive, mechanical aeration increases the amount of aquaculture production possible per unit area. Aerators are rated according to standard aeration efficiency (SAE), an expression of how much oxygen is transferred. Since SAE test conditions are seldom met in culture, actual oxygen-transfer rates are 40 to 60% of the SAE values. Asian-style paddlewheel aerators are widely used but reflect design and operational issues that limit efficiency. Testing has led to more efficient designs that are now widely used in U.S. catfish and shrimp ponds.

Efficiency of Mechanical Aeration
Magazine Article
2015

NOP 15-348 (English)

The issue of price linkage in the catfish supply chain in Uganda is important because catfish has become an important traded species with exports to regional markets rising even faster than production, yet limited research has been undertaken to understand the linkages and the non-linearity in the price transmission mechanism. This paper explores the issue using monthly price data from January 2006 to August 2013, and applies threshold auto-regressive approaches to test for the existence of a long-run relationship and price asymmetry. The results show that prices in the catfish value chain are tied together by a long-run relationship. It is also revealed that ex-vessel and wholesale price adjustments to retail price changes are symmetric while ex-vessel price adjustments to wholesale price changes are shown to be asymmetric. The direction of causal relationships was observed from the retail to the wholesale and ex-vessel markets, indicating that retailers are the price leaders in the Uganda catfish supply chain.

Price Transmission and Threshold Behavior in the African Catfish Supply Chain in Uganda
Journal Article
2015

NOP 15-347 (English)(Spanish)

Culture of C. undecimalis shows great potential as this species tolerates handling and adapts easily to captivity. However, the difficulty in achieving spawning in captivity is a major obstacle for the development of commercial scale farming. Spawning of common snook was achieved using GnRH-a implants in single 100 and 200 µg doses per fish; control group specimens received no hormone and did not spawn. Both GnRH-a trial doses resulted in spawning with up to 100% fertilization rates per experimental unit, and a range of 60 – 76% per treatment. A 50 – 100% hatching rate was obtained and larvae were between 1.56 ± 0.08 and 1.98 ± 0.05 mm total length after yolk sac absorption.

Induced spawning of the common snook (<i>Centropomus undecimalis</i>) in captivity using GnRH-a implants
Journal Article
2015

NOP 15-A05 (English)

Background: cichlids are of economical importance either as food (Nile tilapia) or as ornamental fish (Midas) and both exhibit territorialism and aggressive feeding behavior depending on availability of food and space. Objective: to evaluate the growth rates and behavioral changes of Nile tilapia and Midas kept in mono or polyculture. Methods: Midas and tilapia were maintained in a semi-closed rearing system. Initial weight was 0.83 and 0.81 g for Nile tilapia and Midas, respectively. Four treatments with different fish proportions were used. Midas and tilapia were distributed in 12 glass aquaria with three replicates (n = 30 fish per tank). Treatment ratios between Midas and tilapia were 1:0, 1:1, 2:1 and 0:1, respectively. Fish were fed a commercial diet (40% protein, 12% lipids) for six weeks at 5% weight ratio. Feed offer was adjusted weekly. Observations of behavioral traits were recorded throughout the trial to determine social and feeding conduct. Body composition of fish was assessed at the end of the experiment. Results: Midas modified their feeding behavior and their weight gain increased (3.9 ± 0.3 g) in the 2:1 group. The 0:1 group exhibited the lowest growth rate throughout the experiment (2.9 ± 0.3 g). Midas did not affect Tilapia growth (5.8 ± 0.4 g) across treatments. Interspecies aggressiveness was less evident when reared in monoculture (groups 1:0 y 0:1). Intra and interspecies attacks were higher in the 1:1 and 2:1 groups. Proximate body composition indicated higher lipid levels in Midas across treatments in comparison to tilapia. Conclusions: duoculture benefits growth of juvenile Midas when present at 25-30% of total stocking density with Nile tilapia.

Growth and body composition of Midas (<i>Amphilophus citrinellus</i>) and Nile tilapia (<i>Oreochromis niloticus</i>) reared in duoculture
Journal Article
2015

NOP 15-341 (English)

The use of low-value small-sized fish (LVSSF) both as aquaculture feedstuff for snakehead and for human consumption in Vietnam and Cambodia could result in demand outstripping supply as human population and aquaculture production grow. Replacing LVSSF for snakehead aquaculture with pelleted feed would reduce the pressure on stocks of LVSSF. This study addresses the economics of this replacement strategy for snakehead culture in Vietnam. Economic engineering methods were used to assess the effects of pelleted feed for low, medium and high-productivity scenarios. The study compared net present values (NPV), internal rates of return (IRR) and differences in NPV between farms using pelleted feed and those using LVSSF. It also included sensitivity analyses that related NPV and IRR to increased snakehead prices. Results demonstrated strong economic incentives for high-productivity farms to use pelleted feed. However, pelleted feed was too expensive for medium- and low-productivity farms. NPVs were more sensitive to reductions in the cost of pelleted feed than to increases in the cost of LVSSF or the cost of capital.

Economic Analysis of Alternative Snakehead <i>Channa striata</i> Feed
Journal Article
2015

NOP 15-A01 (English)

Traditional culture of snakehead (Channa striata (Bloch 1793) and Channa micropeltes, (Cuvier 1831), Channidae) in Vietnam have been based on capture of snakehead fingerlings from the wild and feeding them with chopped trash-fish also taken from the wild.. From August to October 2008, freshwater trash fish samples (3 kg composite samples) were collected from three fish distribution sites at Chau Doc, Thoai Son and Chau Thanh districts in An Giang province, in the Mekong Delta, Vietnam. The species composition was determined along with the size frequency, sources, and chemical composition of the freshwater trash-fish used for snakehead aquaculture. Thirty-three species of freshwater fish were identified in the freshwater trash-fish samples, 12 of which were juveniles of commercially important species. Marine trash-fish samples were also collected from the same distribution sites for analysis of chemical composition and product freshness. Chemical composition of freshwater trash-fish indicates their protein levels to be nutritionally adequate for snakehead aquaculture. Marine trash-fish showed high total volatile base nitrogen (TVB-N) values, compared to freshwater trash-fish, indicating that they are not fresh. The fish stocks of these freshwater trash-fish species should be assessed and the inland fishery should be managed properly, especially during the flood season.

Assessment of the Trash-fish Diet for Snakehead Aquaculture in Vietnam : Species Composition and Chemical Characterisation
Journal Article
2015

NOP 15-344 (English)

Culture of snakehead species is limited in Vietnam and banned in Cambodia because of the reliance of the industry on feeding them “small-size” fish (sometimes called trash fish or low-value fish), many of which are juveniles of commercially important species. In an effort to find substitutes for small-size fish, we conducted a series of experiments to test formulated diets with several levels of soybean meal (SBM) replacement of fish meal. Feeding trials lasted eight weeks, after which survival, growth, food conversion ratio and protein efficiency ratio were compared. In the first two experiments, with Channa striata, we substituted SBM, either with or without supplementation of phytase (20mg/kg) (Experiment 1) or taurine (1g/kg) (Experiment 2), for 0, 20, 30, 40, or 50% of the fish meal. Experiment 1 demonstrated that SBM can replace 30% of the fish meal without, and 40% of the fish meal with, phytase supplementation. Experiment 2 showed again that SBM can replace 30% of the fish meal without, and 40% of the fish meal with, taurine supplementation. The third experiment, with Channa micropeltes, which was done only with phytase supplementation, showed that 40% of fish meal can be replaced by SBM. In all the SBM diets, the essential amino acids (EAA) lysine, methionine and threonine were also added to make their dietary levels equal to those in the fish meal control diet. Use of the SBM replacement diets, in addition to conserving the small-size fish in the wild, would result in economic savings (cost/kg of fish produced) of about 11% compared to diets based on fish meal alone.

Development of formulated diets for snakehead (<i>Channa striata</i> and <i>Channa micropeltes</i>): Can phytase and taurine supplementation increase use of soybean meal to replace fish meal?
Journal Article
2015

NOP 15-346 (English)

Identifying the dispersal pathways of an invasive species is useful for adopting the appropriate strategies to prevent and control its spread. However, these processes are exceedingly complex. So, it is necessary to apply new technology and collect representative samples for analysis. This study used Approximate Bayesian Computation (ABC) in combination with traditional genetic tools to examine extensive sample data and historical records to infer the invasion history of the red swamp crayfish, Procambarus clarkii, in China. The sequences of the mitochondrial control region and the proPOx intron in the nuclear genome of samples from 37 sites (35 in China and one each in Japan and the USA) were analyzed. The results of combined scenarios testing and historical records revealed a much more complex invasion history in China than previously believed. P. clarkii was most likely originally introduced into China from Japan from an unsampled source, and the species then expanded its range primarily into the middle and lower reaches and, to a lesser extent, into the upper reaches of the Changjiang River in China. No transfer was observed from the upper reaches to the middle and lower reaches of the Changjiang River. Human-mediated jump dispersal was an important dispersal pathway for P. clarkii. The results provide a better understanding of the evolutionary scenarios involved in the rapid invasion of P. clarkii in China.

Inferring invasion history of red swamp crayfish (<i>Procambarus clarkii</i>) in China from mitochondrial control region and nuclear intron sequences
Journal Article
2015

NOP 15-340 (English)

Microcystins accumulate in aquatic organisms and can be transferred to higher trophic levels, eventually affecting vector animals and consumers. We examined three levels of an aquatic food chain (Microcystis aeruginosa, Daphnia magna and Macrobrachium rosenbergii) to identify the transfer efficiency and risk of microcystin on prawns. Samples were analysed using ultra performance liquid chromatography-mass spectrometry (MS)/MS and microcystin-LR (MC-LR) distributions in prawn tissues were studied. The results showed that prawns accumulate MC-LR both directly from M. aeruginosa and indirectly through D. magna which was pre-exposed to M. aeruginosa. MC-LR was detected in the gills, digestive tracts and hepatopancreas of the prawns 2 h after exposure. MC-LR accumulated in prawns to 0.49 ± 0.04 μg g−1 dry weight in hepatopancreas within 24 h, while it was not detected in muscle samples, and rarely appeared in blood samples in such a short period. Although MC-LR was not detected in muscle, the head including hepatopancreas of the prawns accumulated troublesome amounts of MC-LR. These results demonstrate that microcystis blooms in prawn farming potentially pose a risk to human consumers, although prawns may be exposed to the bloom for a very short time, hence regular monitoring of blue green algae population is recommended.

Evidence of rapid transfer and bioaccumulation of Microcystin-LR poses potential risk to freshwater prawn <i>Macrobrachium rosenbergii</i> (de Man)
Journal Article
2015

NOP 15-A07 (English)(Spanish)

This study was focused on the morphological description of chame larvae from one to six days post-hatching (dph), in order to generate information that helps understanding their feeding ability in early stages. The larvae were obtained by hormonal induction of a broodstock, using implants of GnRH synthetic analogues, during the spawning season from September to November 2010. The samples were included in historesin, and stained with hematoxylin-eosin. It was described that, once the larva hatched has a large amount of yolk it is gradually absorbed (from 1 to 3 dph). At day four, there is an open oral cavity with dental structures, the eye development is complete and there was pigmentation on it, the gills are observable and the foregut was differentiated in anterior and posterior intestine, showing the presence of digestive vacuoles in the anterior intestine. By five dph the larvae has developed muscle fibers and a structure identified as the stomach. At sixth dph, it is possible to identify the pancreas, the intestinal folds, and the brush border membrane, and there were food particles and bacteria rests in the gut. Based on the above, it is concluded that the larvae of D. latifrons from the fourth dph fully developed organs and systems that help the search of food, so they are capable of starting with exogenous feeding.

Comparative histological description of the digestive and visual system development of larval chame <i>Dormitator latifrons</i> (Pisces: Eleotridae)
Journal Article
2015

NOP 15-A08 (English)

The production profits, improve of tilapia, like other The production profits, improve of tilapia, like other fed species, has been constrained by the cost of feeds, which can account for about 70 percent of the production costs of tilapia in several countries and regions (Bolivar et al. 2006, Elnady et al. 2010). There have been many attempts to replace expensive animal protein in tilapia feeds with plant protein sources, such as soybean meal, groundnut seed cake and others. Although animal protein replacement in tilapia profits, improve the supply of high quality fish protein to communities with limited food resources, and contribute to the overall growth of national aquaculture sectors. This article highlights the effects of combinations of fertilizers and feed on tilapia productivity in small earthen ponds. Experiments were conducted in Nepal, Cambodia and Kenya using a similar experimental design, stocking density and feeding regime.

Low-Cost Tilapia Production With Fertilization and Supplementary Feeding
Magazine Article
2015

NOP 13-A06 (English)

The effects of replacing fish meal with Caridina nilotica as a protein ingredient on growth performance, nutrient utilization, carcass, proximate composition and economic benefits in Nile tilapia (Oreochromis niloticus) culture was evaluated. Replacement of the FM with C. nilotica was done at 25%, 50%, 75% and 100% (D25, D50, D75 and D100) and the substitution effects was compared with the control diet (D0, 0% C. nilotica). After 140 days of culture, the best growth performance, nutrient utilization and economic benefits occurred in fish groups fed diets with 25% C. nilotica inclusion. However, growth performance in fish fed diets D50 and D75 were comparable with the control (P > 0.05). At 100% substitution level of FM with C. nilotica, the growth performance and fish survival was lower than control. Protein and lipid contents in the fish and their digestibilities were highest in diet D25 and decreased with increasing levels of substitution of FM with C. nilotica. This study demonstrate that utilization of local protein sources (C. nilotica) can be effectively used to replace up to 75% of FM in the diets without compromising growth performance, survival, nutrient utilization and economic benefits in O. niloticus culture.

Utilization of <i>Caridina nilotica</i> (Roux) meal as a protein ingredient in feeds for Nile tilapia (<i>Oreochromis niloticus</i>)
Journal Article
2015
NOP 15-345 (English)

NOP 15-345 (English)

Aquaculture (fish farming) is an agricultural as well as fisheries activity, competing with other agricultural enterprises and artisanal fisheries for the same basic inputs. Therefore, aquaculture is subject to the same basic resource constraints that traditional agricultural activities face. The literature suggests that competition within a value chain is between chains and not individual actors. This study examined the aquaculture value chain in Kenya, assessing the entire value chain, and determining the appropriate points to participate in economically sustainable ways. The competition analysis assessed attractiveness at each stage of the chain by reviewing the rivalry in terms of five competitive forces within the Kenyan aquaculture industry; competitive rivalry, the threat of new entrants, bargaining power of suppliers, threat of substitutes and bargaining power of buyers. The aquaculture industry in Kenya is assessed using Porter’s model with marketing mix (Ps) and factor evaluation matrix (FEM). Input supply is found to be the most difficult value chain function in which to participate because it requires relatively large initial capital outlays and additional operating funds. Although fish farming is the driving function of the entire value chain, the significant capital investments required could be a barrier to entry. Fish farming has largely benefited from the support of government, NGOs and other regional development initiatives. The study established that the easiest sector to enter (in terms of low barriers to entry and exit and low labor requirements) is the fish marketing sector. This chain function provides the most flexibility and liquidity to participants, whether as full-time or part-time occupation. Overall, participation in the Kenya aquaculture value chain will depend on the prospective entrant’s level of experience, time, capital commitment and financial goal (long term stability versus liquidity). Aquaculture requires a long term commitment and high capital outlays, as well as persistence, and should therefore be considered by those looking for long term stability and not short term benefits. Established fish farmers may consider diversifying into input supply and value addition as well.

Application of Porter's Framework to Assess Aquaculture Value Chain in Kenya
Journal Article
2015

NOP 15-339 (English)

We investigated effects of dietary administration of stinging nettle (Urtica dioica) on growth performance, biochemical, hematological and immunological parameters in juvenile and adult Victoria Labeo (Labeo victorianus) against Aeromonas hydrophila. Fish were divided into 4 groups and fed for 4 and 16 weeks with 0%, 1%, 2% and 5% of U.dioica incorporated into the diet. Use of U.dioica in the diet resulted in improved biochemical, hematological and immunological parameters. Among the biochemical parameters; plasma cortisol, glucose, triglyceride and cholesterol decreased while total protein and albumin in fish increased with increasing dietary inclusion of U.dioica. Among the haematology parameters: red blood cell (RBC), white blood cell (WBC) counts, haematocrit (Htc), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC) and netrophiles increased with increasing dietary inclusion levels of U.dioica, some depending on the fish age. Serum immunoglobulins, lysozyme activity and respiratory burst were the main immunological parameters in the adult and juvenile L. victorianus measured and they all increased with increasing herbal inclusion of U. dioica in the diet. Dietary incorporation of U. dioica at 5% showed significantly higher relative percentage survival (up to 95%) against A. hydrophila. The current results demonstrate that using U. dioica can stimulate fish immunity and make L. victorianus more resistant to bacterial infection (A. hydrophila).

Effects of dietary administration of stinging nettle (<i>Urtica dioica</i>) on growth performance, biochemical, hematological and immunological parameters in juvenile and adult Victoria Labeo (<i>Labeo victorianus</i>) challenged with Aeromonas hydrophila
Journal Article
2015

NOP 15-A03 (English)

This study assessed the potential of three widely-available local oilseed byproducts, soybean (SBM), copra (CM) and palm kernel meals (PKM) as partial replacements of fishmeal in Nile tilapia (O. niloticus) diets in terms of their digestibility and effects on growth and nutrient utilization.

Evaluation of Locally-available Agro-industrial Byproducts as Partial Replacements to Fishmeal in Diets for Nile Tilapia (<i>Oreochromis niloticus</i>) Production in Ghana
Journal Article
2015

NOP 15-A04 (English)

An experiment was conducted in earthen ponds at the Asian Institute of Technology, Thailand to determine different phosphorus fertilizer dose effects on Nile tilapia production, water quality variables, nutrient utilization and cost-benefit under supplemental feeding. Five phosphorus fertilization rates were used as treatments e.g. 100%, 75%, 50%, 25% and 0% of 7 kg P ha week−1. Nitrogen fertilization rate was fixed at 28 kg N ha week−1 for all the treatments. Sex-reversed Nile tilapia were stocked at 3 fish m−2, and 30% CP floating feed fed at 50% satiation feeding rate. Nutrient budget showed higher phosphorus fertilizer input resulted in higher phosphorus sink in the sediment. Mean weight, mean weight gain, daily weight gain and net yield were not significantly different among treatments (P > 0.05). Total Kjeldahl nitrogen, total phosphorus and soluble reactive phosphorus were significantly different among treatments. Economic analysis showed phosphorus fertilization resulted in positive net returns. Though the gross income was not affected by different fertilization rates, significantly lowest cost was found in the treatment using 25% phosphorus fertilizer. It can be concluded from the research that 25% phosphorus fertilization might be used as an alternative strategy of Nile tilapia pond culture in terms of economic return and nutrient loss in sediment.

Optimization of Phosphorus Fertilizer in Supplemental Feed-Fed Based Nile Tilapia (<i>Oreochromis niloticus</i>) Ponds
Journal Article
2015

NOP 15-A15 (English)

Feeding common carp (Cyprinus carpio) testis (CCT) to Nile tilapia during the critical period of sex differentiation caused skewness towards male based on dose dependent manner. Six types of feed containing varied proportion CCT viz.: 0% (Control), 50%, 65%, 80%, 95% and 100% were fed to 9 DAH (days after hatching) tilapia fry for 25, 30 and 35 days. Treatment with CCT and control feed was carried out in 18 glass aquaria of 60cm x 30cm x 45cm while rearing was carried out in 50cm x 50cm x 100cm nylon happas suspended cemented tank up to 160 DAH. There was no significant effect of treatment duration on sex reversal. Highest proportion of male (95.8±7.2%) was obtained with 100% CCT feed fed for 30-35 days compared to lowest (62.5±12.5%) obtained with 50% CCT feed fed for 25-30 days excluding the normal sex ratio with 0% CCT feed. Thus, it was concluded that common carp testis can efficiently masculinize Nile tilapia fry when fed for at least 30 days after hatching.Further refinement of testis could be more effective in sex reversal of Nile tilapia which could replace the use of synthetic androgen (17α- methyltestosterone).

Efficacy of common carp (<i>Cyprinus carpio</i>) testis on sex reversal of Nile tilapia (<i>Oreochromis niloticus</i>) fry
Journal Article
2015

NOP 14-328 (English)

Snakehead fish are the most preferred fish species for food in Cambodia and Vietnam, and are consumed in both fresh and processed forms. The purpose of this paper is to describe the value chains of captured and cultured snakeheads in the Lower Mekong Basin (LMB). The important actors involved in the value chain of snakeheads in the LMB of Cambodia and Vietnam were fishers, fish farmers, wholesalers, retailers, and processors. The value chain of wild captured snakeheads in Cambodia was focused on 11 marketing channels, and for cultured snakeheads in Vietnam, 10 market channels. The distribution of benefits among the chain actors was unequal, with the highest proportion of profit going to wholesalers in Cambodia and collectors in Vietnam. In order to develop the value chain of snakehead for the long-term in the LMB, appropriate plans must be prepared for each country in association with better management and protection of natural aquatic resources.

Value chain of snakehead fish in the Lower Mekong Basin of Cambodia
Journal Article
2015

NOP 15-A06 (English)

The present research work was carried out to determine livelihood conditions of fish and Prawn/ Giant freshwater prawn (Macrobrachium rosenbergii) Gher farmers at Beel Dakatia in Dumuria, Phultala and Daulatpur thana under Khulna district from April to September 2013. From the survey the community indicated that 21-40 age groups made maximum strength and majority of them were Muslims (58%). It was found that 16% of them could sign only and the percentages of school going children were high (86%). In the study area, it was found that 88% were married, 62% of people lived with unit families and highest households were 5-7 people per family. The majority of families (72%) had one person for earning and highest income of the people (44%) were 128 to 256 US dollar ($). About 62% people lived in local house and the construction materials were nipa palm and mud, 72% used electricity. The result also showed that 84% peoples main occupation was fish farming. Majority of the people (52%) used others tube well water for drinking, 56% used closed half build toilet. 52% fishermen got health service from Upazila health complex which was the most preferred place. For their recreation 76% used TV/ Radio. About 78% people used lease land for the fish and prawn farming. Thus to achieve better social structure, the government and its development partner needs to re-orient their programmer and to implement to an affirmative action for the fish and prawn Gher farmers.

Livelihood status of Gher farmers of Beel Dakatia in Khulna district, Bangladesh
Journal Article
2015
Thu, T. T. M., T. N. H. Nguyen, and T. T. T. Hien. 2015. A study of using crude bromelain enzyme in producing salty fermented fish product from commercial snakehead fish. Science and Technology Journal of Agriculture & Rural Development: Ministry of Agriculture and Rural Development, Vietnam 19:78 - 85. Retrieved (http://www.tapchikhoahocnongnghiep.vn/uploads/news/2015_11/11a.pdf).
NOP 15-353 (English)

NOP 15-353 (English)

The study of using crude bromelain enzyme in producing of salty fermented fish product from commercial snakehead fish was conducted from March to November 2014 at college of Aquaculture and Fisheries of Can Tho University with two main experiments (i) the effect of mechanical handle on proximate composition and texture property of product (ii) effect of supplementing crude bromelain enzyme at different rates and different fermentation times on product quality. In the first experiment, snakehead was applied [by] mechanical handle for 10 minutes and soaked with salt for 5, 10, 15, 20, 25 and 30 days. In the control group, fish were not applied [by] mechanical handle and soaked with salt for 30 days. In the second experiment, salty snakehead fish was supplemented with 2, 3, 4 and 5% of crude bromelain and fermented for 2, 4, 6, and 8 weeks. The control group was done without crude bromelain addition and fermented for 8 weeks. The results in the first experiment indicated that the group with mechanical handle snakehead fish and soaked with salt for 20 days gained the highest proximate composition (salt content 20.62%, moisture content 55.53%, protein content 18.94%) and hardness (20091 g force). In the second experiment, salty snakehead fish of 20 days was fermented with 3% crude bromelain and fermented for 6 weeks provided high proximate composition (20.67% of salt, 56.45% of moisture, 19.79% of protein, 8.02 mg total amino acids, 10-2 g fermented fish) and hardness (16607 g force) and had higher sensory score (color: 6.13, aroma: 6.07, taste: 6.00, and overall: 6.20) (1: extremely undesirable and 7: extremely desirable) in comparison with control group. Therefore, applying of crude bromelain enzyme can shorten the processing period of the salty fermented snakehead fish product and still ensures quality on nutrition and sensory quality compared with traditional methods.

A study of using crude bromelain enzyme in producing salty fermented fish product from commercial snakehead fish
Journal Article
2015

NOP 15-A11 (English)

In 2014, the Inland Fisheries Research and Development Institute of the Cambodian Ministry of Agriculture, Forestry and Fisheries undertook a study of the consumption of fish and other aquatic animals by women and pre-school children. The study, supported by Oregon State University through the University of Connecticut under the AquaFish Innovation Lab program, covered 300 women and 343 children in three provinces – Stung Treng and Prey Veng on the Mekong River and Kampong Thom on the Tonle Sap Lake. Interviews over two weeks in June estimated food intake over the previous 24 hours. Evaluations of energy, macronutrients and micronutrients were made using the ASEAN Food Composition Table. To determine nutritional adequacy, nutrient intake was compared with the Recommended Dietary Allowances for Southeast Asia [1st paragraph of introduction]

Fish Consumption Among Women and Pre-School Children in Cambodia
Magazine Article
2015

2014

NOP 14-324 (English)

A 10-week experiment was conducted to determine the optimal protein requirement of Chrysichthys nigrodigitatus, claroteid catfish in twelve 60-L indoor flow through rectangular glass tanks provided with aerated underground water. Four isoenergetic diets were formulated to contain varying crude protein (CP) levels of 32.1%, 34.6%, 42.8%, and 47.1% using fish meal/soybean meal as protein sources. Each diet was fed to triplicate group of 12 fingerlings (initial weight 16.30 ± 0.07 g, mean ± SE) in a completely randomized design. A digestibility trial was conducted with all the diets after the growth trial. Results after ten weeks of feeding showed an increase in body weight gain (BWG%) and specific growth rate with increasing levels of dietary protein up to 42.8% (P < 0.05) but a decline at 47.1% CP. Protein efficiency ratio followed similar trend but there were no significant differences between the treatments. Feed conversion ratio (FCR) reduced as dietary protein level increased, with the minimum FCR in the 42.8% protein diet, although this was not significantly different from the 34.6% and 47.1% protein diets. Analysis of dose (protein level)-response (BWG%) with polynomial broken stick regression suggested that the optimal dietary protein requirement for the juvenile of C. nigrodigitatus was 42.8%.

Effects of dietary protein levels on growth performance of claroteid catfish, <i>Chrysichthys nigrodigitatus</i>, fingerlings
Journal Article
2014

NOP 14-323 (English)

Two genetically improved tilapia strains (GIFT and Akosombo) have been created with Oreochromis niloticus (Nile tilapia), which is native to Africa. In particular, GIFT has been shown to be significantly superior to local African tilapia strains in terms of growth rate. While development economists see the potential for food security and poverty reduction in Africa from culture of these new strains of tilapia, conservationists are wary of potential ecological and genetic impacts on receiving ecosystems and native stocks of tilapia. This study reviews the history of the GIFT technology, and identifies potential environmental and genetic risks of improved and farmed strains and tilapia in general. We also estimate the potential economic gains from the introduction of genetically improved strains in Africa, using Ghana as a case country. Employing a combination of the Economic-Surplus model and Monte Carlo simulation, we found the mean net present value (NPV) of the introduction of the GIFT strain in Ghana to be approximately 1% of the country’s gross domestic product. Sensitivity analysis indicated that the difference in growth or yield between the GIFT and locally-available strains has the largest effect on mean NPV. We conclude that improvements in management practices and infrastructure could increase the yield and profitability of the local strains even if genetically-improved strains are not introduced. These improvements also will ensure the realization of the full potential of introduced strains.

Genetically-improved tilapia strains in Africa: Potential benefits and negative impacts
Journal Article
2014

NOP 14-333 (English)

Osmoregulation is critical for survival in all vertebrates, yet the endocrine regulation of this metabolically expensive process is not fully understood. Specifically, the function of leptin in the regulation of energy expenditure in fishes, and among ectotherms, in general, remains unresolved. In this study, we examined the effects of acute salinity transfer (72 h) and the effects of leptin and cortisol on plasma metabolites and hepatic energy reserves in the euryhaline fish, the tilapia (Oreochromis mossambicus). Transfer to 2/3 seawater (23 ppt) significantly increased plasma glucose, amino acid, and lactate levels relative to those in the control fish. Plasma glucose levels were positively correlated with amino acid levels (R= 0.614), but not with lactate levels. The mRNA expression of liver leptin A (lepa), leptin receptor (lepr), and hormone-sensitive and lipoprotein lipases (hsl and lpl) as well as triglyceride content increased during salinity transfer, but plasma free fatty acid and triglyceride levels remained unchanged. Both leptin and cortisol significantly increased plasma glucose levels in vivo, but only leptin decreased liver glycogen levels. Leptin decreased the expression of liver hsl and lpl mRNAs, whereas cortisol significantly increased the expression of these lipases. These findings suggest that hepatic glucose mobilization into the blood following an acute salinity challenge involves both glycogenolysis, induced by leptin, and subsequent gluconeogenesis of free amino acids. This is the first study to report that teleost leptin A has actions that are functionally distinct from those described in mammals acting as a potent hyperglycemic factor during osmotic stress, possibly in synergism with cortisol. These results suggest that the function of leptin may have diverged during the evolution of vertebrates, possibly reflecting differences in metabolic regulation between poikilotherms and homeotherms.

Role for leptin in promoting glucose mobilization during acute hyperosmotic stress in teleost fishes
Journal Article
2014

NOP 14-A17 (English)

The modeling of common water bodies to determine aquaculture carrying capacity has been identified as a critical need for countries in Southeast Asia. These countries would like to use models for aquaculture in various bodies of water, but modeling capabilities are currently limited. In addition, there is disagreement about how to balance the needs of farmers with protection of ecosystems. Effective management of carrying capacity will require a regional approach and participation by industry, governments, academia and non-governmental organizations.

Modeling Aquaculture Carrying Capacity In Southeast Asia
Magazine Article
2014

NOP 14-A13 (English)

Nitrite, an intermediate compound in the oxidation of ammonia nitrogen to nitrate by nitrifying bacteria in soil and water, is considerably more toxic than nitrate. Exposure to nitrite causes gill lesions and edema in the skeletal muscles of fish, and also affects respiration. Nitrite concentration is affected by the dissolved-oxy-gen and chloride levels in water, as well as species’ differences in nitrite susceptibility. Fish suffering brown-blood disease quickly recover when moved to water with low nitrite concentration.

Nitrite Toxicity Affected By Species Susceptibility, Environmental Conditions
Magazine Article
2014
NOP 14-A15 (English)

NOP 14-A15 (English)

Human activities have altered the concentrations of gases and other compounds in the atmosphere. Acid rain typically does not heavily affect aquaculture operations, and application of agricultural limestone can buffer water against the impacts of acid rain at facilities that use stream water. Due to higher carbon dioxide concentrations in the atmosphere, the amount of carbon dioxide that will dissolve in ocean water has increased. Decreased pH can thin the shells of some molluscan shellfish and reduce survival.

Atmospheric Pollution Affects Water Quality
Magazine Article
2014
NOP 14-A12 (English)

NOP 14-A12 (English)

Hydrogen sulfide, which can form in pond bottom sediment, is toxic to aquatic animals because it interferes with re-oxidation of cytochrome a3 in respiration. The main practices for lessening the risk of hydrogen feres with re-oxidation of cytochrome a3 in respiration. The main practices for lessening the risk of hydrogen sulfide toxicity are conservative feeding to avoid wasted feed on pond bottoms, plenty of aeration to prevent low dissolved-oxygen levels and provide a flow of oxygenated water across the soil-water interface, and liming to prevent acidic sediment and water.

Hydrogen Sulfide Toxic, But Manageable
Journal Article
2014
NOP 14-A11 (English)

NOP 14-A11 (English)

The silicon plants take up in silicic acid from water strengthens cell walls. Among the phytoplankton, diatoms particularly need silicon. Diatoms have good nutritional value and do not degrade water quality, so shrimp farmers often attempt to increase their abundance relative to other planktonic algae. To support diatoms, farmers should use silica products that contain 20% silicon. However, silicates have lower neutralizing values than agricultural limestone or lime, which are cheaper and more readily available.

Silicon, Diatoms In Aquaculture
Magazine Article
2014
NOP 14-A18 (English)

NOP 14-A18 (English)

Each type of aerator has advantages and disadvantages. The combination of paddlewheel aerators and propeller-aspirator-pump aerators can be particularly effective in deep ponds. Diffused-air systems are most appropriate for small ponds. The amount of aeration can be increased as feeding rate increases to conserve energy. Aeration in shrimp ponds usually can be reduced from mid-morning until early evening. Research has demonstrated that considerable energy can be saved by using aerator automation systems.

Species, Pond Size Define Aeration Approaches
Magazine Article
2014

NOP 14-338 (English)

Growing global needs for food call for substantial increases in protein production in coming years, and for diligent conservation efforts. Manures from farm animals have been viewed both as a resource and as a waste product, but they are critically important sources of nutrients for organic and integrated farming and for traditional Asian aquaculture. Given constraints on livestock production and capture fisheries, careful development of the aquaculture industry is a necessity. The production volume and market share of tilapia are advancing extremely rapidly, and so too is the proliferation of misinformation and controversy. Culture and feeding practices differ widely, but feeding is usually recognized as the single largest cost to producers. Traditional Asian integrated farming practices involve the use of manures and other farm wastes to promote algae and zoo-plankton production, serving as a sole or supplemental nutrient source to the food chain that supports tilapia growout. Tilapia also ingest manures. The efficient use of nutrients from manures can have multiple benefits to integrated terrestrial agriculture and aquaculture, as long as product safety and quality are not compromised. With efficient use, handling of manures is simplified, fish production costs are reduced, fish nutrition can be improved, and potentially polluting materials are cycled constructively on integrated farms. Consumer and press reactions to the use of farm manures in food production can be highly polarized. Published responses cover a range of extremes, from enthusiastic endorsement to volatile reactions and outright rejection; in some areas this practice is considered to be more of a “PR (Public Relations) problem” than a health hazard. The perception in online public media that tilapia coming from ponds fertilized with manure are heavily contaminated with pathogens has not been supported by evidence. The perspectives of farmers in two major tilapia production areas (China and the Philippines) are included.

The Value of Pig Manure as a Source of Nutrients for Semi-Intensive Culture of Nile Tilapia in Ponds (A Review)
Journal Article
2014

NOP 14-335 (English)

This paper looks at price integration in the aquaculture and wild-harvested African catfish market channels in Uganda. The issue of integration between the two market channels is important because African catfish has become an important traded species in Uganda with exports to regional markets rising even faster than production, yet limited research has been undertaken to understand price formation in the supply chain. The analysis draws on monthly price data from January 2006 to August 2013, and applies threshold auto-regressive approaches to test for the existence of a long-run relationship and price asymmetry and to determine the time path needed for shocks to be transmitted from one market channel to the other. The results show that, over the studied period prices in both market channels are linked in the long-run, implying that farm-raised catfish forms part of the same market as wild-harvested catfish in the country. The findings have strong implications for aquaculture producers and artisanal fishers as they can serve as a basis for more efficient farm management and marketing decisions.

Price integration in the farmed and wild fish markets in Uganda
Journal Article
2014

NOP 14-329 (English)(Vietnamese)

This study aimed at investigating the types of products from snakehead fish and technological processes for manufacturing these products in An Giang province. It has three main contents including (i) production situation and technological processes for manufacturing the products; (ii) investigating types of products; (iii) trade situation in the markets and customer tastes for the products. The results showed that (i) relatively good technological processes and good quality products were almost from processing facilities that operated longer than 20 years. However, these facilities primarily produced by traditional methods which could only meet the requirement of domestic customers without reaching food safety and hygiene standards for export; (ii) products from snakehead fish primarily were dry salted snakehead fish and salty fermented snakehead fish; (iii) consumption of these products were at the medium level because of high price. Customers aged 30-40 liked eating salty fermented snakehead fish while customers aged 20-30 liked eating dry salted snakehead fish. When buying these products, customers payed attention to quality, safety, hygiene, brand name and price of the products.

Investigations of types of products from snakehead sh (<i>Channa striata</i>) and their production process in An Giang province.
Journal Article
2014

NOP 14-A02 (English)

Aromatase inhibitors can produce monosex populations of fish by blocking estrogen induced ovarian differentiation. Phytochemicals such as flavonoids and other phenolic compounds can exhibit aromatase inhibitor-like characteristics as reported for many of these compounds. Two experiments were conducted with genetically all-female or genetically all-male first feeding Nile tilapia to evaluate the potential in vivo aromatase inhibitory activity of three selected phytochemicals in parallel with synthetic steroidal compound treatments. Experimental diets were the following: control, 17α- methyltestosterone (MT); 1,4,6-androstatrien-3-17-dione (ATD); spironolactone (SPIRO); daidzein (DAID); chrysin (CHR) and caffeic acid (CAFF) at different inclusion levels. Fish were fed for 6 weeks (all-male) and 8 weeks (all-female). Survival, final individual body weight and specific growth rate and final sex ratios were recorded. All phytochemicals were effectively detected using HPLC analyses. No differences were observed in survival, final mean weight, SGR between treatments in all-male tilapia. For all-female tilapia, MT and ATD groups showed significantly smaller final mean weights (p<0.05); still, survival or SGR were not significantly different. Final sex ratios were as follows: for all-male juveniles no effect was observed in the final sex ratio for any of the phytochemicals or spironolactone. The sex ratio of genetically all-female tilapia was not affected by the inclusion of tested phytochemicals and spironolactone, while MT and ATD male ratios of 100% and 50%, respectively. Thus, selected dietary inclusion levels of phytochemicals did not exert an in vivo effect on sex differentiation in Nile tilapia.

Dietary Administration of Daidzein, Chrysin, Caffeic Acid and Spironolactone on Growth, Sex Ratio and Bioaccumulation in Genetically All-Male and All-Female Nile Tilapia (<i>Oreochromis niloticus</i>)
Journal Article
2014

NOP 14-337 (English)

The present study identifies regulatory interactions between leptin A (LepA) and the pituitary hormone prolactin (PRL). In order to measure tilapia (Oreochromis mossambicus) LepA, an enzyme-linked immunosorbent assay (ELISA) utilizing a rabbit polyclonal antibody specific to tilapia LepA was first developed. The antibody shows strong cross reactivity to recombinant tilapia LepA (rtLepA), and a corresponding 16. kDa protein in both tilapia and striped bass plasma, but not to recombinant human leptin (rhLep). The assay has a linear detection range of 0.25-1000 nM, with intra- and interassay variability of 9% and 16%, respectively. Plasma LepA levels measured in tilapia ranged from 0.8 to 3.9 nM, similar to that found for other vertebrates. Hypophysectomy (Hx) increased circulating LepA and lepa mRNA levels in the liver, the dominant source of hormone production. Adminstration of ovine PRL (oPRL, 5. g/g BW) to Hx fish restored circulating LepA and hepatic lepa mRNA levels to those of control fish. Additionally, oPRL reduced lepa mRNA levels in a dose-dependent fashion in cultured hepatocytes following an 18 h incubation. Previous work in our lab indicates that rhLep stimulates PRL release in vitro from tilapia pituitaries. Here, both rtLepA and rhLep (0.5. g/g BW) increased mRNA expression of tilapia prolactin mRNAs (prl1, prl2) in the pituitary in vivo. These results demonstrate that LepA enhances pituitary prolactin synthesis and release, while PRL in turn inhibits hepatic leptin secretion and synthesis in teleosts. We postulate this regulatory interaction may be necessary for mobilizing energy reserves during acute hyper osmotic adaptation.

Prolactin is a major inhibitor of hepatic Leptin A synthesis and secretion: Studies utilizing a homologous Leptin A ELISA in the tilapia
Journal Article
2014

NOP 14-A16 (English)

The AquaFish Innovation Lab has conducted research using value chain analysis as a tool to increase income and nutrition for small-scale fish farmers through improved market participation and efficiency. Integrating women into the aquaculture value chain is part of a systems approach to improve the economic and social benefits of aquaculture. Work in Africa and Asia has identified some of the underlying barriers to women’s participation and begun to develop strategies for overcoming them.

Value Chain Analysis Helps Overcome Gender Barriers In Aquaculture
Newspaper Article
2014

 NOP 14-332 (English)

The trajectory of aquaculture growth in sub-Saharan Africa has necessitated closer attention to the use of environmental best management practices (BMPs). Two BMPs in particular, water reuse and floating feeds, are being promoted for adoption by pond fish farmers in sub-Saharan Africa. In this study, we investigated: (1) the effect of water source and feed type on water quality; (2) the effect of water source and feed type on tilapia growth; and (3) the quality of potential effluents from ponds using different water source and feed types. The study was conducted in Ghana using on-farm experiments involving monitoring of water quality and growth of Nile tilapia (Oreochromis niloticus) for 160 days. Although considered low-intensity production systems, nutrients and solids in the study ponds exceeded levels expected in intensive culture ponds by wide margins, whereas BOD 5 was within the range for semi-intensive ponds. Floating feed was associated with OPEN ACCESS Sustainability 2014, 6 653 higher water quality, especially dissolved oxygen, and higher growth, but water source did not significantly affect growth. Water reuse appears to be a viable BMP for sustainable aquaculture in the region, but the use of floating feed as BMP will depend on the economic profitability of floating feed use.

Effects of Two Environmental Best Management Practices on Pond Water and Effluent Quality and Growth of Nile Tilapia, <i>Oreochromis niloticus</i>
Journal Article
2014

NOP 14-A09 (English)

Aquaculture in Ghana has over-come its historic fits and starts and is helping to narrow the gap between domestic seafood production and consumption. Production is based on Nile tilapia, with 90% of the reported volume raised in cages. Although low productivity and potential under-reporting of pond numbers are limiting the contributions of pond aquaculture, the sector has huge potential to expand and reduce the cost of tilapia. Updated and expanded extension services could help address numerous problems in the sector.

Tilapia Aquaculture in Ghana: Ponds Can Contribute More to Overall Production, Food Security
Magazine Article
2014

NOP 14-327 (English)

Past fish production research done in Kenya suggests a strong production focus, leaving many fish consumer and marketing questions unanswered. This study investigated consumer fish preferences and trends in demand for Nile tilapia and African catfish in five urban centres in Kenya. A total of 384 questionnaires were administered to fish consumers and retailers in open markets, supermarkets, hotels and landing beaches. Descriptive and inferential analyses were done using SPSS Version 20.0. Female consumers were significantly higher (p > 0.05) in all study areas except Nairobi. There were significant differences in levels of preference for either the wild and farmed Nile tilapia (p > 0.05). Main reasons for consuming fish by consumers were health benefits of fish, good taste and ease of cooking. Quantities of fish purchased by consumers was generally small ranging from 1.68 ± 0.20 kgs in Kisumu to as low as 0.30 ± 0.04 kgs in Nyeri. The main factors affecting consumer preference of Nile tilapia fish were price, overall fish quality, nutritional value, and healthiness. In order to promote preference and consumption of farmed fish in Kenya, the government should educate consumers about the safety, healthiness and nutritional value of aquaculture products.

Consumer Perceptions and Preferences of Wild and Farmed Nile Tilapia ( <i>Oreochromis niloticus</i> L .) and African Catfish ( <i>Clarias gariepinus</i> Burchell 1822 ) in Urban Centres in Kenya Methodology
Journal Article
2014

NOP 14-A05 (English)

Abundance, length-frequencies and distribution of Ruditapes philippinarum (Manila Clams) and Tellina (Quidnipagus) palatum were measured at two beaches in Kāne'ohe Bay, O'ahu, Hawai'i in June, 2010. Abundances had decreased from 866.2 m−2 to 3.4 m−2 for Ruditapes and from 75.5 m−2 to 1.5 m−2 for T. palatum since 1977. Distribution of both species was patchy, but both were most commonly found >40 m from shore. Size frequencies of live clams compared with empty shells suggest that few Ruditapes survive to sexual maturity. A similar trend was not detected for T. palatum. Aquaculture trials of R. philippinarum were conducted at the He'eia and Moli'i traditional Hawaiian fishponds in the same bay. The clams failed to thrive, although triploid and diploid Crassostrea gigas performed well in concurrent trials in the same fishponds. Current lower abundances for wild R. philippinarum could be due to factors related to predation or nutrient limitations. Previously, two large sewage outfalls existed at the surveyed clam bed areas which may have temporarily increased nutrient availability for both wild and cultured clams. Current nutrient levels may inhibit Manila clam growth and recruitment in Kāne'ohe Bay.

Abundance and culture trials of <i>Ruditapes philippinarum</i> (Adam and Reeve, 1850), and abundance of <i>Tellina (Quidnipagus) palatum</i> (Iredale, 1929) at two sites in Kāne'ohe Bay, O'ahu, Hawai'i
Journal Article
2014

NOP 13-319 (English)

The Common Snook, Centropomus undecimalis, inhabits riverine and marine areas of Southern Gulf of Mexico, where it is subject to intense use and exploitation. It has been reported that the genetic identification of fish stocks constitutes a valuable tool for wild population management; nevertheless, there is no available information on the genetic identification on fish stocks of this species in the region. The aim of this study was to determine the genetic relationship between C. undecimalis captured in marine and freshwater environments of the Gulf of Mexico and the San Pedro River. For this, muscle tissue samples of 79 specimens were obtained from areas located more than 300 km apart. The genotype of each individual was determined using seven microsatellite primer pairs. Five primers amplified efficiently presenting between six and 28 alleles per locus. High levels of heterozygosis were observed in samples from both environments. Deviation from HWE due to an excess of heterozygotes was observed. The values of genetic difference indicate an absence of population structure (F(ST) = 0.0075 and R(ST) = (0.016, p = 0.051) and similarity in the allele frequencies, defined by Nei's index (0.805). Data showed the existence of a high gene flow due to the number of migrants (Nm = 18.7). Our results suggest that individuals living in these environments belong to the same genetic population. We suggest the development of management and protection plans for this fish species population in the wild.

Genetic variability of the common Snook <i>Centropomus undecimalis</i> (Perciformes: Centropomidae) in connected marine and riverine environments.
Journal Article
2014

NOP 14-A04 (English)

The common snook, Centropomus undecimalis, is a migratory euryhaline fish. In the southern Gulf of Mexico, fishing of large snooks occurs mainly in the marine environment (MA), while medium-size adults and juveniles are caught in freshwater environments (FW); however, large-size adults can also be found in FW far away from the sea, and the effect of different environments on their reproductive cycle is unknown. To describe the reproductive cycle of this species in different salinity habitats, we analyzed macroscopic reproductive characteristics during one annual cycle in FW and MA interconnected by the Grijalva–Usumacinta basin. Specimens with full-grown gonads and capable of spawning were found in FW, an unusual condition not reported for this habitat, but active spawning was observed only in MA. Centropomus undecimalis has a biological strategy that allows the use of FW as a juvenile until it reaches sexual maturity as a male and joins the reproductive stock in MA. Adults of both sexes can remain in both FW and MA without affecting their reproductive cycle, suggesting that those that mature in FW migrate to the sea during the spawning season. 

Reproductive variability of the common snook, <i>Centropomus undecimalis</i>, in environments of contrasting salinities interconnected by the Grijalva–Usumacinta fluvial system
Journal Article
2014
Hien, T. T. T. et al. 2014. Replacing fishmeal by some of soy protein sources in feed for snakehead (Channa striata). Can Tho University Journal of Science 1(Special Issue: Fisheries):310 - 318.
NOP 14-331 (English)(Vietnamese)

NOP 14-331 (English)(Vietnamese)

The study was conducted to determine the appropriate replacing of fish meal (FM) protein by three type’s soybean meal: defatted soybean meal (SB), fermented soybean meal (FSB) and soy protein concentrate (SPC) in snakehead (Channa striata) diet. Four isonitrogenous (45%) and isocaloric (4.6 Kcal/g) diets were formulated. The control diet was prepared with 100% FM protein. Three other diets was replaced 40% FM protein by three type’s soybean meal protein. Results showed that there was no significant difference in survival rate between feeding treatments. Fish growth performance in control diet and diet replaced SPC were significantly higher than the diets replaced SB and FSB. Food intake observed in diet replaced SPC treatment was not significant difference compared to control treatment. There was no significant difference between treatments in Feed Conversion Ratio, Protein Efficiency Ratio and hematological parameters (red blood cells and white blood cells). Hepatosomatic Index calculated in control treatment was significantly higher than those of others. Thus, it can be replaced 40% fish meal (FM) protein by soy protein concentrate (SPC) in snakehead (Channa striata) diet.

Replacing fishmeal by some of soy protein sources in feed for snakehead (<i>Channa striata</i>)
Journal Article
2014

NOP 14-336 (English)

Leaf meals are potential alternatives to soybean meal (SBM) in fish diets in developing countries because they are cheaper. Moringa oleifera (MOR) and Leucaena leucocephala (LEU) reduced nutrient digestibility of diets compared with SBM in an earlier study. However, fish raised outdoors consume natural foods, which might offset the negative effects of leaf-meal diets. We conducted a feeding trial using mixed-sex Nile tilapia (5.2 g) to assess performance of fish fed 36% protein diets with different concentrations of MOR and LEU leaf meals in place of SBM. Fish in static pools were fed daily to apparent satiation for 59 d. Individual weight gain (30.4–34.7 g), survival (91.8–97.3%), feed conversion ratio (FCR, 1.6–1.9), proximate composition, plasma lysozyme activity, and intestinal proteolytic enzyme activity were similar among diets. However, fish fed diets containing leaf meals had higher concentrations of n-3 fatty acids than those fed the SBM control. Despite lower nutrient availability of the leaf-meal diets compared with the soy diet, MOR or LEU could replace up to 30% of the SBM protein without reducing fish performance. Inclusion of poultry meal in the diets and probable nutrient supplementation from natural foods appeared to compensate for the lower nutritional value of the leaf meals compared with SBM.

Effect of Reduced Soybean-Meal Diets Containing <i>Moringa oleifera or Leucaena leucocephala</i> Leaf Meals on Growth Performance, Plasma Lysozyme, and Total Intestinal Proteolytic Enzyme Activity of Juvenile Nile tilapia, <i>Oreochromis niloticus</i> ...
Journal Article
2014

NOP 14-A03 (English)

Vegetable leaf meals are cheaper feed ingredients than soybean meal (SBM) in developing countries, and leaf meals are less important as human food. We evaluated the nutrient digestibility of practical diets containing reduced levels of SBM in combination with leaf meals made from Moringa oleifera and Leucaena leucocephala in Nile tilapia, Oreochromis niloticus. Five isonitrogenous diets (32% crude protein) were made: the control diet contained 50% SBM, and the test diets were made by substituting 15 or 30% of SBM protein with either Moringa or Leucaena. Dry matter, protein, and lipid digestibility decreased with increasing Moringa or Leucaena in the diet. Protein and lipid digestibility were high across diets (75–90%). Ash digestibility of the control diet was similar to that of both Moringa diets, while the ash digestibility of the Leucaena diets was lower than other diets. Overall, nutrient digestibilities of Moringa diets exceeded those of Leucaena diets. Dry matter, protein, and lipid digestibilities decreased with increasing dietary fiber, which increased with increasing leaf meals. Ash digestibility was generally low for all diets. Better digestibility of practical diets containing Moringa compared to Leucaena indicates greater potential for Moringa to replace SBM in Nile tilapia diets without compromising fish performance.

Nutrient Digestibility of Reduced-Soybean-Meal Diets Containing Moringa or Leucaena Leaf Meals for Nile tilapia, <i>Oreochromis niloticus</i>
Journal Article
2014
NOP 14-A19 (English)

NOP 14-A19 (English)

The main pond bottom soil management practices used in semi-intensive culture are pond dryout and liming between crops. These practices accelerate organic matter decomposition, neutralize soil acidity and destroy un-wanted organisms. Since most soils become too dry for microbial decomposition of organic matter within three weeks, there is little need to dry pond bottoms more than that period. Where bottom sediment is deep, remove it to facilitate dryout. Ponds with soil pHs below 7.5 should be limed to enhance decomposition.

Pond Bottom Dryout , Liming
Newspaper Article
2014

NOP 14-334 (English)

Integrated Multi-Trophic Aquaculture (IMTA) is an ecological and economic farming strategy that minimizes waste from culture systems, reduces the risk of diseases and provides additional income source. A trial was conducted to evaluate the effects of adding maize starch on the yield, water quality, formation of bioflocs and economic return in an IMTA system comprising white shrimp (Litopenaeus vannamei), spotted scat (Scatophagus argus) and water spinach (Ipomoea aquatic). Shrimp were randomly assigned to 12 cemented tanks (T1, T2, T3 and T4 with three replicates) and reared in monoculture (T1) without the addition of starch, or in polyculture (with spotted scat and water spinach) with (T3 and T4) or without (T2) the addition of starch. Shrimp in T4 were fed at 80% of the feeding amount of other treatments. The results showed that shrimp survival was higher in T3 and T4 (95.6% and 94.3%, respectively) than in T1 and T2 (51.1% and 56.5%, respectively) (P < 0.01). The shrimp yield was the highest in T3 (0.495 kg m-3), which also had the lowest feed conversion ratio (1.02) and best economic performance. The levels of nitrite-N (NO2-N) were significantly lower in T3 and T4 at the end of the experiment than in other treatments (P < 0.01). Similarly, total ammonia nitrogen (TAN) was lower and total suspended solids (TSS) was higher in T3 and T4 than in T1 and T2 (P < 0.05). The results suggested that the addition of starch into the IMTA system of shrimp, spotted scat and water spinach improved productivity, profitability and water quality. The combination of the IMTA model and biofloc technology had a synergistic effect on overall FCR and economic return, and was more effective at improving shrimp survival, production and reducing nitrite-N and TAN than use of the IMTA model alone. 

Effects of addition of maize starch on the yield, water quality and formation of bioflocs in an integrated shrimp culture system
Journal Article
2014

NOP 14-A07 (English)

Cage-pond integration system is a new model for enhancing productivity of pond aquaculture system. A field trial was conducted using African catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus) in cages and carps in earthen ponds. There were four treatments replicated five times: (1) carps in ponds without cage, (2) tilapia at 30 fish m−3 in cage and carps in open pond, (3) catfish at 100 fish m−3 in cage and carps in open pond, (4) tilapia and catfish at 30 and 100 fish m−3, respectively, in separate cages and carps in open pond. The carps were stocked at 1 fish m−2. The cage occupied about 3% of the pond area. The caged tilapia and catfish were fed and the control ponds were fertilized. Results showed that the combined extrapolated net yield was significantly higher (P < 0.05) in the catfish, tilapia and carps integration system (9.4 ± 1.6 t ha−1 year−1) than in the carp polyculture (3.3 ± 0.7 t ha−1 year−1). The net return from the tilapia and carps (6860 US$ ha−1 year−1) and catfish, tilapia and carps integration systems (6668 US$ ha−1 year−1) was significantly higher than in the carp polyculture (1709 US$ ha−1 year−1) (P < 0.05). This experiment demonstrated that the cage-pond integration of African catfish and Nile tilapia with carps is the best technology to increase production; whereas integration of tilapia and carp for profitability.

Cage-pond integration of African catfish (<i>Clarias gariepinus</i>) and Nile tilapia (<i>Oreochromis niloticus</i>) with carps
Journal Article
2014

NOP 14-A08 (English)

We evaluated the effect of varying cage stocking density (60, 90 and 120 fish m3) and feeding duration (10, 30 and 60 min) in a cage-cum- pond-integrated system on growth performance, water quality and economic benefits in Labeo victorianus culture. Interactions between stocking density and feeding duration significantly (P < 0.05) affected the fish growth performance and yields in the cages-cum-pond system. Stocking density of 60 fish m3 resulted in the highest growth in cages and in ponds regardless of the feeding duration, but produced lower yields than at stocking density 90 fish m3 . The lowest Apparent Food Conversion Ratio (AFCR) in cages occurred at stocking density of 60 fish m3 and feeding duration of 30 min. Growth performance in the open ponds declined with increased feeding duration of the caged fish. Survival in cages and in the open ponds decreased with increased cage density, but was not affected by feeding duration. Low dissolved oxygen were recorded, at stocking density of 120 fish m3, the lowest DO occurred when feeding of caged fish lasted 60 min. Growth performance, water quality and economic benefits in Labeo victorianus culture positively respond to interaction between stocking density and feeding durations.

Effects of stocking density and feeding duration in cage-cum-pond-integrated system on growth performance, water quality and economic benefits of <i>Labeo victorianus</i> (Boulenger 1901) culture
Journal Article
2014

NOP 14-326 (English)

The effect of tank background colour and stocking density on growth rates and survival of Nile tilapia (Oreochromis niloticus) fry (0.32 g) were investigated. The fish were reared in aquari- um with blue, black and clear backgrounds at two stocking densities of 2 fish L-1 and 4 fish L-1. The outside walls and bottoms of each aquarium were painted to achieve one of two colours (blue and black), while noncoloured (clear) aquarium served as a control. The fish were fed a commercial diet (40% crude protein) at a daily rate of 5% of their body weight twice a day for 70 days. The best growth rates, weight gain, specific growth rate, food conversion ratio and survival were achieved in larvae reared under 2 fish L-1 stocking density in the blue back- ground. Fish performance was significantly (P<0.05) retarded in larvae reared in aquarium with black background. Increased aggression was observed under high density or when the fish were reared in clear backgrounds. Fish reared on black backgrounds were distinctively darker compared to those reared in the blue and clear backgrounds. These results suggest O. ni- loticus should be reared at 2 fish L-1 in aquaria with blue backgrounds.

Combined Effects of Stocking Density and Background Colour on Growth Performance and Survival of Nile Tilapia (<i>Oreochromis niloticus</i>, L.) Fry Reared in Aquaria
Journal Article
2014

NOP 14-325 (English)

Teleosts and other aquatic ectotherms have the ability to withstand prolonged periods of low water temperatures (cold-acclimation) and fasting, and can often respond with phases of accelerated (compensatory) growth when favorable conditions are restored. We assessed whether complete feed restriction prior to (24 degrees C, days 0-23) and/or during (14 degrees C, days 24-114) a simulated period of cold-acclimation could elicit episodes of compensatory growth (CG) and catch-up growth upon warm-up to 24 degrees C and satiation feeding (days 115-148). Control hybrid striped bass (HSB: Morone chrysops x Morone saxatilis) were fed to satiation throughout the entire experiment under these temperature fluctuations. Compensatory growth and ultimately catch-up growth were achieved in groups of HSB that were deprived of feed during either the initial period at 24 degrees C (days 0-23), during the cold-acclimation period (14 degrees C, days 24-114), or during both of these periods (days 0-114). Further, it appears that HSB are better able to compensate for weight loss when skeletal length is not significantly compromised during the treatment period, which occurred in HSB feed restricted during cold-acclimation only. The most dramatic CG responses were defined by specific growth rates (SGRs) up to 4.2 times that of controls and were accompanied by hyperphagia and improvements in temporal and overall feed conversion. Levels of plasma insulin-like growth factor (IGF)-1 and muscle IGF-1 mRNA were significantly correlated to growth rate for all groups throughout the experiment (R2 = 0.40, 0.23, respectively), with an overcompensation of both observed in HSB with the most elevated SGRs during the CG response. Interestingly, opposing trends were observed between muscle mRNA expression of growth hormone receptor (GHR)-1 and -2, with fasting at 24 degrees C and 14 degrees C resulting in depressed levels of GHR-1 and elevated levels of GHR-2 relative to controls. Levels of muscle myostatin (MSTN)-1 mRNA were significantly depressed in HSB fasted at 24 degrees C and/or 14 degrees C while MSTN-2 mRNA was lower following initial feed restriction at 24 degrees C. Likewise, levels of unprocessed pro-MSTN (precursor) and mature MSTN protein were both depressed in fasted fish at 24 degrees C. This study demonstrates that a previous period of feed restriction and cold-acclimation followed by realimentation at more favorable water temperatures produces a strong CG response and catch-up growth in fish. These studies also suggest that an overcompensation of circulating and local IGF-1 along with changes in MSTN mRNA and protein expression may contribute to accelerated growth rates characteristic of CG. Furthermore, our studies indicate that overall feed conversion can improve by as much as 30% with CG induced through temperature and feeding manipulations with no adverse effects on growth of HSB. This raises the possibility that CG protocols can improve production efficiency of HSB and other temperate teleosts in pond or tank culture.

Overcompensation of circulating and local insulin-like growth factor-1 during catch-up growth in hybrid striped bass (<i>Morone chrysops</i> x <i>Morone saxatilis</i>) following temperature and feeding manipulations
Journal Article
2014

NOP 15-350 (English)

As a result of the concern and debate about the impacts of intensive aquaculture development on biodiversity, semi-intensive aquaculture is being considered as an alternative. Although the biophysical impacts of aquaculture on biodiversity have been examined, there is only limited understanding of the social and economic impacts of aquaculture on biodiversity, and especially the impacts of the shift from intensive to semi-intensive systems. The purposes of this article are twofold: (1) to identify and discuss the social and economic impacts of aquaculture on biodiversity, and (2) to examine the impacts while moving from intensive to semi-intensive systems. After discussing the findings of our study, we provide some recommendations as to how to minimize social and economic impacts of aquaculture on biodiversity by moving to a lower intensity aquaculture system. The integrated agriculture-aquaculture farming systems, stakeholder involvement in management, and well-defined basic rights are aquaculture systems that contribute to conservation of biodiversity.

The Social and Economic Impacts of Semi-Intensive Aquaculture on Biodiversity
Journal Article
2014

NOP 14-A20 (English)

Facing rising aquafeed costs, researchers and farmers are investigating ways to lessen resources spent on feeds by feeding less and feeding differently. “Greenwater” technology applied through pond fertilization generates food items produced naturally in culture water. In conjunction, feeding on alternate days can maintain good harvest results. Further approaches include product substitutions through alternative sourcing of feed ingredients, increasing the nutritive content of feed to grow healthier fish and improving locally produced, low-cost feeds by the process of pelletization.

Strategies for Reducing Feed Costs in Small-Scale Aquaculture
Magazine Article
2014

NOP 15-A14 (English)

In rural Nepal, widespread poverty is compounded by the lack of access to high-quality, nutritious foods. According to a recent report from the Nepal Demographic Health Survey, 41 percent of children under the age of five are chronically malnourished, and anemia is a significant problem, afflicting 47 percent of children and 36 percent of women. One approach to mitigate the spread of anemia and to improve the overall health of rural Nepalese is to supplement their diets with vitamin-rich protein sources such as fish. Researchers from Nepal’s Agriculture and Forestry University (AFU) recognized the potential of aquaculture to help address this widespread nutritional deficit, and their recent effort in Nepal successfully established more than 70 family-run fishponds, all managed by women. In the first year of operation, the ponds produced over 500 kg of fish for household consumption. [Note: this is the first two paragraphs of the publication]

Aquaculture helps women in Nepal improve household nutrition
Magazine Article
2014

NOP 14-A06 (English)

Based on lessons learned from field trials, carp-small indigenous fish species (SIS)-prawn polyculture technology was improved to a "carp-SIS polyculture" technology suitable for small scale farmers in Terai, Nepal. In December 2008, the project was initiated to improve income and nutrition of Tharu women in Chitwan (100 farmers) and Kailali (26 farmers) districts. SIS dedhuwa, Esomus danricus (Hamilton, 1822) and pothi, Puntius sophore (Hamilton, 1822) were intended to improve household nutrition through increased consumption due to their high micro-nutrient content whereas large carps rohu, Labeo rohita (Hamilton, 1822); mrigal, Cirrhinus mrigala (Hamilton, 1822); silver carp, Hypopthalmichthys molitrix (Valenciennes, 1844); bighead carp, Aristichthys nobilis (Richardson, 1845); common carp, Cyprinus carpio (Linnaeus, 1758) and grass carp, Ctenopharyngodon idella (Valenciennes, 1844) were grown mainly for sale. The farmers consumed 48.7% of the production and raised their fish consumption to twice the national average of 1.85 kg caput -1 year -1. Farmers earned NPR 3,025 (USD 34.23) per household in 270 days which helped them economically. A women fish farmers' co-operative was established. Altogether 156 women directly benefited from the project. The training and project experiences improved their self-confidence. Micro-nutrient analysis of common SIS showed that vitamin A was higher in mara, Amblypharyngodon mola (Hamilton, 1822) whereas iron and zinc were higher in dedhuwa. The approach was found to be a more economic and sustainable, and is being replicated in other districts.

Carp-SIS Polyculture: A New Intervention to Improve Women's Livelihoods, Income and Nutrition in Terai, Nepal
Journal Article
2014

NOP 15-A12 (English)

Small fish have been considered trash fish and were often removed from ponds, based on a misconception that SIS (Small Indigenous Fish Species) exert competition for food and space with the main species cultured. Production was greater in ponds with SIS than those without SIS, suggesting a synergistic effect of SIS on carp production. Small fish contributed an average of 20 percent of total family consumption among SIS-growing farmers. SIS-stocked ponds provided 28 percent greater income over carp-only ponds because of comparatively greater production. Female farmers have learned to stock and grow SIS.

Polyculture with Carp, Nutrient-rich Small Fish and Prawn
Magazine Article
2014

NOP 14-330 (English)(Vietnamese)

This study was conducted by interviewing 64 snakehead farmers (pond culture) in An Giang and Tra Vinh provinces from February to April 2014. The results showed that farm scale in An Giang province was smaller than that in Tra Vinh province, the source of snakehead fingerling was mainly from hatcheries in An Giang. Pellet feed was used in snakehead farming with FCR: 1.32-1.33. Culture period, survival rate and yield were not significantly different between the two provinces; harvest size in Tra Vinh was larger than that in An Giang. Total cost of fish culture was rather high (4.9-5.8 VND billion/ha/crop), ratio of gained profit households in Tra Vinh and An Giang were 15.6% and 37.5%, respectively due to low farm gate price. Weather changes were effected snakehead pond culture such as (prolong hot and drought, hotter in dry season, large temperature variation between day and night, colder in cold season, irregular rain and sunshine and saline water intrusion caused more diseases, poorer water quality, reduced survival rate and yield. Farmers’ adaptive solution was increase the cost of water plumbing and using chemical- drug 24.2 - 29.2 VND million/ha/year.

Assessment on production efficiency and weather change impacts on snakehead pond culture in An Giang and Tra Vinh provinces
Journal Article
2014

NOP 14-A01 (English)

The availability of African lungfish (Protopterus aethiopicus) in many communities in Uganda is declining. Indigenous efforts to culture this fish usually produce poor yields and depend on feeding fish fry, minced meat, and leftover food. This study evaluates three formulated diets (diet-1, diet-2, diet-3) fed to wild caught lungfish fingerlings reared in indoor tanks for 77 days. Experimental fish gradually accepted sinking pellets, and marginal increases in average body weight were observed. Mean (± SE) final weight (15.86 ± 0.80 g) for fish fed on diet-3 was significantly higher (p < 0.05) than fish fed diet-1 and diet-2. Specific growth rates (SGR) for diet-3 were significantly higher (p < 0.05) than diet-1, and marginally more than diet-2 (0.37 ± 0.04 %/ d). Feed conversions were similar (p >0.05), ranging from 1.61 ± 0.26 to 2.07 ± 0.11. Survivals after an 11-week culture were relatively low (< 60%), but generally increased (R2 = 0.667, P = 0.007) with increasing dietary proteins. Diet-3 had a significant higher survival rate (p< 0.05) than diet-1 and diet-2. Significant growth performance was attained with diet-3. This study demonstrated that sinking fish feed pellets can be used to culture wild-caught African fingerlings in captivity.

Culturing the African lungfish in Uganda: Effects of exogenous fish feed on growth performance in tanks
Journal Article
2014

2013

NOP 13-A05 (English)

An experiment was conducted to assess the impacts of inclusion of column feeder rohu (Labeo rohita) on growth and production in freshwater prawn-carp-mola polyculture system at the Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh for a period of 172 days (June-December, 2008). Four stocking densities of Rohu were maintained as 500, 1,000, 1,500 and 2,000 ha -1 in treatment R500, R1,000, R1,500 and R 2,000, respectively in triplicates. All ponds each 120 m2 were stocked with juvenile freshwater prawn (Macrobrachium rosenbergii), silver carp (Hypophthalmichthys molitrix), catla (Catla catla) and small fish mola (Amblypharyngodon mola) at the fixed stocking densities of 20,000, 1,500, 1,000 and 20,000 ha -1 , respectively. Prawns were fed with pelleted feed twice daily started initially with 10% and gradually reduced to 3% of body weight and continued throughout the study period. All fish were fed with mixture of soaked rice bran and mustard oilcake (2:1) at the rate of 3% of the body weight daily. All the water quality parameters such as temperature, transparency, pH, dissolved oxygen, total alkalinity, NH3-N, NO2-N, NO3-N, PO4-P and chlorophyll- a did not differed significantly (> 0.05) among the treatments. The survival rate, mean individual weight and production of prawn were decreased with increasing density of rohu. Therefore, the density of rohu significantly (P < 0.05) influenced the growth and production of freshwater prawn. Catla and Mola production were affected adversely with increasing rohu density. The production of rohu increased with increasing density although the individual weight decreased. The combined production of all finfish was significantly lower in R0 whereas, the combined production of all species including prawn did not differ significantly (P < 0.05) among the treatments. The treatments R0 and R500 fetched higher net profit without significant difference between them. Therefore, inclusion of rohu at a density of 500 ha-1 may be recommended for prawn-carp-mola polyculture.

Impacts of Inclusion of Column Feeder Rohu (<i>Labeo Rohita</i>) at Different Stocking Densities on Growth and Production in Freshwater Prawn-Finfish Polyculture System
Journal Article
2013

NOP 13-A04 (English)

An understanding of specific aquaculture systems and the impacts of their management practices leads to sound and cost-effective policies to protect the aquatic environment. Water samples were collected in 2009 from fish ponds, streams that receive effluents directly from ponds and reference streams in Ghana to assess potential environmental impacts of pond aquaculture. Although relatively dilute, fish ponds had higher levels of all physico-chemical variables measured compared to those of locations upstream and downstream of farms, and to reference locations. Total nitrogen and BOD5 were most clearly statistically significant. Of 292 earthen fish ponds surveyed in central Ghana, approximately 92% were used for either Oreochromis monoculture or Oreochromis–Clarias polyculture. These had similar pond water (i.e. potential effluent) quality but different management practices. The study ponds had the potential to pollute effluent-receiving streams, but their actual impacts will depend on how pond effluents are managed. Conventional treatment of effluents from these small-scale, low-volume operations, which discharge relatively dilute effluents infrequently, might not be cost-effective. 

Characterisation of potential aquaculture pond effluents, and physico-chemical and microbial assessment of effluent-receiving waters in central Ghana
Journal Article
2013

NOP 13-A02 (English)

To evaluate protein and lipid requirement of South American catfish surubim (Pseudoplatystoma sp.) juveniles, nine semi-purified diets containing three levels of protein (40%, 45% and 50%) and three levels of lipid (12%, 16% and 20%) were tested. After 8-week feeding trial, body weight increase averaged 2124.3 ± 295.7%. Growth performance was significantly affected by dietary level of protein (P < 0.05). At the 40% protein level, increasing level of dietary lipid had a positive effect on final individual mean weight (protein sparing effect). Whole body protein and moisture contents were affected by the dietary level of lipid (P < 0.05). Whole body lipid content positively correlated with the level of dietary lipid (P < 0.05). Cannibalism related mortality was observed despite rearing fish in 24 h dark. Fatty acid composition of fish was affected by the dietary lipid level (P < 0.05). Polyunsaturated fatty acids increased with the increasing level of dietary lipid while saturated fatty acids and monounsaturated fatty acids decreased. Trypsin activity in the digestive tract of surubim was influenced by dietary levels of protein and lipid (P < 0.05). Our preliminary results suggest that the optimum protein/lipid ratio might be close to 45/16% for surubim juveniles.

Growth, body chemical composition and trypsin activity of South American catfish, surubim (<i>Pseudoplatystoma</i> sp.) juveniles fed different dietary protein and lipid levels
Journal Article
2013

NOP 13-A07 (English)

Aquaculture is gaining momentum in several parts of the world in recent years. Intensification has become a common practice in both finfish and shellfish culture to optimize the returns. High stocking densities, artificial feeding and fertilization have become common husbandry practices in both carp and shrimp culture systems. Due to intensification of culture practices, diseases of microbial etiology of economical significance has surfaced in rearing and grow out ponds and are major threat to the sustainability of the aquaculture industry. Synthetic chemicals and antibiotics have been used to prevent or treat fish and shrimp and have achieved at least partial success. Vaccination against specific pathogens has been developed recently with some success depending on the particular disease. An alternative approach has been the application of various compounds to boost or stimulate the innate immune system of farmed fish and shrimp. These compounds, termed immunostimulants is considered an attractive and promising agent for the prevention of diseases in fish and shellfish. In recent years, the established beneficial effects of immunostimulants in many livings systems promote their application for disease management in aquaculture practices.

Immunostimulants for Aquaculture Health Management
Journal Article
2013

NOP 14-A14 (English)

Ammonia nitrogen occurs in aquaculture systems as a waste product of protein metabolism by aquatic animals and degradation of organic matter, or in nitrogen. Exposure can reduce growth and increase susceptibility to diseases in aquatic species. Ammonia nitrogen concentrations vary with time of day, water depth and temperature, and increase as biomass and feed input increase. The best management is conservative stocking and feeding rates that minimize ammonia nitrogen and avoid excessive phytoplankton blooms pH.

Ammonia Toxicity Degrades Animal Health , Growth
Magazine Article
2013

NOP 13-A09 (English)

This article presents the use of a stochastic frontier production function to examine the efficiency of resource utilization in pond fish farming in Uganda. The study draws on data from a field survey administered to 200 small-scale fish farmers in three major fish farming districts in Central Uganda: Mukono, Mpigi and Wakiso. The districts were part of a large aquaculture development project funded by the United States Agency for International Development-Aquaculture and Fisheries Collaborative Research Support Program. Productive efficiency was analyzed using stochastic frontier analysis with a translog production function while assuming a truncated-normal distribution for the inefficiency term. The output variable was total quantity of fish produced, while input variables were quantity or value of inputs used in the production process, namely labor, pond size, stocking density, capital and feeds. The estimated index of resource-use efficiency revealed that small-scale farmers were inefficient in resources.

Efficiency of resource use among pond fish farmers in central Uganda: A stochastic frontier production function approach
Journal Article
2013

NOP 13-316 (English)

The worldwide growth of aquaculture has been accompanied by a rapid increase in therapeutic and prophylactic usage of antimicrobials including those important in human therapeutics. Approximately 80% of antimicrobials used in aquaculture enter the environment with their activity intact where they select for bacteria whose resistance arises from mutations or more importantly, from mobile genetic elements containing multiple resistance determinants transmissible to other bacteria. Such selection alters biodiversity in aquatic environments and the normal flora of fish and shellfish. The commonality of the mobilome (the total of all mobile genetic elements in a genome) between aquatic and terrestrial bacteria together with the presence of residual antimicrobials, biofilms, and high concentrations of bacteriophages where the aquatic environment may also be contaminated with pathogens of human and animal origin can stimulate exchange of genetic information between aquatic and terrestrial bacteria. Several recently found genetic elements and resistance determinants for quinolones, tetracyclines, and β-lactamases are shared between aquatic bacteria, fish pathogens, and human pathogens, and appear to have originated in aquatic bacteria. Excessive use of antimicrobials in aquaculture can thus potentially negatively impact animal and human health as well as the aquatic environment and should be better assessed and regulated.

Antimicrobial use in aquaculture re-examined: Its relevance to antimicrobial resistance and to animal and human health
Journal Article
2013

NOP 13-A03 (English)

As an alternative food source to wild fisheries, aquaculture shows a great potential to help meet the growing demand for seafood and animal protein. The expansion of aquaculture has been achieved partly by system intensification, which has drawn vast criticisms of aquaculture for its environmental, social and economic sustainability issues. Life cycle assessment (LCA) has become the leading tool for identifying key environmental impacts of seafood production systems. A LCA evaluates the sustainability of diverse aquaculture systems quantitatively from a cradle-to-grave perspective. It provides a scientific basis for analyzing system improvement and the development of certification and eco-labelling criteria. Current efforts focus on integrating local ecological and socio-economic impacts into the LCA framework. A LCA can play an important role in informing decision makers in order to achieve more sustainable seafood production and consumption. This article reviews recent applications of LCA in aquaculture, compares the environmental performance of different aquaculture production systems, explores the potential of including biodiversity issues into LCA analysis and examines the potential of LCA in setting criteria for certification and eco-labelling.

Role of life cycle assessment in sustainable aquaculture
Journal Article
2013

NOP 13-314 (English)

As aquaculture production expands, we must avoid mistakes made during increasing intensification of agriculture. Understanding environmental impacts and measures to mitigate them is important for designing responsible aquaculture production systems. There are four realistic goals that can make future aquaculture operations more sustainable and productive: (1) improvement of management practices to create more efficient and diverse systems at every production level; (2) emphasis on local decision making, human capacity development, and collective action to generate productive aquaculture systems that fit into societal constraints and demands; (3) development of risk management efforts for all systems that reduce disease problems, eliminate antibiotic and drug abuse, and prevent exotic organism introduction into local waters; and (4) creation of systems to better identify more sustainably grown aquaculture products in the market and promote them to individual consumers. By 2050, seafood will be predominantly sourced through aquaculture, including not only finfish and invertebrates but also seaweeds.

Responsible Aquaculture in 2050: Valuing Local Conditions and Human Innovations Will Be Key to Success
Journal Article
2013
Duffy, T. A., M. E. Picha, R. J. Borski, and D. O. Conover. 2013. Circulating levels of plasma IGF-I during recovery from size-selective harvesting in Menidia menidia. Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology 166(2):222 - 227. Retrieved (http://dx.doi.org/10.1016/j.cbpa.2013.06.001).
NOP 13-320 (English)

NOP 13-320 (English)

Selection for growth-related traits in domesticated fishes often results in predictable changes within the growth hormone-insulin-like growth factor (GH-I GF-1) axis. Little is known about the mechanisms controlling changes in growth capacity resulting from fishery-induced evolution. We took advantage of a long-term study where Menidia menidia were selected for size at age over multiple generations to mimic fisheries-induced selection. This selection regime produced three populations with significant differences in intrinsic growth rate. These growth differences partially rebounded, but persisted even after selection was relaxed, resulting in fast, intermediate, and slow-growing lines. Plasma IGF-1 was measured in these populations as a potential target of selection on growth. IGF-1 was significantly correlated with current length and mass, and was positively correlated with growth rate (g d-1) in two lines, indicating it may be an appropriate indicator of growth capacity. The slow-growing line exhibited higher overall IGF-1 levels relative to the depressed IGF-1 seen in the fast-growing line, contrary to our prediction. We offer possible explanations for this unusual pattern and argue that somatic growth is likely to be under control of mechanism(s) downstream to IGF-1. IGF-1 provides an interesting basis for understanding endocrine control of growth in response to artificial selection and recovery.

Circulating levels of plasma IGF-I during recovery from size-selective harvesting in Menidia menidia
Journal Article
2013

NOP 13-318 (English)

An experiment was conducted in 12 earthen ponds of 200 m2 at Kathar VDC, Chitwan, Nepal for 270 days to analyze the productivity and nutrient budget in some carp based polyculture systems. The experiment was conducted in a completely randomized design with four treatments in triplicate each: a) Carps only or control (7000 fish/ha) (T1); b) Carps (7000/ha) + tilapia (3000/ha) (T2); c) Carps (7000/ha) + tilapia (3000/ha) + sahar (500/ha) (T3); and d) Carps (7000/ha) + tilapia (3000/ha) + sahar (1000/ha) (T4). Silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella), rohu (Labeo rohita) and mrigal (Cirrhinus mrigala) of mean stocking size 3.0, 4.2, 10.0, 18.8, 10.5, 2.2 g, respectively were stocked in all ponds at the ratio of 4:2:1:1:1:1. The mean stocking size of Nile tilapia (Oreochromis niloticus) and sahar (Tor putitora) were 9.7 and 3.4 g, respectively. The ponds were fertilized weekly with urea and di-ammonium phosphate @ 4 g N and 1 g P/m2/day. Fish were fed with locally made pellet feed (20% CP) once in an alternate day at @ 2% body weight. At harvest, the extrapolated fish yield ranged from 1.5 to 1.7 t/ha/year in different treatments, without significant differences among treatments (P > 0.05). Inclusion of sahar in Nile tilapia ponds decreased recruits by 63 to 72%. There were no significant differences in water quality parameters among treatments, except dissolved oxygen concentration, which was significantly lower in T1 and T3 than T2 and T4 (p < 0.05). Both nitrogen and phosphorous were gained from fish species and lost from soil and water. There were no significant differences in nitrogen and phosphorous contents of all inputs and outputs among treatments. The unaccounted nitrogen and phosphorous loss ranged from 9.8 - 17.1% and 51.2 - 64.4%, respectively. The nitrogen and phosphorous required for producing 1 kg fish ranged from 337.5 - 375.9 g and 130.3 - 150.9 g, without significant difference among treatments. The nitrogen and phosphorous discharged for producing 1 kg fish ranged from 1.59 - 4.35 g and 1.6 - 9.3 g, respectively.

Nitrogen and Phosphorous Budget Analysis of Carp Based Polyculture Ponds in Chitwan , Nepal
Journal Article
2013

NOP 13-A08 (English)

An experiment was conducted on environmental implications and its impact on aquatic productivity in the southwest coastal region for a period of 2 months (May-June/2013). Five Rivers such as Pira River, Andarmanik River, Sonatala River, Khaprabhanga River and Rupsaha River were selected for sample collection and were treated as T-1 , T-2 , T-3, T-4 and T-5 . Three sampling sites were selected from each River based on salinity. The overall mean values of water temperature were 28.17 ± 0.98, 27.41 ± 1.21, 28.12 ± 1.11 and 27.13 ± 1.26, 26.62 ± 1.01 0 C in treatment T-1, T-2, T-3, T-4 and T-5, respectively. The mean values of water transparency of treatments T-1, T-2, T-3, T-4, and T-5 were 36.00 ± 1.26, 31.0 ± 0.0894, 34.00 ± 1.94, 28.00 ± 1.46 and 31.00 ± 1.86cm, respectively. The overall mean values of water temperature were 6.56 ± 0.12, 6.47 ± 0.23, 6.34 ± 0.12, 6.19 ± 0.22, and 6.67 ± 0.29 ppm in treatment T-1, T-2, T-3, T-4 and T-5 respectively. pH values were found to fluctuate from 6.72 to 7.64, 6.48 to 7.13, 6.95 to 7.35 and 6.86 to 7.6 in treatment T-1, T-2, T-3, T-4 and T-5 respectively. Mean values of total salinity were 2.17 ± 0.12, 6.17 ± 0.82, 7.17 ± 0.92, 10.17 ± 0.1.12 and 1.78 ± 0.12 mg/l in treatment T-1, T-2, T3, T-4 and T-5 respectively. Mean values of total alkalinity were 187.5 ± 2.25, 165.5 ± 3.1, 185.5 ± 2.15, 175 ± 2.5 and 180.5 ± 3 mg/l in treatment T-1, T-2, T-3, T-4 and T-5 respectively. Mean values of total alkalinity were 187.5 ± 2.25, 165.5 ± 3.1, 185.5 ± 2.15, 175 ± 2.5 and 180.5 ± 3 mg/l in treatment T-1, T-2, T-3, T-4 and T-5 respectively. Mean values of total alkalinity were 187.5 ± 2.25, 165.5 ± 3.1, 185.5 ± 2.15, 175 ± 2.5 and 180.5 ± 3 mg/l in treatment T-1, T-2, T-3, T-4 and T-5 respectively. Total hardness of water was found to range from 37 mg/l to 199 mg/l. The mean values of NH3-N (mgl -1 ) were found to vary from 0.23 ± 0.03 ,0.27 ± 0.08, 0.23 ± 0.03, 0.25 ± 0.03 and 0.27 ± 0.05 mgl -1 in treatment T-1, T-2, T-3, T-4 and T-5 respectively. The mean values of nitrite (NO2) concentration were 0.63 ± 0.06, 0.68 ± 0.08, 0.67 ± 0.09, 0.73 ± 0.03 and 0.67 ± 0.06 mgl -1 in treatment T-1, T-2, T-3, T-4 and T-5 respectively. There were no significantly different of temperature, dissolved oxygen pH and alkalinity among the treatments but significance difference found in transparency, salinity, hardness, ammonia, nitrite using ANOVA (P < 0.05). Ammonia and nitrite concentration of Rupsha River (T-5) higher than other four Rivers due to municipal waste product of Khulna city. A proportionally strong relationship was found among salinity, transparency and hardness. Highest concentration of phytoplankton was found in Rupsha River (lowest salinity) and lowest phytoplankton concentration was found in Khaprabhanga River (highest salinity).

Study on Environmental Implications and Its Impact on Aquatic Productivity in the Southwest Coastal Region
Journal Article
2013

NOP 13-321 (English)

Glucocorticoids (GCs) regulate an array of physiological responses in vertebrates. Genomic GC actions mediated by nuclear steroid receptors require a lag time on the order of hours to days to generate an appreciable physiological response. Experimental evidence has accumulated that GCs, can also act rapidly through a non-genomic mechanism to modulate cellular physiology in vertebrates. Causal evidence in the Mozambique tilapia (Oreochromis mossambicus) suggests that the GC cortisol exerts rapid, non-genomic actions in the gills, liver, and pituitary of this euryhaline teleost, but the membrane receptor mediating these actions has not been characterized. Radio-receptor binding assays were conducted to identify a putative GC membrane receptor site in O. mossambicus. The tissue distribution, binding kinetics, and pharmacological signature of the GC membrane-binding activity were characterized. High affinity (Kd=9.527 , 0.001nM), low-capacity (Bmax = 1.008 , 0.116fmol/mg protein) [3H] cortisol binding was identified on plasma membranes prepared from the livers and a lower affinity (Kd=30.08 , 2.373nM), low capacity (Bmax = 4.690 , 2.373 fmol/mg protein) binding was found in kidney membrane preparations. Competitors with high binding affinity for nuclear GC receptors, mifepristone (RU486), dexamethasone, and 11-deoxycorticosterone, displayed no affinity for the membrane GC receptor. The association and dissociation kinetics of [3H] cortisol binding to membranes were orders of magnitude faster (t1/2=1.7-2.6min) than those for the intracellular (nuclear) GC receptor (t1/2=10.2h). Specific [3H] cortisol membrane binding was also detected in the gill and pituitary but not in brain tissue. This study represents the first characterization of a membrane GC receptor in fishes and one of only a few characterized in vertebrates.

Characterization of membrane receptor binding activity for cortisol in the liver and kidney of the euryhaline teleost, Mozambique tilapia (<i>Oreochromis mossambicus</i>)
Journal Article
2013

NOP 13-317 (English)

This paper used value chain analysis to determine economically viable opportunities for increased female participation in the aquaculture value chains in Kenya. The main opportunities for women are as fish marketers and as fish farmers, especially in the Western Province of Kenya. Fish marketing is economically more viable than fish farming with an overall benefit-cost ratio of over 1.00 while the benefit-cost ratios for fish farmers were less than 0.5. The western region had the strongest fish production sector compared to the Central Province and the Rift Valley and provides relatively better opportunities for women participation in fish production. In the Rift Valley Province, women could work as paid laborers on fish farms as this region showed the largest employment impact on the community from a growth in fish farming activities.

Economically feasible options for increased women participation in Kenyan aquaculture value chain
Journal Article
2013

NOP 13-A01 (English)

Prolactin (PRL) cells of the Mozambique tilapia, Oreochromis mossambicus, are osmoreceptors by virtue of their intrinsic osmosensitivity coupled with their ability to directly regulate hydromineral homeostasis through the actions of PRL. Layered upon this fundamental osmotic reflex is an array of endocrine control of PRL synthesis and secretion. Consistent with its role in fresh water (FW) osmoregulation, PRL release in tilapia increases as extracellular osmolality decreases. The hyposmotically-induced release of PRL can be enhanced or attenuated by a variety of hormones. Prolactin release has been shown to be stimulated by gonadotropin-releasing hormone (GnRH), 17-β-estradiol (E2), testosterone (T), thyrotropin-releasing hormone (TRH), atrial natriuretic peptide (ANP), brain-natriuretic peptide (BNP), C-type natriuretic peptide (CNP), ventricular natriuretic peptide (VNP), PRL-releasing peptide (PrRP), angiotensin II (ANG II), leptin, insulin-like growth factors (IGFs), ghrelin, and inhibited by somatostatin (SS), urotensin-II (U-II), dopamine, cortisol, ouabain and vasoactive intestinal peptide (VIP). This review is aimed at providing an overview of the hypothalamic and extra-hypothalamic hormones that regulate PRL release in euryhaline Mozambique tilapia, particularly in the context on how they may modulate osmoreception, and mediate the multifunctional actions of PRL. Also considered are the signal transduction pathways through which these secretagogues regulate PRL cell function. 

Endocrine regulation of prolactin cell function and modulation of osmoreception in the Mozambique tilapia
Journal Article
2013

NOP 13-315 (English)

We use global value chain (GVC) theory to understand governance of Vietnam's shrimp farming industry. We describe this GVC as buyer-driven with important food safety standards imposed by governments of importing countries and new certification systems promoted by nongovernmental organizations (NGOs). Governance relations are clear between governments in importing countries and Vietnam, and between importers and NGOs. Governance relations become more fragmented further down the chain where large numbers of small-scale producers and traders operate. This fragmentation may adversely affect access to the most lucrative markets and have the unanticipated effect of marginalizing small-scale farmers and traders.

Governance of Global Value Chains in Response to Food Safety and Certification Standards: The Case of Shrimp from Vietnam
Journal Article
2013

NOP 13-322 (English)

Compensatory growth (CG) is a period of accelerated growth that occurs following the alleviation of growth-stunting conditions during which an organism can make up for lost growth opportunity and potentially catch up in size with non-stunted cohorts. Fish show a particularly robust capacity for the response and have been the focus of numerous studies that demonstrate their ability to compensate for periods of fasting once food is made available again. CG is characterized by an elevated growth rate resulting from enhanced feed intake, mitogen production, and feed conversion efficiency. Because little is known about the underlying mechanisms that drive the response, this review describes the sequential endocrine adaptations that lead to CG; namely during the precedent catabolic phase (fasting) that taps endogenous energy reserves, and the following hyperanabolic phase (refeeding) when accelerated growth occurs. In order to elicit a CG response, endogenous energy reserves must first be moderately depleted, which alters endocrine profiles that enhance appetite and growth potential. During this catabolic phase, elevated ghrelin and growth hormone (GH) production increase appetite and protein-sparing lipolysis, while insulin-like growth factors (IGFs) are suppressed, primarily due to hepatic GH resistance. During refeeding, temporal hyperphagia provides an influx of energy and metabolic substrates that are then allocated to somatic growth by resumed IGF signaling. Under the right conditions, refeeding results in hyperanabolism and a steepened growth trajectory relative to constantly fed controls. The response wanes as energy reserves are re-accumulated and homeostasis is restored. We ascribe possible roles for select appetite and growth-regulatory hormones in the context of the prerequisite of these catabolic and hyperanabolic phases of the CG response in teleosts, with emphasis on GH, IGFs, cortisol, somatostatin, neuropeptide Y, ghrelin, and leptin.

Endocrine regulation of compensatory growth in fish
Journal Article
2013

2012

NOP 12-300 (English)

Biological assessment of aquatic ecosystems is widely employed as an alternative or complement to chemical and toxicity testing due to numerous advantages of using biota to determine ecosystem condition. These advantages, especially to developing countries, include the relatively low cost and technical requirements. This study was conducted to determine the biological impacts of aquaculture operations on effluent-receiving streams in the Ashanti Region of Ghana. We collected water, fish and benthic macroinvertebrate samples from 12 aquaculture effluent-receiving streams upstream and downstream of fish farms and 12 reference streams between May and August of 2009, and then calculated structural and functional metrics for biotic assemblages. Fish species with non-guarding mode of reproduction were more abundant in reference streams than downstream (P = 0.0214) and upstream (P = 0.0251), and sand-detritus spawning fish were less predominant in reference stream than upstream (P = 0.0222) and marginally less in downstream locations (P = 0.0539). A possible subsidy-stress response of macroinvertebrate family richness and abundance was also observed, with nutrient (nitrogen) augmentation from aquaculture and other farming activities likely. Generally, there were no, or only marginal differences among locations downstream and upstream of fish farms and in reference streams in terms of several other biotic metrics considered. Therefore, the scale of impact in the future will depend not only on the management of nutrient augmentation from pond effluents, but also on the consideration of nutrient discharges from other industries like fruit and vegetable farming within the study area.

Biological assessment of aquaculture effects on effluent-receiving streams in Ghana using structural and functional composition of fish and macroinvertebrate assemblages
Journal Article
2012

NOP 12-299 (English)

This paper reports the results of a survey conducted to assess the development impacts of USAID-supported aquaculture training programs conducted at three institutions of higher education in Kenya and Thailand. All program participants interviewed reported that they acquired specific knowledge, skills, and attitudes during the training and that it has had an important impact on their professional development. The programs have also had a marked effect on the institutions where the participants now work. Short-term training in the U.S. and short-term training in one’s home country were rated as more effective training models than long-term training in the U.S.

Development Impacts of Long-term Aquaculture Training Programs Conducted in Kenya and Thailand
Journal Article
2012

NOP 12-A04 (English)

Worldwide, rapid expansion of the market for Oreochromis spp. (tilapia) has increased the incentive for culturists to optimize the profitability of production techniques for these fishes. The establishment of best management practices for tilapia production has been slow, in part because they are omnivorous and relatively easy to grow. Their wide distribution in subtropical and tropical areas and the ease of adaptation to different culture methods have contributed to the highly variable approaches that are used to cultivate tilapia commercially. Ongoing refinement of the efficiency of tilapia culture in response to environmental, nutritional, and genetic variables is reliant on accurate assessment of growth rates. We describe herein a molecular method for the rapid assessment of the growth status of these fish. Earlier trials of culture conditions have been dependent on expensive commercial-scale production trials and labor-intensive physical measurements of growth, but expression of the insulin-like growth factor-I (IGF-I) gene provides a nearly instantaneous indicator of the growth status of these fishes. The relative accuracy and efficiency of quantifying the hepatic mRNA (messenger RNA) for this growth regulatory compound and its applicability as a growth indicator or marker in tilapia are discussed. We conclude that IGF-I mRNA abundance is suitable as an alternative approach to the assessment of growth during trials of the relative effectiveness of experimental culture conditions.

Production, Growth, and Insulin-Like Growth Factor-I (IGF-I) Gene Expression as an Instantaneous Growth Indicator in Nile Tilapia <i>Oreochromis niloticus</i>
Book Chapter
2012
Bukenya, J. O., T. S. Hyuha, J. Twinamasiko, and J. J. Molnar. 2012. Economics of Fish Marketing in Central Uganda: A Preliminary Analysis. Pp. 27 - 27 in Southern Agricultural Economics Association (SAEA), Southern Agricultural Economics Association (SAEA). Birmingham, AL. Retrieved (http://ageconsearch.umn.edu/record/119527).
NOP 12-A08 (English)

NOP 12-A08 (English)

The paper examines profitability and market performance of small-scale fish traders selected randomly from a cross-section of nine fish markets in four districts in Central Uganda. Data were collected through a structured questionnaire which was designed to solicit information on traders’ socio-economic characteristics, marketing characteristics, operating costs and returns, and problems associated with fish marketing in the study area. Percentages were used to describe the socio-economic characteristics, market characteristic and problems associated with fish marketing while gross profit and marketing performance models were used to determine profitability, marketing margin and operational efficiency, respectively. The results suggest that fish trade is carried out by both men and women. More men are involved in the trade of fresh fish while more women are involved in the processed (sundried/smoked) fish trade. Some traders dealt in more than one species of fish although a majority sold exclusively in one species. Gross profit was estimated at USh358.40/kg and USh234.73/kg for wholesalers and retailers, respectively, with marketing margins of 19.32% and 16.67% for wholesalers and retailers, respectively. The market operational efficiency was 279.27 percent, implying high efficiency in fish marketing in the study area. The major pressing concerns which included high supply cost, low prices, low fish supply and increased arrests for selling immature fish were common to both retail and wholesale marketing channels.

Economics of Fish Marketing in Central Uganda: A Preliminary Analysis
Conference Paper
2012

NOP 12-302 (English)

Levels of seven hemolymph parameters (considered as indicators of physiological and immune status of organisms) in pond-reared (PR) and lake pen-cultured (PC) adult Chinese mitten crabs sampled from three experimental sites viz., a pond at Huangjin Lake area, a net-pen in the Huangjin Lake and a pond at Lu Lake area were analysed. Two sites in the Huangjin Lake area where the pond meets the lake, possessed good water quality whereas at Lu Lake area where the pond was not connected to the Lu Lake, the water quality was relatively poor. Hemocyanin content and total hemocytes count in PR crabs from Lu Lake area were significantly lower than those of PR and PC crabs from Huangjin Lake area, indicating PR crabs from Lu Lake area had relatively poor physiological and immune status. There were no significant differences in hemolymph profiles between PR and PC crabs from Huangjin Lake area. These results indicate that water quality had a significant effect on the physiological and immune status of cultured Chinese mitten crabs. The results indicate that pond-rearing is better for culture of Chinese mitten crabs, especially in ponds which are connected to natural water resources.

Hemolymph profiles of pond-reared and lake pen-cultured adult Chinese mitten crab, <i>Eriocheir sinensis</i>
Journal Article
2012

NOP 12-313 (English)

To study the variation characteristics and correlation of major ecological factors in intensive shrimp farming ponds, we measured 16 aquatic ecological factors including the concentration of chlorophyll a (Chl-a) as well as the density of zooplankton, heterotrophic bacteria and vibrio, active phosphorus (PO4 3- -P), etc. in 3 farming ponds of Litopenaeus vannamei in Paipu, Danzhou, from April to July in 2011. The results show that the values of DO, pH and transparency decreased slowly, and the total suspended solids (TSS), chemical oxygen demand (COD), nitrite nitrogen( NO2 --N), ammonia nitrogen( NH4 + -N) as well as the density of zooplankton, heterotrophic bacteria and vibrio slowly increased during the culture period. The concentration of Chl-a was low in the earlier stage but increased gradually in the mid and latter stages; Chl-a had a very significant positive correlation with NO3 - -N and a negative correlation with PO4 3- -P. The density of Copepod had a very significantly positive correlation with TSS and a significantly positive correlation with the density of heterotrophic bacteria, vibrio and rotifer, but had no significant correlation with Chl-a and COD. The density of heterotrophic bacteria had a very significant positive correlation with COD and TSS, but had a significantly negative correlation with transparency. The density of vibrio was very significantly correlated with TSS and COD, but had a significantly negative correlation with pH and DO.

Study on variation characteristics and correlation analysis of major ecological factors in intensive shrimp ponds
Journal Article
2012

NOP 12-310 (English)

Integrated multi-trophic aquaculture (IMTA) seeks to biodiversify fed aquaculture (e.g. finfish or shrimps) with extractive aquaculture, recapturing the inorganic (e.g. seaweeds) and organic (e.g. suspension- and deposit-feeders) nutrients from fed aquaculture for their growth. The combination fed/extractive aquaculture aims to engineer food production systems providing both biomitigative services to the ecosystem and improved economic farm output through the co-cultivation of complementary species. Major rethinking is needed regarding the definition of an 'aquaculture farm' and how it works within an ecosystem. The economic values of the environmental/societal services of extractive species should be recognized and accounted for in the evaluation of the full value of these IMTA components. Seaweeds and invertebrates produced in IMTA systems should be considered as candidates for nutrient/carbon trading credits. While organic loading from aquaculture has been associated with localized benthic impacts, there have also been occurrences of increased biodiversity and abundance of wild species in response to moderate nutrient enrichment and the use of infrastructures as substrates. To develop efficient food production systems, it will be important to understand and use the duality of nutrients (essential when limiting/polluting when in excess) to engineer systems producing them in moderation so that they can be partially recaptured while maintaining their concentrations optimal for healthy and productive ecosystems. Measures of species diversity, colonization rates, abundance, growth and ecosystem functions with respect to nutrient partitioning and recycling, species interactions and control of diseases could represent valid indicators for the development of robust performance metrics.

Open-water integrated multi-trophic aquaculture: Environmental biomitigation and economic diversification of fed aquaculture by extractive aquaculture
Journal Article
2012

NOP 12-308 (English)

The Pacific fat sleeper is a potential species for aquaculture in Latin American countries. Nevertheless, production depends on wild caught juveniles, thus needing hatchery produced larvae. Objective: the purpose of this study was to determine the ideal conditions for viable gamete release and larvae laboratory production. Methods: a total of 16 mature male and 16 female fish were allocated to one of four groups (n = 4) that were injected with either saline solution, Desgly10-Ala6 LHRHa, salmon GnRHa + domperidone, or implanted with salmon GnRHa. Results: spermiation was observed in all treatments. Spawning rates were 100% at 24 and 48 h for the GnRHa implanted group, 25% for the LHRHa group, and 0% for the salmon GnRHa + domperidone group (48-72 h post injection). Conclusion: GnRHa and LHRHa are a successful tool for chame induced reproduction. A gross morphological description of oocytes, sperm quality, and first stages of larval development is included.

Production of "Chame" (<i>Dormitator latifrons</i>, Pisces: Eleotridae) larvae using GnRHa and LHRHa
Journal Article
2012

NOP 12-307 (English)

The effects of aquaculture on the environment have been the subject of much examination, but most of the focus has been on shrimp and salmon. These are not the most common species grown in aquaculture, nor the most common systems used. About 60% of production today uses lower intensity culture to produce organisms in natural systems such as ponds. This paper is an overview of the positive and negative environmental impacts of lower intensity aquaculture. The ranked positive impacts of lower intensity aquaculture include: conservation aquaculture that supplements reproduction in natural populations; improving the quality of natural waters through filtering or consuming wastes by cultured organisms; reducing pressure on wild stocks by providing alternative sources in the market; and replacing damaging employment with more sustainable aquaculture jobs. Negative impacts include: escapement of alien species that become invasive; eutrophication of receiving waters from pond effluents; release of parasites and diseases into natural communities; escapement of unique genotypes resulting in genetic alteration of native stocks; land degradation due to pond construction; release of antibiotics or other drugs into receiving waters; depletion of natural resources such as water; loss of benthic biodiversity from settling of sediments; and reductions in natural populations by collection of larval or juvenile fish. Some impacts, especially the use of fishmeal and the transmission of disease, are much less common in lower intensity aquaculture systems. Aquaculture has an important role in current and future food production, and in many cases lower intensity aquaculture provides a sustainable solution to increased aquaculture production.

Is lower intensity aquaculture a valuable means of producing food? An evaluation of its effects on near-shore and inland waters
Journal Article
2012

NOP 12-301 (English)

The AquaFish Collaborative Research Support Program (CRSP) is dedicated to improving gender equality in the aquaculture and fisheries sectors and in the CRSP by creating equal opportunities for women and men in research, training and educational activities. Recognizing the barriers and complex issues women face, the AquaFish CRSP has taken a mindful approach towards gender integration by focusing on women beneficiaries of its research and outreach, and on women in the Program. Gender must be included in projects in a cross cutting and an individual way. Despite these steps, gender-segregated statistics from AquaFish display characteristics of a “leaky pipeline” as seen in other fields of science. During the original Pond Dynamics/Aquaculture CRSP (PD/A) and the subsequent Aquaculture CRSP (ACRSP) (1982-2008), 36.8% collectively, of degree students were women. In the AquaFish CRSP (2006-current), 55 women (55%) of degrees have been awarded to women. Although reaching a 50% target for women is a major accomplishment, the same proportion is not entering higher positions in science or research careers. Surprisingly, women still make up less than 50% of the CRSP short-term trainees. More research is needed to understand leaks in the pipeline and barriers to women’s participation. 

Improving Gender Equity in Aquaculture Education and Training: 30 years of Experiences in the Pond Dynamics/Aquaculture, Aquaculture, and AquaFish Collaborative Research Support Programs
Journal Article
2012

NOP 12-A10 (English)

Poverty and population growth threaten the biodiversity of the Cojimies Estuary and its watershed. Within the estuary lies the Mache-Chindul Reserve, where people live almost exclusively on fishing, shellfishing, subsistence agriculture shrimp farming, wood cutting and breeding livestock. People here have few alternatives for income generation, lack basic services and infrastructure, and have low levels of education. Combined, these factors lead people to worry more about meeting basic needs than about how their livelihoods impact biodiversity. Meanwhile, open access fishing, mangrove-cutting and illegal logging of tropical forests have led to widespread biodiversity loss. [Note: this excerpt is first paragraph of publication.]

Chame (<i>Dormitator latifrons</i>) Aquaculture in Cojimies Estuary: An Option for Livelihood Diversification in Rural Ecuador
Report
2012

NOP 14-A10 (English)

Variation in fish stocking densities translate to difference in growth performance, yields and economic benefits in fish culture. Transferring fish directly from hatcheries to the cages or ponds may induce stress. We evaluated the stress response of Labeo Victoria (Labeo victorianus) in an integrated cage-cum-pond culture during transfer of fish from the hatchery to the cages and ponds at different cage stocking densities. Cages were stocked at varying densities of 10, 30, 60, 90, 120, 150 and 180 fish/m3 and suspended in a static pond of 200 m2. The L. victorianus fingerlings of a mean weight 23.6 ± 1.8 g were stocked in the cages and the pond respectively. 20 fish were sampled during the transfer period from the hatchery to ponds and cages for analysis of primary and secondary parameters of stress response. Primary stress response occurred when fish were directly transferred to cages and ponds at stocking density ≥ 60 fish/m3 and 90 fish/m3 respectively. Parameters of secondary stress response occurred in fish transferred to the cages at stocking density ≥ 120 fish/m3 and in ponds at density ≥ 150 fish/m3. Transfer of fish directly from the hatchery to the ponds induce primary and secondary stress.

Dynamic of Stress Response in Victoria Labeo (<i>Labeo victorianus</i>) during transfer from the Hatchery to cages and Ponds under Differential Caged Stocking Densities
Journal Article
2012

NOP 12-305 (English)

The red swamp crayfish (Procambarus clarkii) was introduced to China in the early 20th century. It has been spread to almost all forms of fresh water bodies including lakes, rivers and even paddyfields in most provinces of China. To clarify issues such as the initial entry point(s), dispersal pattern, genetic diversity and genetic structure of Procambarus clarkii in China, the genetic structure and diversity of P. clarkii populations at 37 sampling sites (35 from China, one from the USA and one from Japan) were analyzed using both mitochondrial gene sequences (COI and 16S rRNA) and 12 nuclear microsatellites. Multiple tests including phylogenetic analyses, Bayesian assignment and analysis of isolation by distance showed that (i) the population from Japan and those collected from China, particularly from NanJing (BGt and XG) and its some neighboring sites (CJr, NT and NB), have similar genetic composition, (ii) relatively high genetic diversity was detected in Chinese populations, (iii) the P. clarkii populations in China did not experience significant population expansions. Taken together, Nanjing, Jiangsu province is the presumed initial entry point, and human-mediated dispersal and adaptive variation are likely responsible for the observed genetic pattern of P. clarkii in China.

Population genetic structure and post-establishment dispersal patterns of the red swamp crayfish <i>Procambarus clarkii</i> in china
Journal Article
2012

NOP 12-311 (English)

From May to September in 2010, water quality parameters such as water temperature, total dissolved salt, dissolved oxygen, pH, transparency, nitrite nitrogen, ammonia nitrogen, nitrate nitrogen, total nitrogen, reactive phosphorus, chlorophyll-a and biochemical oxygen demand were analyzed in 22 Litopenaeus vannamei ponds with different culturing methods in Fengxian District, Shanghai. Water used for Farm No. 1 was natural fresh water which had been precipitated before being introduced to the ponds. Mixed salt were added to the freshwater for culturing shrimp in Farm No. 2. Results were as follows: water temperature, dissolved oxygen and pH didn’t change dramatically and could match the demand of Litopenaeus vannamei. The proportion of nitrate nitrogen in ponds to TIN was the highest, the ratio of ammonia nitrogen to TIN increased with time extension, and that of nitrite nitrogen to TIN increased obviously in the later period of the culture cycle. Contents of reactive phosphorus decreased gradually while the total phosphorus increased in the whole process of culture. Biochemical oxygen demand and chlorophyll-a also increased gradually with the shrimp growing up. Muscle nutritional quality of Litopenaeus vannamei from the two farms were analyzed and the result were as follows: contents of crude protein and crude fat of shrimp muscle in Farm No. 1 were 16.30% and 1.42% respectively, lower than those in shrimp muscle from Farm No. 2 which were 18.30% and 1.61%. Content of total amino acids in shrimp from Farm No. 1 was 23.27%, and the essential amino-acid was 9.09%. While those in shrimp from Farm No. 2 were 27.52% and 10.74% respectively. Contents of flavor amino acids in shrimp Farms No. 1 and 2 were 8.52% and 10.16% respectively.

Comparative analysis of water quality in <i>Litopenaeus vannamei</i> ponds and nutritional quality of shrimp muscle
Journal Article
2012

NOP 12-303 (English)

The expression of the prophenoloxidase (proPO) gene was investigated in nine tissues of red swamp crayfish Procambarus clarkii, by real-time PCR after challenges by CpG oligodeoxynucleotide (ODN), Aeromonas hydrophila and white spot syndrome virus (WSSV). The results can be summarized as follows: (i) the expression level of the proPO gene in haemocytes was highest among nine studied tissues before the challenge; (ii) the expression of proPO increased in all studied tissues after stimulation by CpG ODN and WSSV, and also increased in all tissues, except the ovary, after the A. hydrophila challenge; (iii) the whole expression profiles were different, suggesting that different immune mechanisms may exist for crayfish that are resistant to WSSV and A. hydrophila, although the expression in haemocytes was similar before and after the WSSV and A. hydrophila challenges.

The expression of prophenoloxidase mRNA in red swamp crayfish, <i>Procambarus clarkii</i>, when it was challenged
Journal Article
2012
Qin, L., and S. Buccola. 2012. Econometric Assessment of Research Programs: A Bayesian Approach. Pp. 1 - 21 in Proceedings of the Agricultural and Applied Economics Association's 2012 Annual Meeting, Proceedings of the Agricultural and Applied Economics Association's 2012 Annual Meeting. Seattle, Washington. Retrieved (http://ageconsearch.umn.edu/record/124948/files/Qin-Buccola_ AAEA Selected Paper.pdf?version=1).
NOP 12-A05 (English)

NOP 12-A05 (English)

Effective research-project assessment typically is impeded by project variety. In particular, bibliometric approaches to science assessment tend to offer little information about the content of the projects examined. We introduce here a new approach – based on Bayesian theory – of econometrically evaluating the factors affecting scientific discovery, and use the method to assess a biological research program comprised of numerous heterogeneous projects. Our knowledge metric not only flexibly accommodates project variety but accounts for information in “failed” as well as “successful” studies. Using a mean-absolute-deviation utility functional form to measure new scientific knowledge, we decompose knowledge gain into a mean-surprise and statistical-accuracy effect. The two effects are econometrically examined independently, and then combined into the net knowledge production function. Research FTE and distance to study site have statistically significant but moderate effects on the amount by which research shifts the prediction of scientific outcome. However, scientist education powerfully improves the research study’s predictive accuracy or precision, a one-percent boost in the average investigator’s formal schooling improving precision by 4.3 percent. Largely on the basis of that precision effect, increasing returns to research project scale are evident.

Econometric Assessment of Research Programs: A Bayesian Approach
Conference Paper
2012

NOP 12-312 (English)

In order to overcome the losses caused by long-distance transportation, we try to use artificial seawater for Penaeus vannamei larval breeding locally. In 2011, we added seawater crystal and coarse salt to the natural freshwater from adjacent river for Penaeus vannamei larval breeding in Fengxian district of Shanghai. During the breeding period, we monitored water quality everyday and the results were as following: DO was 7.3(±0.10) mg/L, pH was 8.00(±0.04), temperature was 28.2(±0.20)°C, PO4–P was 0.88(±0.14) mg/L, TP was 1.46(±0.14) mg/L, NO2-–N was 0.21(±0.02) mg/L, NO3-–N was 1.52(±0.10) mg/L, TNH4–N was 2.88(±0.34) mg/L, TN was 7.01(±0.36) mg/L, and CODMn was 18.05 (±1.40) mg/L. Biological and chemical methods were used for water quality control to create a good environment for larval growth.

Research on artificial seawater quality in the <i>Penaeus vannamei</i> larval breeding ponds
Journal Article
2012

NOP 12-A09 (English)

The nibbling frequency of five carp species (rohu Labeo rohita, mrigal Cirrhinus mrigala, catla Catla catla, common carp Cyprinus carpio, silver carp Hypophthalmichthys molitrix) on bamboo lateral sticks (kanchi) colonized by periphyton was examined in fed and unfed systems. There were three treatments: (a) no carp and no supplemental feed (control), (b) carp without supplemental feeding (unfed treatment), and (c) carp with supplemental feeding (fed treatment). For 12 h (07:30-19:30) during six days, nibbling behavior was observed in real time via a digital video camera and recorded on a camcorder for later viewing. Rohu, catla, and common carp nibbled on the kanchi, while mrigal and silver carp did not. In rohu and catla, the nibbling frequency was significantly higher in the unfed treatment than in the fed treatment (p<0.05); supplemental feeding reduced nibbling frequency by 81% and 91%, respectively. Hence, in periphyton-based aquaculture systems, there is no need for a high density of substrates in ponds that receive supplemental feed. Alternatively, the amount of supplied feed can be reduced to force these species to consume more periphyton.

Nibbling Frequency of Carps in Periphyton-Based Aquaculture Systems with and without Supplemental Feed
Journal Article
2012

NOP 12-A01 (English)

Seven criteria (water requirement, water temperature, soil texture, terrain slope, potential farm gate sales, availability of farm inputs, and access to local and regional markets) were analyzed to determine site suitability for tilapia and clarias farming in Uganda. Crisp and fuzzy approaches of criterion classification were implemented using GIS, and the results were compared. There was a statistically significant difference between maps generated by crisp and fuzzy approaches. For both the crisp and the fuzzy approaches, over 98% of the land was classified as moderately suitable or suitable. Overall, the crisp method classified 16,322 hectares (0.09%) as very suitable compared to zero hectares (0%) by the fuzzy method. Simultaneously, the crisp method gave 297,344 hectares (1.96%) as unsuitable compared to 168,592 hectares (0.96%) by the fuzzy method. Of the 138 surveyed fishponds that were operational, the crisp method classified 71% as suitable and 29% as moderately suitable, while the fuzzy method classified 71.7% as suitable and 28.3% as moderately suitable.

Geospatial Modeling of Site Suitability for Pond-Based Tilapia and Clarias Farming in Uganda
Journal Article
2012

NOP 12-A02 (English)

The effect of the dietary protein level on growth and total body chemical composition of the native cichlid Bay snook (Petenia splendida), masculinized and non-masculinized, was studied. Five semi-purified diets with protein levels 35, 40, 45, 50 and 55% crude protein (CP) were formulated and evaluated by triplicate. Groups of 50 juveniles were each stocked in 70 L tanks and fed to apparent satiation for 42 days trial. At the end, weight gain (WG) (403.41%), body length (BL) (6.58 ± 0.10 cm) and specific growth rate (SRG) (1.67%/day) of the masculinized fish were obtained with the 45% CP diet, and they were significantly different (p = 0.002) from the other treatments. In the case of non-masculinized fish, the 45 and 55% CP treatments showed significant differences (p = 0.00001), with respect to other treatments, with a WG of 398 and 394%, SGR of 1.66 and 1.63%/day, protein productive value (PPV) of 28.91 and 29.21%, and feed conversion rate (FCR) of 1.23 and 1.08 respectively. Protein body composition for masculinized fish was different (p = 0.0001) only for fish fed 35% CP compared with fish at the beginning of the experiment. We conclude that the optimum protein requirement, estimated by the broken-line model for masculinized and non-masculinized P. splendida was 45 and 44.8% PC respectively.

Protein requirement in masculinized and non-masculinized juveniles of Bay Snook <i>Petenia splendida</i>
Journal Article
2012
Verri, T. et al. 2012. The SoLute Carrier (SLC) Family Series in Teleost Fish. Pp. 219 - 320 in Functional Genomics in Aquaculture, Functional Genomics in Aquaculture.
NOP 12-A07 (English)

NOP 12-A07 (English)

Human genes encoding passive transporters, ion-coupled transporters, and exchangers are all included in the so-called SoLute Carrier (SLC) gene series (the Human Genome Organization Gene Nomenclature Committee; http://www.genenames.org/), consisting of 51 families and at least 378 genes (http://www.bioparadigms.org). Ortholog genes encoding for transport proteins of the SLC series have comparatively been described in teleost fish, although their functional properties, in terms of kinetic parameters, substrate specificities, and inhibition patterns of the expressed transport proteins, have only sporadically been assessed in vitro. This chapter gives the latest updates for the SLC families and their members in teleost fish as well as relevant links to GenBank database and literature. By using a functional genomics approach, a list (version 1.0) of all currently known SLC families in teleost fish is provided in the form of SLC tables. 

The SoLute Carrier (SLC) gene family series encodes membrane transporters (Hediger et al. 2004). In humans, the SLC family series comprises 51 gene families having at least 378 functional protien-coding genes (http://www.bioparadigms.org). The gene products include passivetransporters (alias facilitated or facilitative transporters or uniporters), co-transporters (alias symporters), and exchangers (alias antiporters), located in all cellular and subcellular membranes (with the apparent exception of the nuclear membrane). Passive transporters move one molecule at a time down a concentration gradient. Conversely, active transporters couple the movement of one type of ion or molecule against its concentration gradient to the movement of another ion or molecule down its concentration gradient. In particular, a co-transporter moves the transported molecule or ion and the co-transported molecule or ion in the same direction across a membrane, while an exchanger moves the transported molecule or ion and the cotransported molecule or ion in opposite directions. Transported substrates include amino acids and oligopeptides, glucose and other sugars, inorganic cations and anions, bile salts, carboxylate and other organic anions, acetyl coenzyme A, essential metals, biogenic amines, neurotransmitters, vitamins, fatty acids and lipids, nucleosides, ammonium, choline, thyroid hormone and urea, and many other solutes.

The SoLute Carrier (SLC) Family Series in Teleost Fish
Book Chapter
2012

NOP 12-A03 (English)(Spanish)

Common snook Centropomus undecimalis is a protandric fish with a high commercial importance and aquacultural potential in Mexico and the United States. Several studies indicate that females have higher growth capacity than males. For this reason, the objective of this research was to evaluate the effect of a 17β-estradiol (E2) diet supplementation on sex proportion for this species. In this sense, an experimental study was conducted where fish were fed for different time periods (7, 14, 21, 28, 35, and 42 days) with food impregnated with 50 mg of E2/Kg, and one control diet without the presence of the steroid. After feeding times, fish were raised for additional 204 days with the control diet to evaluate sex proportion, growth and survival. Our results showed that fish fed with E2 for 21 days or more had the highest female sex proportion (93-100%), while the control group showed the highest male proportion (100%). The highest growth (weight and total length) was detected in fish fed with E2 for 21 days (193.11 ± 1.83 mm and 28.56 ± 0.63 g) compared with the rest of the treatments. Survival did not show statistical differences between treatments (92-98%). We conclude that high percentage of C. undecimalis females can be obtained when fish are fed for 21 days or more with artificial food supplemented with E2.

Feminization of young common Snook <i>Centropomus undecimalis</i> (Bloch 1792) using 17B-estradiol
Journal Article
2012

NOP 12-A06 (English)

Giant river prawn (Macrobrachium rosenbergii) farming plays an important role in the economy of Bangladesh. Presently, it is cultured in around 50,000 ha area with total annual production of 23,240t. Traditional extensive prawn farming has been expanding over the last three decades through the introduction and adoption of improved culture systems, such as culture of prawn-carps, prawn-shrimp-fish and prawn-fish-rice as concurrent and rotational systems. Efforts for the development of improved techniques on broodstock management, seed production and rearing and grow-out of prawn have been made over the last decade. The outcomes are low-cost feed for broodstock, production of post-larvae in net cages (hapa), all-male prawn culture, periphyton based prawn-tilapia culture, C/N based prawn culture, organic prawn farming, prawn-mola culture and prawn-carp-mola polyculture. Despite the development of culture technologies, a number of challenges for sustainable development of prawn farming need to be overcome to realize the potentials of this promising sector. Good aquaculture practices at all levels and application of measures for quality control and food safety would ensure sustainable development of prawn farming in Bangladesh.

Current status and prospects of farming the giant river prawn <i>Macrobrachium rosenbergii</i> (De Man) in Bangladesh
Journal Article
2012

NOP 12-306 (English)

Shifting rainfall and temperature regimes are bringing new challenges to the management of water bodies and fish farms in sub-Saharan Africa (Dixon et al. 2003). Culturing species that are resilient to drought and stressful water quality conditions may be a major part of future African aquaculture. Air-breathing fishes, such as the African lungfish Protopterus aethiopicus, can use atmospheric oxygen to meet all or part of metabolic demands (Miewa et al. 2007). Air-breathing fish have a role in managed fisheries and low-management culture systems where dissolved oxygen concentration is not a limiting factor. Among air-breathing fishes, the African catfish Clarias gariepinus can tolerate low levels of dissolved oxygen but its flesh is held in lower esteem by consumers as compared to lungfish. The quality of Pangasius catfish flesh is high but it is not a native species in Africa.

Prospects and Potential for Aquaculture of African Lungfish in Uganda
Magazine Article
2012

NOP 12-309 (English)

The proximate composition, amino acid and fatty acid profiles in the fillets of wild, pond- and cage-cultured longsnout catfish (Leiocassis longirostris) were determined to identify nutritional differences. Wild fish showed higher (P < 0.05) moisture and viscerosomatic index (VSI), but lower (P < 0.05) protein, ash and gross energy than cage-cultured fish. Pond-cultured fish contained lower (P < 0.05) protein and ash contents, but higher VSI compared to cage-cuItured fish. The amino acid of glycine content was higher (P < (lOS) in wild fish than in pond- and cage-cultured fish. Most of the fatty acids had a significant difference among all fish groups. The percentages of total polyunsaturated fatty acids (E PUFAs) were higher (P < 0.05) in wild and pond-cultured fish than in cage-cultured fish. Pond-cultured fish had higher (P < 0.05) E PUFAs, eicosapentaenoic acid (EPA), docosahxaenoic acid (DHA) and E n-3/E PUFAs ratio than wild and cage-cultured fish. The differences among the wild, pond- and cage-cultured fish may be attributed to dietary components and environmental conditions of the fish.

Comparison of proximate composition, amino acid and fatty acid profiles in wild, pond- and cage-cultured longsnout catfish (<i>Leiocassis longirostris</i>)
Journal Article
2012

NOP 12-304 (English)

In mammals, leptin is an anorexigenic peptide hormone that regulates energy homeostasis. It is produced predominantly by white adipose tissue and circulates as an endocrine indicator of energy reserves. Teleost leptin has been characterized in a few fish species, but its regulation is not well understood, particularly in response to nutritional status. In this study, we cloned a putative leptin in striped bass (Morone saxatilis) and report the first characterization of leptin in a Perciforme, the largest and most diverse order of fish. The striped bass leptin coding sequence was 65% homologous with pufferfish, 52% with Atlantic salmon, and 46% with human. PCR showed that leptin mRNA was exclusively expressed in the liver, and not adipose or other tissues. The leptin coding sequence of striped bass and the more widely cultured hybrid striped bass variety (HSB; Morone chrysops, white bass x M. saxatilis) were identical. We then evaluated whether the metabolic status of HSB might alter leptin gene expression. Juvenile HSB were subjected to 3. weeks feed deprivation followed by 3. weeks of refeeding. Quantitative PCR showed that fasting for 3. weeks reduced hepatic leptin mRNA levels relative to fed controls. Leptin mRNA levels then increased upon refeeding, albeit levels were not completely restored to those seen in control fish fed throughout the experiment. Intraperitoneal injection of human leptin suppressed appetite in HSB. In as much as hepatic HSB leptin mRNA is regulated by nutritional state and has a corresponding anorexigenic effect, our results suggest that leptin may play a role in energy homeostasis in these advanced Perciformes. 

Cloning and characterization of leptin in a Perciform fish, the striped bass (<i>Morone saxatilis</i>): Control of feeding and regulation by nutritional state
Journal Article
2012

2011

Anane-Taabeah, G., E. A. Frimpong, S. Amisah, and N. W. Agbo. 2011. Constraints and Opportunities in Cage Aquaculture in Ghana edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 158 - 165. Retrieved (https://cals.arizona.edu/azaqua/ista/ISTA9/).
NOP 11-292 (English)

NOP 11-292 (English)

This study was conducted to identify why the overall contribution of the aquaculture industry to local fish production in Ghana is low (<1%) although cage aquaculture has a potential to increase production. We administered 106 questionnaires to six respondent groups (current cage fish farmers, potential adopters of cage aquaculture, farmers who have abandoned cage aquaculture, Fisheries Commission, regional and district fisheries officers, and financial institutions) to obtain insight into the constraints in cage aquaculture as well as opportunities that can be exploited to promote cage aquaculture adoption. For the purpose of this study, potential adopters are individuals who have fish-related livelihoods including fishermen, pond-based fish farmers and fish traders. We also interviewed key informants in relevant government institutions. Preliminary results indicate that lack of funds and lack of government extension services are the main constraints in cage aquaculture in Ghana. Lack of funds manifests in farmers’ inability to afford quality floating feed and could explain low production levels of current cage farmers, although most (95%) suggested they could market their fish if they increased production. Lack of funds also accounted for the inability of potential adopters and farmers who have abandoned cage aquaculture to start or continue cage aquaculture respectively. Major opportunities identified include 1) a high interest among potential adopters (97%) to start cage aquaculture and farmers who have abandoned cage aquaculture (100%) to resume if constraints are removed, 2) development of a feed production plant in Ghana by a private enterprise, 3) willingness of some financial institutions to provide loans for cage farmers, and 4) a number of government initiatives to promote cage aquaculture. Our preliminary recommendations are that the Fisheries Commission should work with the financial institutions to help determine farmers’ ability to repay loans and guarantee loans made by the financial institutions. Also, there is a need for a more specialized aquaculture extension service accessible to farmers to help with technical issues built on the model of agricultural extension services in Ghana.

Constraints and Opportunities in Cage Aquaculture in Ghana
Conference Proceedings
2011
Antle, J., and R. Valdivia. 2011. Methods for Assessing Economic, Environmental and Social Impacts of Aquaculture Technologies: Adoption of Integrated Agriculture-Aquaculture in Malawi edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life, Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 174 - 183. Retrieved (http://ag.arizona.edu/azaqua/ista/ISTA9/).
NOP 11-294 (English)

NOP 11-294 (English)

There is a growing demand for assessment of economic, environmental and social impacts of new food-related technologies, including the impacts of new methods for aquaculture management. This paper presents a new ―minimum-data Tradeoff Analysis‖ (TOA-MD) model that can be applied to assess economic, environmental and social impacts in a wide array of agricultural systems that incorporate aquaculture, crops, and livestock (Antle 2011; Antle and Valdivia 2010). This model is widely applicable to assess impacts because it utilizes a generic model structure that can be parameterized with data available from a variety of sources, including farm surveys, experimental data, simulated data from bio-physical simulation models, and expert judgment. A key feature of this model is that it takes into account the fact that farmers systematically selected themselves into adopting and non-adopting groups. Analysis shows that this selection must be taken into account to obtain accurate estimates of impact. To illustrate the use of the TOA-MD model, we use it to implement an impact assessment of integrated agriculture-aquaculture (IAA) systems in southern Malawi developed by the World Fish Center, using a WorldFish farm survey data collected in 2004, together with data from other public sources. We use the TOA-MD model to demonstrate how it is possible to use available data to move a conventional economic impact assessment ―along the impact assessment pathway‖ to estimate adoption rates in the relevant populations, and to quantify impacts on distributional outcomes such as poverty, environmental impacts such as soil and water quality, and social and health-related outcomes such as nutrition or gender impacts. The analysis predicts an adoption rate of about 44%. In two districts, there is a substantial increase in protein consumption associated with the adoption of IAA and substantial reductions in poverty, whereas in others the effects are smaller.

Methods for Assessing Economic, Environmental and Social Impacts of Aquaculture Technologies: Adoption of Integrated Agriculture-Aquaculture in Malawi
Conference Proceedings
2011
Bhujel, R. C. 2011. How to produce billions of high quality tilapia fry edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 123 - 131. Retrieved (http://cals.arizona.edu/azaqua/ista/ISTA9/Book/ISTA%5Cn9%5CnPublications-1st.pdf%7B#%7Dpage=144).
NOP 11-289 (English)

NOP 11-289 (English)

Tilapia has now become a popular protein source to the poor, and also increasingly to middle class people. It serves as a typical model of a success story of farming outside its native area. Annual tilapia production was only 1.5 tons in 1950 which surpassed 1.5 million tons in 2002; increased by 1 million fold. Now it has surpassed even 3 million tons in 2010. Its production will still continue to grow exponentially, if high quality fry are readily available especially in countries like China where fry demand is in billions. How to produce and supply such a huge quantity of high quality tilapia fry has been a question for the countries which have potential to expand tilapia farming for domestic consumption and export markets. In Thailand, shortage of premium quality tilapia fry was realized as early as 1980s as the main constraint to the growth of commercial farming. Therefore, Asian Institute of Technology (AIT) developed a practical technique of mass-scale fry production through a series of on- station experimentation over a decade. The technology is basically to produce all-male fry by maintaining a large number of broodfish in hapas, collecting eggs, incubating them artificially in clean and controlled system and feeding with methyl-testosterone (MT) mixed with high quality feed as early as possible to ensure over 99% males in the fry population. In addition to developing the production technology, AIT also successfully disseminated it applying all sorts of strategies involving public as well as private sector. However, a key turning occurred only after the success of a private hatchery in Thailand that triggering mushrooming of many others. There are over 100 hatcheries of such type in Thailand alone. Now the same trend can be seen in Bangladesh. The technology has now been adopted by many farmers and entrepreneurs of many countries especially in Asia and Latin America. However, in China where about half of the global tilapia is produced, most farmers use hybridization technique to produce mono-sex fry. In Thailand, three hatcheries annually produce 200 million fry each. This means, establishing about five such hatcheries could easily produce 1 billion high quality fry per year. A hatchery in Hainan island of China has been already established by a foreign company which has claimed to achieve the same level of production. However, this technology has not been widely adopted. Adoption of this technology could boost tilapia farming further increasing many folds as the demand for fish for local consumption is huge, and so the export market. Exploring potential and promoting this technology could bring a big leap in tilapia industry in China from its current level. With a view to assisting the industry, establishing functional linkages between China and Thailand and other countries that facilitate cooperation among the researchers / scholars in sharing information and organizing study visits or trainings to government officials and farm/hatchery managers could serve as solutions. This paper describes the techniques and approaches applied by AIT hoping that it provokes policy makers, extension workers, researchers and educators working especially in China, and also other countries to find various ways of collaborations. 

How to produce billions of high quality tilapia fry
Conference Proceedings
2011
Bolivar, R. B., E. T. Jimenez, R. M. Sayco, and R. J. Borski. 2011. Supplemental feeding of Nile tilapia (Oreochromis niloticus L.) in fertilized ponds using combined feed reduction strategies. edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 268 - 274. Retrieved (http://www.cabdirect.org/abstracts/20133318803.html).
NOP 11-297 (English)

NOP 11-297 (English)

The study was conducted in nine 500-m2 earthen ponds at the Freshwater Aquaculture Center, Central Luzon State University, Science City of Muñoz, Nueva Ecija, Philippines, to determine the effect of using combined feed reduction strategies on the grow-out culture of Nile tilapia in fertilized earthen ponds. There were three treatments with three replicates: (I) 67% daily feeding until harvest; (II) 67% daily feeding for 60 days, 50% daily feeding until harvest; (III) 67% daily feeding for 60 days, 100% alternate day feeding until harvest. Ponds were stocked with sex-reversed GIFT tilapia fingerlings at 4 fish m-2. The study showed that Nile tilapia cultured in fertilized earthen ponds using different combined feed reduction strategy had no significant difference in terms of growth performance. Final mean weight and length of Nile tilapia in Treatment I were 183.1±77.1 g and 20.1±2.9 cm, Treatment II had 168.5±39.9 g and 19.9±1.4 cm and Treatment III had 183.1±16.0 g and 20.5±0.6 cm. Yield after harvest in Treatments I, II and III were 2,968.7±439.6, 1,980.7±541.8 and 2,024.7±329.0 kg ha-1, respectively. Net tilapia yield in Treatment I was significantly higher compared to the other treatments considering the higher survival of the treatment. Treatment I gave the highest net return among treatments with a mean value of US$705.90 followed by Treatment III with a mean value of US$6.41 then Treatment II with a mean value of US$-36.12. Net return was low among treatments because of the low survival after the study. Numerically, Treatment I showed the most profitable reduction strategy with the obtained survival, however, analysis of variance showed no significant differences in net return among treatments. With this result, Treatment I seemed to have the best result for tilapia culture, however, previous studies also shows feasibility of the use of other feed reduction strategies if more viable survival is attained leading to better FCR and net return.

Supplemental feeding of Nile tilapia (<i>Oreochromis niloticus</i> L.) in fertilized ponds using combined feed reduction strategies.
Conference Proceedings
2011
Borski, R. J. et al. 2011. Fishmeal-free diets improve the cost effectiveness of culturing Nile tilapia (Oreochromis niloticus l.) in ponds under an alternate day feeding strategy edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 95 - 101. Retrieved (https://cals.arizona.edu/azaqua/ista/ISTA9/Book/ISTA 9 Publications-1st.pdf).
NOP 11-287 (English)

NOP 11-287 (English)

Feed constitutes 60-70% of total production costs of tilapia ( Oreochromis spp. ). Reductions in quantity of feed used for fish growout and in the cost of formulated feeds are two approaches to containing feed costs. Our previous studies show that alternate day feeding at full ration produces Nile tilapia ( O. niloticus ) of comparable body size and harvest yield as those fed daily at full ration. The reduced feed consumption and 100% improved feed conversion with fish on the alternative day feeding strategy provided a significant cost savings to the semi-intensive growout of Nile tilapia in ponds in the Philippines. The cost of commercial fish feeds are rising sharply as the demand for fishmeal increases and its supply declines. We evaluated the growth performance of tilapia fed on alternate days with diets that incorporated plant ingredients widely available in the Philippines or other semi-tropical or tropical regions (cassava meal, copra meal, coconut oil, rice bran) and that contained porkmeal to replace fishmeal. Fish were grown out in ponds for 120 days with isocaloric- balanced, 0% and 6% fishmeal diets contained 31% crude protein and 6% crude fat. Fish showed similar performance on diets containing 0% and 6% fishmeal. Final body weight, total length, specific growth rate were virtually identical in fish on the two diets. Survival rates were 84% and 89% for fish on the 0% and 6% fishmeal diets, respectively. Feed consumption and feed conversion were also similar among the two groups. Total extrapolated yield at harvest was 3062 and 3080 kg fish/hectare for the 0% and 6% fishmeal groups, respectively. A marginal budget analysis showed an 8% improved return on fish fed the cheaper diet lacking fishmeal. This along with the alternative day feeding strategy previously shown to be as effective as daily feeding protocols has the potential of reducing overall feed costs for growing marketable size tilapia by > 60%. Collectively, the results show that substitution of diets containing fishmeal with cheaper and more sustainable sources of protein are effective options for reducing the costs without negatively impacting the production of tilapia.

Fishmeal-free diets improve the cost effectiveness of culturing Nile tilapia (<i>Oreochromis niloticus</i> l.) in ponds under an alternate day feeding strategy
Conference Proceedings
2011
Boyd, C. E., and L. Li. 2011. Intensity of Freshwater Use for Aquaculture in Different Countries edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 68 - 74. Retrieved (https://ag.arizona.edu/azaqua/ista/ISTA9/../BoydFreshwaterDifferentCountries.docx).
NOP 11-284 (English)

NOP 11-284 (English)

The intensity with which 172 countries use freshwater for aquaculture was estimated by dividing annual, freshwater aquaculture production (tonne/yr) by annual total natural renewable freshwater (km3/yr). The freshwater aquaculture production:renewable freshwater ratio (AFR) varied among countries from 0 to 15,000 tonne/km3. Country-level AFRs were assigned to AFR classes as follows: no freshwater aquaculture, 0 tonne/km3; low, < 100 tonne/km3; medium, 100-1,000 tonne/km3; high, > 1,000 tonne/km3. The number of countries in each AFR class follows: no freshwater aquaculture, 35; low, 80; medium, 45; high, 12. There seems to be adequate renewable freshwater to allow considerable expansion of freshwater aquaculture – especially outside of Asia.

Intensity of Freshwater Use for Aquaculture in Different Countries
Conference Proceedings
2011
Buccola, S., L. Qin, and R. Fare. 2011. What Influences the Success of Aquacultural Research Projects? edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 1(1):167 - 173. Retrieved (https://cals.arizona.edu/azaqua/ista/ISTA9/Book/ISTA 9 Publications-1st.pdf).
NOP 11-293 (English)

NOP 11-293 (English)

No research program can enjoy long-run success without a periodic assessment of how it is performing and what factors influence success and failure. While most such assessments are informal and specific to a particular study, formal evaluations eventually become important at the program level. A formal analysis the same as an informal one in the sense of comparing research outputs with the inputs or efforts expended to achieve them (a “knowledge production function”). Approaches to research assessment thus differ only in how such outputs and inputs are to be understood, measured, and compared. To help solve these difficulties, we examine here a new approach to research assessment. The new method focuses directly on the information a research study has generated, enabling a more exact and more contemporaneous matching of that information to the skills, expenditures, and capital devoted to the study. We apply the approach to the 167 167 55 past and on-going aquacultural research investigations which AquaFish CRSP is pursuing in eleven countries.

What Influences the Success of Aquacultural Research Projects?
Conference Proceedings
2011

NOP 11-277 (English)

Topmouth culter (Culter alburnus), a freshwater carnivorous fish of the Cyprinidae, is one of the most popular fish species in aquatic market in China. The anatomy and histology features of fish intestine are very useful for understanding digestive physiology, diagnosing some intestinal diseases and formulating suitable feeds. Thus, here we first characterize topmouth culter intestine via light microscope, transmission electron microscope and scan electron microscope. The 'Z' shaped intestine can be divided into three parts (e.g. the anterior intestine, middle intestine and posterior intestine), with an intestinal coefficient of 0.68. The anterior intestine possessed the longest mucosa folds and thickest muscularis among the three intestinal parts, and microvilli were very well-developed whilst many mitochondria, endoplasmic reticulums and lysosomes were found in which. This indicated the anterior intestine was a main region for digestion and absorption of food in the topmouth culter. While the vacuoles observed in the posterior intestine may be closely related to the intracellular digestion. Neutral and acid mucus were strongly present throughout the intestine. This detailed descriptive paper will be very helpful for studies of topmouth culter related to its digestive physiology, intestinal disease control and feed nutrient.

Anatomical and Histological Characteristics of the Intestine of the Topmouth Culter (<i>Culter alburnus</i>)
Journal Article
2011

NOP 11-273 (English)

We conducted surveys of six hatcheries and 18 farms for data inputs to complete a cradle-to-farm-gate life cycle assessment (LCA) to evaluate the environmental performance for intensive (for export markets in Chicago) and semi-intensive (for domestic markets in Shanghai) shrimp farming systems in Hainan Province, China. The relative contribution to overall environmental performance of processing and distribution to final markets were also evaluated from a cradle-to-destination-port perspective. Environmental impact categories included global warming, acidification, eutrophication, cumulative energy use, and biotic resource use. Our results indicated that intensive farming had significantly higher environmental impacts per unit production than semi-intensive farming in all impact categories. The grow-out stage contributed between 96.4% and 99.6% of the cradle-to-farm-gate impacts. These impacts were mainly caused by feed production, electricity use, and farm-level effluents. By averaging over intensive (15%) and semi-intensive (85%) farming systems, 1 metric ton (t) live-weight of shrimp production in China required 38.3 ± 4.3 GJ of energy, as well as 40.4 ± 1.7 t of net primary productivity, and generated 23.1 ± 2.6 kg of SO(2) equiv, 36.9 ± 4.3 kg of PO(4) equiv, and 3.1 ± 0.4 t of CO(2) equiv. Processing made a higher contribution to cradle-to-destination-port impacts than distribution of processed shrimp from farm gate to final markets in both supply chains. In 2008, the estimated total electricity consumption, energy consumption, and greenhouse gas emissions from Chinese white-leg shrimp production would be 1.1 billion kW·h, 49 million GJ, and 4 million metric tons, respectively. Improvements suggested for Chinese shrimp aquaculture include changes in feed composition, farm management, electricity-generating sources, and effluent treatment before discharge. Our results can be used to optimize market-oriented shrimp supply chains and promote more sustainable shrimp production and consumption.

Life cycle assessment of Chinese shrimp farming systems targeted for export and domestic sales
Journal Article
2011

NOP 10-258 (English); and NOP 11-298 (English)

Problems of limited number of dry feeds as supplement or replacement of live feeds have led to poor larval nutrition in many species of fish. Therefore, the suitability of co-feeding 8-day-old African catfish (Clarias gariepinus) post-hatch larvae using live feed (Artemia salina) and formulated dry diet containing freshwater atyid shrimp (Caridina nilotica) during weaning was investigated. The experiment ended after 21 days of culture and respective groups compared on the basis of growth performance, survival, feed utilization and nutrient utilization. Larvae co-fed using 50% Artemia and 50% formulated dry diet resulted in significantly (P < 0.05) better growth performance, food gain ratio (FGR), protein efficiency ratio (PER) and productive protein values (PPV) than other treatments. The lowest growth performance occurred in larvae weaned using 100% formulated and commercial dry diets. Better survival of over 90% was obtained in larvae weaned using 50% Artemia and 50% dry diet, while abrupt weaning using 100% dry diets resulted in lower survival (<75%). These results support a recommendation of co-feeding C. gariepinus larvae using a formulated dry diet containing C. nilotica and 50% live feed when weaning is performed after 8 days post-hatching period. 

Growth performance, survival, feed utilization and nutrient utilization of African catfish (<i>Clarias gariepinus</i>) larvae co-fed <i>Artemia</i> and a micro-diet containing freshwater atyid shrimp (<i>Caridina nilotica</i>) during weaning
Journal Article
2011

NOP 11-286 (English)

This study investigated whether the result of contest for social dominance among individuals in Oreochromis niloticus can be predicted by assessing the duration of appetite inhibition (DAI) during the isolation period. Fifty all-male juvenile O. niloticus of similar size were isolated for 10 days and were used in a social pair study. The DAI of each fish was observed when fish was transferred to the isolation unit. Body weight of dominant and subordinate individuals was recorded before and after the encounter. Eye color pattern (ECP) was also observed during the social encounter. The study revealed that tilapia with shorter DAI during the isolation had a greater possibility to win the fight for social dominance. Formation of stable dominant-subordinate relationship was observed in 24 of the 25 tested pairs. A total of seventeen fishes (70.93%) out of the 24 fishes that became dominant have shorter DAI compared to that of their conspecifics (Binomial test, P = 0.03). This indicates that social dominance can be predicted using the DAI of the fish during isolation. Reduced growth rate of both dominant and subordinate fish and a well-described physiological end result of social stress were observed one day after the social interaction. The significantly greater weight loss ( P < 0.01) in subordinate fish (2.88 ± 0.21 g) compared to dominant fish (2.11 ± 0.19 g) a day after the establishment of social hierarchy was mainly attributed to behavioral differences such as appetite rather than to differences in physical activities. Death, which is the most overwhelming effect of stress, was observed in the subordinate individuals. All subordinate fish died within a week after the social interaction.

Duration of Appetite Inhibition Predicts Social Dominance in Nile Tilapia, <i>Oreochromis Niloticus</i> L.
Conference Proceedings
2011
de Oca, G. A. Rodriguez- et al. 2011. Use of Gonadotropin Releasing Hormone Analogs on the Induced Reproduction of Chame Dormitator Latifrons edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 187 - 191. Retrieved (https://cals.arizona.edu/azaqua/ista/ISTA9/).
NOP 11-296 (English)

NOP 11-296 (English)

Chame (Pacific Fat Sleeper) is considered a relevant upcoming fish species for aquaculture; particularly in Ecuador and some preliminary trials in Mexico. Nevertheless, the reported production for the last 15 to 20 years in culture has been dependent of wild-caught juveniles. Thus, we are conducting research focused on the achievement of controlled reproduction and larvae production as well as to get relevant information on the reproductive biology of the fish. At this moment we have successfully induced gamete release in both genders using the following procedures: An experiment was conducted with 16 females divided into the following groups: control group (0.5 ml/kg 0.9% saline solution), Desgly10- Ala6 LHRHa injected at 40 µg/kg (priming dosage) and 80 µg/kg (resolving dose), 2 injections of Ovaprim® at 0.5 ml/kg or a single implant 75 µg (Ovaplant®). Spawning results showed 100% success within 24h and 48h for the Ovaplant group, and 25% for the LHRHa treatment but 0% for Ovaprim group within 48-72h. Only one natural spawn was observed. Obtained data establishes oocyte size as 300 µm and a relative fecundity of 80,000 to 100,000 cells per gram. All delivery treatments were effective to induce spermiation in volumes from 0.5 to 10 ml per male (LHRHa injected at 40 µg/kg, Ovaprim® at 0.5 ml/kg or a single implant 75 µg (Ovaplant®); however several males released sperm naturally up to 1 ml throughout the reproductive season. Obtained data indicates that sperm activation time is close to 4 minutes, and overall concentration is within the range of 1 to 2X10^9 cells per milliliter. Increased sperm motility is achieved after predilution on a 1:10-1:40 ratio in Ringer´s solution. As optimal salinity values, both for fertilization and egg incubation, our results indicate that there is no sperm activation above 5‰ of salinity; similar data were recorded for optimal incubation salinity as no hatching was observed above 5‰ salinity. These findings are relevant due to the differences with other spawning protocols previously used, given that other trials reported the need of repeated injections of Human chorionic gonadotropin (HcG) up to 10,000 UI per fish. Another difference with previous studies was the observance of only partial spawns. We conclude that these protocols allow to successfully obtaining viable gametes for chame larvae production.

Use of Gonadotropin Releasing Hormone Analogs on the Induced Reproduction of Chame <i>Dormitator Latifrons</i>
Conference Proceedings
2011
Fitzsimmons, K., R. Martinez-Garcia, and P. Gonzalez-Alanis. 2011. Why tilapia is becoming the most important food fish on the planet edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 1 - 8.
NOP 11-283 (English)

NOP 11-283 (English)

Tilapia has become the shining star of aquaculture with farms starting and expanding across the globe while consumption races ahead of even the most ambitious farm building plans. 2010 saw farmed tilapia exceed 3.2 million metric tons per annum, surging further ahead of the salmon and catfish industries. We are also seeing an explosion of product forms in the grocery stores that is only matched by the variety of preparations we see in the restaurant trade. The global adoption of tilapia as a substitute for all kinds of wild-caught fish has driven demand higher every year, even through the global recession of recent years. The description of tilapia as an “aquatic chicken” becomes more accurate every day. It’s wide acceptance across all cultural, religious, and economic groups is similar to chicken. A variety of breeds and strains have been developed and by most measures, tilapia is now the most highly domesticated of farmed fishes. Unique amongst the major farmed fishes, tilapia maintains a key role in rural aquaculture improving the welfare of the poorest farmers while at the same time, it is reared in the most high tech production systems and is sold into international markets for up-scale markets. Tilapia is still the darling of the environmental community and the industry continues to polish its “green” credentials. Three or four closely related species of tilapias readily hybridize in captivity and produce fecund F1 progeny. This has provided a huge genetic base for the geneticists to perform basic selective breeding. The domestication of tilapias has been a great driver of productivity during the 1990’s and 2000’s. There is also a concerted effort to describe the tilapia genome. When these genetic maps are distributed we can expect a second wave of genetic research that should further improve productivity. All of this will have been accomplished without the need of transgenics or genetically modified organisms. The basic biology of the fish along with the skill of traditional breeders has provided all of the progress to this point and much more in the near future. Tilapia continues its march towards eventually overtaking carp as the most important farmed fish crop. With a much wider distribution of production and consumption and a huge base of value added product forms, it is almost certain that tilapia production will someday eclipse that of carp. As tilapia production and consumption grows globally, it is likely to become the foundation product for all farmed fishes, just as chicken is the base for the poultry industry. So someday soon instead of referring to tilapia as the aquatic chicken we may be referring to chicken as the “terrestrial tilapia”.

Why tilapia is becoming the most important food fish on the planet
Conference Proceedings
2011

NOP 11-282 (English)

The objective of this study was to compare haematological and serum biochemical parameters of cultured and wild specimens of the northern snakehead, Channa argus, to establish baseline values. Thirty sexually immature and disease-free wild fish (37.70 ± 13.68 cm total length, 555.3 ± 449.0 g weight) and 30 cultured fish (36.82 ± 1.72 cm total length, 450.5 ± 58.8 g weight) were examined. In cultured northern snakehead, the average values of alanine aminotransferases (370.1 IU L)1), aspartate amino transferases (1145.3 IU L)1), albumin (15.84 gL)1), direct billuribin (6.15 lmol L)1), urea (1.40 mmol L)1), glucose (21.54 mmol L)1) and cholesterol levels (6.60 mmol L)1) were significantly higher (P < 0.05) than in the wild fish. In wild specimens the corresponding values were 9.81 IU L)1, 394.1 U L)1, 12.90 g L)1, 2.57 lmol L)1, 0.97, 2.36 and 4.38 mmol L)1, respectively. No significant difference (P > 0.05) was found for total protein, globulin, total biliru- bin, chromium, sodium, chloride or triglyceride levels between wild and cultured populations. The mean values of the red blood cell (RBC) counts, hematocrit, haemoglobin, and mean corpuscular volume (MCV) were significantly higher (P < 0.05) in the cultured population, while the values of the white blood cell (WBC) counts, erythrocyte sedimentation rate (ESR), mean corpuscular haemoglobin (MCH), and mean corpuscular haemoglobin concentration (MCHC) were significantly higher (P < 0.05) in the wild population. The study showed that the environmental conditions significantly impacted the status of the fish. It is suggested that these physiological parameters can be conveniently employed as health monitoring tools in fish culture practices.

Haematological and serum biochemical characterization and comparison of wild and cultured northern snakehead (<i>Channa argus</i> Cantor, 1842)
Journal Article
2011
Hung, L. T., V. C. Luong, N. P. Hoa, and J. S. Diana. 2011. Impacts of the Introduction of Alien Tilapias (Oreochromis spp.) on the Fisheries and Biodiversity of Indigenous species in Tri An Reservoir, Vietnam edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 75 - 85. Retrieved (https://cals.arizona.edu/azaqua/ista/ISTA9/).
NOP 11-285 (English)

NOP 11-285 (English)

This study was conducted at Tri An Reservoir of Vietnam from November 2007 to June 2009 to determine the impact of tilapias (Oreochromis spp.) on the fisheries and biodiversity of indigenous species in the reservoir. Historical and currently data on fish caught rom and fish species composition was collected. There are currently 19 different types of fishing gears in use at the reservoir, of which 14 fishing gears caught tilapias. Of the five fishing gears with highest total catches, only two caught tilapias. There were only 4.62% and 5.09% of tilapias in fishermen harvest and landing point records, respectively. However, tilapias (Oreochromis spp.) were 6th of 40 fish species caught from fishermen data, indicating the rather low productivity of most other fish species in the reservoir. Among the six species with highest biomass, the only economically valuable species recorded were the silver barb (Barbonymus gonionotus ) and tilapias. The species with little or no economic value that are abundant in the reservoir (glass fish Parambassis siamensis, river sprat Corica soborna, repassan Cyclocheilichths repasson and wrestling halfbeack Dermogenys pusillus), accounted for 64% of estimated total fish harvest (3823 tons) in the reservoir in 2008. The high production of low value species is also evidenced by their abundance at landing points, with glass fish and river sprat accounting for 355.91 and 243.68 of the total of 1661 tons landed in 2008. These indicated that the abundance of low economic value fishes may affect fisheries and fish biodiversity much more than the impact of alien tilapias species.

By using gill nets instead of seining, fish species composition was composed of more species with high economic value. Estimated tilapia catches and landing records show that tilapia species are abundant (84.62 of the total 1661 tons at landing points), second most only to silver barb (147.59 of 1661 total tons). This pattern holds despite the fact that tilapia haven’t been stocked regularly as silver barb and other cultured fish species, indicating a favorable development of tilapia species in the reservoir. During the peak catches of tilapias in August in 2008, the other top five most commonly caught fishes are not at their peak catches, indicating a likely impact of tilapias on other economically important fish species such as silver barb, common carp (Cyprinus carpio), repassan and Labiobarbus spilopleura.

Impacts of the Introduction of Alien Tilapias (<i>Oreochromis spp.</i>) on the Fisheries and Biodiversity of Indigenous species in Tri An Reservoir, Vietnam
Conference Proceedings
2011

NOP 11-279 (English)

The study had three overriding objectives. Firstly, to assess the profitability of small-scale aquaculture production enterprises in central Uganda; secondly, to ascertain the factors affecting profitability; and thirdly, to identify the constraints to fish farming in the region.The data were collected through a survey questionnaire administered to a random sample of 200 small scale fish farmers in the three major fish farming districts of Mpigi, Mukono and Wakiso in central Uganda. The analysis was carried out using descriptive statistics, enterprise budgeting and ordinary linear regression. Although the results show small-scale aquaculture enterprises to be profitable in the study region, the estimated profit margins are relatively small. Farming experience, fish price, record keeping, feed cost and volume of fish harvested were the most influential factors in explaining profitability. The key factors identified as hindrances to aquaculture development in the region included predators, unavailability of credit facilities, expensive feeds, shortage and poor quality of fingerlings.

Profitability analysis of small scale aquaculture enterprises in Central Uganda
Journal Article
2011
Jamandre, W. E., U. Hatch, R. B. Bolivar, and R. J. Borski. 2011. Improving the Supply Chain of Tilapia Industry of the Philippines edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) (1):132-150. Retrieved (https://cals.arizona.edu/azaqua/ista/ISTA9/Book/ISTA 9 Publications-1st.pdf).
NOP 11-290 (English)

NOP 11-290 (English)

This study evaluated the Philippine tilapia supply chain including the roles of key actors, logistical issues, external influences, and transaction flows among market levels. It identified improvement areas and provided recommendations for the industry. Key players include hatcheries, nurseries, commercial/small-scale farmers, consumers and institutional buyers. Pampanga, Batangas and Laguna are major tilapia sources while Metro Manila, Angeles and Baguio are the major demand centers. Dagupan is the major tilapia transshipment point for Northern Luzon. Many farmers employ a 'circuitous' production technique to meet markets' preferences. Direct buying and selling at central markets are the common operations of the tilapia industry. Consumers generally prefer whole live fish with size from 250-300 grams per fish. The requirements of institutional buyers are more varied. Filleted tilapia requires about 2-3 pieces per kg. High costs of logistics and transactions; lack of cold storage and transport vehicles; and meeting delivery requirements are the major concerns of nurseries, farmers and traders. Irregular supply of desired quality and volume of tilapia, limited capital for expansion, and predatory market practices are the main concerns of processors. Some recommendations to address the issues and concerns, are: encourage the establishment of more nurseries while intensifying technology transfer to farmers; conduct promotions for niche opportunities of tilapia; motivate small farmers to link with supply chains through an incentive mix; institutionalize an accreditation program for feed manufacturers, hatcheries, processors, etc.; and provide capital windows to improve facilities and reduce logistics and transaction costs in the entire supply chain.

Improving the Supply Chain of Tilapia Industry of the Philippines
Conference Proceedings
2011

NOP 11-276 (English)

The role of cortisol as the only corticosteroid in fish osmoregulation has recently been challenged with the discovery of a mineralocorticoid-like hormone, 11-deoxycorticosterone (DOC), and necessitates new studies of the endocrinology of osmoregulation in fish. Using an in vitro gill explant incubation approach, DOC-mediated regulation of selected osmoregulatory target genes in the gill was investigated and compared with that of cortisol in two euryhaline teleosts, Mozambique tilapia (Oreochromis mossambicus) and striped bass (Morone saxatilis). The effects were tested in gills from both fresh water (FW)- and seawater (SW)-acclimated fish. Both cortisol and DOC caused an up-regulation of the Na(+),K(+)-ATPase α1 subunit in SW-acclimated tilapia but had no effect in FW-acclimated fish. Cortisol conferred an increase in Na(+),K(+),2Cl(-) cotransporter (NKCC) isoform 1a transcript levels in FW- and SW-acclimated tilapia, whereas DOC had a stimulatory effect only in SW-acclimated fish. Cortisol had no effect on NKCC isoform 1b mRNA levels at both salinities, while DOC stimulated this isoform in SW-acclimated fish. In striped bass, cortisol conferred an up-regulation of Na(+),K(+)-ATPase α1 and NKCC transcript levels in FW- and SW-acclimated fish, whereas DOC resulted in down-regulation of these transcripts in FW-acclimated fish. It was also found that both corticosteroids may rapidly (30 min) alter the mitogen-activated protein kinase signalling pathway in gill, inducing phosphorylation of extracellular signal-regulated kinase 1 (ERK1) and ERK2 in a salinity-dependent manner. The study shows a disparate organization of corticosteroid signalling mechanisms involved in ion regulation in the two species and adds new evidence to a role of DOC as a mineralocorticoid hormone in teleosts.

Differential effects of cortisol and 11-deoxycorticosterone on ion transport protein mRNA levels in gills of two euryhaline teleosts, Mozambique tilapia (<i>Oreochromis mossambicus</i>) and striped bass (<i>Morone saxatilis</i>).
Journal Article
2011
Li, Y. et al. 2011. DNA extraction from crayfish exoskeleton. Indian Journal of Experimental Biology 49(12):953 - 957. Retrieved (https://www.ncbi.nlm.nih.gov/pubmed/22403870).
NOP 11-281 (English)

NOP 11-281 (English)

Crayfish exoskeleton (CE) samples are generally less invasive and easy to be collected. However, it is difficult to extract DNA from them. This study was intended to investigate CE as a DNA source and design an easy and efficient DNA extraction protocol for polymerase chain reactions. Specific primer pair (PPO-F, PPO-R) was used to amplify extracted DNA from CE, and compared to crayfish tail muscle DNA sample. Moreover, seven microsatellites markers were used to amplify the CE DNA samples set. Since the extracted DNA from CE is suitable for gene amplification, the results present usefulness of CE as an easy and convenient DNA source for PCR-based population genetic research.

DNA extraction from crayfish exoskeleton
Journal Article
2011
NOP 11-278 (English)

NOP 11-278 (English)

Cyanobacterial blooms in eutrophic freshwater systems are a worldwide problem, creating adverse effects for many aquatic organisms by producing toxic microcystins and deteriorating water quality. In this study, microcystins (MCs) in Microcystis aeruginosa, and Daphnia magna exposed to M. aeruginosa, were analyzed by HPLC-MS, and the effects of M. aeruginosa on D. magna were investigated. When D. magna was exposed to M. aeruginosa for more than 2 h, Microcystin-LR (MC-LR) was detected. When exposed to 1.5 x 10(6), 3 x 10(6), 0.75 x 10(7), and 1.5 x 10(7) cell/mL of M. aeruginosa for 96 h, average survival of D. magna for treatments were 23.33%, 33.33%, 13.33%, 16.67%, respectively, which were significantly lower than the average 100% survival in the control group (P < 0.05). The adverse effects of M. aeruginosa on body length, time for the first brood, brood numbers, gross fecundity, lifespan, and population growth of D. magna were density-dependent. These results suggest that the occurrence of M. aeruginosa blooms could strongly inhibit the population growth of D. magna through depression of survival, individual growth and gross fecundity. In the most serious situations, M. aeruginosa blooms could undermine the food web by eliminating filter-feeding zooplankton, which would destroy the ecological balance of aquaculture water bodies.

Effects of Microcystis aeruginosa on life history of water flea <i>Daphnia magna</i>
Journal Article
2011

NOP 11-275 (English)

Microcystins (MC) are secondary metabolites of toxic cysanobacteria. The algae and metabolites often combine to cause strong discoloration of the water, accumulation at the surface in discrete scums and sometimes emit a strong odor (Figure 1, Figure 2A, Cai et al. 1997, Liang et al, 2001, Zurawell et al. 2005). MC belong to a family of extremely toxic compounds and are a health hazard to aquatic animals and even humans (Ding et al. 1998, 1999, Falconer 1991, Hernandez et al.,2000, Lawton et al. 1994). Researchers have identified blooms of cyanobacteria from eutrophic freshwater bodies in many parts of the world, and their occurrence can create a major water quality problem. For example, massive fish kills occasionally have been related to severe cyanobacterial blooms. Chromic damages, such as development of liver tumors may arise from long-term exposure to low concentrations of MC (Chen et al, 2006, Ding et al. 1998,1999, Ibelings and Chorus 2007, Lankoff et al. 2004, Li et al. 2007, Shen et al. 2003, Smith and Haney 2006, Zimba et al. 2006)

The dangers of microcystins in aquatic systems and progress of research into their detection and elimination
Magazine Article
2011
NOP 11-271 (English)

NOP 11-271 (English)

Cyanobacterial blooms in eutrophic freshwater systems are a worldwide problem, creating adverse effects for many aquatic organisms by producing toxic microcystins and deteriorating water quality. In this study, microcystins (MCs) in Microcystis aeruginosa, and Daphnia magna exposed to M. aeruginosa, were analyzed by HPLC-MS, and the effects of M. aeruginosa on D. magna were investigated. When D. magna was exposed to M. aeruginosa for more than 2 h, Microcystin-LR (MC-LR) was detected. When exposed to 1.5 x 10(6), 3 x 10(6), 0.75 x 10(7), and 1.5 x 10(7) cell/mL of M. aeruginosa for 96 h, average survival of D. magna for treatments were 23.33%, 33.33%, 13.33%, 16.67%, respectively, which were significantly lower than the average 100% survival in the control group (P < 0.05). The adverse effects of M. aeruginosa on body length, time for the first brood, brood numbers, gross fecundity, lifespan, and population growth of D. magna were density-dependent. These results suggest that the occurrence of M. aeruginosa blooms could strongly inhibit the population growth of D. magna through depression of survival, individual growth and gross fecundity. In the most serious situations, M. aeruginosa blooms could undermine the food web by eliminating filter-feeding zooplankton, which would destroy the ecological balance of aquaculture water bodies.

Effects of <i>Microcystis aeruginosa</i> on life history of water flea <i>Daphnia magna</i>
Journal Article
2011

NOP 11-270 (English)

The development of digestive enzymes during the early ontogeny of the Mayan cichlid (Cichlasoma urophthalmus) was studied using bio- chemical and electrophoretic techniques. From yolk absorption (6 days after hatching: dah), larvae were fed Artemia nauplii until 15 dah, afterward they were fed with commercial microparticulated trout food (45% protein and 16% lipids) from 16 to 60 dah. Several samples were collected including yolk-sac larvae (considered as day 1 after hatching) and specimens up to 60 dah. Most digestive enzymes were present from yolk absorption (5–6 dah), except for the specific acid proteases activity (pepsin-like), which increase rapidly from 8 dah up to 20 dah. Three alkaline proteases isoforms (24.0, 24.8, 84.5 kDa) were detected at 8 dah using SDS–PAGE zymogram, corresponding to trypsin, chymotrypsin and probably leucine aminopeptidase enzymes, and only one isoform was detected (relative electromobility, Rf = 0.54) for acid proteases (pepsin-like) from 3 dah onwards using PAGE zymogram. We concluded that C. urophthamus is a precocious fish with a great capacity to digest all kinds of food items, including artificial diets provided from 13 dah.

Development of digestive enzymes in larvae of Mayan cichlid <i>Cichlasoma urophthalmus</i>
Journal Article
2011

NOP 11-A01 (English)

The abstract and paper are not available to the public. The original paper was published in Ocean and Fisheries [in Chinese].
 

Application of water treatment techniques in shrimp farming
Journal Article
2011
Martinez-Garcia, R. et al. 2011. Development of Sustainable Aquaculture Practices in Tabasco, Mexico Using Novel IAA Technology edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 1:151 - 157. Retrieved (https://cals.arizona.edu/azaqua/ista/ISTA9/Book/ISTA 9 Publications-1st.pdf).
NOP 11-291 (English)

NOP 11-291 (English)

The treatment and discharge of aquaculture effluent and resulting negative impacts on the environment remains a critical issue that is threatening the sustainable growth of the aquaculture industry. Three optimal sites has been selected to carry out IAA systems in order to deplete eutrophication, two indigenous communities, one from the highlands and other one from the wetlands were selected to produce agro and aqua products with the same amount of energy, also a demonstration system is building at UJAT. Part of our progress so far is: two workshops; the first one on integrated systems and the second one on bioflocs systems with more than 60 attendants among farmers, students and technicians. In Caridad Guerrero the highland indigenous community we have a 90% progress for the setting up phase, habanero pepper will be growth with Tilapia water effluents. In the wetland community there is a progress of 40% the group is already organize and training is given, the demonstration system at UJAT has a 30% progress, materials and instruments have been already purchased and the design was made. In overall the project suffered a delayed due to major flooding events in the region. Introduction

Development of Sustainable Aquaculture Practices in Tabasco, Mexico Using Novel IAA Technology
Conference Proceedings
2011

NOP 11-288 (English)

The study was conducted to evaluate the use of lyophilized testes from carabao (B. b. carabanesis), bull (B. indicus) and boar (S. domesticus) in the masculinization of Nile tilapia (O. niloticus) fry, specifically, their efficacy in producing phenotypic males and their influence on the growth and survival rate of Nile tilapia fry on a 28-day treatment period in outdoor tanks. The experimental treatments evaluated were: Treatment I- lyophilized testes from carabao, Treatment II- lyophilized testes from bull, Treatment III- lyophilized testes from boar, Control I- methyltestosterone (MT)- treated diet and Control II- untreated diet. Percent phenotypic males, specific growth rate and survival rate were determined after 28 days of treatment in outdoor tanks. Results revealed that Nile tilapia fry fed with MT-treated diet gave the highest percent phenotypic males with a mean of 96.67%. Those fry fed with lyophilized testes from bull, boar and carabao gave means 80.67, 79.33 and 72.67%, respectively. There was a significant difference (P<0.05) among the treatments. Based on the Chi-square test (α ≤ 0.05), the higher percentages of males produced from androgen-treated fry which are significantly different from that of untreated fry showed that lyophilized testes diets and MT-treated diet were effective in masculinizing Nile tilapia fry. Lyophilized testes from bull, carabao and boar gave higher specific growth rate of tilapia fry with means 15.85, 15.29 and 14.82%, respectively. Tilapia fry fed with lyophilized testes from carabao and boar did not differ significantly (P>0.05) from MT-treated fry but differed significantly (P<0.05) from those untreated fry. Those fry fed with lyophilized testes from bull were found to be significantly different (P<0.05) from the two controls. All the experimental treatments gave relatively high survival rate of the tilapia fry with no significant differences (P>0.05).

Masculinization of Nile Tilapia (<i>Oreochromis niloticus</i> L.) using Lyophilized Testes from Carabao (<i>Bubalus bubalis carabanesis</i> L.), Bull (<i>Bos indicus</i> L.) and Boar (<i>Sus domesticus</i> L.)
Conference Proceedings
2011

NOP 11-272 (English)

In this study, the physiological and biochemical response of Nile tilapia (Oreochromis niloticus) after 96 and 24 h exposure to aqueous extracts of neem (Azadirachta indica) in extract concentrations ranging from 0 to 32,000 mg/L was evaluated. After 96 h and 24 h exposure, the LC50 of neem extract was estimated at 3,200 and 6,800 mg/L, respectively. Plasma cortisol increased beyond pre-treatment levels at neem extract concentrations above 2,000 mg/L over 96 h and above 4,000 mg/L over 24 h. Blood glucose increased at neem extract concentrations above 1,000 and 5,000 mg/L at 24 nd 96 h, respectively. Neem extract concentration had little effect on serum sodium and plasma chloride. Hematocrit was higher than the control at neem extract concentrations above 1,000 mg/L in the 96 h exposure and above 2,000 mg/L in the 24 h exposure. Plasma ammonia increased significantly at neem extract concentrations above 2,000 mg/L for both the 96 h and 24 h tests. Immediately after beginning treatment, cortisol levels increased significantly at neem extract concentrations above 2,000 mg/L in the 96 h test and 4,000 mg/L in the 24 h toxicity test. Exposure to neem extract interfered with the antioxidant defense system of the fish by reducing liver catalase activity. Even though extracts of neem are less toxic at low concentration, concentrations exceeding 3,200 mg/L influence physiological and biochemical disturbances in fish.

Physiological and Biochemical Responses of Nile Tilapia (<i>Oreochromis niloticus</i>) Exposed to Aqueous Extracts of Neem (<i>Azadirachta indica</i>)
Journal Article
2011

NOP 11-A03 (English)

Survival and physiological response of Labeo victorianus juveniles under varying salinity gradients were studied during a 6 h transport. Salinity ranges were: 0, 0.25, 0.5, 1, 2, 4, 8 and 10 psu. To each transport bag, 100 juvenile L. victorianus (mean weight = 8.0 ± 1.1 g, stocking biomass = 16 kg m− 3) were transferred. Water temperature, dissolved oxygen (DO), pH, total ammonia nitrogen (TAN) and carbon dioxide (CO2) were measured before and after transport. Plasma cortisol, blood glucose, plasma sodium, plasma chloride and blood ammonia were also determined. No juvenile mortalities occurred in salinity ranges of 1 to 4 psu. After transport, survival and parameters of physiological response in the juvenile of L. victorianus were significantly different among different salinity treatments (p < 0.05). Low survival, of less than 70% occurred in control treatments (0 psu) and in salinities 0.25, 0.5 psu and at 10 psu. Increased salinity correlated negatively with TAN and CO2 in water after transport. Plasma cortisol in salinities of 0.5 to 8 psu, blood glucose and blood ammonia in salinities ranging from 1 to 4 psu as well as plasma sodium and plasma chloride in salinity ranging from 1 to 8 psu were similar before and after transport. This study recommends salinity ranges of 1 to 4 psu for minimizing the physiological effects associated with both the primary and secondary physiological response induced by transport stress in juvenile L. victorianus.

Survival and physiological response of <i>Labeo victorianus</i> (<i>Pisces: Cyprinidae</i>, Boulenger 1901) juveniles to transport stress under a salinity gradient
Journal Article
2011

NOP 11-274 (English)

Sahar (Tor putitora) is an economically important indigenous fish in Nepal, with major efforts to conserve and propagate the species. It is a predator and may function to control recruitment by naturally produced Nile tilapia (Oreochromis niloticus) in ponds. Sahar (Tor putitora) were cultured with Nile tilapia (Oreochromis niloticus) to evaluate control of tilapia recruitment in aquaculture ponds. Two experiments were conducted to assess the effects of the sahar to tilapia stocking ratio on the recruitment and growth of mixed-sex Nile tilapia. The first experiment was conducted in 100m2 earthen ponds at the Institute of Agriculture and Animal Science, Chitwan, Nepal to determine these effects. The second experiment was conducted on farm at Kathar, Chitwan, Nepal to verify the results in working ponds. The on-station experiment had four treatments with three replicates each: tilapia monoculture (T1), 1:16 sahar to tilapia ratio (T2), 1:8 sahar to tilapia ratio (T3), and 1:4 sahar to tilapia ratio (T4). Tilapia were stocked at 2 fish m-2 (average size 11.3g), and sahar were stocked at treatment densities (15.2g average size) in each pond. The ponds were fertilized weekly using diammonium phosphate (DAP) and urea at the rate of 0.1g P m-2d-1 and 0.4gNm-2d-1 respectively. Tilapia were fed with a locally made pelleted feed (27% crude protein), at the rate of 2% body weight every other day after attaining a size of 100g. Results showed significantly increased average harvest size (P<0.05) for treatment 2, when sahar were stocked with tilapia compared to the tilapia monoculture. The number of recruits significantly decreased (P>0.05) when sahar were stocked, and recruit numbers were inversely proportional to stocking density of sahar. Stocking of sahar reduced tilapia recruitment in a mixed-sex Nile tilapia pond culture system and produced better tilapia growth and production. Stocking at a 1:16 sahar to tilapia ratio gave the best overall performance.The on-farm experiment was composed of three treatments with three replicates each: tilapia monoculture (T1), 1:33 sahar to tilapia ratio (T2), and 1:16 sahar to tilapia ratio (T3). Ponds were fertilized every two weeks with DAP and urea at the same rate as on-station experiment, but there was no feeding. On-farm results showed significantly higher tilapia growth with a 1:33 stocking ratio of sahar to tilapia compared to tilapia monoculture. As with the on-station experiment, the number of recruits decreased with increasing stocking density of sahar. Lower sahar stocking provided higher growth and production of stocked tilapia, though there were fewer recruits at these levels. There might have some growth depression of tilapia at higher sahar stocking densities. Stocking sahar to Nile tilapia at 1:33 showed better overall performance than monoculture but not the 1:16 treatment in terms of Nile tilapia growth, production, growth of sahar and gross income.

Polyculture of Sahar (<i>Tor putitora</i>) with mixed-sex Nile tilapia
Journal Article
2011
Sinh, L. X., R. S. Pomeroy, and D. M. Chung. 2011. Value Chain of Cultured Snakehead Fish edited by L. Liu and Fitzsimmons, K. Better Science, Better Fish, Better Life Proceedings of the Ninth International Symposium on Tilapia in Aquaculture (ISTA 9) 184 - 186. Retrieved (http://cals.arizona.edu/azaqua/ista/ISTA9/Book/ISTA%5Cn9%5CnPublications-1st.pdf%7B#%7Dpage=144).
NOP 11-295 (English)

NOP 11-295 (English)

Snakehead fish is the fish species which is mostly preferred by consumers in the Mekong Delta of Vietnam. However, it is difficult to develop this industry due to a number of reasons. This study was carried out with the aims to describe the value chain of cultured snakeheads and to analyze the distribution of cost-benefit among the chain actors in the delta. Among 10 common market channels, two most important ones in term of total production were Channel 3 (Fish farmers – Wholesalers – Retailers – End consumers in the Mekong Delta), and Channel 9 (Fish farmers – Wholesalers – Wholesalers in Ho Chi Minh City). Profit was unbalant distributed among the chain actors, mainly for the wholesalers (87.9-93.4% of total profit of the whole chain). In order to have an appropriate development of snakehead industry, to improve profit of the whole chain and to have a better competition power, the followings should be given more consideration: (i) more proper planning of cultured area and technological supports, and marketing of fish products; (ii) To encourage the application of pelette feed in order to reduce the pressure on fresh water wild fish stocks; and (iii) To have incentive policies/regulations that help to encourage the processors to export, especially processed products for a long-term market expansion in terms of higher production, more export value, and stable price of snakehead products. Key

Value Chain of Cultured Snakehead Fish
Conference Proceedings
2011

NOP 11-A02 (English)

A sustainable semi-intensive pond aquaculture technology including major carp species as ‘cash-crop’ and small indigenous fish species (SIS) as food for the farmers' families is being optimized in Bangladesh. This is done through manipulations of the fish species combinations stocked, considering the ecological effects produced by bottom feeders on the pond bottom and filter feeders in the water column. The present paper presents results of experiments performed simultaneously in 64 farmers' fish ponds, located in 4 distant agro-ecological regions of Bangladesh. In each region each experiment involved 4 treatments, 4 replicates per treatment. The control polyculture was the traditional stocking of 33 rohu (Labeo rohita), 33 catla (Catla catla), and 34 common carp (Cyprinus carpio) per 100 m2, with the addition of 250 SIS and 3 silver carp (Hypophthalmichthys molitrix) per 100 m2. In previous experiments this silver carp addition was found to have no effects on the other fish and on the environment, compared to the traditional stocking without silver carp. Interferences on the water column (Water treatment) were achieved changing the density of the herbivorous fish (reducing catla density to 24/100 m2 and increasing silver carp to 12/100 m2), and on the bottom (Bottom treatment) doing so on the benthophagous fish (replacing 10/100 m2 common carp by mrigal). Both interferences were simultaneously carried out in the Water and Bottom treatment. Harvesting weight and biomass, growth rate, survival and yield of each species and total yield, food conversion ratio and income obtained in the different treatments and regions are presented and their interactions through the food web are discussed. Performing the same experiment in four distant regions of the country allowed observing if the effects of the Water column and/or Bottom interventions differ among regions, and accelerating the dissemination of the “cash-SIS” technology throughout the country. The manipulations performed did not affect the small fish mola, which reproduced and yielded equally well in all the polycultures. This allowed a continuous mola supply for consumption by the farmers' families throughout the culture season, and opened the option to consume or sell the larger amounts of mola gathered at final harvest. Manipulation of species composition proved to be a useful tool to affect the pond ecosystem towards improving fish yield and corresponding income. Just by substituting almost a third of the catla by silver carp increased total yield by 16%. When also almost a third of the common carp was substituted by mrigal, total yield increased a further 3%. In both cases selling the whole production increased income by 27%, which gives the farmer the option to keep part of the fish for family consumption.

Manipulation of species combination for enhancing fish production in polyculture systems involving major carps and small indigenous fish species
Journal Article
2011

2010

NOP 11-280 (English)

The concentrations of heavy metals, Mn, Zn, Fe and Hg were determined in sediments and in the whole soft tissue of the clam Galatea paradoxa from two clam fishing locations, Ada and Aveglo at the Volta estuary in Ghana from March to September 2008. Thirty clams were obtained from each sampling location monthly and grouped into three size classes of 10 individuals each based on shell lengths as follows: small (25 -40mm), medium (41-55mm), and large (above 55mm). Metal concentrations in the tissues of the different clam size-classes from the two stations were similar and did not vary significantly. A comparative evaluation of the metal concentrations in the clams and sediments however, revealed significant variations in concentrations for Zn, Fe and, Hg. Concentration of Fe in the sediment from Ada for June was 18 times higher than the concentration in the clams similarly, Hg concentrations were approximately 5 times higher in the clam tissues than in the sediments. On the basis of calculated BSAFs the metal enrichment in the tissues of the clams rank in the following order Hg > Mn > Fe. The BSAFs indicated a significant accumulation of Hg in the clam tissues relative to the concentrations of other metals in the sediments. The concentrations of the studied metal in the clam and sediment samples are similar to those observed in areas under low pollution impact and the current the levels of contamination of these metals in the estuary do not exceed the clams' capacity of regulation.

Bioaccumulation of heavy metals in the tissue of the Clam <i>Galatea paradoxa</i> and sediments from the volta estuary, Ghana
Journal Article
2010

NOP 09-A06 (English)

The livelihoods of forest fringe communities in Ghana depend, largely, on the renewable natural resources that they can find in the forests and any activities that impacts on the integrity of the forest disrupt the livelihood of the dependent communities. Forest fragmentation continues to take place in Ghana, mainly in response to a growing demand to feed an ever increasing population and for timber exploitation for export. One of the forest fringe communities in Ghana where the rural livelihoods of the people have been compromised due to deforestation and climate change is the Offin basin. The removal of forests impacts on local climate, water availability, and livelihoods due to influence of forests on precipitation and water balance. Fluxes in the quantity and frequency of rainfall contribute to decreasing food production and water availability. This study examines forest loss, precipitation and ambient temperature patterns in the forest fringe communities in the Offin river basin over the past four and a half decades and assesses current impacts and trends on rural livelihoods and coping strategies by the communities. The forests provide the communities with fuel-wood, fish and game, medicinal plants, food sources, and recreation. Between 2000 and 2005 deforestation rate in the basin was 2%. Mean annual precipitation decreased by 22.2% between 1960 and 2000 in response to a 1.3 degrees C rise in ambient temperature over the same period. Considerable changes in the frequency of rainfall and its unpredictability impacted negatively on the livelihood of the fringe communities who are predominantly cocoa and subsistence crop farmers. The livelihood resources of the community are severely constrained leading to reduction in food security and economic losses. In response to deforestation and associated climatic changes, several coping strategies for sustenance of livelihoods have been adopted by the forest fringe communities.

Livelihood trends in Response to Climate Change in Forest Fringe Communities of the Offin Basin in Ghana
Journal Article
2010

NOP 10-267 (English)

The study was conducted with snakehead Channa striata fingerlings (4 - 5g per fish) to determine the appropriate replacing levels of fish meal (FM) protein by soybean meal (SBM) protein with or without phytase supplementation. Nine isonitrogenous (45%) and isocaloric (4.7 Kcal g-1) diets were formulated to replace FM protein by SBM protein. The control diet was prepared with FM protein. The other groups, FM protein was replaced by SBM protein in the diets at replacing levels of 20%, 30%, 40%, and 50% with or without phytase. The experiment results showed there were no significant differences in survival rate among the treatments (P > 0.05), ranging between 54.4% and 63.3%. Fish growth had a downward trend (from 0.28 to 0.14 g.day-1), the opposite was true for feed conversion efficiency (from 1.07 to 1.78) when SBM protein was increased in formulated feed. In addition, phytase did not affect body composition and there were not significant differences in hepatic somatic index among the treatments (P > 0.05). In terms of economic profits, compared to control diet, replacement of FM protein by SBM protein with phytase supplement at 40% in Channa striata diets decreased slightly by 0.89%. To sum up, FM protein in Channa striata fingerlings diets can be replaced by SBM protein at 30% and 40%, without or with phytase supplements, respectively in which growth performances, feed utilizations are not affected.

Replacement of fish meal protein by soybean meal protein with or without phytase supplemetion in snakehead (<i>Channa striata</i>) diets
Journal Article
2010
NOP 10-265 (English)

NOP 10-265 (English)

Since typical water treatment processes are ineffective at removing toxic microcystins, techniques for eliminating microcystin-producing algae in water bodies have been developed. The most promising microcystin control in aquaculture is flocculation and sedimentation of harmful algal blooms with clay. In a study with tilapia in a eutrophic fish pond, the authors found that polymeric aluminum chloride-modified clay had a faster and slightly stronger effect in removing M. aeruginosa than a more environmentally friendly chitosan-modified clay.

Clay flocculation counters mycrosystin pollution in China study
Magazine Article
2010

NOP 10-269 (English)

Aquaculture ponds sequester about 16.6MTyr(-1) of organic carbon worldwide representing around 0.21% of annual, global carbon emissions.

Role of aquaculture pond sediments in sequestration of annual global carbon emissions
Journal Article
2010
NOP 10-266 (English)

NOP 10-266 (English)

Farm cages should be sited where water quality is good and water velocity is adequate. The size, shape, and position of cages should be selected to favor rapid flushing. Fish can typically be cultured at greater density in small cages than in larger ones. Cages should be oriented with the greatest surface area perpendicular to the prevailing current. Cages should occasionally be fallowed over moved to allow benthic communities to recover.

Cage Design, Placement Affect Water Quality
Magazine Article
2010
Brown, C. L., D. M. Power, and J. M. Nunez. 2010. Disorders of Development in Fish. Fish Diseases and Disorders Vol 2: Non-infectious Disorders 2(5):166 - 181. Retrieved (https://www.cabi.org/cabebooks/ebook/20103120414).
NOP 10-A08 (English)

NOP 10-A08 (English)

Among physical deformities in fish, skeletal, gill and fin malformations are most common, and they can range from barely detectable to lethal. With few exceptions, the motivation among fish growers to eliminate physical malformations is strong; at the very least these deformities reduce the market value of aquaculture crops. At worst they can cause the loss of an entire cohort. The search for definitive information about the causes of deformities in fish leads us in several directions - some genetic configurations can increase the susceptibility to physical and developmental malformations, but in other cases morphologically similar deformities are clearly not heritable. Slight aberrations in the rearing environment, e.g. temperature, water flow rate or diet, can trigger high rates of deformities in a clutch of fish. Occasionally, associations are made between handling stress and an elevated incidence of deformities, suggesting that stress can disrupt a genetically predetermined plan of development. The sum of the available evidence suggests that certain fishes are more susceptible to environmentally induced aberrations of development than are others. In other words, some species appear to adapt relatively well to captive rearing and may be more suitable for culture and domestication than others. This is not surprising, considering the widely varying degrees to which other animals adjust to captivity and the relatively small fraction that have adapted well.

Disorders of Development in Fish
Case
2010

NOP 10-A02 (English)

The haematological and biochemical characteristics of two healthy farmed cyprinids, the topmouthculter Culter alburnus and yellowcheek carp Elopichthys bambusa, were investigated in this study. Erythrocytes, thrombocytes, lymphocytes, monocytes and granulocytes (i.e. neutrophils and eosinophils) were observed in these two ¢sh. Every type of these cells (excluding the erythrocyte and lymphocyte) showed similar sizes in the topmouth culter and yellowcheek carp. Thrombocytes and neutrophils were the two most abundant leucocytes in the topmouth culter while thrombocytes and lymphocytes were the two most frequent leucocytes observed in the yellowcheek carp. The erythrocyte counts, haemolobin concentrations and values of serumglucose in these two fish were high.There were significant differences in the leucocyte counts, haemoglobin concentrations, mean cellular haemoglobin contents, mean cell haemoglobin concentrations and values of serum glucose, triglyceride, total bilirubin, alkaline phosphatase and chlorine between the topmouth culter and the yellowcheek carp.The information of haematology and blood biochemistry obtained here would be useful for the prevention and diagnosis of diseases of farmed topmouth culter and yellowcheek carp.

Haematological and biochemical characteristics of two aquacultured carnivorous cyprinids, topmouth culter <i>Culter alburnus</i> (Basilewsky) and yellowcheek carp <i>Elopichthys bambusa</i> (Richardson)
Journal Article
2010

NOP 10-A03 (English)(Spanish)

En el presente trabajo se describe la variación reproductiva en hembras de Centropomus parallelus empleando el diámetro de ovocitos a lo largo del tiempo de muestreo; se determinó el grado de madurez de los mismos y se usó este valor como indicador para aplicar tratamientos hormonales e inducir desoves. Se determinó que la temporada reproductiva para las poblaciones de la costa de Tabasco de esta especie se presenta de octubre a marzo, siendo el mes de marzo ideal para la inducción a desoves al observar hembras con diámetros promedio de ovocitos de 426.07 ± 37.54 µm. Para el mes de octubre se observaron los diámetros de ovocitos más pequeños con 324.86 ± 105.02 µm.

Reproductive variation in wild females of <i>Centropomus parallelus</i> by using the diameter of oocytes
Journal Article
2010

10-A13 (Spanish)

En el presente trabajo se describe la variación reproductiva en hembras de Centropomus parallelus empleando el diámetro de ovocitos a lo largo del tiempo de muestreo; se determinó el grado de madurez de los mismos y se usó este valor como indicador para aplicar tratamientos hormonales e inducer desoves. Se determinó que la temporada reproductiva para las poblaciones de la costa de Tabasco de esta especie se presenta de octubre a marzo, siendo el mes de marzo ideal para la inducción a desoves al observar hembras con diámetros promedio de ovocitos de 426.07 ± 37.54 m. Para el mes de octubre se observaron los diámetros de ovocitos más pequeños con 324.86 ± 105.02 m.

Variación reproductiva en hembras silvestres de chucumite Centropomus parallelus mediante el empleo del diámetro de ovocitos
Journal Article
2010

NOP 10-A01 (English)

The role of women in gleaning fisheries tends to be underestimated and poorly documented although they play an important role in coastal food security and income generation. This article describes two initiatives for co-management of women dominated cockle (Anadara spp.) fisheries implemented in Zanzibar Island of Tanzania and in Nicaragua that were based on a Fiji model. In each case, significant progress was made at the pilot scale but required adaptation to the community and national context. The Nicaragua case resulted in increasing densities of cockles inside and outside small scale no-take zones in a small estuary after a two-year period of implementation. In Zanzibar, out of several no-take sites established on reef flats, only one showed similar results. Other sites’ poor performance is likely due to poor site selection, small size, and non-compliance. Varying degrees of poaching affected both locations and continues to be an issue. In Zanzibar, local and national government played highly supporting roles whereas in Nicaragua, local government was supportive but national government continues to exhibit top-down decision-making, while still evaluating the alternative co-management approach. In both cases, university extension initiatives were influential in building community capacity for management and playing an advocacy role with national government. Both locations are poised for scaling up to more geographic sites as well as fostering policy change that can lead to more integrated and ecosystem-scale approaches to sustainable fisheries management.

Small Scale Fisheries Management: Lessons from Cockle Harvesters in Nicaragua and Tanzania
Journal Article
2010

NOP 10-264 (English)

International production continues to grow rapidly (10-15% yearly) as markets in developed countries import more and consumption in the producing countries also increases. China continues to be the largest producer, consumer, and exporter with about 1.2 million metric tons of production in 2009. Indonesia, Thailand, Vietnam, and Philippines have all increased production by 10 to 20% per year in 2008 and 2009. Indonesia's production in 2008 reached 328,831 tons, becoming the world's number two producer, followed closely by Thailand and Egypt.

Tilapia Update 2010
Magazine Article
2010

NOP 10-A04 (English)

Organic contents in fourteen ponds of a Litopenaeus vannamei culturing farm in Fengxian District of Shanghai were investigated during two aquaculture cycles from April to September in 2009. Total organic carbon(TOC), Chemical oxygen demand(CODMn), and Biological oxygen demand (BOD5) were analyzed respectively. The results showed that BOD5 were (8.62±3.08)mg/L and (10.47±3.87) mg/L in the two cycles of April to July and July to September respectively, CODMn were (13.09±3.98) mg/L and (16.16±6.07) mg/L,while TOC were (17.60±5.91) mg/L and (20.32±6.07) mg/L.TOC/CODMn were 1.35±0.22 and 1.32±0.30, and TOC/BOD5 were 2.10±0.44 and 2.08±0.63, while BOD5/ CODMn were 0.66±0.13 and 0.65±0.11. Significant relationships lied among the three water quality parameters. Linear regression equations and related coefficients were as follows. In cycle 1: BOD5 = 0.4174 TOC + 1.2777, r = 0.8022. CODMn = 0.5616 TOC + 3.2091, r = 0.8342. BOD5 = 0.6264 CODMn + 0.4209, r = 0.8106. In cycle 2: BOD5 = 0.4764 TOC + 0.7902, r = 0.7480. CODMn = 0.7941 TOC + 0.0237, r = 0.7962. BOD5 = 0.568 CODMn + 1.2912, r = 0.8920. The results showed that the equations established among TOC, COD and BOD5 could be used to calculate the other two parameters if anyone of them had been measured so that further comparison with some water quality standards or correlated researches could be carried out, which would benefit water quality management and healthy culturing of L. vannamei.

Relevance analysis of organic pollutants parameters in ponds of <i>Litopenaeus vannamei</i> culturing
Journal Article
2010

NOP 10-262 (English)

Recent, fervent international dialogue concerning the existence and magnitude of impacts associated with aquaculture has had both positive and negative outcomes. Aquaculture stakeholders have become sensitized to requirements for improved environmental management of aquaculture. On the other hand, in some cases aquaculture development has been negatively affected by some of the unwarranted and unproved allegations to the detriment of the stakeholders most in need of aquaculture development (i.e., resource users, particularly the poor, who are dependent on natural resources). These resource users are targeted by, and directly influence biodiversity and conservation agendas; hence the need to understand how to gain their active participation. This discussion focuses on examples of how aquaculture research and development can be a useful tool or strategy for resource management initiatives and provide tangible positive including increased stakeholder participation and cooperation, offering alternatives to resource extraction and use in otherwise difficult or intransigent resource management conflicts.

Aquaculture Research and Development as an Entry-Point and Contributor to Natural Resources and Coastal Management
Journal Article
2010
Hien, T. T. T., L. Q. Toan, T. T. Be, and N. H. Trung. 2010. Replacing fish meal by soybean meal in giant snakehead (Channa micropeltes) diets. The Scientific Journal of Can Tho Universityc Journal of Can Tho University.
NOP 10-268 (English)(Vietnamese)

NOP 10-268 (English)(Vietnamese)

This study was designed to determine the maximum replacing levels of fish meal protein (FM) by soybean meal protein (SBM), defatted with phytase enzyme supplementation for Channa micropeltes. FM in the basal diet was replaced by SBM in the diets at replacing levels of 20, 30, 40, and 50% with 0.02% phytase supplementation. Channa micropeltes fingerlings (4.3±0.03 g/fish) were randomly distributed into 15 tanks (100 liters/tank) with 25 individuals per tanks. Fish were fed twice a day to satiate. After 8 weeks of feeding, there were no significant differences in survival rate (SR) among the treatments, ranging between 77.3% and 80%. Compare to control treatment (FM), replacement of 20, 30 and 40% of FM by SBM did not significantly affected on growth performance, feed conversion ratio (FCR) and protein efficiency ratio (PER) while the replacing level of 50% significantly reduced these parameters, except FCR. Results also showed that there weren’t significant differences in crude protein content in whole body as the dietary soybean meal replacement levels increased. From economic view, replacement of FM by SBM up to 40% in Channa micropeltes diets reduced feed costs/kg diet and feed costs/kg weight gain by 10.8% and 4.83%, respectively.

Replacing fish meal by soybean meal in giant snakehead (<i>Channa micropeltes</i>) diets
Journal Article
2010

NOP 10-261 (English)

The aim of this study was to describe the ontogenetic development of the testis and the alimentary tract in longnose gar (Lepisosteus osseus) related to fish size and age at the onset of exogenous feeding and late ontogenesis. Using light microscopy, testes were first detected histologically by the appearance of primordial germ cells 9 days after the first exogenous feeding [31-31.5mm total body length(TL)] and presumptive seminiferous tubules (maleness characteristic) in fish of 107mm TL. The present histological studies indicated that the alimentary tract of lepisosteids is completely functional at the beginning of exogenous feeding, several days before the completion of yolk absorption. Based on these results, we have concluded that garfish larvae/juveniles can be effectively trained to consume formulated diets at early stages, after an initial feeding of live food for 2-3 days (23.5mm TL). Our findings provide evidence of the first controlled rearing of longnose gar using live and formulated diets, providing the possibility of experimental work with this non-teleost fish.

Development of testis and digestive tract in longnose gar (<i>Lepisosteus osseus</i>) at the onset of exogenous feeding of larvae and in juveniles
Journal Article
2010

NOP 10-A05 (English)

Water quality parameters in 22 ponds of a Litopenaeus vannamei culture farm in Fengxian District of Shanghai were investigated from April to September in 2009. Fifteen parameters including chlorophyll-a (Chl. a), temperature, pH, dissolved oxygen (DO), transparency, suspended substance (SS), total organic carbon (TOC), biological oxygen demand (BOD5), chemical oxygen demand (CODMn), nitrite nitrogen (NO2--N), nitrate nitrogen (NO3--N), ammonia nitrogen (NH3-N), total nitrogen (TN), active phosphorus (PO43--P) and total phosphorus (TP) were determined. Descriptive statistics was conducted and the correlation between Chl. a and other parameters was analyzed. The statistical analysis results showed that Chl. a had extremely significantly linear positive correlation with SS, TOC, BOD5, CODMn, TN and TP. Significantly linear positive correlation existed between Chl. a and DO. Extremely significantly linear negative correlation was confirmed between Chl. a and transparency while Chl. a had significantly linear negative correlation with PO43--P. Chl. a had no significant correlation with water temperature, pH, NO2--N, N03--N and NH3-N. According to the principles of selecting independent variables in the multiple linear regression analysis, four water quality parameters including TOC, TN, PO43--P and TP were used for establishing the stepwise regression model which was Chl. a=-0.054 5+0.003 49 TOC+0.015 3 TN-0.418 PO43--P+0.276 TP (r=0.715 5). The effects of these four factors on Chl. a were tested using the partial regression coefficient. The most influential water quality parameter on Chi. a were TP and then TOC, PO43--P, TN in turn. The results would help further study on ecological rules and water environmental protection in aquaculture ponds.

Multivariate statistical analysis of chlorophyll-a and water quality parameters in ponds of <i>Litopenaeus vannamei</i> culturing.
Journal Article
2010

NOP 10-A06 (English)

Nitrogen and phosphorus budgets in the higher-place ponds of Litopenaeus vannamei were studied systematically to investigate the effects of stocking seasons, shrimp larvae strains and grading culture on shrimp production. Results indicate that feed is the main source of nitrogen and phosphorus inputs, accounting for 91.76% ~ 93.68% and 94.55% ~ 96.97% of total inputs, respectively, while 29.46% ~ 40.46% of total nitrogen and 12.64% ~ 17.41% of total phosphorus were deposited into harvested shrimp; 24.63% ~ 54.52% of total nitrogen and 23.03% ~ 59.02% of total phosphorous were discharged into effluent; 14.10% ~ 44.59% of total nitrogen and 27.59% ~ 62.25% of total phosphorous were accumulated in pond sediment. Shrimp production is significantly affected by different stocking seasons and shrimp larvae strains. The average growth rate of trial ZS in summer reaches 0.175 g·d- 1 , which is 73.0% and 139.3% higher than that of trial ZF in fall and trial ZW in winter, respectively. The survival of ZWis 77.70% ~ 87.75% , which is significantly higher than that of ZS and ZF. Compared with ZWstocked at the same season, the survival of trial BW is 62.10% ~ 72.30% with yield per unit area of 8 821~ 9 878 kg·hm- 2 , which are both significantly low. Trial ZWb of grading cultured shortens the culture cycle by 56.13%.

Study on nitrogen and phosphorus budgets and production performance in higher-place pond of <i>Litopenaeus vannamei</i>
Journal Article
2010
NOP 10-260 (English)

NOP 10-260 (English)

The first reports of tilapia in Honduras date from the mid-1930's when broodstock of Java tilapia (Oreochrimis mossambicus) was introduced to Honduras from El Salvador. In 1955, the Honduran government, through the Secretariat of Natural Resources, created the Jesus de Otoro Aquaculture Station for the culture of freshwater shrimp (Macrobrachium rosenbergii). In 1958, because of various problems, this activity was discontinued. In 1968, the station resumed activities, this time oriented to the culture of tilapia. Two additional aquaculture stations were created by the government during the 1960s and 70s. The El Carao National Fish Culture Research Station was constructed in 1979. That station was utilized to initiate a national program of fish culture through extension programs and distribution of tilapia fingerlings to local farmers. The program focused on promoting subsistence-level fish culture throughout the country. Target groups included rural farmers and community organizations.

Markets for Honduran tilapia
Magazine Article
2010

NOP 10-A10 (English)

In Nigeria, fish provide the cheapest source of animal protein, especially in the rural and urban communities. Presently, the domestic fish supply in the country stands at about 400,000 t/yr. Eighty percent of the supply comes from the artisanal capture fisheries. The domestic fish supply is far below the demand because of the progressive increase int eh country's population. this has necessitated the importation of frozen fish to offset the gap in the domestic demand.

The annual trade statistic from the Central Bank of Nigeria shows that Nigeria expended over US$200 million annually on the importation of frozen fish to offset the production in the country (CBN 2006). Continued importation of frozen fish had been identified as one of the major sources of drain on the country’s foreign reserves.

With the decrease in artisanal fish supply from ocean fisheries as a result of overfishing and pollution, many concerns are raised among the policymakers about the possibility of capture fisheries bridging the gap between supply and demand in the country. Aquaculture, in light of this development, had been suggested, over the years, as a more environmentally friendly source of fish protein for the country.

Aquaculture is predominantly an extensive land-based system, practiced at subsistence levels (Fagbenro 2002). Its current yield is put at 14,388 t/yr, so there is considerable potential for commercial aquaculture development (Fagbenro and Adebayo 2005). Recent published annual agricultural production statistics by the Central Bank of Nigeria, show that the contribution of aquaculture to total fisheries production in Nigeria increased from about 11 percent in 2003 to 21 percent in 2005 (CBN 2006). This is an indication that aquaculture activity in the country is taking a giant step toward repositioning. Continued expansion of aquaculture production across the country however, is expected to play an important role in ensuring sustainable fish production among other benefits in the country in the future.

Therefore, examining resource use and technical efficiencies of aquaculture farms in the country will provide the decision makers a control mechanism with which to examine the performance of these farms. This study intends to provide such an examination by comparing aquaculture farms across Southwest Nigeria. [Note: The text above is the article’s introduction.]

Farm-level efficiency and resource use: application of stochastic frontier analysis to aquaculture farms in Southwest Nigeria
Magazine Article
2010

NOP 10-A09 (English)

The effects of selective harvesting (SH) ad claw ablation (CA) of blue-clawed (BC) prawns on an all-male freshwater prawn-finfish polyculture system were compared with control (Co) in quadruplicate. Ponds were stocked with all-male freshwater prawn Macrobrachium rosenbergii, silver carp Hypophthalmichthys molitrix, catla Catla catla and mola Amblypharyngodon mola at 12,000, 2,000, 500, and 20,000 ha-1 respectively. Prawns were fed with pelleted feed. Ponds were fertilized regularly with urea, triple super phosphate and cow-dung. SH of BC prawns in treatment SH and CA in treatment CA started on the 60th day during a 137-day culture and continued at 15-day intervals until the final harvest. Water quality parameters and plankton abundance did not vary significantly (P > 0.05) among the treatments. Treatment SH resulted in a higher (P < 0.05) net production of freshwater prawn (437 kg ha-1), with better survival and mean weight, followed by CA (354 kg ha-1) and Co (322 kg ha-1). The combined net production of prawn plus finfish was also higher in SH (1244 kg ha-1) as compared with CA (1161 kg ha-1) and Co (1137 kg ha-1), although the finfish production did not differ significantly. The periodic SH of BC prawns showed a better economic return with a BCR of 1.71.

Effects of selective harvesting and claw ablation of all-male freshwater prawn (<i>Macrobrachium rosenbergii</i>) on water quality, production and economics in polyculture ponds
Journal Article
2010

NOP 10-A07 (English)

Fish culture in ponds and cages is very common in freshwater areas of the Mekong Delta of Vietnam, where aquaculture plays a very important role in national fisheries production. The farming of giant snakehead began in the 1960s while the culture of common snakehead occurred since the mid 1990s. There are two groups of snakehead, that is, Parachanna and Channa. The Channa group is recorded to have 27 species and distributed in most of the Asian countries while Parachanna are mainly distributed in Africa, with three species, only. There are four species of Channidae in the Mekong Delta: Channa gachua (Ca Chanh duc), Channa lucius (Ca Day), Channa striata (Ca loc den), Channa micropeltes (Ca loc bong) (Khoa & Huong, 1993). However, two species - Ca loc den or Common snakehead (C. striata), and Ca loc bong (C. micropeltes) - are the main species of snakehead farmed in the delta. In Asian countries snakehead is cultured in semi-intensive or intensive systems in earthen ponds, cages, garden ditches and rice fields (Ling, 1997; Xuan et al., 1994). Long et al. (2004) estimated the production of cultured snakehead in the MKD in 2002 to be about 5,300 tonnes, mainly from An Giang, Dong Thap, Can Tho and Kien Giang provinces. Our estimated production of snakehead from the provinces in 2009 was about 30,000 tones, of which 7,500 tones was giant snakehead. All of the snakehead fi sh farmers surveyed in this study practiced aquaculture spontaneously at a small scale without any planning or sector management. However, the information on snakeheads is not much available (Huan, 2007) while there are many issues which need to be solved, in particular, dependence on the supply of small fish which are used for snakehead feed is an important source of animal protein for a significant proportion of population in the delta. It should be noted that there are three typical geographical conditions in freshwater areas of the delta by annual flood level, that is, deep flooded areas (more than 2 m depth in the peak of floods), medium flooded area (1-2 m depth), and shallow flooded area (less than 2 m depth). The wild fish stocks and fishing activities may differ in these areas.

Current situation and challenges for farming of snakehead fish (<i>Channa micropeltes</i> and <i>Channa striatus</i>) in the Mekong Delta, Vietnam
Magazine Article
2010
Un, S., R. S. Pomeroy, N. So, and K. Chhay. 2010. Market Channel and Trade of Fermented Small-Sized Fish Paste in Cambodia. International Journal of Environmental and Rural Development 1(1):145 - 151. Retrieved (http://iserd.net/ijerd11/11145.pdf).
NOP 10-263 (English)

NOP 10-263 (English)

Fermented small-sized fish paste is considered to be one of the main food sources for Cambodians, especially for the poor. However, most small-sized fish are used as direct feed for aquaculture or dried for animal feed. This study was conducted in order to identify market channel and trade of fermented small-sized fish paste. Phnom Penh city, Kendal, Kampong Chhnang, Battambang, and Siem Reap Provinces were selected as the study areas. The study revealed that there were three main sources of product which should be considered when analyzing total volume of annual production. The total production of the fermented fish paste in 2007-2008 was around 6,659 tons, of which 50.18% was domestically consumed and 49.82% exported to Thailand and Vietnam. Marketing and trading differed according to trading sites, stakeholder characteristics, and fish species containing in the fermented fish paste.

Market Channel and Trade of Fermented Small-Sized Fish Paste in Cambodia
Journal Article
2010

NOP 10-257 (English)

An experiment was conducted in 21 outdoor cement tanks (2.5 x 2 x 1.2 m) from 8 December 2005 to 3 March 2006 to determine the effects of adding red tilapia (Oreochromis spp.) at different densities and sizes on production, water quality and nutrient recovery in intensive culture tanks of white shrimp (Litopenaeus vannamei). Shrimp post larvae of 0.06 g were stocked into all tanks at a density of 60 post larvae m- 2, while either small (13.8 x 0.2 g) or large (41.9 x 0.3 g) mono-sex tilapia fingerlings were stocked into the shrimp tanks two weeks later at low (0.4 fish m- 2), medium (0.8 fish m- 2) or high (1.2 fish m-2) density. Water depth in all tanks was maintained at 1m and salinity at 20 ppt. Water loss due to evaporation was compensated weekly. The experiment was conducted in a 2 x 3 factorial design, while three additional tanks for shrimp monoculture were set as a control. All treatments and the control were randomly allocated to tanks in triplicate each. Shrimps were fed three times daily with commercial pellets using feeding trays made with metal frame and nylon mesh (0.6 x 0.6 x 0.05 m) at the same feeding rates as those for the control. No separate feed was given to tilapia. The highest shrimp survival rate of 66.8% was obtained in the small-low density tilapia treatment, which was significantly higher than those in other treatments and the control. The small-low density tilapia treatment had the highest shrimp yield and lowest feed conversion ratio, which was similar to those in the control and the large-low and small-medium density tilapia treatments, but significantly better than those in other treatments. Factorial analyses revealed that the increase of tilapia density from 0.4 to 1.2 fish m-2 and size from 13.8 to 41.9 g negatively affected shrimp production performance but remarkably increased the combined production of shrimp and tilapia. Polyculture incorporated 36.0-49.5% of the total nitrogen input and 14.2-26.5% of the total phosphorous input into shrimp and tilapia, which were significantly higher than those (27.1% and 8.9%) in the monoculture, respectively. The nutrient recovery efficiency increased with increased tilapia stocking size and density. Polyculture with small tilapia stocked at low density had the best economic performance among all treatments and control, and significantly better than small-high, large-medium and large-high density tilapia treatments. It was concluded that addition of red tilapia at suitable stocking densities and sizes into intensive white shrimp monoculture can improve productivity, profitability, nutrient utilization and environmental friendliness of shrimp monoculture. The suitable stocking density and size of red tilapia identified in this study were 0.4 fish m-2 and 13.7 g respectively. Red tilapia could be stocked at higher density and larger size up to 1.2 fish m-2 and 42 g respectively to maximize system productivity and minimize nutrient waste without affecting shrimp survival, but economic performance could be negatively affected. Shrimp-tilapia polyculture should be promoted to improve sustainability of shrimp culture.

Effects of addition of red tilapia (<i>Oreochromis spp.</i>) at different densities and sizes on production, water quality and nutrient recovery of intensive culture of white shrimp (<i>Litopenaeus vannamei</i>) in cement tanks
Journal Article
2010

NOP 10-259 (English)

To determine the cytotype with better traits for the aquaculture practices of the dojo loach Misgurnus anguillicaudatus from the viewpoint of fish farming improvement, factorial crosses (2na (TM) Euro x 2na (TM),, 2na (TM) Euro x 4na (TM),, 4na (TM) Euro x 2na (TM),, 4na (TM) Euro x 4na (TM),) were conducted between natural diploids (D) and tetraploids (T), producing DD, DT, TD, and TT groups (female listed first). The potential benefits of the different cytotypes in culture were evaluated by comparing growth performance and survival rate for a 15-month rearing trial under the same production conditions. The average fertilization rate in DT and TT was significantly lower than in the DD and TD groups, possibly indicating the poor fertilizing capacity of the tetraploid sires. Survival rate in DT and TD was slightly lower than in DD but significantly higher than in the TT groups. Tetraploid females produced obviously larger eggs than diploids and, subsequently, significantly longer initial body length of TT and TD than DD and DT fry. However, from the second month of the growth trial, TT suffered higher mortality than other cytotypes, which significantly influenced morphometric growth parameters. The TD group exhibited superior growth performance throughout the experiment. The mean body length of DT was comparable with that of DD fish during the first 7 months but began to outgrow DD from the 9th month. This study suggests that the relatively better growth of tetraploid and higher survival rate of diploid can be integrated via interploidy hybridization to get TD triploids with better culture traits.

Comparative studies on survival and growth performance among diploid, triploid and tetraploid dojo loach <i>Misgurnus anguillicaudatus</i>
Journal Article
2010

2009

NOP 09-A12 (English)

Natural occurrence of hexaploid loach Misgurnus anguillicaudatus detected in central China is reported here for the first time. The evidences from karyotyping, DNA content analysis and nuclear volume measurements were described to confirm the hexaploid nature of the identified individual.

First record of the natural occurrence of hexaploid loach <i>Misgurnus anguillicaudatus</i> in Hubei Province, China
Journal Article
2009

NOP 09-A05 (English)

This study was designed to generate information on the microbiological quality of the clam, Galatea paradoxa harvested from the Volta estuary in Ghana. Total Viable Counts (TVC) for heterotrophic bacteria, Total coliforms (TC) and Faecal Coliforms (FC) as indicators of faecal contamination, were evaluated in the rainy season (June-August) and in the dry season (January-February). G. paradoxa from the estuary were found to be highly contaminated with the above mentioned micro-flora. There was a significant seasonal variation (p < 0.03) in the levels of total heterotrophic bacteria (TVC), total coliforms (TC) and faecal coliforms (FC). Total viable counts of heterotrophic bacteria in clams in the rainy season (June-August) was significantly lower (p < 0.03); (June, 1.0 x 10(7) cfu/g) than for the dry season (February, 7.0 x 10(10) cfu/g). Total coliforms (TC) and FC portrayed a similar trend, being significantly higher (p < 0.01) in the dry season (1.0 x 10(11)) than the rainy season (2.4 x 104 and 1.3 x 104/g). Considering the importance of the clam fishery as an affordable protein source and a source of livelihood to the riparian communities along the Volta estuary, it is recommended that monitoring and regulatory controls of the fishery and growing waters be enforced whilst public education on the importance of depuration as a means of decontaminating the clams be pursued vigorously.

Bacteriological contamination of the freshwater clam (<i>Galatea paradoxa</i>) from the Volta estuary, Ghana
Journal Article
2009

NOP 09-252 (English)

This is the first controlled experiment to quantify the effect of introduced tilapia on indigenous species. This experiment was conducted in small earthen ponds (100 m2) to assess the impact of mixed-sex or all-male Nile tilapia (Oreochromis niloticus) on small indigenous species (SIS) commonly found in south Asia, mola (Amblypharyngodon mola), chela (Chela cachius) and punti (Puntius sophore). Ponds were fertilized, then stocked with 0.56 fish m-2 of water surface area in the mixed-sex and all-male tilapia treatments and 0.42 fish m-2 in the treatment without tilapia. No additional nutritional inputs were applied after stocking. Treatments were: mixed-sex tilapia with SIS, mono-sex male tilapia with SIS and SIS without tilapia (control). All treatments were stocked with 14 fish per species. All species reproduced during the 21-month culture duration. The number of recruits varied by species, Tilapia reproduced in greater numbers than SIS. Tilapia numbers at harvest were the highest (451 ± 25/100 m2) in the mixed-sex treatment compared with mola (221 ± 22/100 m2), chela (94 ± 8/100 m2) and punti (100 ± 7/100 m2). The number of mola was higher (399 ± 33/100 m2) in the all-male tilapia treatment. There was reduction in the number of mola and chela in the treatment containing mixed-sex tilapia. Gut content analysis combined with water sampling revealed that all fish species fed selectively. Significant interspecies dietary overlap was found between Nile tilapia and SIS and among SIS. Thus, there is potential for tilapia to compete with indigenous fish species when space and other resources are limiting, but a longer duration study with varying level of management is needed to determine how successfully tilapia competes with locally adapted SIS. 

The effect of the introduction of Nile tilapia (<i>Oreochromis niloticus</i>, L.) on small indigenous fish species (mola, <i>Amblypharyngodon mola</i>, Hamilton; chela, <i>Chela cachius</i>, Hamilton; punti, <i>Puntius sophore</i>, Hamilton)
Journal Article
2009

NOP 09-A04 (English)

The Volta basin clam, Galatea paradoxa, is collected for food and remains an important affordable protein source for the riparian communities in the catchment. Clams accumulate metals in their soft tissues, which can be toxic to humans when consumed. A study was, therefore, carried out to examine the concentrations of Mn, Zn, Fe and Hg in G. paradoxa, at 3 different size classes: small (20 - 40 mm), medium (41 – 60 mm) and large (>60 mm) at Ada and Aveglo in the Volta estuary area in Ghana. The concentrations of heavy metals in the clams varied considerably between the two locations. There were, however, no significant differences (p > 0.05) in Mn, Fe and Zn concentrations among the different size classes, indicating a similar bioavailability of the metals at both locations and, possibly, an efficient metabolism to keep the concentrations of Mn, Fe and Zn relatively similar. Mercury concentrations in the Ada clams varied significantly (p < 0.05) among the different size classes. A Risk Analysis indicated that the concentrations of heavy metals in the clams were within acceptable limits and safe for human consumption.

Effects of clam size on heavy metal accumulation in whole soft tissues of <i>Galatea paradoxa</i> (Born, 1778) from the Volta estuary, Ghana
Journal Article
2009

NOP 09-249 (English)

South American catfish, barred surubim (Pseudoplatystoma fasciatum) juveniles (117.6 ± 11.8 mg individual weight; 28.3 ± 2.5 mm total length) were fed various diets: one live (Tubifex worms), two commercial (Aglo Norse and Bio Kyowa), and one semi-purified formulated diet (75% peptide based protein) over a 2-week period. Fish fed the Aglo Norse diet showed the highest growth performance, but cannibalism also was very high (42%). Fish fed peptide based formulated diet demonstrated the lowest growth rate, with no cannibalism. The highest survival was achieved with fish fed Tubifex worms (100%). Lipid level in the whole body of the fish fed four different experimental diets did not differ significantly, averaging 3.6 ± 0.7%. Fatty acid composition of neutral and phospholipid fractions of whole body lipids of fish reflected the fatty acid composition of the diets. The high level of 20:4n-6 in Tubifex worms resulted in a high level of this fatty acid in the tissue of fish fed this diet. It remains uncertain how high survival and no cannibalism is related to dietary lipids / fatty acids. In all cases, the increasing ratio of n-3 HUFA (highly unsaturated fatty acids) / n-6 HUFA in phospholipid fractions suggested the elongation and desaturation of 18:3n-3 to 22:6n-3 via 20:5n-3. Moreover, in respect to the 20:4n-6 levels in the diets, an increase in the concentration of this fatty acid in phospholipid fraction suggests that South American catfish can transform linoleate into arachidonate. 

Growth, fat content and fatty acid profile of South American catfish, surubim (<i>Pseudoplatystoma fasciatum</i>) juveniles fed live, commercial and formulated diets
Journal Article
2009

NOP 09-A11 (English)

Results of a 120-day study showed that Nile tilapia fingerlings produced in incubation units, hapas or ponds exhibited similar growout performance. Although not statistically significant, the tilapia from artificial incubation units performed optimally. Fish from hapas also did very well. These treatments produced the greatest yield of fish, and a greater proportion of harvested animals fell in larger size categories.

Tilapia Fingerlings From Varied Systems Deliver Similar Growout Performance
Magazine Article
2009

NOP 09-251 (English)

The effects of the duration of the light phase photoperiod (8 h light or 16 h light) on the growth and hepatic insulin-like growth factor-I (IGF-I) gene expression in Nile tilapia Oreochromis niloticus were evaluated. There was a slight but not significant tendency for fish in the long light phase group (L(P)) to display elevated specific growth rate (G) both in mass (M) and standard length (L(S)) compared with that in the short light phase group (S(P);P = 0.057 for G(M);P = 0.055 for G(L)). Significantly, higher food conversion efficiency was observed in the L(P) than in the S(P). There were significant positive correlations between IGF-I concentrations and G, both in M and L(S). A significantly negative correlation was observed between IGF-I mRNA level and eye colour pattern. The lack of significant differences in G and hepatic IGF-I gene expression, despite the significant difference in feed conversion efficiency, may be related partly to the development of different levels of social interactions in the different groups within a photoperiod regime leading to increased variation of results within each group. These findings suggest that hepatic IGF-I gene expression has potential utility as a growth rate indicator for this species of fish and social status, as quantified by eye colour pattern, appears to be a much stronger determinant of growth rate and IGF-I transcript level than does light phase photoperiod length.

Influence of the photoperiod on growth rate and insulin-like growth factor-I gene expression in Nile tilapia <i>Oreochromis niloticus</i>
Journal Article
2009

NOP 09-247 (English)

This overview examines the status and trends of seafood production, and the positive and negative impacts of aquaculture on biodiversity conservation. Capture fisheries have been stabilized at about 90 million metric tons since the late 1980s, whereas aquaculture increased from 12 million metric tons in 1985 to 45 million metric tons by 2004. Aquaculture includes species at any trophic level that are grown for domestic consumption or export. Aquaculture has some positive impacts on biodiversity; for example, cultured seafood can reduce pressure on overexploited wild stocks, stocked organisms may enhance depleted stocks, aquaculture often boosts natural production and species diversity, and employment in aquaculture may replace more destructive resource uses. On the negative side, species that escape from aquaculture can become invasive in areas where they are nonnative, effluents from aquaculture can cause eutrophication, ecologically sensitive land may be converted for aquaculture use, aquaculture species may consume increasingly scarce fish meal, and aquaculture species may transmit diseases to wild fish. Most likely, aquaculture will continue to grow at significant rates through 2025, and will remain the most rapidly increasing food production system.

Aquaculture Production and Biodiversity Conservation
Journal Article
2009

NOP 09-256 (English)

Social surveys of three farming systems in Thailand showed significant differences. Prawn farming provided a good income and primary employment for farmers, who sold their prawns locally. Tilapia farming provided additional food and income to farmers who were otherwise employed, mostly in rice culture. Shrimp farming provided a good income and employment favored over other job opportunities. It added food locally as well as for export.

Outreach Assessment: Studies to Examine Aquaculture Liks to Thai Communities
Magazine Article
2009

NOP 09-A03 (English)

Global production and consumption of tilapia continues to rise. In 2008, China remained the major producer, with gains by its Asian neighbors and parts of Latin America. The global economic downturn and rising production costs hurt some smaller producers. China consumed half its huge production and showed a trend toward greater consumption of value-added tilapia. In U.S. retail stores, tilapia is now the second best-selling fish. The tilapia industry is working to bring “greener” tilapia products with improved quality control to market.

Tilapia Production, Market Report: Production, Consumption Increase Despite Economic Downturn
Magazine Article
2009

NOP 09-A20 (English)

We have chosen the silver arowana (Osteoglossum bicirrhosum), a representative of the most ancient teleost family Osteoglossidae, to address the question of yolk nutrients utilization. Silver arowana have particularly large eggs (1–1.5 cm of diameter) and a unique morphology of the yolk. We present evidence that the yolk cytoplasmic zone (ycz) in the ‘‘yolk sac juveniles’’ is a very complex structure involved in sequential processes of yolk hydrolysis, lipoprotein particles synthesis, their transport, and exocytosis.Vacuoles filled with yolk granules in different stages of digestion move from the vitellolysis zone through the ycz to be emptied into the microvillar interspace in the process of exocytosis. The area of the ycz with the abundance of the mitochondria must play an important role in providing energy for both the transport of vacuoles and the release of their contents. Therefore, we postulate that the function of yolk syncytial layer (ysl) as the‘‘early embryonic patterning center’’ transforms in fish larvae or yolksac juveniles into a predominantly specialized role as the yolk trophoblastic layer ( ytl) involved in yolk nutrients utilization. In addition to discovering the mechanism of transformation of the ysl function into ytl function, we suggest that the machinery involved in nutrient mobilization and exocytosis in yolk of arowana yolksac juveniles can be very attractive system for studies of regulatory processes in almost all secretory pathways in animal cells. 

The Nature of Exocytosis in the Yolk Trophoblastic Layer of Silver Arowana (<i>Osteoglossum bicirrhosum</i>) Juvenile, the Representative of Ancient Teleost Fishes
Journal Article
2009

NOP 09-A07 (English)

Two experiments were conducted to evaluate the initial stocking density in larvae of Bay snook, Petenia splendida, and Mexican mojarra, Cichlasoma urophthalmus, using a recirculation system. Five initial stocking densities (0.5, 1, 5, 10, and 20 larvae/L) were evaluated by triplicate for 45 d. Weight and total length (TL) were measured every 15 d, and fish production was calculated for each density. The larvae stocked at the lowest densities (0.5 and 1 larvae/L) presented the highest growth for both species: C. urophthalmus (0.78 g and 45-mm TL, and 0.76 g and 45-mm TL, respectively) and P. splendida (0.80 g and 52-mm TL, and 0.79 g and 49-mm TL, respectively). However, lowest fish production was recorded (35 and 69 fish per tank, respectively, for C. urophthalmus and 34 and 70 fish per tank, respectively, for P. splendida) compared with those at densities of 5, 10, and 20 larvae/L (336, 584, and 604 fish per tank, respectively, for C. urophthalmus and 341, 679, and 912 fish per tank, respectively, for P. splendida). The polynomial model for biomass production related to the stocking density shows that the optimum stocking densities for C. urophthalmus and P. splendida are 12 and 14 larvae/L, respectively.

Evaluation of larval growth and survival in Mexican Mojarra, <i>Cichlasoma urophthalmus</i>, and bay snook, <i>Petenia splendida</i>, under different initial stocking densities
Journal Article
2009

NOP 09-248 (English)

An experiment was conducted in a randomized block design to compare growth and economic performance between monosex and mixed-sex culture of red mud crab (Scylla olivacea Herbst, 1796) fed with trash fish at 5-10% body weight per day in the mangrove tidal flat at Burigoaliny Union of Satkhira District, Bangladesh. The experiment had three treatments in triplicate each: (a) all-male culture, (b) all-female culture and (c) mixed-sex culture. Crabs of 80-120 g in size were stocked at a density of 0.5 crab m(-2) and cultured for 100 days. Specific growth rates (SGRs) by weight and internal carapace width (ICW) in the all-male culture were significantly higher than those in the all-female culture (P < 0.05), while SGRs in the mixed-sex culture showed no significant differences from those in the all-male and all-female culture (P > 0.05). No significant differences in final mean body weight, ICW, daily weight gain, survival rate, gross and net yields were found among all the treatments (P > 0.05). The area of high water level with mangroves gave significantly better results in terms of feed conversion ratio, survival rate, gross and net yields than the area of low water level (P > 0.05). The experiment suggests that the all-female culture in the area of high water level with mangroves could be suitable in developing commercial pen culture of red mud crabs in Bangladesh.

Comparisons of growth and economic performance among monosex and mixed-sex culture of red mud crab (<i>Scylla olivacea</i> Herbst, 1796) in bamboo pens in the tidal flats of mangrove forests, Bangladesh
Journal Article
2009

NOP 09-A02 (English)

With its large quantities of water and little industry to pollute it, Guyana has the potential to become a greater player in global aquaculture. Collaboration among government agencies, universities, commercial farms and international aid groups is advancing aquaculture in the country. Currently, small farmers produce tilapia, pacu and shrimp for primarily local consumption. Further integration of aquaculture and agriculture has additional potential.

Aquaculture In Guyana: Tilapia, Pacu, Shrimp Raised with Plant Crops
Magazine Article
2009

NOP 09-A10 (English)

Aquaculture systems have the benefit of being highly intensive with demonstrated economic returns. Aquaculture can be an efficient strategy for economical land use and serve as an alternative means of livelihood for rural communities. Consequently, fish farming can play a major role in environmental conservation and restoration programs by reducing extensive land use. However, regional variability in climate, soils, and water quality are limiting constraints on aquaculture success. This study was conducted to assess the potential for culture of two warm water fish species, Nile tilapia (Oreocromis niloticus, Linnaeus) and African catfish (Clarias gariepinus, Burchell) at the high altitudes of the River Njoro watershed. Growth performance of Nile tilapia and African catfish were evaluated for 180 days in ponds fertilized with organic manure and stocked at a rate of two fish per square meter for tilapia, and 0.5 fish per square meter for catfish. Results from this study demonstrated remarkable growth in Nile tilapia but poor growth and condition in African catfish. After several attempts, African catfish eggs fertilized for the study failed to hatch, most probably due to low temperatures and the poor water quality of the Njoro River. These results demonstrate the feasibility of Nile tilapia culture at high altitudes of the watershed, while African catfish culture was limited by poor growth performance and seed availability. The farming of Nile tilapia is therefore recommended in the Njoro River watershed as a potential alternative livelihood strategy to intensive agriculture.

The Potential for Culture of Nile Tilapia and African Catfish in the River Njoro Watershed
Report
2009

NOP 09-A23 (English)

To facilitate economical culture of black pacu, Colossoma macropomum, and red pacu, Piaractus brachypomus, in the Amazon region of South America, we assessed locally available alternative energy sources for practical diets. We tested the effects of control diets (containing wheat products) versus diets with different Amazonian feedstuffs (yucca, Manihot sculenta, plantain, Musa paradisiaca, or pijuayo, Bactris gasipaes) on the performance of the pacus in three feeding trials. Black pacu (22.5 ± 0.03 g; Trial 1) or red pacu (2.56 ± 0.01 g; Trial 2) were fed diets containing 30% wheat bran (control) or cooked or uncooked yucca, plantain, or pijuayo for 12 wk. In Trial 3, larger black pacu (86.9 ± 6.4 g) were grown to market size in 24 wk on similar diets. Weight gain, feed conversion, survival, alternative complement activity, and lysozyme were similar among diets. Hepatosomatic index, liver glycogen, and dry matter were affected by diet in Trials 1 and 2, but effects were not consistent among trials. In Trial 3, protein efficiency ratio was lower in fish fed the diet containing wheat middlings. However, relative to wheat bran or wheat middlings, all feedstuffs tested were effective energy sources for juvenile black pacu and red pacu.

Effects of Carbohydrate-Rich Alternative Feedstuffs on Growth, Survival, Body Composition, Hematology, and Nonspecific Immune Response of Black Pacu, <I>Colossoma macropomum</I> and Red Pacu, <I>Piaractus brachypomus</I>
Journal Article
2009

NOP 09-255 (English); NOP 09-A21 (English)

Shrimp mariculture, the leading form of aquaculture for the Pacific coast of Mexico is facing catastrophic losses due to disease and falling prices. Previous work conducted by a multi-institutional, international team since 1997 has built a solid foundation for diversification of aquaculture in Pacific Mexico emphasizing the use of native species, particularly those low on the food chain and with low culture technology requirements. Among the leading candidates are bivalves, which are currently cultured and fished extensively along the Gulf of California Coast, with much of the production attributed to wild capture fisheries. Great potential exists, however, to expand current aquaculture production through strengthening existing operations, either by developing new markets or increasing sales in current ones according to consumer preferences.

From the Mexican government's perspective, specifically from CONAPESCA (National Aquaculture and Fishery Commission), economic diversification for aquaculture is stated as a prioritized policy goal. Today, the most available and feasible biotechnologies for species diversification in the country are tilapia and oyster farming (Martinez-Cordero 2007). In the last three years the Program Alianza para el Campo (Alliance for the countryside), which is the main federal program operated at the national level that promotes and supports the development of aquaculture projects, has financed tilapia and oyster projects at different scales of operation in many states. Social groups, like cooperatives, are usually selected to receive support for oyster farming, and in Sinaloa, coastal communities have benefited from this program. This includes fishermen entering aquaculture activities for the first time, which the Mexican government calls system conversion. Women's groups are also being involved in oyster culture efforts by the Autonomous University of Sinaloa. 

While monetary assistance has been given to help in the establishment of new aquaculture enterprises, little work has been done to assess the social and economic impacts of increased production. Moreover, research on assessing market demand for said species and assisting farmers in market identification and market penetration strategies is lacking. 

The objective of this work is to assist oyster aquaculture cooperatives in the region of Bahia Santa Maria (BSM), Mexico, to identify opportunities for the marketing of oysters within the state of Sinaloa. 

Marketing Extension and Outreach in Sinaloa, Mexico: A Preliminary Analysis of Preferences for Oysters
Journal Article
2009

NOP 09-A18 (English)

The authors performed a small- scale survey of owners/managers of restaurants in Sinaloa, Mexico, to assist aquaculture cooperatives in identifying opportunities for marketing oysters within the state. Results showed that potential buyers preferred live, large- sized oysters with a three-day shelf life. Buyers also considered water quality at product origin and mode of transportation, important factors in food safety. All would pay more for quality product with year-round delivery.

Oyster Preferences in Sinaloa, Mexico; Survey: Buyers Would Pay More for Quality and Availability
Magazine Article
2009

NOP 09-A16 (English)

Benthic macroinvertebrate assemblages at eight stations in the Moiben River, corresponding to different catchment land uses, were assessed in 2006 as indicators of water quality. The relative abundance per taxon, diversity index, richness index, evenness, dominance, percentage of five dominant taxa and percentage Ephemeroptera + Plecoptera + Trichoptera (EPT) individuals were determined per sampling period per station. Significant spatio-temporal variation was observed in relative abundance, with Diptera dominating the study area. Ephemeroptera, Plecoptera and Trichoptera dominated the headwater stations, whereas Coleoptera, Oligochaeta and Chironomidae dominated further downstream. Significant relationships were recorded between physico-chemical parameters — conductivity, BOD, temperature, and discharge — and the occurrence of specific taxa, mainly Heptagenia, Caenis, Baetis, Branchiobdella, Potamon, Ilyocoris, Elmis and Chironomus. Significant changes in macroinvertebrate assemblages were primarily due to changes in water quality. As elsewhere, macroinvertebrate communities proved to be good indicators of water quality and should be used as bioindicators in long-term monitoring of this river.

Macroinvertebrate assemblages as biological indicators of water quality in the Moiben River, Kenya
Journal Article
2009

NOP 09-A17 (English)

A Benthic Index of Biotic Integrity (B-IBI) was developed for the Moiben River. The index assesses effects of human disturbance on the biotic condition of stream macroinvertebrate communities. Eight stations were selected to represent different land-use types including forestry, settlement, grassland and mixed farming, practiced at different intensities. A total of 22 metrics were correlated against habitat quality and water quality parameters to determine their interrelationships. Ten metrics were shown to be responsive to changes in water and habitat quality, so could be used to separate sites according to levels of degradation. These were taxa richness (of Ephemeroptera, Plecoptera, Trichoptera and intolerant taxa richness), assemblage composition (percentage Ephemeroptera + Plecoptera + Trichoptera [EPT] individuals, and percentage of individuals in dominant taxa), pollution tolerance (percentage of tolerant individuals) and three functional feeding group metrics (ratio of scraper:filterer individuals, percentage gatherer genera, and percentage predator individuals). We calculated B-IBIs by summing metrics for each site, after transforming them to a discrete 1, 3, 5 scale. Values for the final index correlated well with measures of human influence based on qualitative assessment of habitat quality (Pearson's r2= 0.88). This preliminary benthic macroinvertebrate B-IBI shows promise for developing biological standards, which would facilitate long-term monitoring of streams in the upper reaches of Lake Victoria Basin.

A preliminary benthic macroinvertebrate index of biotic integrity (B-IBI) for monitoring the Moiben River, Lake Victoria Basin, Kenya
Journal Article
2009

NOP 09-A19 (English)

In Bangladesh, a sustainable semi-intensive pond aquaculture technology including large carp species as cash-crop and small indigenous fish species (SIS) as food for the farmers' families is being optimized. The present paper is on the effects on fish performance and pond ecology of interfering in the water column and/or on the bottom through changes in the polyculture composition. The Control polyculture was the ‘no-effect’ combination consisting of the traditional 33 rohu–33 catla–34 common carp stocking with the addition of 250 SIS and 3 silver carp per 100 m2 of pond, as resulted from a previous experiment. Interferences on the water column were achieved by changing the density of the herbivorous fish (reducing the density of catla to 24/100 m2 and increasing that of silver carp to 12/100 m2), and on the bottom by doing so on the benthophagous fish (replacing 10/100 m2 common carp by the same amount of mrigal). Mola was the SIS included in the polyculture.Interfering in the water column and/or in the pond bottom through the polyculture composition produced complex responses in the pond ecosystem affecting the large carps' performances, while it did not significantly affect the reproduction and the harvested biomass of the small fish mola. Relationships among the different fish species and the environment are described for each polyculture. The four polycultures tested allowed a good production of large carp species as cash-crop, of silver carp as an option to consume or to sell, and of the small species mola as food for the farmers' families. The Control polyculture is appropriate to produce relatively large herbivorous species, mainly silver carp. The polyculture combination in the Water treatment is appropriate to obtain a larger amount of smaller silver carp that can be afforded by the poor people but also smaller rohu and catla, while maintaining the same level of total yield and income with reduced feed conversion ratio (FCR) than in the Control treatment. The polyculture combination in the Bottom treatment allowed a larger fish species diversity and also produced smaller herbivorous fish with still reduced FCR, while maintaining the same level of total yield and income than the Control treatment. The polyculture combination in the Water&Bottom treatment gave the best results: it allowed a larger fish species diversity, is appropriate to obtain a larger amount of small silver carp that can be afforded by the poor people, and gives the highest total yield and income with the lowest FCR.

Effects of intervention in the water column and/or pond bottom through species composition on polycultures of large carps and small indigenous species
Journal Article
2009

NOP 09-250 (English)

Commercial production of tilapia in Kenya has potential for expansion, but growth and development of the tilapia industry in Kenya will depend upon its profitability and the effect of associated risks. Data from pond experiments, on-farm trials, and farm surveys were used to develop enterprise budgets and a risk analysis for nine production scenarios. The nine scenarios include: 1) monoculture of sex-reversed male tilapia fed either rice bran, a pelleted experimental diet, or a pelleted pig finisher diet; 2) clarias monoculture fed with each of the three diets; and 3) tilapia-clarias (sex-reversed male fingerlings) polyculture fed with each of the three diets. Net returns/ha were highest for production with the pig finisher diet, with clarias in monoculture the highest followed by tilapia in monoculture and then the polyculture system. The lowest net returns/ha were obtained with clarias fed rice bran. Profitability was affected by feed cost and tilapia survival. Tilapia monoculture systems had lower probabilities of financial losses than either clarias monoculture or the polyculture system. Use of the pelleted diets also resulted in lower probabilities of financial losses. Lower yields from the rice bran feed scenario resulted in its greater sensitivity to fluctuating costs of rice bran and survival of tilapia.

Economic and Risk Analysis of Tilapia Production in Kenya
Journal Article
2009

NOP 09-A22 (English)

This study examines income generation potential and resource-use efficiency of 120 aquaculture farms in Oyo state Nigeria. The data collected were analyzed using gross margin and stochastic frontier production (SFP) model. Result of gross margin (GM) shows that the farms were quite profitable with an average GM of N207, 000 per annum. The SFP model reveals that, elasticities of all considered inputs were positive and significantly different from zero. Returns to scale of 1.16 computed as sum of the inputs elasticities suggests that, an average farm from the study exhibits increasing returns to scale. Further analyses reveal that, an average technical efficiency estimate of about 81% was obtained from SFP model. This suggests that, about 19% potential yield are forgone due to inefficiency from the study. The result of sources of technical efficiency differential shows that extension; education, stocking density, and credit significantly influenced technical efficiency of the farms. Also, result of simulated marginal effects of these variables on technical efficiency shows that extension has the highest marginal effects on the efficiency estimates followed by credit, education, and stocking density. The study, therefore, suggests that, significant level of profit obtained from the study is synonymous to improve efficiency environment observed among the farms as promotion of aquaculture development has the potential in alleviating household income poverty in the country. © Central Fisheries Research Institute (CFRI) Trabzon, Turkey and Japan International Cooperation Agency (JICA).

An examination of income generation potential of aquaculture farms in alleviating household poverty: Estimation and policy implications from Nigeria
Journal Article
2009

NOP 08-242 (English)

Concentrations of quercetin in fish tissues were measured for the first time using HPLC-electrochemical detection method. Its identity was also ascertained with UV-photodiode array detection. Quercetin, in aglycone form, was at measurable concentrations in tilapia plasma, liver, and whole body homogenate when fed with diets containing 1% quercetin (aglycone) for 1 or 15 weeks. Hydrolysis with glucuronidase/sulfatase treatment for the purpose of cleaving conjugates did not increase quercetin levels, suggesting that glucoronide or sulfate conjugates are not the major metabolic forms in Nile tilapia (Oreochromis niloticus). No quercetin was detected in plasma of rainbow trout (Salmo gairdneri) or white sturgeon (Acipenser transmontanus) fed commercial diets. The results suggest that quercetin is absorbed in tilapia and that this flavonoid is deposited mainly in aglycone form in the body after absorption.

Determination of quercetin concentrations in fish tissues after feeding quercetin-containing diets
Journal Article
2009

NOP 09-A01 (English)

The regulation of growth hormone (GH) secretion by ghrelin during variable metabolic states is poorly understood. We examined plasma GH and ghrelin in hybrid striped bass (HSB) undergoing seasonally-based feeding and temperature manipulations. Fasting for 21 days (d) at 24C resulted in catabolism and up-regulation of plasma GH and ghrelin relative to fed controls. Continued fasting during cold-banking (14C, 90d) resulted in a further 43-fold increase in ghrelin while GH remained elevated. A subsequent 19 day refeeding period at 24C elicited hyperphagic and compensatory growth responses, accompanied by declines in ghrelin and GH. We then tested the role of ghrelin in stimulating GH release in vivo and in vitro. Intraperitoneal injections of ghrelin resulted in dose-dependent increases in plasma GH after 6 hours (h). Ghrelin also increased GH release from HSB pituitaries during 6 h incubations. Lastly, we assessed how metabolic state, ghrelin and insulin-like growth factor-I (IGF-I) affect in vitro pituitary GH release. Spontaneous GH release was 5.2-fold higher from pituitaries of fasted compared with fed animals. Ghrelin was equally effective in stimulating GH release from pituitaries of fed and starved animals, while it was ineffective in enhancing GH release from pituitaries of starved (21d) then refed (4d) HSB. Incubation with IGF-I inhibited GH release regardless of metabolic state. These studies are the first to show that seasonally-based periods of feed deprivation and low temperature yield sustained increases in GH secretion that are likely mediated, at least partially, through elevated ghrelin, reduced IGF-I negative feedback and fasting-induced spontaneous GH release.

Plasma ghrelin and growth hormone regulation in response to metabolic state in hybrid striped bass: Effects of feeding, ghrelin and insulin-like growth factor-I on in vivo and in vitro GH secretion
Journal Article
2009

NOP 09-253 (English)

The government of Kenya encourages aquaculture development by offering credit facilities through the government agricultural finance institution, Agriculture Finance Corporation. Nevertheless, the level of credit use in fish farming is very low. Access to credit is among several factors that affect farmers' decision of whether to use particular technology or services. The study examined factors that affected the decision of fish farmers in Kenya to utilize credit facilities in fish production using a profit model. The analysis suggests that farmers in the Western province will have a 19% more probability of using credit facilities for their fish farming operations than farmers from the other provinces such as the Rift Valley, Central, and the Eastern province. The effect of tilapia sales on the probability of credit use by fish farmers is more than three times that of catfish sales. Total pond acreage owned by fish farmers had a positive effect on credit use but the effect was very small and negligible. The level of fish farmers' use of credit facilities is very low, and there is probably the need to educate farmers on credit use and for the government agricultural lending agency and other commercial agricultural lenders to invest in this enterprise. Kenyan lending institutions have financed traditional agricultural enterprises, and with the growing production of farmed fish, more research is needed to document the aquaculture business model to assist in assessing the profitability potential in aquaculture.

Analysis of the use of credit facilities by small-scale fish farmers in Kenya
Journal Article
2009

NOP 09-254 (English)

Aquaculture information sources for small-scale fish farmers: The case of Ghana
Journal Article
2009

NOP 09-246 (English)

The objective of this study was to review the state of grow-out production for giant river prawns (Macrobrachium rosenbergii) in Thailand, assess the perceived ecological impacts of the industry, and suggest avenues by which farmers might adopt more environmentally sound culture systems. A socioeconomic and technical survey of 100 prawn farmers was conducted during 1 May to 31 July 2005 in Thailand. The majority of respondents were male (70%) and average age was 46 ± 1. Most farmers (77%) had completed an elementary level of schooling (4 years) and experience on the farm as owner, manager, or both averaged 10 ± 1 years. Most respondents (92.9%) obtained information about prawn culture from their neighbors and only 19% received formal training. Monoculture was the dominant system (96%) while remaining farmers utilized polyculture with prawns and white shrimp (Litopenaeus vannamei). The most common management strategy included a 30-60 day nursery phase for postlarvae and harvesting with the combined method, culling only the largest market-sized individuals beginning at 5 months followed by every 30 to 45 days (66%). Culture practices at the time of this survey are best described as intensive. Most farmers stocked at densities below 20 pieces m- 2 and average production was 2338 kg ha- 1 yr- 1, values typically described as semi-intensive. However, some farmers utilized higher stocking densities and obtained production values above those described as semi-intensive. Additional intensive practices were common, including the use of commercially produced feed, frequent water exchange, aeration, and lime and dolomite application. After the culture period water was generally discharged directly into canals without treatment. Average net profits were 3918 US$ ha- 1 yr- 1. The major problems identified were seed supply (67%), disease outbreak (64%), and external pollution (37%). External pollution was reported to have severe impacts on 16%, moderate impact on 46%, and no impact on 38% of farms. Pollution sources were identified as agriculture (75.4%), aquaculture (39.3%), and industrial and domestic waste (27.9% each). At the time of this survey the giant river prawn industry in Thailand was valued at US$79,096,000 and ranked third globally behind China and India. To maintain this level of production, research on alternative practices is necessary to balance adequate environmental benefits and economic returns similar to or better than the current monoculture system. Two avenues to transition to these practices include augmenting existing certification programs and community training sessions to introduce best culture practices and provide a venue for farmers to plan local water supply management.

Social, economic, and production characteristics of giant river prawn <i>Macrobrachium rosenbergii</i> culture in Thailand
Journal Article
2009

NOP 09-A15 (English)

In the recent years, aquaculture has played an economically important role in the Mekong Delta. Catfish, snakehead fish and freshwater prawn significantly contributed to an in increased total freshwater aquaculture production. Of which, snakehead was an important species cultured in Mekong Delta. There are four key popular culture systems of snakehead fish, including pond culture, hapa culture, cage culture and nylon tank culture. Data collected from provinces in the Mekong Delta showed that the snakehead production in region was about 30,000 tons in 2009, of which Channa micropelte was 7,500 tons. However, the farmers in the Mekong Delta attended to small scale systems and spontaneous systems. There are four species of snakehead fish cultured in Mekong Delta, comprising of Channa gachua, Channa lucius, Channa striata, Channa micropelte. Channa striata and Channa micropelte are two main cultured species in Mekong Delta now. The followings are briefly described snakehead fish culture technologies and production of the two main snakehead species in the Mekong Delta.

Snakehead aquaculture in the Mekong Delta, Vietnam
Magazine Article
2009

NOP 09-A08 (English)

At world-wide level the use of steroids to obtain all-male population in cichlids, has been widely used with the objective to avoid the reproduction process and to canalize the energy of the food in weight gain. In this sense, the application of steroids has been commonly through the artificial diets. Nevertheless, for some cichlid such as tenhuayaca or bay snook Petenia splendida, which is considered an appropriate species for aquaculture in the Southeastern of Mexico and Central America, the use of artificial diets during the larval period is not possible, for this reason the use of live preys is required which could be use as vehicle for the steroids. In the present study the production of all-male population was evaluated in P. splendida using Artemia nauplii as vehicle for the steroid 17-α methyltestosterone (MT). For this study the first feeding larvae were fed with Artemia nauplii with MT for 5, 10, 20, 28, 45 and 60 days of feeding, and a control treatment without MT. Significant differences were detected in the masculinization percentage and survival of the larvae fed for 60 days with MT using Artemia nauplii (96% and 85% respectively) compared with the control treatment where only 56% of males and a similar survival of 83% were obtained. For this reason, we conclude that the use Artemia nauplii as vehicle of MT is a suitable alternative to obtain all male production in P. splendida when larvae are feed for 60 days.

Mazculinization of the native cichlid Tenhuayaca, <i>Petenia splendida</i> (Günther, 1862), using <i>Artemia nauplii</i> as vehicle of the steroid 17-α methyltestosterone
Journal Article
2009

NOP 09-A13 (English)

The effects of a single intramuscular injection of gonadotropin releasing hormone analogue (GnRHa) alone or in combination with the dopamine antagonist domperidone (DOM) on ovulation induction of loach Misgurnus anguillicaudatus broodstocks collected from the wild were tested under routine hatchery conditions. The ovulation ratio, latency period, ovulation index, fertilization success and hatching rate were evaluated. The following hormone treatments were tested: 2nmg kg-1 BW of CPE as a positive control (PC), GnRHa alone at doses of 10ug (G10), 20ug (G20), 40ug (G40) and 60ug (G60) kg- 1 BW and combinations of GnRHa and DOM at doses of 5ug + 2.5mg (GD5), 10ug + 5mg (GD10), 20ug + 10mg (GD20) and 40ug + 20mg (GD40) kg-1, respectively. Physiological saline injected fish were used as a negative control (NC). The results showed that the combination of 20ug + 10mg (GD20) and 40ug + 20mg (GD40) kg-1 of GnRHa and DOM, respectively, injection led to higher ovulation ratio and shorter latency periods in comparison with the control and the other hormone treatments (P < 0.05), and there was no significant difference between the two ovulating groups with respect to ovulation ratio and latency period (P > 0.05). There was a significant difference between the GnRHa alone groups and the GnRHa + DOM combined groups on the ovulation index (the former < the latter, P < 0.05), while no significant differences in the fertilization success and hatching rate were found in any of the hormone treatments (P > 0.05). Only 20% of the fish ovulated in group G10 and G20, and no fish ovulated in group NC, suggesting a dopaminergic inhibitory action on gonadotropin (GtH) secretion in this fish at the preovulatory stage. Therefore, it can be concluded that like many other cyprinids, dopamine inhibitory action was operating in loach and it was necessary to combine GnRHa with a dopamine antagonist for ovulation induction. As a result, ovulation can be induced successfully in loach broodstocks with 20ug kg-1 GnRHa + 10mg kg-1 DOM treatment in a single injection without any negative effect on egg quality. Application of this combination could be beneficial for hatchery and broodstock management in loach culture.

Effects of GnRHa (D-Ala6, Pro9-NEt) combined with domperidone on ovulation induction in wild loach <i>Misgurnus anguillicaudatus</i>
Journal Article
2009

NOP 09-A14 (English)

The effectiveness of co-feeding loach (Misgurnus anguillicaudatus) larvae with live and microparticle diets on weaning performance was dbescribed here. Dry weight, total length, length and weight-specific growth rate (SGR) and survivals were monitored at 23-25 degrees C from the 4th day post hatching (dph) in different diet regimes, which included: microparticle diets (A), live cladocerans (B), enriched cladocerans (C), half microparticle diets plus half live cladocerans (D) and half microparticle diets plus half enriched cladocerans (E). The SGR (L and W) were significantly lower in treatment A than in other treatments after completing metamorphosis (day 4-20, P < 0.05). On 30 dph, dry weight (mg) and total length (mm) were significantly lower in treatment A than in other treatments (P < 0.05). There were no significant differences in growth in treatments B, C, D and E before 30 dph. However, when live feed was withdrawn from 31-60 dph, in metamorphosed fish, there were significant differences (P < 0.05) among the treatments in survival and growth. Metamorphosed fish in treatment E had higher survival than the fish in other treatments at the end of the experiment. The SGR (L and W) of weaned fish in treatments B and C were similar but lower than in treatments A, D and E respectively. However, dry weight and total length in treatment A were significantly lower than in treatments D and E. It is suggested that weaning of M. anguillicaudatus from early development would appear to be feasible and that larval co-feeding improves the growth and the survival.

Effects on growth and survival of loach (<i>Misgurnus anguillicaudatus</i>) larvae when co-fed on live and microparticle diets
Journal Article
2009

NOP 07-227 (English)

To obtain the phylogenetic relationship between diploid and tetraploid Misgurnus anguillicaudatus, the mitochondrial cyt b gene in the diploid and tetraploid weather loach were isolated and sequenced. The DNA sequences were analyzed using MEGA 3.0 software to determine the phylogenetic relationship. Forty-five variable sites among cyt b gene sequences and 18 amino acid substitutions occurred within the diploid and tetraploid loaches as deduced from the nucleotide sequences analysis of the cyt b gene. The nucleotide pairwise distance between diploid and tetraploid loach ranged from 0.001 to 0.025. Phylogenetic analysis revealed evolutionary relationships between diploid and tetraploid loach. Our results indicated a significant difference between diploid and tetraploid loach about the cyt b gene. ANOVA analysis indicated that there were no significant genetic variations within diploid loaches (Fst = 0.2529, P > 0.05) and within tetraploid loaches (Fst = 0.0564, P > 0.05), neither. However, significant genetic differences were found between diploid and tetraploid loaches (Fst = 0.7634, P < 0.05). Thus, it is concluded that no reproductive isolation was found within the same cytotypes of different localities, but there was reproductive isolation between these two cytotypes. The diploid loach existed before the tetraploid loach in nature. The present study is the first to describe the phylogenetic relationships of natural polyploidy weather loach using mtDNA cyt b gene.

Comparative and evolutionary analysis in natural diploid and tetraploid weather loach <i>Misgurnus anguillicaudatus</i> based on cytochrome b sequence data in central China
Journal Article
2009
NOP 09-A09 (English)

NOP 09-A09 (English)

A recent publication questions the nutritional value of tilapia in the human diet following the movement to eat fish for their omega fatty acid (FA) content. It suggests that tilapia have an elevated amount of omega-6 FAs (n-6) and a deficient amount of omega-3 FAs (n-3), a possibly unhealthy proportion for humans. A high n-6:n-3 ratio is problematic because too much arachidonic acid, an n-6 FA, promotes inflammation, which aggravates heart disease and other illnesses. This paper analyzes the numbers from different tilapia composition studies in an effort to understand the range of n-6 and n-3 totals and ratios present in both farmed and wild tilapia. Generally, wild tilapia have more n-3 FAs than farmed tilapia, but diet adjustments can alter the body composition of the domesticated variety. Consumers should consider fish as part of a balanced diet and evaluate their FA needs on an individual basis.

Omega-6 (n-6) and omega-3 (n-3) fatty acids in tilapia and human health: a review.
Journal Article
2009

2008

NOP 08-244 (English)

The present study examines the effect of four semi-purified diets (casein–gelatin based) where the source of fatty acids was free (esterified) oleic acid and linoleic acid (LA) (LOA diet), linseed and olive oil (predominantly LA and linolenic acid) (LO diet), cod liver oil (rich in highly unsaturated fatty acids) (CLO diet), and soybean lecithin (phospholipids; mostly LA) (LE diet) on the growth of juvenile South American catfish (surubim, Pseudoplatystoma fasciatum, Pimelodidae) (0.98 6 0.04 g individual weight). Fish were fed at a restricted–readjusted feeding rate for 8 wk. At the end of the experiment, LE-diet-fed fish grew significantly larger than those of the other three groups (P , 0.05). Considerable cannibalism was observed in all the treatments. It is suggested that the quantitative growth performance may possibly change under other conditions, with less or no cannibalism. Survival did not differ significantly among the fish fed four different diets. Muscle and liver lipid contents did not vary among dietary treatments (P , 0.05), but whole-body lipid concentrations were affected by dietary treatments. Fish fed LE diet contained significantly lower lipid level than those fed three other diets (P , 0.05). Muscle and liver fatty acid profiles reflected dietary fatty acid composition. Arachidonic acid level was significantly higher in muscle and liver of fish fed LOA and LE diets than in those fed LO and CLO diets. The results suggest that the efficiency of elongation and desaturation of 18C fatty acids depends on the dietary lipid source, and South American catfish has considerable capacity to transform linoleate to arachidonate.

Effects of different dietary lipid sources on the survival, growth, and fatty acid composition of south american catfish, <i>Pseudoplatystoma fasciatum</i>, surubim, juveniles
Journal Article
2008

NOP 08-A18 (English)

The objective of the study was to assess growth, sex conversion rate and percent survival of Nile tilapia (Oreochromis niloticus L.) fingerlings of the GIFT strain reared in twelve 500 m2 earthen ponds. Each pond was stocked with size #24 sex-reversed tilapia fingerlings at a density of 4 pcs/m2. The kinds of hatching system where the tilapia fry were hatched served as the treatments in this study and were as follows: I – artificial incubation-hatched fry, II – hapa-hatched fry, III – pond-hatched fry and IV – combination of hatched fry by stocking 33.3% from each hatching system. Each treatment was replicated three times. After the pond rearing, analysis of variance indicated no significant differences on the gain in length, gain in weight, specific growth rate, sex conversion rate and survival of tilapia fingerlings among treatments (P > 0.05). It is concluded that the hatching systems used in the study had no significant effects on the specific growth rate, gain in length and weight, sex conversion rate and percent survival of tilapia fingerlings. Therefore, any hatching system can be used to produce tilapia fry for pond rearing.

Growth Evaluation , Sex Conversion Rate and Percent Survival of Nile Tilapia ( <i>Oreochromis Niloticus</i> L .) Fingerlings in Earthen Ponds
Conference Proceedings
2008
Bolivar, R. B. et al. 2008. Economic Gains to Fish Farmers Resulting from Research Conducted Under the Aquaculture Collaborative Research Support Program. in Proceedings of the Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development, Proceedings of the Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development, edited by J. Mumford and Leach, A. Corvallis, Oregon: International Institute of Fisheries Economics & Trade. Retrieved (http://hdl.handle.net/1957/37487).
NOP 08-A06 (English)

NOP 08-A06 (English)

The Aquaculture Collaborative Research Support Program (ACRSP) has been actively engaged in aquaculture research, training, and outreach activities in more than 24 countries in Africa, Asia, and the Americas since its inception in 1982. These efforts, made successful through close collaboration between researchers and educators at US and Host Country institutions, have resulted in many new management strategies that can be put into practice by fish farmers, both in the countries directly participating in the program and in neighboring countries regionally. Most of these new strategies have significant economic implications, resulting mostly from reductions in the costs of pond inputs, more efficient management of ponds, or a combination of the two. Three examples of improved management strategies that have come out of the ACRSP effort are highlighted in this poster. These include new pond fertilization strategies developed in several of the participating host countries, innovative cost-cutting approaches to fish feeding, and the use of in-pond cages to more efficiently utilize pond space. These practices will be briefly described, with particular focus on how and to what extent they contribute to more efficient production and/or increased income for fish farmers.

Economic Gains to Fish Farmers Resulting from Research Conducted Under the Aquaculture Collaborative Research Support Program
Conference Paper
2008

NOP 08-234 (English)

The Aquaculture Collaborative Research Support Program (ACRSP) has been actively engaged in tilapia production research and the dissemination of research results in a number of tropical countries since its inception in 1982. Much of the program’s success over the years has come as a result of the excellent collaborative partnerships that the US and host country institutions formed while working together in each project. To facilitate more direct collaboration among ACRSP host country institutions, lead researchers from Honduras, Kenya, Mexico, the Philippines and Thailand initiated an information exchange project in 2005. The main objectives of this activity were to compare tilapia culture practices in use in the five countries, to consider ways in which new and successful techniques might be transferred to other countries or regions and to develop mechanisms for continued communication and collaboration. As a starting point for the activity, the participants conducted an informal survey of tilapia culture techniques presently in use in their home countries. The results of that survey are reported here.

A Comparison of Tilapia Culture Technologies: Linking Research and Outreach Results across Geographic Regions
Magazine Article
2008

NOP 08-232 (English)

This study was to assess effects of the pretreatment in all-plant based diets with microbial phytase on phosphorous utilization and growth performance of Nile tilapia (Oreochromis niloticus). Pretreatment trials were conducted using phytase at graded doses to determine the optimal dose of phytase. Available phosphorus (P) levels increased significantly with the increased doses of phytase and the dose of 1000 U kg(-1) was most efficient. Based on the pretreatment trials, plant based diets for Nile tilapia were formulated by pretreating with phytase at 1000 U kg(-1). Experimental diets were supplemented with graded levels of mono calcium phosphate (MCP) at 25, 18.75, 12.5, 6.25 and 0 g kg (-1) diet. In addition, there were three controls: one phytase control, one inorganic P control and one pretreatment control. The results showed that diets pretreated with phytase gave better growth performance, feed conversion ratio and protein efficiency ratio of Nile tilapia compared with the phytase control diet and pretreatment control diet (P < 0.05). There were no significant differences in growth performance of Nile tilapia between the inorganic control diet and phytase pretreated diets supplemented with MCP at 25, 18.75 and 12.5 g kg- I (P < 0.05), which resulted in significantly better performance than those at 6.25 and 0 g kg(-1) (P 0.05). Dietary interaction effects of phytase were observed for phosphorus retention efficiency and phosphorus load. Apparent digestibility coefficient of P (ADCp) was improved significantly by phytase pretreatment (P < 0.05). No significant difference was detected on ADC of crude protein among all experimental diets (P > 0.05).

Effects of pretreatment with microbial phytase on phosphorous utilization and growth performance of Nile tilapia (<i>Oreochromis niloticus</i>)
Journal Article
2008

NOP 08-A02 (English)

Tilapia-shrimp polyculture has played an important role in current efforts to control luminous bacterial disease caused by Vibrio harveyi. At present, green water technology is most extensively used by shrimp farmers in Negros Island in the central Philippines. While the contribution of tilapia as a biomanipulator is highlighted in the literature, the mechanism of action is not well understood. Data were gathered from shrimp ponds practicing two production systems: (a) green water system (probiotics + tilapia) and (b) closed/semiclosed system (probiotics alone). There was no difference between luminous Vibrio count (P < 0.05) in both systems, and water quality was found to be similar (P < 0.05). Because the green water system uses a bigger reservoir to raise the tilapia biomass, the net shrimp production was lower. In terms of direct cost of production, however, the green water system was 10 - 15% lower than the closed/semiclosed system because of significantly less aeration required. The polyculture maintained a more stable plankton environment during the early months of culture, which increased survival of shrimps. Various pathways are presented for the control of luminous bacterial growth in polyculture ponds: (a) fish feeding on organic wastes and conversion to feces; (b) selective fish foraging to increase the dominance of beneficial phytoplankton; (c) bioturbation of pond sediments; and (d) release in the water column of antimicrobials, fungi, or competing bacteria from the skin and gut mucus of tilapia.

Tilapia-shrimp polyculture in Negros Island, Philippines: A review
Journal Article
2008

NOP 08-231 (English)

Growth, plasma steroids, and the appearance of gonads (histology and gonadosomatic index) were followed in South American catfish (surubim, Pseudoplatystoma sp.) raised in captivity in the aquaculture facility at The Ohio State University, Columbus, Ohio, USA, from 2003 until 2006. Broodstock growth showed a great individual variation and it did not seem sex dependent. The levels of 11-ketotestosterone were high in males during the reproductive season. Three out of six females spawned after receiving two doses of carp pituitary extract (0.5 and 5 mg/kg) at 11-h intervals. Fertilization was performed in only one female in February 2006. Egg size was 0.73 +/- 0.06 mm in diameter at stripping. Two males released sperm, and it was used for fertilization. Sperm concentrations were 24 x 109 and 15.5 x 109 spermatozoa/mL in Male 1 and Male 2, respectively, and viability was confirmed after activation in 0.3% NaCl. Embryo survival at 9 h after fertilization was 44 and 23% for Male 1 and Male 2, respectively. Embryos hatched 15 h after fertilization. Larvae were 3.53 +/- 0.09 mm in length at hatching and were successfully raised (72% survival after 2 wks) using live brine shrimp nauplii.

Growth, maturation, induced spawning, and production of the first generation of South American catfish, <i>pseudoplatystoma</i> sp., in North America
Journal Article
2008
Duc, N. M., and H. Kinnucan. 2008. Effects of US Antidumping under the Byrd Amendment: The Case of Catfish edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A09 (English)

NOP 08-A09 (English)

The Byrd Amendment permits US firms that petition successfully for antidumping duties to collect tariff revenues. Whether these payments strengthen the duty’s ability to raise price depends crucially on market structure. In a competitive market where domestic and imported goods are imperfect substitutes, the payments are akin to a production subsidy and thus undermine the duty’s ability to raise price. Applying the theory to antidumping duties imposed by the United States on catfish imports from Vietnam, a three-equation model estimated using monthly data from January 1999 to August 2006 showed the duties to have had a modest yet positive effect on the US price. Although the weak price effect is consistent with supply enlargement induced by the payments, our econometric results suggest substitution effects coupled with incidence shifting are stronger causal factors.

Effects of US Antidumping under the Byrd Amendment: The Case of Catfish
Conference Proceedings
2008
Duc, N. M. 2008. Aquaculture and Happiness – A Microeconometric Analysis in Vietnam edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A08 (English)

NOP 08-A08 (English)

The contribution of aquaculture development to the Vietnamese national economy and to farmers’ incomes has been documented in various government reports as well as working papers produced by development projects. However, the role of aquaculture in the life satisfaction of poor farmers has not been considered rigorously. In particular, it is very difficult to find any literature relating aquaculture adoption to job or life satisfaction of the adopters. Due to the controversial role of income in creating happiness and the increased contribution of fish production in the livelihoods of small scale farmers, there exists a question of whether income increases from adoption of aquaculture would raise happiness of farmers. This study identifies some determinants of job satisfaction and subjective well-being of small scale fish farmers in Vietnam and examines the role of earnings from fish production in generating their happiness. Cumulative logistic models with data from a 2001 survey in Southern Vietnam show that relative income, not absolute income, from aquaculture raises their job satisfaction. Higher satisfaction is also associated with involvement in extension services, a larger relative pond surface and a higher expectation level on earnings from aquaculture. The role of income per capita in job satisfaction or happiness is not confirmed. Happiness of the farmers increases with cash earnings from fish farming and income from wild fish relative to total household income.

Aquaculture and Happiness – A Microeconometric Analysis in Vietnam
Conference Proceedings
2008
Feng, W., Z. Xiaoshuan, W. Weisong, and F. Zetian. 2008. On the power structure of aquatic product supply chain in China edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A16 (English)

NOP 08-A16 (English)

It is helpful to keep the stability of aquatic product supply chain and promote higher development of fishery economy to research power structure of aquatic product supply chain. This paper analyzes the power structure of aquatic product supply chain via the behavior theory in marketing discipline, cased study by Beijing and Guangdong province. The result shows the main reasons for lower operational performance in aquatic product supply chain are rather unbalance cost and benefit of power structure across the supply chain.

On the power structure of aquatic product supply chain in China
Conference Proceedings
2008

NOP 08-238 (English)

The most important quality issue for tilapia is the presence of off-flavors that derive from cyanobacteria and actinomycetes, which can be addressed by depuration. Methyltestosterone has been proven safe for sex reversal of fry. Farmers use lower stocking densities and improve water quality to reduce the need for antibiotics. Biosecurity and BMPs reduce contamination by environmental pollutants.

Food Safety, Quality Control in Tilapia Products
Magazine Article
2008

NOP 08-240 (English)

Banda Aceh, at the north end of the island Sumatra, took the full brunt of the December 2004 tsunami. Over 33,000 households in the region had registered their primary income as being generated from aquaculture before the disaster. Along the coasts the majority of aquaculturists were small-scale shrimp farmers, operating family owned ponds (tambaks) of less that a hectare each. All of the shrimp produced were marketed locally. No freezing facilities were present, so shrimp could only be sold on ice or as dried products. Even before the tsunami, many of the farmers were plagued with low growth and survival rates resulting from poor water quality and several diseases. A virtual monoculture of shrimp, multiple-reuse of effluent waters, removal of mangroves and other vegetation and overfed ponds had contributed to a significant reduction in production in the years immediately prior to the tsunami. The tsunami itself essentially destroyed all the coastal ponds of Aceh province. The wave rushed over most of the villages built on the coastal berms and pushed much of the village contents into the ponds. Virtually all of the dikes, control structures, canals and other infrastructure elements were completely obliterated. Many of the shrimp ponds had been constructed in the coastal lagoons behind the beaches where most of the population lived. The lagoons had contained extensive mangrove forests before the shrimp ponds removed a considerable percentage of them. In addition to the farms destroyed, the local aquaculture research and extension station at Ujong Battee was almost completely destroyed and the regional fisheries and aquaculture trades school in Ladong lost an entire bus load of faculty and students en-route to a picnic when the waves struck.

Aquaculture restoration in the tsunami zone, Ach Province, Indonesia
Journal Article
2008

NOP 08-A21 (English); NOP 08-A23 (English)

There is considerable controversy in the literature regarding the existence of a “longitudinal slit” versus a “duct” connecting the respiratory gas bladder with the alimentary tract in various species of garfishes (Lepisosteidae). The aim of the present work has been to address these discrepancies on the basis of our own work on longnose gar Lepisosteus osseus in conjunction with a review of the literature. We provide anatomical evidence for a better understanding of the functional advantages of the “longitudinal slit” versus the “duct” in respect to feeding and respiration in juveniles longnose gar. The anterior part of the garfish body cavity, from the oral cavity to the stomach, was used for morphological and histological analysis. It has been observed that the air bladder in the longnose gar is open to the alimentary tract through a longitudinal slit which is present in the glottis on the dorsal side of the esophagus. The external side of the glottal ridges in the anterior esophagus, on the side of the opening, consist of stratified squamous epithelium which then turns into the pseudostratified columnar ciliated epithelium in the posterior esophagus. The glottal ridges are comprised of epithelia and radially arranged striated muscle fibers surrounded by connective tissue. It can be surmised that the tunica muscularis in the anterior esophagus of garfish aids the glottis in moving air in and out because it supports the dorsal retractor muscle in propelling air through the longitudinal slit from the buccal cavity. When the buccal cavity of the garfish is contracted during holding prey, the muscles of the gas bladder wall and tunica muscularis, located inside and outside the glottal ridge, participate in exhalation.

Morphological analysis of the functional design of the connection between the alimentary tract and the gas bladder in air-breathing lepisosteid fish
Journal Article
2008

NOP 08-243 (English)

Tilapia, Oreochromis sp., production in the Central American region in recent years. Yet, commercial tilapia aquaculture has not developed in Nicaragua on the scale that it has in other neighboring countries. Although demand for tilapia products exists, lack of thorough understanding of domestic markets and coordinated production and marketing efforts have hampered the development of a domestic market. The objectives of this study were to quantify domestic marketing costs for tilapia produced in Nicaragua and develop profitable marketing alternatives for tilapia farmers. Results suggested targeting primarily outlets with higher sales prices such as restaurants with supplemental production delivered to local supermarkets. The model chooses cities with weekly restaurant demand capable of absorbing the farm's production with excess product sold to alternative outlets. Supply of farm-raised tilapia production in most regions of Nicaragua was insufficient and created problems associated with frequent and dependable deliveries required by higher paying outlets (restaurants and supermarkets). Larger farms will generate greater returns with regular consistent deliveries to higher priced restaurant outlets. Smaller farms with limited production volumes were not able to meet weekly delivery requirements. Biannual deliveries reduced transportation cost and sales price and were not profitable. However, sustaining markets with infrequent deliveries may not be feasible. This analysis provides guidelines for targeting those specific markets that optimize returns to specific farm sizes in specific regions. 

Optimizing tilapia, <i>oreochromis</i> sp., marketing strategies in Nicaragua: A mixed-integer transshipment model analysis
Journal Article
2008

NOP 08-236 (English)

Locally generated squid-processing byproduct was processed into concentrated hydrolysate (22% solids, 17.3% protein, and 3.0% lipid, primarily phospholipids—11.6% eicosapentaenoic acid/24.5% docosahexaenoic acid on a lipid weight basis). Two microparticulate diets (65% protein, 19% lipid, 7.5% carbohydrate, and 19.12 MJ/kg energy, on a dry weight basis) were prepared using squid hydrolysate (SH) and squid-herring hydrolysate as sole protein sources (73.3 and 78.65% of the whole diet, respectively). A 22-d feeding trial with summer flounder, Paralichthys dentatus, larvae of 17 d after hatch showed that the survival rate (92%) of larvae fed SH was significantly (P < 0.05) higher than those of larvae fed live Artemia nauplii (81%) and a commercial diet, Proton (65%), while specific growth rates (SGR) were comparable (2.23% /d for SH and 2.86% /d for Artemia) with the lowest for Proton (1.39% /d). After switching from commercial and Artemia diets to a SH diet for 17 d following the 22-d feeding, significant improvements were seen in survival rates of post-weaning larvae fed previously commercial (65.28–76.57%) and Artemia diets (81.25–89.07%).

Development of a Squid-hydrolysate-based Larval Diet and its Feeding Performance on Summer Flounder, <i>Paralichthys dentatus</i>, Larvae
Journal Article
2008

NOP 08-A25 (English)

A sustainable semi-intensive pond aquaculture technology including major carp species (Indian, Chinese and common carp) as cash-crop and small indigenous fish species (SIS) as food for the farmers' families is being optimized in Bangladesh. Silver carp inclusion in the polyculture is now being considered, because this very efficient filter feeder has a strong impact on pond ecology and also on the farmers' family nutrition because it is a cheap fish that the family can afford to eat instead of selling. The present paper is centered on the reduction of silver carp negative effects on other species while keeping the advantages of increased total yield and income due to silver carp stocking. It presents the results of two experiments, one on-station and one on-farm, in which 3–5 silver carp/100 m2 were added or partially substituted major carp filter feeders. The basic stocking density was 100 carps (rohu, catla and a bottom feeder, either mrigal or common carp, at a 1:1:1 ratio) and 250 SIS (punti and mola) per 100 m2. In the on-station experiment silver carp density was 3 and 5 fish/100 m2 and the large carp bottom feeder was common carp. In the on-farm experiment silver carp density was 5 fish/100 m2 and the bottom feeder was either common carp or mrigal. Most of the water quality and fish performance parameters tested were not affected by the polyculture composition. Adding 3–5% silver carp or substituting 3–5% of the herbivorous fish species by this highly efficient filter feeder increased grazing pressure on the phytoplankton, which led to a 25–40% reduction of the chlorophyll concentration in the water column. The increased grazing pressure was not enough to affect other water quality parameters and fewer effects on the availability of food for the other fish species occurred than when the silver carp addition was 10% of the polyculture, as reported in a previous work. The strong negative effects of silver carp on the other species of the polyculture and the higher total yields and income recorded in previous experiments with the addition of 10 silver carp/100 m2 were much weaker and their expression depended on other pond conditions when 3 or 5 silver carp/100 m2 were added or substituted the same number of rohu or catla, either when the bottom feeder was mrigal or common carp. It was concluded that stocking 3 silver carp/100 m2 over the usual 100 large carp and 250 SIS /100 m2 can be considered a ‘no effect’ stocking density in relation to the control without silver carp, while stocking 10 silver carp/100 m2 should be preferred by farmers to keep the option of selling or consuming the silver carp.

The Effects of Partially Substituting Indian Carps or Adding Silver Carp on Polycultures Including Small Indigenous Fish Species (SIS)
Journal Article
2008

NOP 08-237 (English)

A África é o berço de espécies produzidas intensivamente em vários países, como a tilápia e o bagre africano; mesmo assim, até recentemente as espécies eram pouco cultivadas no continente. A despeito da grandeza do continente africano, com mais de 30 milhões de km2, 53 nações, 37.500 km de área costeira e mais de 200.000 km2 de áreas alagadas e rios que abrigam uma abundante fauna aquícola, a produção de pescados em 2005 alcançou apenas 8 milhões de toneladas. Desse total, a aqüicultura contribuiu com pouco mais de 656 mil toneladas, com destaque para o Egito, responsável por 82% dessa produção. Especialistas, no entanto, concordam que há na África grande potencial para a expansão da aqüicultura e demanda crescente por alimentos; afinal, estima-se que sejam mais de 800 milhões de africanos, a maioria extremamente carentes. A seguir, apresentamos um panorama da aqüicultura desenvolvida em três países africanos – África do Sul, Gana e Quênia – resultado das recentes visitas realizadas pelo projeto Aquafish CRSP, criado pela USAID - Agência Americana para o Desenvolvimento Internacional (veja Box).

Aqüicultura na África: O Projeto Interegional de Intercâmbio de Tecnologia sobre Produção de Tilápias e outros Ciclídeos
Magazine Article
2008
Nguyen, L., P. Nguyen, T. Le, and C. U. Le Tat. 2008. Technical approaches and aquaculture development alternatives edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development.
NOP 08-A10 (English)

NOP 08-A10 (English)

Tam Giang - Cau Hai lagoon systems covered over 22.000 ha, along coastal region from North to South of Thua Thien Hue with 70 km and more than 400.000 inhabitants are living around in lagoon systems. There are many livelihood activities as fishing, aquaculture and farming. Aquaculture systems are diversified: pond, net-closure in high and low tide systems and farmers and communities had to choose and select proper species and models for adaptation of the regions but they still have not successful, even they lost investment money and capital by environmental problems and uncorrected carrying capacity leading to diseases and low productions. Research results were showed the different technical approaches and aquaculture system alternatives for property aquaculture models in the regions. More than 267 aquaculture households of 15 communes in 5 districts that related to Tam Giang - Cau Hai lagoon were investigated and shown the figures on over 4000 ha of aquaculture water area of 33 communes: high/low tides of pond systems; cage culture in low tide systems; sandy shrimp culture system; integrated poly-culture and monoculture, while P. monodon was main species in all of systems and models. Efficiency of different alternatives were conducted in intensive of high tide was highest income, net income 100 - 700 mil. VND; semi-intensive of high tide-mono, 10 - 25 mil.; semi-intensive high tide-integrated poly-culture, 20 -40 mil.; semi-intensive-low tide-mono, 3 - 10 mil.; extensive-low tide-poly, 30 -50 mil.; marine water cage culture-poly, 25 - 35 mil., respectively. Effect of different species alternatives were on 267 households in differences, 26.99; 90.22; 221.13; 48.21, P < 0.01. The stock density and composition was conducted in differences of income and benefit for farmers, P < 0.05. Water control and management, dietary composition and feed processing, animal health management were effected on the income and benefit of aquaculture models, P < 0.01 and 0.001.

Technical approaches and aquaculture development alternatives
Conference Proceedings
2008
Ogundari, K. 2008. Farm-level efficiency and resource-use: application of stochastic frontier analysis to aquaculture farms in southwest Nigeria edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development 1 - 8. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A04 (English)

NOP 08-A04 (English)

There are two distinctive issues in marketing of fishermen catch; one is the issue of agent-principal relationship due to asymmetric information whereby the agent takes over the function of marketing once the catch is landed. There has been allegation that giving of credit is a form of trade that benefits the agent who has control over the daily fishermen catch. Another form of marketing strategy which I believe have never been investigated before at least in Malaysia or in fishing industry is the way by which fishermen catches are brought to the market place. Many studies and analysis found that those who have dominant strategy in the market will be affected by the way simultaneous or sequential, collusive or non-collusive marketing strategies. This study is intended to verify the theoretical findings of game theory with the empirical evidences using real world data from fisheries statistics.

Farm-level efficiency and resource-use: application of stochastic frontier analysis to aquaculture farms in southwest Nigeria
Conference Proceedings
2008
Ogundari, K. 2008. An Examination of Productivity Potential of Aquaculture Farms in Alleviating Household Poverty: Estimation and Policy Implications from Nigeria. Pp. 449 - 459 in Proceedings of the Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development Biennial Conference, Proceedings of the Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development Biennial Conference, edited by J. Mumford and Leach, A. Corvallis, Oregon: International Institute of Fisheries Economics & Trade. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A13 (English)

NOP 08-A13 (English)

This study examines income generation potential and resource- use efficiency of aquaculture farms in Nigeria. A total of 120 aquaculture farms were sampled. Using gross margin (GM) analysis, the result shows that, all the sampled farms were able to cover their total operating expenses with an average GM > 200,000 naira per annum. The assessed parameters of resource use-efficiency of the farms with stochastic frontier models (SFM) revealed that, elasticities of inputs, such as: pond size, feeds, fingerlings, and other costs were significantly different from zero. While returns to scale of 1.16 obtained from the analysis suggests that, an average farm from the study, exhibits increasing returns to scale. The estimated efficiency score revealed a significant level of inefficiency with an average technical efficiency of about 81%. This suggests that about 19% potential yield are forgone due to inefficiency from the study. The result of sources of technical efficiency shows that; extension, education, stocking density, and credit significantly influenced efficiency of the farms. Similarly, the result of the simulated marginal effects of the inefficiency variables shows that, extension has the highest marginal effects on the efficiency score follows by credit, education, and stocking density. The implications of these findings, therefore, suggest that, aquaculture will provide potential channel of income generation for households in the country considering the size of the profit obtained from the analysis. However, as matter of policy concern, extension with the highest simulated marginal effects on the efficiency score is expected to generate a large increase in the overall performance of the sector if strengthen for sustainable fish production in Nigeria.

An Examination of Productivity Potential of Aquaculture Farms in Alleviating Household Poverty: Estimation and Policy Implications from Nigeria
Conference Paper
2008

NOP 08-235 (English)

The effects of feeding on the development and growth of pike perch muscle and on proliferation of their progenitor myogenic cells were evaluated. Larvae were fed starting on Day 5 after hatching with Artemia nauplii, two commercial diets (Aglo Norse [AN] and Biokyowa [BK]), and two formulated diets (C [nonhydrolyzed casein] and CH [25% casein hydrolysate]). The survival, body mass, and length of pike perch juveniles fed Artemia nauplii and AN and BK diets were significantly higher compared to the C and CH groups. The highest somatic growth rate was associated with an increased contribution of hyperplasia to white muscle growth. Significantly higher frequency of proliferating cell nuclear antigen- and Ki-67-positive nuclei in the white muscle of fish fed Artemia nauplii and commercial diets compared to those fed C and CH feeds indicates that feeding affected the number of fibers. The pike perch fed the CH diet exhibited significantly lower total cross-section area and average fiber area, additionally to the pathological changes in muscle morphology. The larvae fed natural food and diets promoting a fast growth rate exhibited a higher contribution of hyperplasia to muscle growth, which in turn, promoted an increase in the body size of adult fish.

The effects of feeding on muscle growth dynamics and the proliferation of myogenic progenitor cells during pike perch development (<i>Sander lucioperca</i>)
Journal Article
2008

NOP 08-239 (English)

Growth in fish and other vertebrates is under endocrine control, particularly through the growth hormone (GH)–insulin-like growth factor (IGF) axis. For this reason, it has been of interest to aquaculture researchers and the industry to establish endocrine biomarkers that can both reflect and predict growth rates in fish subject to various biotic and abiotic manipulations. Ultimately, by understanding the hormones that control growth and utilizing them as biomarkers, we hope to achieve optimal growth conditions in the aquaculture environment with less need for lengthy and costly grow-out trials. While the most appropriate endocrine biomarkers for growth can be both species and situation specific, IGF-I may be the most promising candidate for measuring instantaneous growth in fish. This is based on the direct contributions of IGF-I in regulating cell proliferation and ultimately somatic growth, along with its previously established correlations with the specific growth rate in fish under various conditions that alter growth. However, other endocrine indices, such as GH and IGF-binding proteins (IGFBPs), are also important contributors and may in some instances prove a strong corollary to growth rate. This review discusses the potential utility of GH, IGF-I, and IGFBPs as growth biomarkers for those manipulations most relevant to the aquaculture industry, namely, feeding regimen, diet composition, temperature, photoperiod, and stress.

Endocrine Biomarkers of Growth and Applications to Aquaculture: A Minireview of Growth Hormone, Insulin-Like Growth Factor (IGF)-I, and IGF-Binding Proteins as Potential Growth Indicators in Fish
Journal Article
2008
Poot-Lopez, G. R., and E. G. Leyva. 2008. Bioeconomic analysis of ration size in intensive tilapia culture edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A05 (English)

NOP 08-A05 (English)

Balanced feed represents approximately 60 % of production costs in fish culture and ration size has significant effects on this parameter. Ration size varies according to culture strategies and producer knowledge. It can also have environmental implications since feed can be a pollutant. A bioeconomic model was developed for an intensive system with recirculation considering different ration sizes (100 % recommended levels, 80 %, 50 % and satiety). Assumptions for model parameterization were based on previous production experiments and market factors in Mexico. The 80 % ration resulted in the greatest reduction in water changes, energy and operating capital, and was profitable. The 50 % and satiety rations were not profitable, and the latter had the highest water change and operating capital requirements.

Bioeconomic analysis of ration size in intensive tilapia culture
Conference Proceedings
2008
Poot-Lopez, G. R., and E. G. Leyva. 2008. Partial Substitution of Balanced Feed by Chaya Leaves in Nile Tilapia edited by A. Leach and Mumford, J. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A14 (English)

NOP 08-A14 (English)

Tilapia culture in Yucatan State, Mexico, is largely semi-intensive. The producers are mostly poor farmers who receive government subsidies for purchase of fingerlings and balanced feed. Feeding practices are often inadequate (satiety rations), moreover, producers frequently suffer financial and resource shortfalls. During feed shortages producers are known to use empirical application of chaya (Cnidoscolus chayamansa) leaves, used traditionally in human and animal nutrition. A study was done of growth in juvenile tilapia using diets containing balanced feed with chaya (25 and 50% of substitution), complete, half-complete and satiety rations of balanced feed, during the warm season. The results were used to develop a bioeconomic model and implemented in MS Excel program, with a one-day time step. In order to minimize the cost of tilapia feeding, and maximize the benefits by using a limited amount of balanced feed per cycle. In addition the analysis was completed using the Marginal Rate of Technical Substitution (MRTS). According to results from MRTS, it is necessary to add 2.51-3.91 units of chaya for each reduced unit of balanced feed, to maintain the same level of production. In a resource limited situation, substitution of 50% of balanced feed for raw chaya leaves generates a harvest size greater than complete and satiety rations of 24.8 and 28.8% respectively. When considering sale prices that are consistent with size at harvest and costs, treatments with chaya considerably maximized profits.

Partial Substitution of Balanced Feed by Chaya Leaves in Nile Tilapia
Conference Proceedings
2008
Portella, M. C., and K. Dabrowski. 2008. Diets, Physiology, Biochemistry and Digestive Tract Development of Freshwater Fish Larvae. Pp. 227 - 279 in Feeding and Digestive Functions in Fishes, Feeding and Digestive Functions in Fishes, edited by J.E.P. Cyrino, Bureau, D.P., and Kapoor, B.G. Enfield, New Hampshire, US: Science Publishers. Retrieved (http://www.crcnetbase.com/doi/10.1201/b10749-7).
NOP 08-A22 (English)

NOP 08-A22 (English)

Live preys’ availability to larval fish is determined on the basis of suitable size, frequently described as gape width/prey size proportion (Dabrowski and Bardeg, 1984). In some cases, larval freshwater fish, like the 4-5 mm total length yellow perch (Kolkovski and Dabrowski, 1998), eat prey smaller than 50-100 μm in width, whereas in the case of the first feeding larval walking catfish (Clarias), the largest size of Artemia nauplii offered, 205-295 μm (4% of fish body length), increased the growth, but compromised survival in comparison to ungraded size nauplii. Nauplii graded into two categories – below 59 μm and 59-183 μm, mesh size net – even when fed in excess, resulted in much lower fish size and survival was 14-28% in comparison to 67% in fish fed with unsieved Artemia (Petkam and Moodie, 2001). Therefore, it is important to readjust the feed particle size (live or inert) to the optimum acceptable size of larval fish. 

Diets, Physiology, Biochemistry and Digestive Tract Development of Freshwater Fish Larvae
Book Chapter
2008

NOP 08-233 (English); NOP 08-A24 (English)

An experiment was conducted to compare rice straw mat and kanchi (bamboo sticks) as substrates in periphyton-based polyculture systems. The experiment had three treatments: (a) no substrate (control), (b) rice straw as a substrate (3 x 2.7 kg pond-1) and (c) kanchi as a substrate (390 kanchi pond-1). Fingerlings (n = 40) of rohu, Labeo rohita (24.5 +/- 0.5 g); mrigal, Cirrhinus mrigala (25.1 +/- 0.6 g); catla, Catla catla (25.8 +/- 0.5 g); common carp, Cyprinus carpio (27.6 +/- 0.6 g), and silver carp, Hypophthalmichthys molitrix (30.4 +/- 0.9 g) were stocked at a 3:2:2:2:1 ratio and cultured for 90 days. There were no differences in the number of plankton, periphyton and macro-zoobenthos among the treatments. The total plate count of bacteria was higher in the rice straw treatment (41,320 million cfu m-2) than that in the kanchi treatment (11,780 million cfu m-2). Growth and the final mean weight of rohu, catla and common carp were higher in the substrate treatments than those in the control. Rice straw and kanchi treatment, respectively, resulted in 38% and 47% higher combined total weight gain over control. Gross margin analysis showed that rice straw treatment resulted in more profit than the control and kanchi treatment. Therefore, rice straw has the potential to be used to increase production in the low-input rural aquaculture.

Comparison of rice straw and bamboo stick substrates in periphyton-based carp polyculture systems
Journal Article
2008

NOP 08-245 (English)

This article investigates social, political and cultural aspects of sea turtle management led by the Tobian community at Helen Reef in the Republic of Palau. We use participant observation, unstructured interviews and examination of community-based natural resource management literature to compare and contrast the Tobian community with several other communities in Palau in order to identify some of the underlying factors that we believe contributed to the successful implementation of the Tobian community-based program. These factors include: robust structure of local and extra-local partnerships; remote location of the resource and small scale of the managing community; realized community benefits in terms of jobs and improved capacity to monitor and manage natural resources; adaptive capacity and autonomy in decision-making; and strong connections to traditional natural resource management systems. Sea turtle conservation and management is a large scale issue; preventing further decline of endangered sea turtles will require management at multiple scales. For the Tobian community, success may be attributable to several key factors that come together to produce a decentralized community-based program that operates with an adaptive, collaborative and bottom-up structure. This model may be applicable to comparable communities; it is, however, important to recognize that diverse societies will have a variety of formulas for success.

A comparative study of community-based sea turtle management in Palau: Key factors for successful implementation
Journal Article
2008
Sinh, L. X. 2008. Considerations on the policy environment for aquaculture in Vietnam edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A17 (English)

NOP 08-A17 (English)

The fishery sector, including capture, aquaculture, processing and supportive services, plays an important role to the whole economy of Vietnam. Total aquatic production of the country increased about 3 times after 15 years, from 1.02 million tones in 1990 to 3.43 million tones in 2005. The growth of aquaculture production was from 0.30 million tones in 1990 to 1.44 million tones in 2005 or increased 4.6 times, faster compared with that of capture (from 0.79 to 1.99 million tones, respectively). Aquaculture becomes more and more crucial when it contributes over 50% of the total aquatic production of Vietnam. How to obtain a sustainable development of the whole sector, particularly aquaculture, is a big and difficult question which requires the answers from different aspects, not only technical and socio-economic aspects but also environmental and political aspects. This paper is aimed at the policy environment for aquaculture development in Vietnam. Economic reform or Doi moi process started from the end of 1980s leading to further improvement in the policy environment and helped to result in an impressive development of Vietnam's fishery sector, especially aquaculture sub-sector. Major considerations are focused on: (1) Land reform policy/Laws with conversion of inefficient agricultural land into aquaculture; (2) Environmental Laws with with the use and management of water, natural aquatic resources and wetland forests; (3) Finance and investment; (4) Seed supply, use and management; (5) Feed supply, use and management; and (6) Chemicals and medicine supply, use and management. The analysis is also linked with processing and export of aquatic products, the integration process (WTO), and three most important cultured species in Vietnam at the present time, i.e., tra/basa (Pangasius hypophthalmus/Pangasius bocourti), black tiger shrimp (Penaneus monodon) and hard clam (Meretrix lyrata). It is revealed that many of the issued policies and regulations were ineffective or even unacted while more and appropriate ones need to be provided for further development of aquaculture and fishery sector.

Considerations on the policy environment for aquaculture in Vietnam
Conference Proceedings
2008
Sinh, L. X., N. T. Long, and D. M. Chung. 2008. Near-Shore Trawling Fisheries In The Mekong Delta Of Vietnam edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A07 (English)

NOP 08-A07 (English)

Local community in the Mekong Delta is said to be “fish eating society” where 70% of their animal protein relies on fish products. The Mekong Delta contributes more than 60% of total aquaculture production and 40% of total wild fish catch of Vietnam. Among a large number of fishing boats, trawlers have developed and dominant in Vietnam fisheries. The small-scale trawlers cover about 70% total number of fishing boats and have been given too much concern in terms of both natural aquatic resources management and other socio-economic problems. This paper describes the small-scale trawling fisheries in the Mekong Delta using surveyed data from 176 small and near-shore trawling fishers Bentre, Soctrang, Baclieu, Camau and Kiengiang provinces, and compares the differences of major indicators between three main fisher groups: (i) Group 1 - Inside and around Camau National Park, 38 fishers; (ii) Group 2- Near, is that, ≤ 30 km from Camau National Park, 40 fishers, and (iii) Group 3 – Far, is that, > 30 km from Camau National Park, 98 fishers. The analysis shows that small scale and near-shore fishing puts more pressure on the natural aquatic resources in the coastal areas of the Mekong Delta while there has been insufficient management on this type of fisheries. Mangroves and Camau National Park regconised by the local fishers via direct benefits obtained from the park. Shrimp and squid are two most important species of near-shore trawling fisheries but less efficient to the fishers who live near the park. Better investment for off-shore fishing and more alternatives of better income occupations are important to protect the natural aquatic resources along the coasts of the Mekong Delta, especially Cmau National Park.

Near-Shore Trawling Fisheries In The Mekong Delta Of Vietnam
Conference Proceedings
2008
Subba, R. N. 2008. Role of aquaculture in poverty reduction and empowerment of women in India through the medium of self-help groups edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A11 (English)

NOP 08-A11 (English)

Aquaculture remains as a suitable avenue in India for augmenting fish production, which is easy, cost effective and sustainable at the same time. It provides livelihoods to rural people through generating income and employment and reduces poverty by developing and strengthening community based approaches. The expansion of farmed fishery development in community water tanks and other water bodies makes remarkable additional contribution towards the nutritional well being and socio-economic advancement of rural farmers including women. This augurs well for the sustained development of these areas wherein fish can play an important role in providing required thrust in their economy and in the improvement of the economic status of the people living in the surroundings. In recent times, self-help groups (SHGs) have emerged as an alternative mechanism to promote savings habit among poor and to provide small and short term loans to its members at lower interest to meet their necessities, consumption and income generation activities like aquaculture. Women are considered as appropriate tool for implementing community and self-development programmes. Against this background, an attempt is made in this paper to review and examine the relevant literature regarding the efficacy of SHGs and other programmes and their impact on the fisherwomen and other stakeholders and also on aquaculture. Research results show that the SHGs are very successful as can be judged from the fact that a large number of people have accepted the system and taken up fish production as their main means of livelihood and source of main or additional income.

Role of aquaculture in poverty reduction and empowerment of women in India through the medium of self-help groups
Conference Proceedings
2008
Subba, R. N. 2008. International Seafood Trade and Its Impacts on Fisheries and Fishing Communities edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A12 (English)

NOP 08-A12 (English)

This paper makes an attempt to examine the emergence of international trade in seafood and its impacts on the fisheries and fishing communities in India. It suggests some measures and strategies to maximize the benefits through sustainable fisheries development. Seafood is one of the leading non-traditional exports identified by the Government of India. Until 1960s, much importance was not attached towards export trade in general. With the changed policy of Government, seafood was considered as one of the thrust areas for augmenting exports; consequently, earning of foreign exchange was made as one of the basic objectives of marine fisheries development. Efforts were made to increase fish production, especially of shrimp, whose unit value was far higher in the international markets. Different kinds of fishing vessels including small mechanized boats, sona boats, larger deep sea trawlers were deployed and almost all of them confined their fishing operations to the inshore regions of the sea. Consequently, the production of fish as well as shrimp have gone up manifold thus enhancing the quantum and value of exports. However, the excessive fishing effort and over fishing in the inshore regions brought down the production levels leading to depletion and stagnation. No doubt the international trade has positively created massive infrastructure and employment besides huge foreign exchange earnings. But the over fishing has forced to withdraw some of the larger and mini-trawlers and the industry has suffered with shortage of raw material for the trade. Shrimp farming was taken up on a larger scale to offset the shortage but unplanned growth of the same met with disease attack and Supreme Court's restrictions on environmental considerations. The paper further discussed the negative as well as positive impacts encountered by the fishermen due to mechanization and shrimp farming on the one hand and that of Tsunami and WTO on the other and suggested remedial measures.

International Seafood Trade and Its Impacts on Fisheries and Fishing Communities
Conference Proceedings
2008

NOP 08-A03 (English)

The levee pond is by far the most popular pond type for fish production. The specific object of this study was to develop a tool enabling extension, nongovernmental organization (NGO) agents, contractors and engineers in developing countries for computing levee pond excavation costs. We developed a spreadsheet-based computational tool in English and Spanish on the Microsoft Excel platform. Knowing the original land slope and desired pond volume, one may compute excavation amounts that provide an acceptable cut-fill estimates based on a comparison with AutoCAD Civil 3-d®. The model computes projected costs in user-selected currency. Guidelines are provided for establishing pond bottom elevations and achieving the desired water depth. The model is relevant for small to medium sized levee ponds customarily used in aquacultural production in developing countries.

Spreadsheet tool for computing levee pond excavation costs for developing countries
Journal Article
2008

NOP 08-A01 (English)

Culture performance beyond metamorphosis of larval loach (Misgurnus anguillicaudatus) was examined in a feeding experiment of the early development stage (20 days after hatch; DAH). Total length, dry weight, length- and weight-specific growth rate (SGR) and survival were monitored in different diet regimes. During 20 days, diet treatments included: microparticle diets (A); live daphnia (Moina micrura) (B); live daphnia plus live chlorella (Chlorella pyrenoidosa) (C); and live daphnia plus microparticle diets (D). Fish survival rates during 20 days were 21.23 ± 4.2% (A), 73.19 ± 2.8% (B), 90.76 ± 3% (C) and 91.46 ± 3.1% (D), respectively. Length- and weight-specific growth rate after 20 DAH (final mean SGR; % day-1) were 5.36 ± 0.44 and 15.75 ± 1.52 (A), 9.29 ± 1.25 and 23.47 ± 2.23 (B), 9.42 ± 1.55 and 24.88 ± 2.9 (C) and 9.55 ± 1.23 and 24.40 ± 2.75 (D), respectively. Fish in treatments B, C and D displayed higher growth rates and were significantly longer and heavier than fish in treatment A by the end of the experiment (P < 0.05). Fish in treatment A had highly significant greater (P < 0.001) mortalities than in treatments B, C and D. There were no significant differences in any growth parameter between fish in treatments B, C and D, but the survivals in treatments C and D (90.76% and 91.46%) were significantly higher than in treatment B (73.19%, P < 0.05). The results demonstrated that enriched prey and co-feeding may serve as a potential feeding strategy for loach larvae, and the form of co-feeding reduces the costs and dependence on live foods to a certain extent. We concluded that larval loach should be reared over metamorphosis using either of the following methods: feed with live daphnia supplemented with microparticle diets or with live chlorella. However, a prolonged rearing period of loach larvae is needed to detect nutritional problems and observe remote effects of co-feeding on weaning in the future. 

Effects of daphnia (<i>Moina micrura</i>) plus chlorella (<i>Chlorella pyrenoidosa</i>) or microparticle diets on growth and survival of larval loach (<i>Misgurnus anguillicaudatus</i>)
Journal Article
2008

NOP 08-A20 (English)

The diel feeding rhythm and ontogenesis during early life stage of loach Misgurnus anguillicaudatus were investigated under experimental conditions (light: L 06:00 - 18:00, D 18:00 - 06:00 h). Morphological and behavioral developments of loach from newly hatched to 40 days after hatching were observed. Larvae were able to prey on daphnia 3 - 4 days after hatching at 23 +/- 0.5C. As the larvae grew, they showed an increasing feeding capacity and a distinct feeding rhythm. Feeding intensity and incidence for day-4 larvae were highest at 10:00 and 16:00 h. The highest levels of feeding intensity for day-12 larvae occurred at 08:00, 12:00, and 18:00 h as did feeding incidence. By day 20, when the larvae metamorphosed, the highest levels of feeding intensity occurred at 06:00, 18:00, and 24:00 h and were concurrent with the highest feeding incidence. After metamorphosis, feeding capacity had again increased considerably and, in contrast to the earlier stages before day 20, feeding intensity for day-30 juveniles peaked at 05:00 and 20:00 h, about 1 - 2 h after the maximum feeding incidence. The feeding rhythm of loach juveniles at day 40 was almost the same as the day-30 juveniles. The estimated maximum daily feeding rates were 43.1%, 33.4%, 19.0%, 12.8%, and 5.8% of body weight on days 4, 12, 20, 30, and 40, respectively. Thus, loach was found to have different feeding rhythms in the pre- and post-metamorphosis stages, with the highest feeding activity in daytime during the larval planktonic stage before metamorphosis, and intensely nocturnal feeding behavior during the juvenile benthic stage after metamorphosis.

Transpositional feeding rhythm of loach <i>Misgurnus anguillicaudatus</i> from larvae to juveniles and its ontogenesis under artificial rearing conditions
Journal Article
2008
Yi, Y., and J. S. Diana. 2008. Strategies for Nile Tilapia (Oreochromis niloticus) Pond Culture. 8th International Symposium on Tilapia in Aquaculture (ISTA) 2008 11 - 14. Retrieved (https://cals.arizona.edu/azaqua/ista/ISTA8/ISTA8.htm).
NOP 08-241 (English)

NOP 08-241 (English)

Different strategies for Nile tilapia (Oreochromis niloticus) culture in ponds with a series of progressive inputs were compared. The sequential experimental stages to increase fish production through intensification were: 1) triple superphosphate (TSP) only; 2) chicken manure only; 3) chicken manure supplemented with urea or urea and TSP; 4) urea and TSP; 5) continually supplemental feeding; 6) staged supplemental feeding; 7) feeding alone. The results showed that the choices of input regimes with increasing economic gains are: 1) fertilizing ponds with moderate loading of chicken manure; 2) fertilizing ponds with chicken manure supplemented with urea and TSP; 3) fertilizing ponds with urea and TSP; 4) fertilizing ponds initially with urea and TSP in combination of supplemental pelleted feed at 50% satiation level at later stage of grow-out cycle.

Strategies for Nile Tilapia (<i>Oreochromis niloticus</i>) Pond Culture
Conference Proceedings
2008
Zhang, X., F. Wang, W. Wu, and Z. Fu. 2008. On Consumer's WTP (Willingness to Pay) for Fishery Product Traceability System in China edited by J. Mumford and Leach, A. Fourteenth Biennial Conference of the International Institute of Fisheries Economics & Trade, July 22-25, 2008, Nha Trang, Vietnam: Achieving a Sustainable Future: Managing Aquaculture, Fishing, Trade and Development. Retrieved (http://oregonstate.edu/dept/IIFET/publications.html).
NOP 08-A15 (English)

NOP 08-A15 (English)

Quality safety traceability system has adopted by most fishery enterprises as an important part of the strategic management. As the consequence, the end product is supposed to be higher. That consumers whether to accept has a direct impact on system successful implementation. This paper proposes a framework to research consumer awareness of fishery product and the traceability system and the degree of willingness to pay, cased study of consumers in Beijing on. The results contribute to the effectively apply the traceability system by aquatic products enterprises.

On Consumer's WTP (Willingness to Pay) for Fishery Product Traceability System in China
Conference Proceedings
2008

NOP 08-A19 (English)

In search for an easy, rapid and cost-effective method to determine the ploidy levels of diploid and tetraploid dojo loaches Misgurnus anguillicaudatus distributed naturally in China, direct (karyotyping) and indirect (flow cytometry, erythrocyte nuclear measurements and morphometric analysis) methods were compared. The results revealed that all techniques employed may be successfully used to determine the ploidy levels. It was discovered that karyotyping is cumbersome; flow cytometry is expensive whereas erythrocyte nuclear measurement requires a long time and intensive labour. On the other hand, the morphometric analysis method, especially the measurement of head length (HL), snout length (SL) and depth of caudal peduncle (CPD), is the simplest, with no damage to the fish and can be considered a practical alternative to other techniques. The discriminant function developed from the specimens, D = 7.539(HL ⁄ CPD) - 2.342(HL ⁄ SL) - 5.636, categorized an observation as a diploid if the discriminant analysis gave a positive score, while negative scores were categorized as tetraploids.

Comparison of ploidy level screening methods in Chinese dojo loach (<i>Misgurnus anguillicaudatus</i>)
Journal Article
2008

2007

NOP 07-A01 (English)

Microbrewing science: a primer on yeast culture for classic brewing
Book
2007

NOP 07-228 (English)

Goal, Scope, and Background. Aquaculture activities are well known to be the major contributor to the increasing level of organic waste and toxic compound in the aquaculture industry. Along with the development of intensive aquaculture in China, concerns are evoked about the possible effects of ever-increasing aquaculture waste both on productivity inside the aquaculture system and on the ambient aquatic ecosystem. Therefore, it is apparent that appropriate waste treatment processes are needed for sustaining aquaculture development. This review aims at identifying the current status of aquaculture and aquaculture waste production in China.

Main Features. China is the world's largest fishery nation in terms of total seafood production volume, a position it has maintained continuously since 1990. Freshwater aquaculture is a major part of the Chinese fishery industry. Marine aquaculture in China consists of both land-based and offshore aquaculture, with the latter mostly operated in shallow seas, mud flats and protected bays. The environmental impacts of aquaculture are also striking.

Results. Case studies on pollution hot spots caused by aquaculture have been introduced. The quality and quantity of waste from aquaculture depends mainly on culture system characteristics and the choice of species, but also on feed quality and management. Wastewater without treatment, if continuously discharged into the aquatic environment, could result in remarkable elevation of the total organic matter contents and cause considerable economy lost. Waste treatments can be mainly classified into three categories: physical, chemical and biological methods.

Discussion. The environmental impacts of different aquaculture species are not the same. New waste treatments are introduced as references for the potential development of the waste treatment system in China. The most appropriate waste treatment system for each site should be selected according to the sites' conditions and financial status as well as by weighing the advantages and disadvantages of each system. Strategies and perspectives for sustainable aquaculture development are proposed, with the emphasis on environmental protection.

Conclusions. Negative effects of waste from aquaculture to aquatic environment are increasingly recognized, though they were just a small proportion to land-based pollutants. Properly planned use of aquaculture waste alleviates water pollution problems and not only conserves valuable water resources but also takes advantage of the nutrients contained in effluent. It is highly demanding to develop sustainable aquaculture which keeps stocking density and pollution loadings under environmental capacity.

Recommendations and Perspectives.  The traditional procedures for aquaculture waste treatment, mainly based on physical and chemical means, should be overcome by more site-specific approaches, taking into account the characteristics and resistibility of the aquatic environment. Further research needs to improve or optimize the current methods of wastewater treatment and reuse. Proposed new treatment technology should evaluate their feasibility at a larger scale for practical application.

Environmental Impact of Aquaculture and Countermeasures to Aquaculture Pollution in China
Journal Article
2007
NOP 07-220 (English)

NOP 07-220 (English)

Phytate is the main storage form of phosphorus (P) in many plants, but phytate-bound P is not available to monogastric or agastric fish animals. Phytase, an enzyme specific to hydrolyze indigestible phytate, has been increasingly used in fish feed during the past two decades, mainly in response to heightened concerns over P pollution to the aquatic environment. Since global phosphate reserves are not renewable, phytate-P as an alternative and economical P source can be effectively converted to available-P by phytase. The capability of this enzyme to enhance bioavailability of P and reduce P load is well documented. Phytase supplementation also leads to improved availability of other minerals and trace elements. Nevertheless, there is still no consistent conclusion that phytase could enhance protein and energy utilization. Studies in amino acid digestibility after phytase supplement are mutative and the underlying mechanisms have not been fully understood. Because phytase is very sensitive to pH and temperature, the utilization of phytase in fish feed is still on its first stage compared with that of in poultry and swine feed. A wide variety of phytases were discovered and characterized in order to find the optimum enzyme which is stable in application, resistant against high temperatures, dust-free, and easy to handle. Initial steps to produce phytase in transgenic plants and fish animals are also undertaken. In this review, the authors focus on comparing properties of phytase from different sources, examining the effects of phytase on P utilization and aquatic environment pollution, meanwhile providing commercial potentiality and impact factors of phytase utilization in fish feed. © 2007 Elsevier Inc. All rights reserved.

Application of microbial phytase in fish feed
Journal Article
2007

NOP 07-221 (English)

Many aspects of teleost physiology are subject to regulation by social interactions. To evaluate the relationship of social status with growth, eye color pattern and hepatic Insulin-like Growth Factor-I (IGF-I) mRNA expression, 30 Oreochromis niloticus were isolated for 10 days and were used in a social pair study. Results revealed that growth of both dominant (except 1 day after social interaction) and subordinate individuals was suppressed, but growth suppression was greater in the subordinates. The dominant fish completely inhibited the feeding of the subordinate individuals during and 1 day after they were introduced into the aquaria together. After that, a pattern of highly aggressive attacks by dominant fish only partially inhibited feeding by the subordinates. Differential alterations in growth rate between dominants and subordinates were attributed more to behavioral changes (i.e., feeding) as transduced by physiological regulators (i.e., IGF-I level and possibly serotonin and/or neuropeptide Y) but may also be due to changes in metabolism. The fish's relative position in the social hierarchy consistently influenced the levels of IGF-I mRNA in the liver and the eye color pattern. Lower social status depressed hepatic IGF-I levels while dominant status stimulated hepatic IGF-I production, possibly in response to inhibition of somatostatin release in the hypothalamus, leading to greater secretion of pituitary growth hormone (GH). A significant positive association was detected between the IGF-I mRNA expression of the dominant fish and the level of aggression (number of attacks) during the encounter. Social status also influenced the eye color pattern of the fish. During aggressive interactions, most of the fish (22 out of 24) displayed decreased eye darkening. At the later part of the encounter, all subsequent subordinates displayed eye-darkening patterns which acted as a social signal announcing social submission. After the encounter dominant fish had paler eye color pattern than subordinates.

The influence of social status on the rate of growth, eye color pattern and insulin-like growth factor-I gene expression in Nile tilapia, <i>Oreochromis niloticus</i>
Journal Article
2007

NOP 07-223 (English)(Spanish)

The peripheral blood cells of one-year-old Chinese sturgeon (Acipenser sinensis) have been studied by light microscopy and transmission electron microscopy. The erythrocyte count was 84.86 x 104 cell mm-3 in the peripheral blood of the fish and that of leukocytes was 2.24 x 104 cell mm-3. The erythrocytes and four main types of leucocyte-thrombocytes, lymphocytes, granulocytes (including neutrophils and eosinophils), and monocytes, were identified in the peripheral blood. In addition to normal erythrocytes, reticulocytes and division of erythrocytes were observed. Thrombocytes were the most numerous among the leukocytes, and the number of neutrophils with lobated nuclei was larger than for other fish. The structures of the erythrocytes, lymphocytes, monocytes, granulocytes, and thrombocytes of the fish were studied. The erythrocytes were almost completely devoid of organelles, except for some mitochondria and granules. A large number of vacuoles and a few organelles were observed in cytoplasm of the monocytes. There were many microvilli on the membrane and pseudopodia-like cytoplasm bulge in the lymphocytes. The neutrophils were round or oval in shape with bilobed, trilobed, or multilobed nuclei whereas the eosinophils had big special granules, dark stained. There were many vesicles in some thrombocytes, which were related to its phagocytosis; some thrombocytes had almost no cytoplasm or organelles.

Morphological studies of peripheral blood cells of the Chinese sturgeon, <i>Acipenser sinensis</i>
Journal Article
2007
NOP 07-222 (English)

NOP 07-222 (English)

The purpose of this study was to determine whether diploid, triploid and tetraploid loach (Misgurnus anguillicaudatus) differed in terms of their main haematological and physiological characteristics. Diploid and tetraploid fish were produced by crossing of natural diploids (2n Å~ 2n) and natural tetraploids (4n Å~ 4n), respectively. Triploid fish were produced by hybridization between diploid males and tetraploid females. The blood cells were significantly larger in polyploids, and the volumetric ratios of erythrocytes and leucocytes (thrombocyte and neutrophil) in tetraploids, triploids and diploids were consistent with the ploidy level ratio of 4:3:2. No significant differences were observed in haematocrit among polyploids. The erythrocyte count decreased with increased ploidy level, while total haemoglobin, mean cell volume, mean cellular haemoglobin content, and mean cell haemoglobin concentration all increased with increase in ploidy level. Erythrocyte osmotic brittleness declined in polyploids so that polyploid erythrocytes were more resistant to osmotic stress than diploid ones. Overall, loach with higher ploidy levels showed evidence of some advantages in haematological characteristics.

Haematological characterization of loach <i>Misgurnus anguillicaudatus</i>: Comparison among diploid, triploid and tetraploid specimens
Journal Article
2007

NOP 07-A14 (English)

A sustainable semi-intensive pond aquaculture technology including major carp species as cash-crop and small indigenous fish species (SIS) as food for the farmers' families is being optimized in Bangladesh. The inclusion of silver carp (Hypophthalmichthys molitrix), a cheap large species affordable by poor farmers, is now being considered. As part of a study on the effects of this filter feeder on polycultures including the large carps rohu (Labeo rohita), catla (Catla catla) and common carp (Cyprinus carpio) and the SIS punti (Puntius sophore) and mola (Amblypharyngodon mola), an experiment was carried out under farm conditions to test the effects of silver carp and of each SIS species on the growth, survival and yield of the large and small species and on pond ecology.The experiment was performed in 38 farmers' fishponds of different sizes, from 220 m2 to 1200 m2. The results show that the larger the fish pond the better rohu performance, the larger punti fry weight and the lower punti fry harvested biomass. Pond size did not affect other fish species. The addition of 250 mola and/or punti per 100 m2 fishponds affected rohu and catla and did not affect common and silver carps. The addition of mola alone reduced rohu's parameters by 15%. The addition of SIS in the three combinations tested (250 mola, 250 punti, 125 of each species) reduced catla's parameters by 20–24%. Punti fry were larger when both SIS were stocked and punti fry biomass was larger when only punti were present. Total mola harvested biomass and yield were larger when the entire SIS stocked were only mola. The addition of 10 silver carp over the 99 large carps stocked per 100 m2 fishponds negatively affected rohu and catla growth and yield by about 15–21% and 45–50% respectively but not their survival, did not affect common carp performance, did not affect punti and mola reproduction in the ponds, reduced punti yields by 25%, reduced mola performance by about 35%, and silver carp own biomass increased total yield and total income in about 12% each. These effects are explained and discussed considering fish interactions through the food web. The decreased income from selling the more expensive large carps is more than compensated by that obtained from silver carp, which allows the option to the farmer to sell part of the silver carp to complete the cash income that would have been obtained from large carps only if silver carp would not be stocked, and consume the rest with the family.

Effects of silver carp and the small indigenous fish mola <i>Amblypharyngodon mola</i> and punti <i>Puntius sophore</i> on fish polyculture production
Journal Article
2007

NOP 07-230 (English)

Economic profitability of Nile tilapia (Oreochromis niloticus) production in Ghana was analyzed using a dynamic model that simulates individual fish growth and takes fish population dynamics in the pond into account. The results suggest that the current practiced mixed-sex tilapia culture with catfish predation was economically sustainable. However, to increase returns on investments, extension efforts should be geared towards developing a Nile tilapia production system that is based on a hand-sexed all-male tilapia culture. Other fundamentals include pond studies to determine optimal pond size, availability of affordable feed and quality fingerlings. Under an improved production system, profits are high enough to justify investment through borrowed capital.

Economic analysis of Nile tilapia production in Ghana
Journal Article
2007

NOP 07-A05 (English)

Economic profitability of Nile tilapia production in Kenya was analysed using a model that simulated individual fish growth and took fish population dynamics in the pond into account. The results suggest that the currently practiced mixed-sex tilapia culture is economically unsustainable. It is suggested that research and extension efforts be geared towards developing monosex Nile tilapia production systems. Nile tilapia culture with African catfish predation should be viewed as an intermediate step towards all-male Nile tilapia culture. This will allow accumulation of both physical and human capital to support all-male tilapia culture. Under all-male culture, economic returns are high enough to justify investment in Nile tilapia culture using borrowed capital. However, the success of monosex culture will depend on the availability and affordability of quality fingerlings and low-cost fish feeds. The results have a wide application in Sub-Saharan Africa where mixed-sex Nile tilapia culture is common.

Economic profitability of Nile tilapia (<i>Oreochromis niloticus</i> L.) production in Kenya
Journal Article
2007

NOP 07-226 (English)

There is a policy of increased support of aquaculture development in Sub-Saharan Africa. In the region, aquaculture expansion has the potential to create new jobs and improve food security among poor households. Three computable general equilibrium models were used to estimate the effects of aquaculture expansion and increased input productivity on poverty reduction in Ghana, Kenya, and Tanzania. The results suggest that there will be positive effects on per capita income for all households in Ghana and Kenya. In Tanzania some rich households will experience income loss, because of resource shift from other sectors to aquaculture. Because of reduction in poverty associated with price reductions, and increases in minimum income associated with income expansion, the poverty gap decreased in all household groups. Because of high sectoral linkages, aquaculture development is a potential candidate for sector-specific policy support to address poverty reduction in Sub-Saharan Africa.

Potential effect of aquaculture promotion on poverty reduction in Sub-Saharan Africa
Journal Article
2007

NOP 07-A02 (English)

A study evaluating the effects of formaldehyde, sodium chloride, potassium permanganate and hydrogen peroxide treatment on the hatching success of C. gariepinus eggs was carried out from April to July 2006. Eggs were artificially fertilized, 50 counted and subjected to a static bath dip treatment in given concentrations of the above chemicals for either 15, 30 or 60-minute durations before being incubated at 27 ± 1 °C for 24 h. Treatment efficacy was assessed by comparing the percent egg hatch in the treatment group to the untreated control group. Eggs treated with formaldehyde and sodium chloride at 250, 500 and 1000 ppm recorded greater mean percent hatch compared to the untreated controls. Likewise, percent hatch of eggs treated with hydrogen peroxide and potassium permanganate at concentrations ranging from 100 - 1000 ppm and 0.5 - 4.0 ppm respectively were greater relative to the untreated controls. The highest mean percent hatch recorded in the study was in eggs treated with 2 ppm potassium permanganate for 30 min (96.7%). Although formaldehyde and potassium permanganate gave the best performance, on the basis of safety concerns, ease of availability and cost, we recommend 1000 ppm sodium chloride treatment of catfish eggs for routine use by rural fish farmers to improve catfish egg hatchability. © 2007 Elsevier B.V. All rights reserved.

Effects of formaldehyde, sodium chloride, potassium permanganate and hydrogen peroxide on hatch rate of African catfish <i>Clarias gariepinus</i> eggs
Journal Article
2007

NOP 07-A13 (English)

Culture of Red Facu (RP), Piaractus brachypomus and Black Facu (BP), Colossoma macropomum is increasing due to increasing demand from human populations and declining supply caused by depletion of wild fish so practical diet formulations need to be developed for pacu. Insulin assays are a valuable tool in assessing carbohydrate utilization in fish for diet development. Therefore, we conducted procedures to validate an Enzyme-Linked Immunososorbent Assay (ELISA) for detection of plasma insulin concentrations in RP and BP. Red and black pacu were fed a commercial catfish diet containing approximately 40,010 soluble carbohydrates (32% protein, 6% fat). Both species were then bled and plasma was used for validation of the assay. An ELISA was conducted using the Food and Drug Administration's Center for Veterinary Medicine validation of analytical procedures methodology. The results from this assay validation study indicate that an ELISA insulin kit was not suitable for experimental detection of blood plasma insulin concentrations in RP and BP. Ahnost no insulin (0.34 to 0.48 ng mL-1, for red pacu; 0.40 to 0.67 ng mL-1, for black pacu) was detected in unknown blood plasma samples from the fish. This indicated that the mammalian insulin antibodies are more derived or that the molecular structure of the insulin variants produced by pacu are not capable of being bound by the antibodies in the ELISA assay. The accuracy (mean recovery of spiked samples was 56.0010 for RP and 68.6% for BP), linearity (R2 = 0.0011 for RP and R2 = 0.1822 for BP), precision (mean recovery of serial dilutions was 212.8% for RP and 209.2% for BP) and reproducibility of the data were poor.

An Enzyme-Linked Immunosorbent Assay Is Not Effective for Sampling Blood Plasma Insulin Concentrations in Red Pacu, <i>Piaractus brachypomus</i> and Black Pacu, <i>Colossoma macropomum</i>
Journal Article
2007

NOP 07-229 (English)

This study compared the effectiveness of different extension techniques at communicating high-input inorganic fertilization (HIG) technology to small-scale, northeast Thai fish farmers. HIG adoption rates and associated fish production during 1997 / 1998 varied according to extension intensity across three farmer groups. Short training sessions were found to be equally effective at communicating HIG technology to farmers as longer on-farm trials. Both forms of extension were more effective than farmer-to-farmer communication at producing higher fish yields. Yields across all groups, however, were significantly lower than HIG-projected yields, suggesting that extension methodology did not exclusively affect production in this system. Farmer income, land holdings, attitudes, predisposition to risk, and fertilizer price all may have affected production. Improving production will involve a multifaceted approach, possibly including development of less capital-intense technologies, focus on short training sessions, encouragement of farmer cooperatives, and advocacy of economic policies that improve farmer access to credit and local markets.

Impacts of Extension Practice: Lessons From Small Farm-Based Aquaculture of Nile Tilapia in Northeastern Thailand
Journal Article
2007

NOP 07-225 (English)

The effects of dietary α-lipoic acid (LA) and vitamin C on the fatty acid (FA) composition in the brain and muscle and vitamins E and C levels in the brain were studied in the fish Piaractus mesopotamicus. A two-factorial design, where diets were devoid or supplemented with ascorbate (500 mg AA kg−1) and/or lipoic acid (1000 mg kg−1), was used. The levels of eicosapentaenoic acid (20:5 n−3, EPA) increased ( P < 0.01) in muscle polar lipids (PL) in LA groups (6.93% ± 0.43 vs. 5.83% ± 0.40 and 6.68% ± 0.53 vs. 6.00% ± 0.39), and the same trend was also seen in the brain, however not significant. These changes are suggested to be caused by a change in lipid metabolism rather than being a direct effect of protection by LA against lipid peroxidation. No interaction of vitamin C and LA neither effects of LA on vitamin E (15.1–19.2 mg α-tocopherol g−1 tissue) or vitamin C (total AA, 41.7–89.8 μg g−1 tissue) in brain was detected.

Effects of α-lipoic and ascorbic acid on the muscle and brain fatty acids and antioxidant profile of the South American pacu <i>Piaractus mesopotamicus</i>
Journal Article
2007

NOP 07-A04 (English)

This study investigated the effects of two levels of feeding (1 or 4% BW day−1), two levels of stocking densities (3 or 10 female m−2) and two levels of water-flow rates (0.06 ± 0.00 or 0.35 ± 0.04 L s−1) on the fecundity, relative fecundity, spawning frequency and egg quality of Nile tilapia, Oreochromis niloticus (L.) with the goal of improving hatchery seed production. Males and females, 125 days of age, were stocked in recirculating concrete tanks. Eggs were collected every four days directly from the mouths of incubating females. Fecundity (eggs spawn−1), body weight gain (g day−1) and egg diameter (mm) and weight (mg), percent protein and lipid, fertilization and hatchability were measured over 120 days. Higher eggs kg female−1 day−1 (312 ± 36) was observed in treatments with lower levels of stocking density (3 female m−2) and water-flow rate (0.06 ± 0.00 L s−1) under both feeding rates. The rate was 2 to 4 fold higher than the others. Overall, high feeding level (4% BW day-1) increased growth (g day−1) by 35% and eggs spawn−1 by 18% and did not affect eggs kg female−1 day−1, spawn female−1 and eggs m−2 day−1. Higher stocking density (10 female m−2) lowered eggs spawn−1 by 19%, eggs kg female−1 day−1 by 52% and spawn female−1 by 40%. Higher water-flow rate (0.35 ± 0.04 L s−1) increased growth (g day−1) by 33%, and lowered eggs kg female−1 day−1 by 51%. The variables also did not affect percent egg fertilization, hatchability, crude lipid and protein or egg diameter (mm). However, egg weight (mg) was higher in groups fed a lower ration (1% BW day−1) with higher stocking density (10 female m−2) and higher water-flow rates (0.35 ± 0.04 L s−1). Feeding levels interacted with water-flow rates in improving growth (g day−1) while stocking density interacted with water-flow rates in lowering eggs kg female−1 day−1 and spawn female−1. The eggs kg female−1 day−1 obtained in this study from the best treatments is comparable with the highest egg production rates reported by others for O. niloticus. This suggests that lower feeding level (1% BW day−1), lower stocking density (3 female m−2) and lower water-flow rate (0.06 ± 0.00 L s−1) could be adopted as a management strategy to improve current tilapia hatchery seed production, although, optimum water flow-related stocking density needs further investigation.

Effects of feeding, stocking density and water-flow rate on fecundity, spawning frequency and egg quality of Nile tilapia, <i>Oreochromis niloticus</i> (L.)
Journal Article
2007

NOP 07-A03 (English)

In an attempt to better understand and characterize the variability in the female reproduction of individual Thai-Chitralada strains of Nile tilapia, Oreochromis niloticus (L.), tagged mature females (n = 68) from a single population were monitored in a hapa-in-pond system over a 12-month experimental period. Spawn female−1, eggs female−1 day−1, eggs kg female−1 day−1, day spawn−1 and weight (g) at first spawning of individual females were determined from the regular weekly sampling of weight (g) and eggs per spawn. For analysis, the females were grouped into two, high spawning (HSF) and low spawning frequency (LSF) classes based on their spawning frequency (SF) record. Moreover, nested under these two classes were two groups each based on growth rate, i.e., high frequency – large size (HL), high frequency – small size (HS), low frequency – large size (LL) and low frequency – small size (LS). There was no difference in eggs spawn−1 among all females. The HSF group produced 68% and 361% more eggs female−1 day−1 than the population mean and LSF group respectively. Eggs female−1 day−1 and spawn female−1 remained high in the HSF group and low in the LSF group throughout the 12-month experimental period. This suggests that individual female spawning activity is consistent within a population in a common environment. The inter-spawn interval increased with age in all four groups, and day spawn−1 was shorter by 130% in HSF females compared with day spawn−1 in LSF. The HSF group also spawned more successively (≥3), while the LSF group of females had fewer successive spawns (≤2). Body weight (g) had no influence on the number of eggs produced. The study indicates that separating frequently spawning females could be used as an important strategy to improve commercial seed production of Nile tilapia.

Characterization and comparison of variations in reproductive performance of Chitralada strain Nile tilapia, <i>Oreochromis niloticus</i> (L.)
Journal Article
2007

2006

NOP 06-218 (English)(Spanish)

The detection of the prodynorphin gene in anuran amphibians and lungfishes may indicate that this gene arose as a result of the duplication of the proenkephalin gene early during the divergence of the Sarcopterygii, or that this gene may predate the divergence of the ray-finned fish and the lobe-finned fish. The cloning of prodynorphin-related genes from the pufferfish and zebrafish supports the latter hypothesis. This study analyzes trends in the radiation of the prodynorphin gene in teleosts. Prodynorphin cDNAs were cloned from the brain of the eel Anguilla rostrata and the Nile tilapia, Oreochromis niloticus. These teleost prodynorphin sequences have distinct α-neoendorphin, dynorphin A, and dynorphin B sequences, and a novel opioid sequence, YGGFI. The relationship of these teleost prodynorphin sequences to other actinopterygian and sarcopterygian prodynorphin sequences will be discussed.

Trends in the evolution of the prodynorphin gene in teleosts: Cloning of eel and tilapia prodynorphin cDNAs
Journal Article
2006

NOP 06-A05 (English); NOP 06-A14 (English)

Although many freshwater prawn farms in Bangladesh are small-scale operations, larger commercial facilities are driving production increases in the country. A survey of 100 prawn farmers from four prawn-farming areas indicated that nearly all farmers practice polyculture of prawns with carp. Primarily using hatchery fry, they apply modified extensive practices that include fertilization and supplemental feed.

Bangladesh Prawn-Farming Survey Reports Industry Evolution
Magazine Article
2006

NOP 07-A07 (Spanish)

Se realizó un estudio nutricional en juveniles de la tilapia O. niloticus, a fin de determinar el efecto de la sustitución de la harina de pescado (sardina 66% PC) con harina de cerdo (57% PC, de la empresa National Renderers Association, Inc.) sobre la sobrevivencia, el crecimiento y la utilización del alimento. Para ello, se diseñaron y fabricaron siete alimentos experimentales: un alimento control, que contenía 100% de H. de pescado, 5 alimentos en los que se sustituyó gradualmente (60, 70, 80, 90 y 100%) la proteína aportada por la harina de pescado con proteína aportada por harina de cerdo, y un alimento con 100% h. de cerdo + h. de charal (como atrayente). Se utilizaron un total de 210 juveniles (6.98 g peso promedio inicial), los cuales fueron distribuidos en 21 tanques con capacidad de 70 litros, a razón de 10 organismos/tanque, y 3 réplicas por tratamiento, dentro de un sistema de recirculación cerrado. El experimento duró 56 días, durante los cuales se registraron diversos parámetros de evaluación nutricia como sobrevivencia, crecimiento en peso y longitud, factor de condición, consumo de alimento, FCA y PER. No se detectaron diferencias significativas (P > 0.05) en la sobrevivencia, ni en el crecimiento en peso o longitud de los organismos alimentados con los diferentes alimentos durante el experimento. De la misma manera, los índices de calidad del alimento no mostraron diferencias significativas entre los tratamientos. El consumo de alimento no se vio afectado por la inclusión de la harina de cerdo, aún en el nivel de sustitución de 100%, así como tampoco por la inclusión de harina de charal, usada como atrayente. El menor factor de conversión del alimento (1.91) se obtuvo con los peces alimentados con el alimento donde se sustituyó el 100% de la harina de sardina. Se concluye que la harina de cerdo NRA (57% PC) puede ser utilizada como ingrediente para sustituir parcial y totalmente la harina de sardina (65% PC) en alimentos con 35% de PC para juveniles masculinizados de la tilapia O. niloticus, sin que se vean afectados la supervivencia, el crecimiento, el consumo o los índices de utilización del alimento, bajo condiciones de cultivo en laboratorio.

Evaluación de la sustitución parcial y total de harina de sardina con harina de cerdo en alimentos para juveniles de la tilapia del Nilo <i>Oreochromis niloticus</i>: efecto sobre la supervivencia, el crecimiento y la utilización del alimento
Conference Proceedings
2006

NOP 06-207 (English)(Spanish)

Nile tilapia Oreochromis niloticus were produced in an experimental, on-farm grow-out cycle in which economic and production efficiencies were partially examined. Milled feeds were provided either daily (control) or on alternate days (experimental) at a given percentage of body weight, ranging from 20% initially to 2% at the end of the experiment. Growth, survival, feed conversion efficiency, cost, yield, and income were considered under the two strategies. Although the cost of feeds was cut in half by the experimental feeding treatment, feeding on alternate days did not reduce Nile tilapia growth or production performance variables, and yields were not significantly different. A trend favoring larger fish among the controls was not significant, and profit margins were higher for the alternate-day feeding strategy than for the control strategy. Although feed conversion ratios varied considerably among the nine participating farms, the improved efficiency in the experimental groups was consistently observed and was statistically significant. It is possible that the improved performance attained by alternate-day feeding is a result of reduced feed waste, either through more complete consumption of or improved nutrient absorption from available feeds.

Alternate-Day Feeding Strategy for Nile Tilapia Grow Out in the Philippines: Marginal Cost – Revenue Analyses
Journal Article
2006
Boyd, C. E. 2006. Management of Bottom Soil Condition and Pond Water and Effluent Quality. Pp. 449 - 467 in Tilapia: Biology, Culture, and Nutrition, Tilapia: Biology, Culture, and Nutrition, edited by Chhorn Lim and Webster, Carl D. The Haworth Press, Inc. Retrieved (https://www.crcpress.com/Tilapia-Biology-Culture-and-Nutrition/Webster-Lim/p/book/9781560228882).
NOP 06-212 (English)(Spanish)

NOP 06-212 (English)(Spanish)

Good bottom soil condition and high-quality water are essential ingredients for successful pond aquaculture of tilapia and other species. Some problems with pond soil and water quality are related to site characteristics (Hajek and Boyd 1994). Soils may have undesirable properties such as acidity, high organic matter content, or excessive porosity. Water supplies may not be large enough or the source water naturally may be of poor quality or polluted with domestic, industrial, or agricultural wastes. Even if a good site is available, large inputs of nutrients and organic matter in feeds to enhance aquacultural production can lead to excessive phytoplankton, low dissolved oxygen concentration, high ammonia concentration, poor bottom soil condition, and other problems (Boyd and Tucker 1998). Many soil and water quality problems can be avoided by attention to site selection, pond design, and pond construction and by the use of moderate stocking and feeding rates. Nevertheless, sites are seldom perfect, and often, site limitations are not adequately mitigated during design and construction. Pond managers also may strive for unrealistically high production. Thus, soil and water quality problems are not uncommon in pond culture of tilapia. When soil and water quality in ponds are impaired, fish suffer stress. This makes them more susceptible to disease, and they do not consume feed efficiently or grow as well as they should. Effluents from ponds with poor-quality water may have low dissolved oxygen concentration and high concentrations of nutrients, organic matter, and suspended solids. Release of such effluents into natural waters can cause pollution that harms aquatic communities and lessens the quality of water for other beneficial uses. The purpose of this chapter is to discuss management of soil and water in ponds and to present suggestions for reducing the volume and improving the quality of pond effluent.

Management of Bottom Soil Condition and Pond Water and Effluent Quality
Book Chapter
2006

NOP 07-A12 (English)

The program generally aimed to perform an economic evaluation of Freshwater Aquaculture Technologies (FAT) and policies in selected production systems. It has two project components; one dealt with the analysis of matured FATs both at micro and macro levels (specifically its effects on fish supplies, income, consumption, and employment); the other dealt with policy studies on the role of fishery organizations, land use and fishery rights, dissemination strategies, and trade- related concerns. The nature of the studies required the collection of primary and secondary data. For the primary survey, 540 adopters and 108 non-adopters were interviewed in Luzon covering three top producing regions. The same sampling frame applied to the choice of provinces, towns and barangays. But at the barangay level, 8 adopter-respondents while 2 non-adopter-respondents were selected. The areas covered were Nueva Ecija, Bulacan and Pampanga for fishponds and hatcheries; Laguna, Batangas, and Isabela for fish cage/pens and hatcheries. The matured FATs are focused on grow-out and hatchery. For grow-out system, it included fishponds, cages, and pens. The technologies under grow-out were on broodstock improvement, level of management (extensive, semi-extensive, and intensive), and post harvest activities. For the hatchery component, the study looked at pond, hapa, and tank. The sex-reversed tilapia was included under this component. The preliminary results of Study 1 under Project 1 were focused on the identification of financial benefits and costs of the matured technologies. The yield difference between adopters and non-adopters was 3,030 kg per cycle or about 59% in favor of adopters. Hence, there is an impression that the technology had benefited the adopters. Likewise, Study 2 of Project 1 identified and assessed the economic benefits and costs of FATs. It found out that tilapia’s contribution to aquaculture was around 9.46% annually from 1992-2000. During the same period, tilapia production had behaved cyclically with an upswing in the first three years, downswing in the middle three years, and another upswing in the last three years. Historically, the significant government programs related to the fishery sector were the Kilusang Kabuhayan at Kaunlaran Biyayang Dagat Program, CB-NFAC Supervised Credit Program, among others. Under Study 1 of Project 2, the organizations were identified and classified as Fisheries Organizations, Fisheries and Agricultural Resource Management Council, and Cooperatives. The organizations were generally aimed to provide technical, financial, and marketing assistance to members. However, the sustainability of these services was delimited by lack of sufficient funds hence, most organizations had failed to deliver and sustain those services to their members. Study 2 made a preliminary review of relevant local laws, rules, regulations, and ordinances within the spirit of the Fisheries Administrative Code. All of the ordinances were meant to ban the use of illegal fishing methods or practices, which are detrimental to fish population, environmental protection and the like. However, the respondents qualified that its aggressive enforcement happened only during the onset of its implementation in the late 80’s. Study 3 focused on determining the most effective dissemination strategy of FAT to intended clienteles. Training programs administered by BFAR, DA, LGUs and Santeh Feed Company were the dominant dissemination mode for FAT. The use of print media such as brochure/leaflet/techno guides came next as important mode while the use of broadcast media was the least preferred. Study 4 had shown that the trade policies of the country in 1960s up to 1980s were characterized by lifting of import and foreign exchange restrictions; on and off imposition of quantitative restrictions, and tariff rates. But in the mid 90s, major tariff reform programs were implemented until the country’s accession to the WTO-GATT accord. In 1996, quantitative restrictions were lifted, tariff rates for sensitive agricultural products were raised while minimum access volume to these products were defined. The fishery sector was still protected as indicated by positive Effective Protection Rates (EPRs). The trade balance volume of the sector remained negative in most years (from 1990-2000). However, the value of trade balance remained positive, which indicates better terms of trade for fishery products in the export markets. To know the impacts of trade reform on the sector, the initial regression results revealed that the real GDP and (production) was positively (negatively) and significantly affected by EPR.

Economic Evaluation of Freshwater Aquaculture Technologies and Policies in Selected Production Systems
Report
2006

NOP 06-A13 (English)

Effect of salinity on carrying capacity of a recirculation system for Nile tilapia, Oreochromis niloticus L.; production was assessed. Survival, growth and feed conversion ratio of adult Nile tilapia fed 30% crude protein diet for 88 days were measured at three different salinity levels (8, 15 and 25 g L−1) and two stocking densities (20 and 40 m−3) in three independent recirculating systems. Highest survival (98%) and a linear growth in net biomass (P < 0.01) was observed in both densities at 8 g L−1 and in 20m−3 treatment at 15 g L−1. Highest net biomass growth was observed in the 40 m−3 stocking density treatment at 8 g L−1 salinity level (P < 0.05). Overall biomass growth was significantly affected by salinity indicating a decrease in Nile tilapia carrying capacity with increased salinity. About 11,000 kg ha−1 crop−1 of Nile tilapia can be obtained in recirculating systems at 8 g L−1 salinity, significantly higher than the net production at 15 g L−1 (5,200 kg ha−1 crop−1) and 22 g L−1 (4,425 kg ha−1 crop−1).

Effect of salinity on carrying capacity of adult Nile tilapia <i>Oreochromis niloticus</i> L. in recirculating systems
Journal Article
2006
Contreras-Sánchez, W. M., and K. Fitzsimmons. 2006. Tilapia, Sustainable Aquaculture from the New Millenium ; Proceedings 7th International Symposium on Tilapia Aquaculture. Boca Del Rio, Veracruz, Mexico 6-8 September, 2006. Pp. 389 - 389 in Tilapia, Sustainable Aquaculture from the New Millennium Proceedings of the 7th International Symposium on Tilapia in Aquaculture, Tilapia, Sustainable Aquaculture from the New Millennium Proceedings of the 7th International Symposium on Tilapia in Aquaculture. American Tilapia Association and Aquaculture CRSP.
NOP 07-A06 (English)

NOP 07-A06 (English)

Tilapia are now the second most important farmed fishes in the world. They are the most widely grown of any farmed fish and are adaptable to a wide variety of water conditions. Tilapia have rapidly become one of the most popular seafood items in developed countries. In developing countries, Tilapia have long been recognized as an "aquatic chicken" that can be grown at many degrees of sophistication and prepared in a myriad of recipes. 

ISTA VII is the seventh in the series of meetings that have brought together scientists, farmers, and seafood buyers from around the world to provide the most complete and up-to-date information available regarding tilapia in aquaculture. 

The proceedings includes 38 papers and 31 abstracts. The keynote paper discusses the global outlook for Tilapia culture emphasizing Latin America. It provides a summary available for this fast growing culture species. Streptococci and other pathologies are having major impacts on Tilapia culture today and this proceedings contains six papers discussing the latest research in the field. The section on nutrition and feeds contains nine papers ranging in topic areas from compensatory growth to probiotic bacteria to dietary formulations and ingredients. A total of nine complete country reports from Latin America, Africa and the Middle East provide background on regional efforts. The section on economics, marketing and trade includes recent information on both small-scale aquaculture development opportunities and global supplies and markets. The book provides the latest contributions in this important series and would be useful to students, academics, governmental and non-governmental agencies, and growers interested in the most recent reviews and scientific communications in the field. 

The Proceedings of the 7th International Symposium on Tilapia in Aquaculture, Vera Cruz, Mexico, 6 - 8 September 2006, were published by the American Tilapia Association and Aquaculture CRSP. 389 pp.

Tilapia, Sustainable Aquaculture from the New Millenium ; Proceedings 7th International Symposium on Tilapia Aquaculture. Boca Del Rio, Veracruz, Mexico 6-8 September, 2006
Conference Paper
2006

NOP 06-216 (English)(Spanish)

IGF-I is a mitogenic polypeptide that is an important regulator of growth in fish. The potential of IGF-I mRNA abundance as a rapid growth indicator in the Nile tilapia, Oreochromis niloticus, was evaluated. Hepatic IGF-I cDNA was isolated and partially cloned. The partial sequence having 539 bases encodes for the signal peptide, mature protein and a portion of the E domain. The deduced 68 amino acid sequence for mature IGF-I showed 84-90% and 77-79% sequence identity with fish and mammalian counterparts, respectively. The deduced amino acid sequence for domains B and A was most conserved (93-97%) relative to other fishes. A sensitive TaqMan real time qRT-PCR assay for O. niloticus was developed based on the mature IGF-I peptide for measures of hepatic IGF-I mRNA levels. Hepatic IGF-I mRNA levels were found to be significantly correlated with growth rate of fish reared under different feeding regimes and temperature conditions. Higher feed consumption and water temperature produced faster-growing fish and increased hepatic IGF-I mRNA expression. These findings suggest that hepatic-derived IGF-I plays a key role in controlling growth in O. niloticus and indicates that IGF-I mRNA quantification could prove useful for the rapid assessment of growth rate in this species.

Insulin-like growth factor-I cDNA cloning, gene expression and potential use as a growth rate indicator in Nile tilapia, <i>Oreochromis niloticus</i>
Journal Article
2006
Engle, C. R. 2006. Marketing and Economics. Pp. 619 - 644 in Tilapia: Biology, Culture, and Nutrition, Tilapia: Biology, Culture, and Nutrition, edited by Chhorn Lim and Webster, Carl D. Binghamton, NY: The Haworth Press, Inc. Retrieved (https://books.google.com/books?id=VzWuIvXHmY0C&pg=PA619&dq=doi:10.1300/5513_19&hl=en&sa=X&ved=0ahUKEwjct93_kevSAhUX7mMKHa2XDoIQ6AEIHDAA#v=onepage&q=doi%3A10.1300%2F5513_19&f=false).
NOP 06-214 (English)

NOP 06-214 (English)

The economic history of the development of the tilapia industry world-wide is a fascinating study of a fish enterprise that has been managed successfully on nearly every scale of business. This by no means implies that all attempts to raise tilapia have been successful, but rather that examples of successful tilapia enterprises can be found over a wide range of sizes, scales, and business organization. In 2002, tilapia were being grown and sold in 81 different countries, on every major continent, and in tropical, subtropical, and temperate climates. Tilapia are produced by near-subsistence farmers as a savings account for hard times; caught and consumed by subsistence fishermen; raised and sold to local village markets and upscale domestic markets; exported to high-end sales outlets in the United States, Japan, and Europe; and raised by hobby farmers in the United States and Europe. Tilapia are positioned, often in the same countries, as low-priced products for the poor; as ethnic products; and as gourmet, luxury, upscale products for white tablecloth restaurants. Tilapia are raised in virtually all conceivable types of production systems and in both fresh and saltwater. Regardless of an individual’s particular perspective, the tilapia are undoubtedly the most ubiquitous, the most successful, and the most adaptable aquaculture species in the world. This chapter explores the development of tilapia markets, from the early markets that were developed for wild-caught tilapia, home consumption of farmed tilapia, sales to local markets and upscale domestic markets, and export marketing. Issues and challenges related to these various targeted markets are discussed. The costs of producing tilapia on a variety of scales of production and in different production systems are also examined.

Marketing and Economics
Book Chapter
2006

NOP 06-A07 (English)

With almost half the global production and a quarter of global consumption, China is a critical player in the tilapia industry. In recent years, the quality and variety of Chinese tilapia products have improved, and state-of-the-art processing plants now handle the huge volume of product. New products and packaging are promoting additional international demand.

Tilapia Production in China: Huge Output Balanced by Huge Consumption
Magazine Article
2006
Fitzsimmons, K., and P. Gonzalez-Alanis. 2006. Future Expansion of Global Supplies and Markets for Tilapia Products-2006. Pp. 312 - 312 in Proceedings for the 7th International Symposium on Tilapia in Aquaculture (ISTA7), Proceedings for the 7th International Symposium on Tilapia in Aquaculture (ISTA7), edited by W.M. Contreras-Sánchez and Fitzsimmons, K. Vera Cruz, Mexico. Retrieved (http://www.was.org/Shopping/ista-7th-international-symposium-on-tilapia-in-aquaculture-proceedings).
NOP 07-A11 (English)

NOP 07-A11 (English)

Tilapia production and consumption have risen rapidly in recent years to 2,096,187 mt in 2005. Expansion of up to 10% per year is anticipated in coming years with global production of 3,000,000 mt per year likely for 2010. China currently produces one half of the global supply and consumes one quarter. As Chinese tilapia aquaculture intensifies, its production level can be expected to continue rapid increases. As the Chinese standard of living increases, the amount of value-added product consumed will increase. North American and European demand for value added products is also increasing rapidly. Center cut loins, breaded and seasoned products will fuel much of the added growth in demand. More and more of these value added products will be prepared in the producing countries allowing them to capture more of the value chain and profits. Rapid growth in the production and processing sectors will be seen in Southeast Asia and Latin America. Increased production and consumption in the Middle East will be led by Egypt. Egypt's ability to invest in high quality processing and packaging could open valuable European markets. Tilapias have passed the salmonids in global production and consumption and should eventually surpass the carps. While this may take 20 years or more, the continued rapid increase in tilapia culture and consumption along with the relatively static condition of the carps make this scenario fairly certain.

Future Expansion of Global Supplies and Markets for Tilapia Products-2006
Conference Paper
2006
Fitzsimmons, K. 2006. Prospect and Potential for Global Production. Pp. 51 - 73 in Tilapia: Biology, Culture, and Nutrition, Tilapia: Biology, Culture, and Nutrition, edited by C.D. Webster and Lim, C. Binghamton, NY: The Haworth Press, Inc. Retrieved (https://www.crcpress.com/Tilapia-Biology-Culture-and-Nutrition/Webster-Lim/p/book/9781560228882).
NOP 06-210 (English)(Spanish)

NOP 06-210 (English)(Spanish)

During the 1990s,tilapia products became an important commodity in the international seafood trade. Tilapia farming has grown from an industry based on fish introduced around the world by development agencies to feed the rural poor to highly domesticated livestock production with sales now exceeding $2 billion a year. The description of the tilapia as the aquatic chicken becomes more appropriate every day. As in the case of chicken farming, tilapia farming can be successful on any scale, from subsistence farmers with a few essentially feral fish in a pond to multinational corporations rearing highly domesticated fish with farms and processing plants in several countries. Tilapia have been domesticated more quickly and to a greater extent than any other group of fish. They surpasses salmonids in economic importance in 2004 and may eventually equal the carps. World production of farmed tilapia exceeded 2,002,087 metric tons (mt) in 2004 (Figure 2.1), with China the major producer and consumer. The mainland provinces’ production in 2003 was 897,300 mt, and Taiwan produced another 90,000 mt. Other Asian countries produced 440,000 mt. The United States is the world’s major importer of tilapia. Its 2005 imports were 126,00 mt, with a value of $374 million, divided between frozen whole fish, frozen fillets, and fresh fillets. These products represent a live weight of 281,000 mt. Adding the 2005 domestic production of 9,000 mt sets the U.S. consumption of live weight fish at 290,000 mt or 638 million pounds. Tilapia have already become one of the most important farm-raised fish and have an increasing role in the international seafood trade. Humans living where tilapia are native have consumed the fish for centuries. Many common names are found for the fish across Africa, Asia, and the Middle East. In the 1930s, scientists realized the potential of the fish as a food source, efficiently transforming plant materials to fish biomass. Missionaries and others interested in improving the welfare of the rural poor determined that tilapia could be stocked into ponds and lakes as an additional food source. Tilapia could grow with minimal inputs and still make a high-quality contribution to the diet of poor farmers. Subsequently, tilapia were stocked into countries across the tropics and subtropics, often into reservoirs behind newly constructed dams. Tilapia are adept pioneer fish, efficiently utilizing available resources and capitalizing on new and altered ecosystems. Usually, the native fish fauna had not had time to respond to the new lacustrine environment, and officials felt that they were ‘improving’ the fish community. With hindsight, it appears that tilapia have acted alongside other environmental changes to contribute to declines in native fish fauna (Pullin et al. 1997). [This excerpt is first two paragraphs from chapter introduction]

Prospect and Potential for Global Production
Book Chapter
2006
Fitzsimmons, K. 2006. Harvest, Handling, and Processing. Pp. 607 - 618 in Tilapia: Biology, Culture, and Nutrition, Tilapia: Biology, Culture, and Nutrition, edited by C.D. Webster and Lim, C. Binghamton, NY: The Haworth Press, Inc. Retrieved (https://www.crcpress.com/Tilapia-Biology-Culture-and-Nutrition/Webster-Lim/p/book/9781560228882).
NOP 06-213 (English)(Spanish)

NOP 06-213 (English)(Spanish)

Quality control of tilapia products has been one of the most critical aspects of the success of the industry. Maintaining and improving the quality of the various product forms have been central to the rapid growth of demand for tilapia products in the market. This attention paid to detail starts while the fish are still growing in their various production systems. Processors and farmers work together to ensure that fish are not contaminated by chemical pollutants or by parasites. Virtually all farms check their water sources on a regular basis to ensure high quality. Many farmers now use bird nets or greenhouse covers to keep out birds and other sources of potential contamination. The following are brief descriptions of some of the preharvest and postharvest considerations for growing, harvesting, and processing tilapia. [This excerpt is first paragraph of the chapter's introduction]

Harvest, Handling, and Processing
Book Chapter
2006

NOP 06-A11 (English)

A sustainable semi-intensive pond aquaculture technology including major carp species as cash-crop and small indigenous fish species (SIS) as food for the farmers' families is being optimized in Bangladesh. The inclusion of silver carp (Hypophthalmichthys molitrix), a cheap large species affordable by poor farmers, is now being considered. As part of a study on the effects of this filter feeder on polycultures including the large carps rohu (Labeo rohita), catla (Catla catla) and common carp (Cyprinus carpio) and the SIS punti (Puntius sophore) and mola (Amblypharyngodon mola), an experiment was carried out to test the effects of silver carp and of each SIS species on the growth, survival and yield of the large and small fish and on pond ecology.The ecology of the ponds was dominated by changes in time, strongly related to the development of a surface plankton scum at the beginning of the culture season and weather conditions. The surface scum increased decomposition processes and decreased algal development in the water body, promoted photosynthesis and ammonium release and reduced nitrification. Over those effects, the presence of silver carp in the ponds decreased algal biomass through grazing and promoted nitrification providing and re-suspending particles in the water column. These effects were also produced by mola, but were evident only in the absence of silver carp. Punti stirring on the pond bottom increased nutrient flow from the sediments into the water column and promoted nitrification, but were also evident only in the absence of silver carp. The addition of 10 silver carp over the 99 large carps stocked in the 100 m2 fishponds did not affect punti and mola reproduction in the ponds, negatively affected rohu and catla growth and yield by about 20–25% but not their survival, did not affect common carp performance, reduced punti harvested biomass by 10%, reduced mola performance by about 50%, and silver carp's own biomass increased total yield and total income in about 20% each. The addition of 250 mola or punti to the large carp polycultures did not affect the performance of any of the large carps. The decreased income from selling the more expensive large carps was more than compensated by that obtained from silver carp, which increased total income by 13–24% as compared to the corresponding treatments without silver carp. This allows the option to the farmer of selling part of the silver carp to complete the cash income that would have been obtained from large carps only if silver carp would not be stocked, and consume the rest with the family.

Effects of silver carp and small indigenous species on pond ecology and carp polycultures in Bangladesh
Journal Article
2006

NOP 06-A03 (English)(Spanish)

In Tanzania, Nile tilapia culture is a promising aquaculture enterprise. Information on production costs could assist fish farmers in economic and financial planning. Economic profitability of small-scale Nile tilapia production in Tanzania is analyzed using a model that simulates individual fish growth and takes into account fish population dynamics in the pond. The results suggest that the current practiced mixed-sex tilapia culture without predation is not economically sustainable. Extension efforts should be geared toward developing a Nile tilapia production system that is based on a hand-sexed all-male tilapia. Meanwhile catfish can be introduced in ponds to control overcrowding in mixed-sex tilapia culture without predation. Studies to determine optimal pond sizes, availability of feed, and a quality fingerling supply chain are also fundamental for developing a sustainable Nile tilapia production system in Tanzania. Under improved Nile tilapia production systems, returns are high enough to justify investment through borrowed capital from formal institutions.

Economic Analysis of Nile Tilapia ( <i>Oreochromis niloticus</i> ) Production in Tanzania
Journal Article
2006

NOP 06-217 (English)(Spanish)

Tilapia production in Honduras has increased in recent years. However, lack of thorough understanding of domestic markets and coordinated production efforts have hampered the development of a domestic market. This study quantified marketing costs for tilapia marketed in Honduras and developed a mixed-integer transshipment mathematical programming model to identify the most profitable marketing alternatives for small- and medium-scale farmers. Of the total marketing costs ($0.07 - $0.41/kg), 40 - 73% were for transportation and 13 - 30% for packaging costs. This depended upon farm size, location, and the specific market targeted. Model results suggested restaurants as primary targets with supplemental production delivered to supermarkets in relative proximity to the selected restaurants. The model selected cities with sufficient restaurant demand to absorb the farm's total production. Farms with high production levels can take advantage of the reduced transport cost of larger trucks and sell excess product to alternative outlets whereas small-scale farm volumes were too low to supply markets on a weekly basis. Farms located in the East and South regions had a marketing advantage over farms in other regions due to proximity to the most profitable Distrito Central outlets. To successfully compete for Honduran markets other than the low-priced local open-air markets will require farm sizes greater than 6 ha to supply a minimum weekly production of 900 kg.

A mixed-integer transshipment model for tilapia (<i>oreochromis</i> sp.) Marketing in Honduras
Journal Article
2006

NOP 06-219 (English)(Spanish)

Two feeding experiments were conducted to evaluate the effect of feeding duration of dietary salt (NaCl or S) on hematocrit, blood glucose, serum osmolality, and cortisol of Nile tilapia, Oreochromis niloticus, acclimated for various time periods to salt water (SW) of different salinities (three-factor experiment). Quadruplicate groups of fish averaging 5.52 ± 0.13 g (Experiment I) and 10.04 ± 0.19 g (Experiment II) were fed to apparent satiation twice daily with the following four feeding regimens: feeding the control diet (C) for 6 weeks (6-wk C); feeding the 6% NaCl (S) diet for 6 weeks (6-wk S); feeding the C diet for 2 weeks; and the S diet for 4 weeks (2-wk C 4-wk S); and feeding the C diet for 4 weeks and S diet for 2 weeks (4-wk C 2-wk S). At the end of week 6, fish in each aquarium were weighed for growth measurement. Fish from each replicate aquarium in Experiment I were transferred to SW at 0, 15 and 30 ppt whereas those from Experiment II were transferred to SW at 0, 10, and 20 ppt. Hematocrit (Experiment II only), blood glucose, serum osmolality, and cortisol were determined at 48 and 96 hours, and 0, 6, 12, 24, and 48 hours for Experiments I and II, respectively, after transfer to SW. In both experiments, weight gain after 6 weeks of feeding did not differ (> 0.05) among treatments, although all fish in the treatment receiving the NaCl-containing diet had consistently higher weight gain than those fed the C diet. Dry matter diet intake and survival were similar in both studies. Feed efficiency, however, was significantly different only in Experiment I, and was consistently better for the groups that were fed the NaCl-containing diet. All fish transferred to 30 ppt salinity died within 8 hours. No mortality occurred in fish transferred to 0, 10, 15, or 20 ppt salinity. Feeding dietary salt had no effect on blood glucose and hematocrit levels in either study. Serum osmolality of fish in Experiment I decreased in fish fed dietary salt, but the differences were not always significant. This value was similar among fish fed dietary salt in Experiment II. In both experiments, blood glucose and serum osmolality significantly (< 0.05) increased, whereas hematocrit decreased with increasing water salinity. Duration of exposure to SW also significantly (< 0.05) increased blood glucose levels but decreased hematocrit values. Duration of SW exposure had no effect on serum osmolality. The interaction between dietary salt and water salinity; water salinity and exposure time; and dietary salt and exposure time had no effect on hematological and serological values in both experiments, except blood glucose and plasma osmolality and cortisol in Experiment II were significantly (< 0.05) affected by water salinity and exposure time. The interaction between the three main factors had no effect on measured hematological parameters.

Effect of Feeding Duration of Sodium Chloride-Containing Diets on Growth Performance and Some Osmoregulatory Parameters of Nile Tilapia, <i>Oreochromis niloticus</i>, After Transfer to Water of Different Salinities
Journal Article
2006

NOP 06-209 (English)(Spanish)

Tilapia is the second-most cultured fish species in the world, and its production is increasing each year. However, for several reasons profit margins remain slim. Tilapia: Biology, Culture, and Nutrition presents respected international experts detailing every aspect of tilapia production around the world. Biology, breeding and larval rearing, farming techniques, feeding issues, post-harvest technology, and industry economics are clearly presented. This concise yet extensive reference provides the latest research and practical information to efficiently and economically maximize production in diverse locales, conditions, and climates. Tilapia: Biology, Culture, and Nutrition comprehensively explores all types of tilapia with a detailed biologic description of the fish that takes readers from egg through harvesting. The book authoritatively discusses production issues such as feed nutrition, temperature, water quality, parasites, and disease control to guide readers on how to best encourage fast, efficient growth. Economic and marketing information are examined, including industry data and projections by country. Each chapter approaches a specific facet of tilapia and provides the most up-to-date research available in that area. This resource gives the most current, detailed information needed for effective tilapia farming in one compact economical volume. Extensively referenced with an abundance of clear, helpful tables, photographs, and figures.

Tilapia: Biology, Culture, and Nutrition
Book
2006

NOP 06-A01 (English)(Spanish)

Development of aquaculture in Africa is limited by cost and shortage of fish feeds, poor financial resources and knowledge base of small-scale farmers. Consequently use of on-farm resources for producing tilapia is an attractive means of developing low-cost aquaculture. This study compared yields and economic benefits of Oreochromis niloticus and Clarias gariepinus polycultured over a 180-day period in twelve 800 m2 ponds limed and fertilized (5kg Phosphorus, 20kg Nitrogen per hectare) prior to receiving 1550 tilapia and 50 catfish each. Fish were fed twice daily at 2% body weight with Rice Bran, Pig Finisher, and a Formulated Diet feeds. Gross production in rice-bran fed fish was significantly lower (P < 0.05) with a gross yield of 4,448 kg, than both pig finisher (6,575 kg) and formulated diet (6,359 kg). Relative profitability analysis showed that Pig Finisher pellet was the best followed by Rice Bran at normal selling rice of US$1.29 (Kshs 90.00) per kg of fish. Pig Finisher and Rice Bran had lower Break Even Prices than Formulated Diet. Partial and full enterprise budgeting analyses, used here as tools to compare relative profitability of nutrient regimes, are essential to fish farmers and financial institutions willing to make investment decisions in fish farming.

Yields and economic benefits of tilapia (<i>Oreochromis niloticus</i>) and catfish (<i>Clarias gariepinus</i>) polyculture in ponds using locally available feeds
Journal Article
2006
Madriaga, L. B., and R. B. Bolivar. 2006. Sugarcane Bagasse as Periphyton Substrate in the Culture of Nile Tilapia (Oreochromis niloticus) in Fertilized Ponds. Pp. 124 - 124 in Proceedings for the 7th International Symposium on Tilapia in Aquaculture (ISTA7), Proceedings for the 7th International Symposium on Tilapia in Aquaculture (ISTA7), edited by W.M. Contreras-Sánchez and Fitzsimmons, K. Vera Cruz, Mexico. Retrieved (http://www.was.org/Shopping/ista-7th-international-symposium-on-tilapia-in-aquaculture-proceedings).
NOP 07-A08 (English)

NOP 07-A08 (English)

The study aimed to test the suitability of sugarcane bagasse as substrate in periphyton based aquaculture. The study was conducted at the College of Fisheries-Freshwater Aquaculture Center, Central Luzon State University, Science City of Munoz, Nueva Ecija, Philippines from July to November, 2005. Two ponds, each measuring 500 m2 , were stocked with tilapia fingerlings (size #12) ata density of 3 fish m-2 . The experiment had two treatments: 1- with sugarcane bagasse bundles as substrate, 11- without substrate. Ten poles made-up of galvanized iron were installed in each pond at a regular interval of 200 cm. A bundle of sugarcane bagasse substrate with a length of 60 cm and diameter of 14 cm was placed in each pole. An improvised glass slide holder containing ten glass slides was placed next to the bagasse substrate for the determination of periphyton productivity and chlorophyll a. In Treatment II, since there was no sugarcane bagasse substrate, only the glass slide holder with ten glass slides was placed in each pole. Among the two treatments, Treatment I gave significantly higher fish final mean weight and total fish weight at harvest. The final mean weight of the fish in Treatment I was 65.95.

Sugarcane Bagasse as Periphyton Substrate in the Culture of Nile Tilapia (<i>Oreochromis niloticus</i>) in Fertilized Ponds
Conference Paper
2006

NOP 06-A12 (English)

A sustainable semi-intensive pond aquaculture technology including major carp species as cash-crop and small indigenous fish species (SIS) as food for the farmers' families is being optimized in Bangladesh. The inclusion of silver carp (Hypophthalmichthys molitrix), a cheap large species affordable by poor farmers, is now being considered. As part of a study on the effects of this filter feeder on polycultures including the SIS punti (Puntius sophore) and mola (Amblypharyngodon mola), an experiment was carried out in the ponds of the Bangladesh Agricultural University, Mymensingh, to test this fish effects in the presence of the bottom feeders either common carp (Cyprinus carpio) or mrigal (Cirrhinus cirrhosus) on production/reproduction of SIS, on the other fish species and on pond ecology. The data were analyzed using univariate and multivariate statistical techniques. Reproduction of both SIS species occurred in all ponds, their fry numbers, weight and biomass at harvest not being affected either by silver carp or by the bottom feeder species. The addition of silver carp in mrigal ponds had a negative effect on both adult SIS, while its addition to carp ponds had a weaker negative effect on mola and a positive effect on punti. Common carp favored mola growth and reduced punti survival. Silver carp performance was not affected by the species of bottom feeder present. Common carp performance was not affected by silver carp. Mrigal harvesting biomass and survival were not affected by silver carp, but its harvesting weight, growth rate and yield decreased respectively by 29%, 42% and 39% in its presence. Large carp and total harvested biomass and yields were over 50% higher when silver carp was also present. In the presence of silver carp, large carp and total yields were 20% higher in common carp ponds, while in its absence they were somewhat higher in mrigal ponds. The FCR calculated considering only the large fish were 10% higher in mrigal ponds. FCR calculated including all species were somewhat higher in common carp ponds without silver carp, and 35% higher in mrigal ponds with silver carp. The observed results are explained and discussed considering the feeding habits of each species, the natural food web, and the ecological processes developing in the ponds. The addition of silver carp did not reduce the income obtained from the cash-crop species and could contribute to the nutrition and/or extra income of the farmer's family. From the production and ecological point of views, addition of silver carp to common carp ponds is a better proposition than to add it to mrigal ponds.

Effects of the filter feeder silver carp and the bottom feeders mrigal and common carp on small indigenous fish species (SIS) and pond ecology
Journal Article
2006
Molnar, J. J. et al. 2006. Exploring the Potential for Aquacultural Development to Promote Food Security Among Indigenous People in Guatemala. Pp. 297 - 298 in Proceedings for the 7th International Symposium on Tilapia in Aquaculture (ISTA7), Proceedings for the 7th International Symposium on Tilapia in Aquaculture (ISTA7), edited by W.M. Contreras-Sánchez and Fitzsimmons, K. Vera Cruz, Mexico. Retrieved (http://www.was.org/Shopping/ista-7th-international-symposium-on-tilapia-in-aquaculture-proceedings).
NOP 07-A10 (English)

NOP 07-A10 (English)

Guatemala is a multi-ethnic, multilingual and highly stratified society in which 55 percent of its 14.7 million people are indigenous Maya, Xinca and Garifuna peoples. The people of non-European origin are much poorer and reside in more remote and difficult locations than their the wealthier Ladino minority (Smith 1984). The guiding questions for the study centered on understanding the motivating interests, barriers, and appropriate intervention points for aquacultural development in indigenous communities. The total of freshwater ponds in Guatemala is about 100 ha, an area less than 10 percent of the total surface dedicated to shrimp production. Some additional 26 ha produce freshwater prawns for domestic consumption. In 1989, FAO reported that five tilapia species (T. mossambicus, T. rendalli, O. niloticus, O. aureus, and S. hornorum) have been introduced into the region and stocked in ponds, in large water bodies, or released in open watersheds. The Peace Corps and governmental technical assistance constructed nearly 600 small ponds in recent decades. Most ponds are managed on subsistence and semi-commercial levels, but the coffee crisis and growing market potential have increased interest in tilapia production. Fish are harvested for home consumption and surpluses are sold in local markets. Women often are responsible for the daily management and feeding of ponds while the men are primarily responsible for pond construction and harvest. Two case study areas in were chosen where several indig- enous communities have sustained involvement in tilapia culture over extended periods. Each set of communities is located at moderate altitudes in Central Guatemala in coffee-growing areas. Although the ponds are small, communal interest in tilapia production is sustained by the absence of alternative sources of fish. The purpose of this paper is to outline the prospects for small and medium-scale tilapia culture in Chimaltenango and Quetzaltenango -- locales where the need the great, market access is often limited, and conditions are often less than optimal for production. The guiding questions for the study centered on understanding the motivating interests, barriers, and appropriate intervention points for aquacultural development in indigenous communities. The results generate insights into the strategies for advancing aquaculture among Guatemala's poorest peoples in areas with appropriate soil and water resources.

Exploring the Potential for Aquacultural Development to Promote Food Security Among Indigenous People in Guatemala
Conference Paper
2006
Morrison, C. M., K. Fitzsimmons, and J. R. Wright. 2006. Atlas of Tilapia Histology. edited by C. Browdy. Baton Rouge, Louisiana: World Aquaculture Society. Retrieved (http://www.was.org/Shopping/atlas-of-tilapia-histology).
NOP 06-215 (English)(Spanish)

NOP 06-215 (English)(Spanish)

Tilapia have become one of the most important domesticated fish around the world. The group’s importance to household income in the developing world is increasing as the vast majority of tilapia are reared by small farmers in relatively poor tropical countries for domestic consumption, local trade, and for international exports. Tilapia have become a major commodity in international trade. With the expansion of culture of these species worldwide, interest in the biology of the fish in general and health in particular have increased. The Atlas of Tilapia Histology provides a key reference work on normal anatomy and histology of Oreochromis niloticus. The book is comprehensive with 197 full color annotated plates depicting Tilapia strains, gross anatomy with dissections and histology. Detailed depictions are provided for integumentary, muscular, skeletal, circulatory, hematopoietic, digestive, respiratory, renal, excretory, reproductive, nervous, sensory and endocrine systems. The detailed table of contents and comprehensive index allow the reader to quickly locate areas of interest and the spiral binding and glossy pages are designed for bench top laboratory use. Although the fish is very hardy, the increased densities, polyculture and unusual environments in which the fish is reared, are exposing them to pathogens and stress conditions that lead to disease conditions. This reference will provides a powerful tool to allow farmers and fish health professionals to make quicker and more accurate diagnoses. It should be of particular interest to producers and breeders who need references to compare “normal” fish with newly bred strains and hybrids or fish reared in unusual environmental conditions.

Atlas of Tilapia Histology
Book
2006

NOP 06-A02 (English)(Spanish)

 

Nile tilapia Oreochromis niloticus is the primary tilapia species being cultured in the world, but many of the stocks being cultured were founded from a limited number of fish collected from the wild in the 1960s and 1970s. Such limited founding stocks and the numerous generations since offers the possibility of inbreeding depression. An evaluation of reproductive and growth characteristics of one highly domesticated stock of O. niloticus (Ivory Coast), two stocks not as domesticated (Egypt and Sagana), and one recently collected from the wild (Lake Victoria) was conducted at Auburn University. Brood fish held in 2-m3 hapas were checked weekly; females holding eggs or sac fry in their mouths were transferred to the hatchery to continue eggs and sac fry incubation. Growth was evaluated during primary (1-30 days post-swimup) and secondary nursery (31-90 days post-swimup). The four strains differed in relative fecundity (seed/g female), percentage of females that spawned (11.6% to 57.2%) and in incubation success (5.3% to 91.3%). The combined effects of relative fecundity, percentage of females spawning, and incubation success, resulted in the Ivory Coast strain giving eight times more fry per kg of female brooder used than the Lake Victoria strain. Average weights of fingerlings for the four strains at the end of primary nursery ranged from 2.1 to 2.8 g; survival was similar for all strains. Secondary nursery results for the Egypt and Ivory Coast strains were similar when in a common production setting for 60 days. Average weights of Egypt and Ivory Coast fingerlings were 21.8 ± 7.3 and 21.0 ± 6.5 g, respectively, when produced in organically fertilized ponds, 87.9 ± 23.1 and 103.2 ± 3.9 g when produced in outdoor tanks and given a commercial feed, and 36.1 ± 2.6 and 36.5 ± 2.4 g when produced in a recirculating system and given a commercial feed. No genotype-environment interaction for growth or survival by Egypt and Ivory Coast strains was seen in three secondary nursery settings. © 2005 Elsevier B.V. All rights reserved.

Evaluation of reproductive performance and early growth of four strains of Nile tilapia (<i>Oreochromis niloticus</i>, L) with different histories of domestication
Journal Article
2006

NOP 06-208 (English)(Spanish)

We evaluated the effects of casein-based semipurified diets, alone or supplemented with native Peruvian plants, on growth, feed efficiency and histology of the digestive tract of red pacu, Piaractus brachypomus, juveniles over an 8-week feeding trial. Three tanks were randomly assigned to one of four casein-gelatin (40:8) diets containing a supplement of 15% wheat meal (control) or an identical level of substitution of three South American native plant as follows: camu-camu fruit (Myrciaria dubia), aguaje fruit (Mauritia flexuosa) or maca tuber meal (Lepidium meyenii). The fish (initial weight, 2.04 +/- 0.06 g) were fed experimental diets at decreasing feeding rates from 4 to 2.6% of body weight. After 8 weeks of feeding, fish fed a diet supplemented with maca meal showed significantly higher (P < 0.05) weight gain, specific growth rate, protein efficiency ratio (PER), apparent net protein utilization (NPU) and instantaneous feed intake than fish fed other diets. Feed conversion ratio (FCR), PER and NPU in fish fed the casein-gelatin diet supplemented with maca meal were among the best ever reported in the scientific literature, 0.64 +/- 0.03, 3.13 +- 0.15 and 23.8 +/- 2.0, respectively. The camu-camu meal had a negative impact on diet palatability and utilization, which resulted in slower growth. The stomach, intestine, pancreas and pyloric caeca at the start and end of the experiment showed normal differentiation and appearance of cells and tissues. The liver parenchyma showed lipid infiltration and pigment accumulation in all samples at the initiation of the experiment and may be attributed to the period of decreased feed intake prior to the study. At the end of the study, similar histopathologies were recorded in all samples from the control and camu-camu groups. Normal liver histology (polyhedral hepatocytes with centrally located nuclei) was observed in two of three samples from the maca group and all the samples from the group that was fed the aguaje-supplemented diet.

Effect of diets formulated with native Peruvian plants on growth and feeding efficiency of red pacu (<i>Piaractus brachypomus</i>) juveniles
Journal Article
2006

NOP 06-A08 (English)

Effects of dietary alpha-lipoic acid (LA) and ascorbic acid (AA) on the growth, tissue vitamin C and tocopherol (vitamin E) levels, and malondialdehyde levels were examined in the tropical fish pacu, Piaractus mesopotamicus. Pacu juveniles were fed one of four casein-gelatin-based diets for 8 weeks: with 0.05% AA and 0.1% LA (+AA+LA), with AA and without LA (+AA-LA), without AA and with LA (-AA+LA), and without AA and LA (-AA-LA). When the fish received quantities of feed equal to 1.9 - 2.5% of its body weight, growth was not influenced, regardless of the presence of AA or LA throughout most of the experimental period. Growth was, however, slightly but significantly lower at week 8 in the AA-deficient/LA-supplemented group. An AA-deficient diet caused a highly significant reduction in both total AA and dehydroascorbic acid content in the liver and gill tissues. This reduction of tissue AA concentrations was reversed in a significant manner by LA (antioxidant-sparing effect). The 8-week-long vitamin C deprivation was sufficient to initiate the reduction in tissue ascorbic acid; however, total ascorbate in the liver of fish in the (-)AA/(+)LA group was 127.7 +/- 54.3 nmol g-1 tissue, whereas it was 28.6 +/- 26.3 nmol g-1 in the (-)AA/(-)LA group, a 4.4-fold difference. This mitigating effect of the addition of the endogenous antioxidant LA to the diet indicates that LA exerts a vitamin C-sparing effect in teleost fish that by far exceeds the phenomena demonstrated in non-scurvy-prone mammals. There was no difference among the different diet groups for vitamin E and malondialdehyde levels in the liver. These results suggest that LA is a potent substance for the prevention of AA deficiency in cultured fishes. The optimal dietary level of LA needs to be determined in the light of the slight reduction in body weight gain after 8 weeks of feeding in the absence of AA.

α-Lipoic acid-enrichment partially reverses tissue ascorbic acid depletion in pacu (<i>Piaractus mesopotamicus</i>) fed vitamin C-devoid diets
Journal Article
2006

NOP 06-A10 (English)

An experiment was carried out in 18 earthen ponds to investigate the effects of the addition of common carp Cyprinus carpio (L.) and artificial feed on natural food availability, food utilization and fish production in rohu Labeo rohita (Hamilton) ponds. Ponds were fertilized fortnightly with cow manure, urea and triple super phosphate. Rohu was stocked in all ponds at a density of 1.5 rohu m−2. All treatments were carried out in triplicate. Treatments were: rohu with and without formulated feed, rohu plus 0.5 common carp m−2 with and without feed, and rohu plus 1 common carp m−2 with and without feed. The time period between stocking and harvesting was four and half months. Stocking 0.5 common carp m−2 enhanced natural food availability in the pond, food utilization and rohu growth and production (P < 0.05). The effect was less pronounced when stocking 1 common carp m−2. Formulated feed administration did not influence phytoplankton availability (P > 0.05) but increased zooplankton and benthic macroinvertebrate availability (P < 0.001). Feed administration also enhanced growth of rohu and common carp (P < 0.001). Rohu naturally ingests more phytoplankton than zooplankton but in the presence of formulated feed rohu shifted its natural food preference from phytoplankton to zooplankton. Common carp naturally ingests mainly zooplankton and benthic macroinvertebrate and small quantities of phytoplankton. However, when offered formulated feed, the latter becomes the preferred food item.

Growth, production and food preference of rohu <i>Labeo rohita</i> (H.) in monoculture and in polyculture with common carp <i>Cyprinus carpio</i> (L.) under fed and non-fed ponds
Journal Article
2006
Schreck, C. B. et al. 2006. Growth Performance of a Genetically Improved Line of Nile Tilapia Under Tropical Conditions in Tabasco, Mexico. Pp. 229 - 230 in Proceedings for the 7th International Symposium on Tilapia in Aquaculture (ISTA7), Proceedings for the 7th International Symposium on Tilapia in Aquaculture (ISTA7), edited by W.M. Contreras-Sánchez and Fitzsimmons, K. Vera Cruz, Mexico. Retrieved (http://www.was.org/Shopping/ista-7th-international-symposium-on-tilapia-in-aquaculture-proceedings).
NOP 07-A09 (English)

NOP 07-A09 (English)

The establishment of good quality broodstock treatments, their distribution to local hatcheries, and the implementation of intensive masculinization programs are basic steps for sustainable aquaculture. The selective breeding program supported by the CRSP from 2001 to 2003 was initiated using 220 females and 110 males obtained from a batch of fish purchased from Egypt by the state government. A second line is currently being selected from wild animals. We have identified a stock of wild Nile tilapia in the Usumacinta River that shows several advantageous phenotypic traits (small head, small tail, large body, and uniform color). For the first year of work, we were able to combine the efforts of the CRSP project and another supported by the National Council for Science and Technology (CON- ACyT-Mexico). This action allowed us to work at the Mariano Matamoros Hatchery using 200, 1,000, and 2,000 m2 ponds and to use fish first selected by Mario Fernandez in 2000. To date, we have selected organisms from the third generation (F3) based on a combination of length and condition factor and we are currently raising a fourth generation. In this study we evaluated six tilapia lines (three more than the originally proposed lines) in terms of growth, condition factor fillet production and feed conversion factor. The lines evaluated were: Tabasco-l, Control, Teapa, Wild-I, Wild 2 y Stirling. Fish were stocked in 2 m3 hapas at a density of 25 fish/m3. All hapas were placed in a single earthen pond. Average initial weight was 50 g. Best values obtained for weight correspond to the line Tabasco-1 averaging 446.2 g at the end of the grow-out trial. This line had a 1.77 g/day growth rate. Followed by the Stirling line with an average final weight of 439.47 g (1.74 g/day). The lowest value was obtained from fish of the Teapa line (original broodstock of the state hatchery) with an average final weight of 343.86 g (1.30 g/day). Fillet yield was higher for the Tabasco-l line (31.44% of body weight) and an average fillet weight of 130.1g, followed by the Stirling line (31.30% and 125.3g) Once again, the lowest value corresponded to the Teapa Line (28.70% and 99.6 g). From the first generation, the Tabasco-l line has demonstrated the productive potential that represents to farmers, allowing high yields at harvesting.

Growth Performance of a Genetically Improved Line of Nile Tilapia Under Tropical Conditions in Tabasco, Mexico
Conference Paper
2006

NOP 06-A04 (English)

These preliminary studies were conducted to understand some of the basic reproduction parameters of the indigenous carp, Spinibarbus denticulatus (Oshima 1926) as a prelude to more specific research studies, and the subsequent development of hatchery technology. Gonad and oocyte development was assessed over a 12 month period. Observation of the annuli rings of the fish scale was found to be a reliable means of measuring fish age. Mature males were smaller and matured earlier (4 years) than females (5 years). The gonadosomic index revealed two peaks (April and October). Oocytes, developing at various stages were examined from January to March. In January the oocytes sizes were uniformly small. Two distinct oocyte-size groups were observed in the February sampling and three size groups were observed in March. The proportion of large-size oocytes (55%) was higher compared to mid-size (26%) and small-size (19%) oocytes during the near peak spawning months. The average number of oocytes in the ovaries in a female was 31,041. The mean sperm concentration was 8.42±0.36 million cells per ml with only a small amount (3.3±0.2 ml) of total expressible milt per male. However, when induced with LHRHa the milt production increased to 6.2±0.5 ml without an increase in the total number of sperm cells. The species shows potential for mass production; however, low fecundity and late puberty could present obstacles to artificial seed production.

A Preliminary Study on the Maturation and Reproduction of <i>Spinibarbus denticulatus</i> (Oshima, 1926), an Indigenous Species of Northerm Vietnam
Journal Article
2006
Watanabe, W. O., K. Fitzsimmons, and Y. Yi. 2006. Farming Tilapia in Saline Waters. Pp. 347 - 447 in Tilapia: Biology, Culture, and Nutrition, Tilapia: Biology, Culture, and Nutrition, edited by Chhorn Lim and Webster, Carl D. The Haworth Press, Inc. Retrieved (https://www.crcpress.com/Tilapia-Biology-Culture-and-Nutrition/Webster-Lim/p/book/9781560228882).
NOP 06-211 (English)(Spanish)

NOP 06-211 (English)(Spanish)

Although tilapia culture has been limited primarily to freshwater and low-salinity brackish water, a high degree of salt tolerance exhibited by certain species has suggested that they might be cultured in high-salinity brackishwater and marine systems, enabling their exploitation in tropical and coastal areas (Kuo and Neal 1982; Payne 1983; Hopkins et al. 1989; Watanabe, Burnett, et al. 1989; Watanabe 1991; Suresh and Kweilin 1992; Watanabe et al. 1997). In many areas, limited fresh water supply is an important constraint to further expansion of the industry, which will therefore have to turn to mariculture. To date, the most comprehensive research on saltwater culture of tilapia has been conducted with the Florida red tilapia. The objectives of this chapter are to review the biotechnical and socioeconomic data for saltwater culture of the Florida red and other saline-tolerant tilapia, including the areas of hatchery design and management, broodstock husbandry and seedstock (eggs, yolksac fry, and free-swimming fry) production, nursery production of fingerlings, juvenile grow-out in land-based and sea cage systems, disease control, economics, and marketing. Although tilapia are being considered for culture in lagoonal systems where salinities under 15 ppt (Legendre et al. 1989), the present review is restricted to high-salinity culture systems of ≥ 15 ppt, conditions tolerated by relatively few species of commercial importance. [This excerpt is the chapter's introduction]

Farming Tilapia in Saline Waters
Book Chapter
2006

NOP 06-A06 (English)

Sediment samples were collected from 42 catfish (Clarias hybrid) ponds, 40 freshwater prawn (Macrobrachium rosenbergii) ponds and 18 carp (Puntius spp.) ponds in Thailand. Regression analysis revealed that pond age (1 - 30 years) was not a major factor influencing the physical and chemical composition of pond sediments. Sediment depth, F+S horizon thickness and bulk density of S horizon were greater (P < 0.05) in carp ponds than in catfish and prawn ponds. This occurred because sediment was removed from catfish and prawn ponds more frequently than from carp ponds. Total carbon, organic carbon and total nitrogen concentrations were greater (P < 0.05) in carp ponds than prawn and catfish ponds. Few ponds had sediment organic carbon concentrations above 3%, and carbon:nitrogen ratio values did not differ (P > 0.05) among ponds for the three species. Total phosphorus and other sediment phosphorus fractions increased in the order prawn ponds, carp ponds and catfish ponds. Sediment sulphur concentrations also increased in the same order. There were no differences in major or minor nutrient concentrations in sediment that would influence aquacultural production. Although there were significant correlations (P < 0.05) between various sediment quality variables, no single variable or group of variables would be useful in estimating sediment quality. Pond bottom management practices used by producers in Thailand included drying of pond bottoms between crops, liming, tilling and periodic sediment removal. These practices have maintained relatively good bottom quality. They should be continued in Thailand and adopted in other places.

Physical and chemical characteristics of sediments in catfish, freshwater prawn and carp ponds in Thailand
Journal Article
2006

NOP 06-A09 (English)

An on-station trial was conducted in fourteen 100-m2 earthen ponds at the Bangladesh Agricultural University (BAU), Mymensingh, Bangladesh during July-December 2001. This trial was designed to evaluate different fertilization regimes currently used for aquaculture in Bangladesh, and to compare effects of different fertilization regimes on fish production, water quality, and economic returns. There were five fertilization regimes for culture period as treatments: (A) PROSHIKA fertilization regime - weekly application of 1,000 kg cow dung per hectare; (B) BRAC fertilization regime – weekly application of 156 kg cow dung, 28.125 kg urea and 13.1 kg TSP per hectare; (C) CARITAS fertilization regime – fortnight application of 1,500 kg cow dung per hectare; (D) BAU fertilization regime - fortnight application of 1.250 kg cow dung, 31 .25 kg urea and 15.625 kg TSP per hectare; (E) A/CRSP fertilization regime developed from Nile tilapia (Oreochromis niloticus) ponds - weekly application of 250 kg cow dung (dry matter) per hectare supplemented with urea and TSP to give 28 kg N and 7 kg P/ha/wk. Six carps species used in this on-station trial were silver carp (Hypophthalmichthys molitrix), mrigal (Cirrhinus mrigala), rohu (Labeo rohita), calla (Cat/a cat/a), grass carp (Ctenopharyngondon idella) and common carp (Cyprinus carpio) stocked at a ratio of 9:8:6:6:3:2 at a stocking density of 1.02 fish/m2, giving 27, 24, 18, 9, 6, fish per 100-m2 pond, respectively. Mean stocking sizes of carps ranged from 6.3 to 10.1 g. Among all tested fertilization regimes, A/CRSP fertilization regime resulted in the highest fish production, followed by BAU, BRAC, CARITAS and PROSHIKA fertilization regimes (P < 0.05). The two fertilization regimes (PROSHIKA and CARITAS) using cow dung as the sole nutrient input during the culture period gave very poor fish growth performance and low production, mainly due to the low soluble nutrients derived from cow dung. The other three fertilization regimes (A/CRSP, BAU and BRAC) using the combination of organic and inorganic fertilizers resulted in much higher carp production. Analysis of water quality showed that the nutrients in A/CRSP fertilization regime were oversupplied, as this regime was developed in Nile tilapia monoculture system with higher intensification compared to the carp polyculture in the present trial. BAU fertilization regime gave the highest profitability among all fertilization regimes, followed by BRAC and A/CRAP Therefore, it is concluded from the present study that BAU fertilization regime is the most appropriate for carp polyculture ponds in Bangladesh while A/CRSP fertilization regime is suitable to carp polyculture ponds with higher intensification.

On-Station Trials of Different Fertilization Regimes Used in Bangladesh
Journal Article
2006

2005

NOP 05-A04 (English)

NOP 05-A04 (English)

The Food and Agriculture Organization (FAO) of the United Nations has provided an annual series of world aquaculture production statistics since 1950. The FAO is interested in including information on land and water use in aquaculture in their statistics. An expert consultancy on land and water use in aquaculture was convened at FAO headquarters in Rome, Italy, from 7 - 10 October 2002. It was apparent during the consultancy that variables related to water use should be defined. The purpose of this paper is to define water use variables for aquaculture, give examples of water use calculations and consider methods and benefits of water conservation in aquaculture. Water use in its broadest definition should include all of the water needed to produce an aquaculture crop. However, some of the water introduced into aquaculture production units subsequently is discharged and available to downstream water users. In cage and net pen culture, water simply passes through production units and only a small quantity is removed in biomass at harvest. Brackishwater or seawater availability usually is not diminished by coastal aquaculture. Therefore, the greatest concern should be consumptive water use by freshwater aquaculture, for this reduces the volume of water available for other beneficial uses. The volume of water consumed per unit of aquaculture product would be a helpful variable, for it would allow estimates of the economic value of water in aquaculture.

Water use in aquaculture
Journal Article
2005
Camargo, W. N. et al. 2005. Live Diets for Pacu Larvae Tested in Peru. Global Aquaculture Advocate, 78 - 80.
NOP 05-A08 (English)

NOP 05-A08 (English)

The results of a study in Peru that evaluated three food sources for larval C. macropomum and P. brachypomus indicated that although Artemia are a more readily available and reliable larval food source, Moina sp. appear to be a cost-effective substitute for use in the Amazon Basin.

Live Diets for Pacu Larvae Tested in Peru
Magazine Article
2005
Campos-Baca, L., and C. C. Kohler. 2005. Aquaculture of Colossoma macropomum and Related Species in Latin America. Pp. 541 - 561 in Aquaculture in the 21st Century: Proceedings of the American Fisheries Society Symposium, vol. 46, Aquaculture in the 21st Century: Proceedings of the American Fisheries Society Symposium, edited by A.M. Kelly and Silverstein, J. Bethesda, Maryland, USA: Fisheries and Illinois Aquaculture Center. Retrieved (http://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=1066&context=fiaq_pubs).
NOP 05-A09 (English)

NOP 05-A09 (English)

Colossoma macropomum (Cuvier 1818), known as black pacu in the United States, is the second largest scaled fish after Arapaima gigas (Osteoglossidae) in the Amazon basin, reaching weights of 30 kg in the natural environment (Goulding and Carvalho 1982). The fish has excellent characteristics for use in aquaculture (Campos 1986; Saint-Paul 1986, 1991; Van der Meer 1997), which include, reproducing under aquaculture conditions; being low on the food chain; accepting prepared feed; being highly resistant to disease, handling, and poor water quality; having rapid growth; being amenable to high density; having high market acceptability; commanding a high price; and also, being marketable as an ornamental fish. Countries in Latin America culturing Colossoma and similar species include Argentina, Bolivia, Brasil, Colombia, Costa Rica, Ecuador, Mexico, Panama, Peru, and Venezuela (Figure 1). Colossoma macropomum has also been introduced into the United States, Africa, and Southeast Asia (Lovshin 1995). Until recently, problems associated with larval production and nutrition, exasperated because much of the information about its culture is disperses or unpublished, have limited viable aquaculture ventures with this group of Amazonian fishes. Brazil is the first country that has commercially cultured these characids (Da Silva et al. 1976). Very few researchers have access to the advances in culture of characids because much of the research appears in agency reports and, to further complicate dissemination of information, appears in different languages. There are hundreds of papers scattered throughout the region that require scientific analysis to establish a successful cultural program. Approximately 54% of the publications/reports are in Portuguese, 40% are in Spanish, and very few are in English and other languages. This chapter is an attempt to compile some of the more relevant information on C. macropomum and related species. 

Aquaculture of <i>Colossoma macropomum</i> and Related Species in Latin America
Conference Paper
2005

NOP 05-206 (English)(Spanish)

An experiment was conducted in rice field plots each of 30 m2 to determine the appropriate combination of feeding and fertilization regimes for the giant freshwater prawn Macrobrachium rosenbergii (De Man, 1879) cultured along with rice in rice fields. There were four treatments: rice culture only with regular fertilization (A, control); rice-prawn integrated culture with regular fertilization (B); rice-prawn integrated culture with basal fertilization and commercial feed (C) and rice-prawn integrated culture with regular fertilization and commercial feed (D). Juvenile prawns of 1.5-g size were stocked on the third day after rice transplantation at a density of 2 prawns m-2 and fed twice daily at 5% reducing to 2% of body weight during the experiment. The rice yield in treatment D (0.42 kg m-2) was significantly higher than that in other treatments (0.34, 0.36, 0.34 kg m-2 in treatments A, B, C respectively). Prawns grew significantly faster (P < 0.05) in treatments C and D (23.8 plus or minus 0.9 and 22.0 plus or minus 1.7 g prawn-1 respectively) than in treatment B (14.7 plus or minus 1.6 g prawn-1). Prawn production in treatment C (347 plus or minus 13 kg ha-1 crop-1) was significantly (P < 0.05) higher than that (234 plus or minus 30 kg ha-1 crop-1) in treatment B, while in treatment D (296 plus or minus 53 kg ha-1 crop-1) it was not significantly different from that in treatments B and C (P > 0.05). Treatment C gave the highest economic returns among all treatments, followed by treatments D and B, indicating that the combination of basal fertilization and commercial feed is the most appropriate nutrient input regime for the rice-prawn integrated culture system.

Effects of different fertilization and feeding regimes on the production of integrated farming of rice and prawn <i>Macrobrachium rosenbergii</i> (De Man)
Journal Article
2005

NOP 04-A04 (English)(Spanish)

A feeding trial was conducted to examine the supplemental effects of maca (Lepidium meyenii, Walper) meal and its components extracted by four different solvents on growth performance, feed utilization, and survival in rainbow trout fry. Eight casein-based semipurified diets were formulated to be isonitrogenous and isocaloric to contain the maca meal, its four extracts, mixture of the four extracts, and maca meal after extraction. The eight diets were each supplemented with 15% wheat flour (control diet, diet 1), 15% maca meal (diet 2), 12.5% maca meal after the extraction (diet 3), a mixture of four maca meal extracts (diet 4), a hexane extract (diet 5), a dichloromethane extract (diet 6), an ethyl acetate extract (diet 7), and a methanol extract (diet 8). In vitro 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical inhibition indices were observed to increase in a dose-dependent manner as the concentration of methanolic extracts of maca meal increased. For the antioxidant activities of the four extracts, only the methanolic extract showed a higher inhibition rate against DPPH radical compared to other extracts by hexane, ethyl acetate, and dichloromethane. After a 14-week feeding trial, fish fed diet 2 exhibited the highest (P < 0.05) growth among all the dietary treatments. Fish fed diets 2, 3, and 8 had significantly higher growth than the fish fed the control and the other diets. Feed intake was significantly higher in fish fed diets 2, 3, and 8 than fish fed the control diet and diet 5. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were also significantly improved in the fish fed diets 2 and 3 than in fish fed the diets 1 (control), 5, 6, and 7. Survival was significantly higher in fish fed diet 2 than the control diet, diet 5, and diet 6. The results indicate that certain compounds in maca meal have growth enhancing effects in rainbow trout juveniles. The compounds of interest have high polarity and can be extracted by methanol. This compound has an antioxidant capacity that might increase resistance against stress and/or diseases. ?? 2004 Published by Elsevier B.V.

Activity-guided fractionation of phytochemicals of maca meal, their antioxidant activities and effects on growth, feed utilization, and survival in rainbow trout (<i>Oncorhynchus mykiss</i>) juveniles
Journal Article
2005

NOP 05-A06 (English)

Lack of suitable diets for semi-intensive production of Oreochromis niloticus in Kenya has necessitated use of expensive diets designed for intensive production. To address this problem, two isonitrogenous (24% protein) diets were formulated and evaluated for production\nof O. niloticus in fertilized ponds. One diet contained vitamins and minerals premix (CV) while the other had no premix (CW). Growth of fish fed on the formulated feeds was compared with groups of fish fed on commercial pig pellets (PP) and wheat bran (WB). There were significant differences in mean weights, growth rates and feed conversion ratios between the formulated and the other diets. No significant differences in these parameters were observed between CV and CW and also between PP and WB. Fish that fed on the formulated feeds produced significantly lower number of juveniles than those fed on PP and WB. Fish fed on WB gave the best economic returns while those on PP had the least returns. Present results suggest that vitamins and minerals premix may not be necessary in diets for semi-intensive production of O. niloticus. Present results showed that the formulated feeds produced higher yields than PP and WB, but WB had the best economic returns among the test diets.

Growth and economic performance of Nile tilapia (<i>Oreochromis niloticus</i> L.) fed on two formulated diets and two locally available feeds in fertilized ponds
Journal Article
2005

NOP 05-A07 (English)

A study was conducted to compare nutritive value and economic performance of a high cost formulated pellets for tilapia (TP), rice bran (RB), and Pig finisher pellets (PFP) in production of Oreochromis niloticus in fertilized ponds. Sex-reversed male O. niloticus were stocked at a density of 19,375 fish ha-1 and Clarias gariepinus was introduced at 625 fish ha-1 to control any tilapia breeding. Fish were fed daily at 2% body weight in three treatments with four replicates for 180 days. Growth and fish yields were similar (P > 0.05) in treatments PFP and TP, but significantly lower (P < 0.05) in RB treatment. Feed conversion ratio was similar in treatments PFP and TP but significantly higher (P < 0.05) in RB treatment. Pond water quality parameters were not significantly different (P > 0.05) among treatments; exceptions were alkalinity, pH and DO, which differed significantly (P < 0.05) among treatments. Partial enterprise budgets demonstrated that net returns were positive for all the treatments, and that RB had the least investment costs. However, PFP was the most profitable while TP, gave the least returns among the test feeds. In conclusion, PFP is a suitable alternative but RB is inferior to TP in production of O. niloticus in fertilized ponds.

Comparative evaluation of nutritive value and economic performance of specially prepared diet for tilapia with rice bran and commercial pig finisher in Projects of Nile Tilapia (<i>Oreochromis niloticus</i>) in Fertilized Ponds
Journal Article
2005

NOP 05-205 (English)(Spanish); NOP 05-A02 (English)(Spanish)

This study was conducted in the 5.24-ha Truong Dang Cove of Tri An Reservoir of Vietnam during June 2002-May 2003 to describe cove culture of marble goby (Oxyeleotris marmorata, Bleeker) with silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), common carp (Cyprinus carpio) and grass carp (Ctenopharyngodon idella) stocked at 960, 470, 470, 470 and 170 fish/ha, respectively. After about 7 months of culture period from October 2002 to May 2003, gross yield of marble goby was 251.1 kg/ha/crop, while gross yields of silver carp, bighead carp, common carp and grass carp were 90.5, 114.3, 84.6 and 35.0 kg/ha/crop, respectively. Survival was 73.7% for marble goby and 55.1 - 62.8% for carps.

Results indicated that the cove had relatively good physicochemical conditions with diversified natural food resources such as terrestrial vegetation, phytoplankton, zooplankton, benthos, detritus, small wild fish and prawns. The major food item of marble goby was small freshwater prawns, followed by small wild fish and benthos. Addition of marble goby to carp polyculture in cove gave much higher economic return, compared to that without marble goby (US$2713.2 vs. US$260/crop). This study has demonstrated that cove culture of marble goby is a prominent prospect ecologically, technologically and economically. ?? 2004 Elsevier B.V. All rights reserved.

Cove culture of marble goby (<i>Oxyeleotris marmorata</i> Bleeker) and carps in Tri An Reservoir of Vietnam
Journal Article
2005

NOP 07-224 (English)(Spanish)

This study was supported by Aquaculture Collaborative Research Support Program (ACRSP) of the United States Agency for International Development (USAID) and conducted in Honduras by the Pan-American Agriculture School (PAS) from September 2003 and July 2004. The objective of the study was to evaluate tilapia fingerling production and examine the factors that influence the way farmers produce and distribute fingerlings and to provide recommendations to improve the quality and availability of fingerlings in Honduras. The study describes the socioeconomic characteristics of tilapia fingerling producers, their production techniques, as well as their needs for training and technical assistance in Honduras. Sixteen farmers were identified, visited, and interviewed. A sample from each farm of the 13 producing and distributing fingerlings was taken to the Aquaculture Station at the PAS to determine their count and evaluate their quality based on uniformity of size, color, and male gender. Seven of the fingerling farms are family owned, four are private companies, one is a cooperative, one is operated by a nonprofit organization (NGO), another is run by a university, and two by the government. In aggregate, they produce approximately 15.3 million fingerlings a year. Most (75%) of the fingerling producers interviewed also produce marketing size tilapia, produce other aquaculture species, and have other farm enterprises. Results show that fingerling sex reversal with hormone-treated feed is practiced by 13 of the 16 farmers. Tilapia fingerling producers have between 4 and 6 years of formal education and an average of 6.7 years of experience (range of 0 – 25 years). The results of the study suggest that a farmer's experience growing tilapia food fish is positively correlated to production of quality fingerlings. Analysis of the fingerling samples shows that there is variability on the quality of the fingerlings from one farm to another.

Tilapia Fingerling Production in Honduras
Thesis
2005

NOP 05-A01 (English)(Spanish)

The effect of diets in which 50% of casein-gelatin protein was replaced with extracted soybean meal (SBM) or soybean protein concentrate (SPC) on first-feeding rainbow trout and juvenile South American pacu was examined following 3-6 fold body weight gain. A casein-gelatin-based diet supplemented with essential amino acids, lipids and other ingredients was used as control. After 4-weeks feeding, rainbow trout growth was significantly depressed in both SBM- and SPC-replacement treatments whereas pacu, the adults of which are considered omnivorous or frugivorous, showed significantly improved weight gain on the SBM-replacement diet. The enterocytes of posterior intestine of all control fish, and SBM-fed pacu showed regular shapes. Their supranuclear regions contained numerous small absorptive vacuoles. In trout fed SPC and SBM diets, and in SPC-fed pacu, posterior intestine enterocytes were excessively vacuolized. The highest pancreas activity (measured as the number of proenzyme granules) occurred in control fish. The liver cells showed regular development in both species fed the control diet and in pacu fed SBM and SPC diets. On the contrary, the hepatocytes of SBM and SPC-based diet fed rainbow trout showed anomalies. In both species, the average hepatocyte nuclear volumes significantly differed among the feeding groups. The results of histological analyses indicated that absorption and transport of nutrients to liver and pancreas were affected by the presence of soybean products in experimental diets. The SBM diet was beneficial for pacu but adversely affected rainbow trout, while the SPC diet resulted in extensive pathologies of digestive tract and most likely affected nutrient utilization in both species. ?? 2005 Elsevier B.V. All rights reserved.

Growth and morphological changes in the digestive tract of rainbow trout (<i>Oncorhynchus mykiss</i>) and pacu (<i>Piaractus mesopotamicus</i>) due to casein replacement with soybean proteins
Journal Article
2005

NOP 05-A03 (English)(Spanish)

Pond fertilization studies usually are restricted by availability of ponds forcing researchers to limit treatments to maintain adequate replicates for statistical analysis. Data from a wide range of fertilizer rates applied over a single season in unreplicated ponds were treated using regression analysis to establish the optimum phosphorus application rate for bluegill (Lepomis macrochirus) ponds. The response to phosphorus fertilization conformed to a saturation model (R2 = 0.92). Bluegill production increased with greater fertilization rate up to 3 kg P2O5 ha-1,but production was similar (501 - 558 kg ha-1) at rates of 3 - 7 kg P2O5 ha-1. The observation that 3 kg P2O5 ha-1 per application was adequate phosphorus fertilization for bluegill ponds with sufficient nitrogen agrees closely with the usual recommendation of 4 kg P2O5 ha-1 per application. Results of this re- search also revealed that nutrient assessment in bluegill ponds can be based on total nitrogen and to- tal phosphorus analyses, and Secchi disk visibility may be used as an index of plankton abundance.

Determination of the phosphorus fertilization rate for bluegill ponds using regression analysis
Journal Article
2005
Yi, Y., C. K. Lin, and J. S. Diana. 2005. Effects of fertilization rates on growth performance of red tilapia at different salinities. Pp. 439 - 450 in 6th International Symposium on Tilapia Aquaculture, 6th International Symposium on Tilapia Aquaculture, edited by K. Fitzsimmons, Bolivar, R.B., and Mair, G. Manila, Philippines. Retrieved (http://www.was.org/Shopping/ista--6th-international-symposium-on-tilapia-in-aquaculture-proceedings).
NOP 04-A23 (English)

NOP 04-A23 (English)

An experiment was conducted at the Asian Institute of Technology, Thailand, to investigate effects of fertilization rates and salinity levels on the growth of sex-reversed, Thai red tilapia (Oreochromis sp.). The experiment was designed to test two fertilization rates (28 kg N and 7 kg P ha-1 week-1, N: P = 4:1; and 14 kg N and 7 kg P ha-1 week-1, N: P = 2:1) and three salinity levels (10, 20, and 30 ppt) in brackishwater. An additional treatment using optimized fertilization rates (28 kg N and 7 kg P ha-1 week-1, N: P = 4:1) in freshwater ponds served as control. Red tilapia fingerlings (20.2 - 23.7 g size) were stocked at 2.4 fish m-2 in 5-m2 cement tanks with soil bottoms. These were cultured for 160 days.

Growth performance of red tilapia was better in brackishwater than in freshwater. Growth of red tilapia in brackishwater was inversely related to the salinity levels (r = -0.63, P < 0.05), decreasing significantly with increasing salinity. For a given salinity level, there was no significant difference in size at harvest for the two fertilization regimes (P > 0.05). Best growth performance was achieved in the treatment with N:P ratio of 4:1 at 10 ppt salinity.

Effects of fertilization rates on growth performance of red tilapia at different salinities
Conference Paper
2005

2004

NOP 04-199 (English)(Spanish)

In April 1999, the Institute for Investigations of the Peruvian Amazon (IIAP) located in Iquitos (Loreto region) with the Italian NGO Terra Nuova and Southern Illinois University at Carbondale (SIUC), through the auspices of the PD/A CRSP-USAID program, initiated the Food Security Program for Familiar Productive Units (PROSEAL) between the Iquitos-Nauta Road and the Tigre River (Santa Helena and Huayococha). The goal of this program was to produce fish in ponds and floating cages as a way of providing tools to improve the animal protein intake of the Quichuas indigenous population and other rural poor. This article is restricted to the experiences gained through a demonstration project on floating cages. Fish culture in cages floating directly in the natural environment in the Peruvian Amazon has not been reported previously; thus, many issues had to be resolved for it to be successful. The two predominant concerns were:1) the behavior of major predators, such as dolphins (Inia geofroensis and Sotalia fluviatilis), crocodiles (Cayman sclerops), and pirañas (Serrasalmus natereri) towards the unprotected floating cages containing large numbers of fish; and 2) the sociological fact that natives of the region possessed a strong traditional hunting and gathering tradition, with fish culture activities being alien to them. The fishes selected for cage culture were the gamitana (Colossoma macroponum – also known as black cachama or tambaquí), and paco (Piaractus brachypomus), also known as pacú, white cachama, pirapitinga or morocoto. The two species have the advantage of being well known to the local population, although, recent captures have decreased dramatically as a result of excessive fishing pressure on natural stocks by the Iquitos-based commercial fishing fleet. In this article, we report preliminary results obtained from gamitana and paco culture in floating cages in the Tigre River.

Gamitana (<i>Colossoma macropomum</i>) and Paco (<i>Piaractus brachypomus</i>) Culture in Floating Cages in the Peruvian Amazon.
Journal Article
2004

NOP 04-A12 (English)

Arapima gigas (Osteoglossidae), also known as paiche (Peru) or piraruccu (Brazil and Columbia), is one of the major scaled fish in the Amazon region (Figure 1), living in the lagoons or meanders along the large rivers of the vast region. This colossal fish feeds mainly on small fish (Imbiriba 2001) and reproduces throughout the year, though mostly between October and February (Guerra 1980). It produces a copious number of fry in a single spawning event, all of which swim very closely to the mother's head for several days post-hatch. The fillet is of excellent quality and is a highly prized favorite among consumers in the Amazonian region (Rebasa et al. 1999). The meat of this fish lacks intermuscular bones or spines, with a dressout yield of 57 percent (Imbiriba et al. 1996). This far the supply, despite high demand, has been adequate in the marketplace, but with increasing fishing pressure on natural stocks, a drastic decline in population has become apparent. Consequently, A. gigas appears as an endangered species in the Convention on International Trade of Wild Fauna and Flora Species (CITIES), Appendix II.

Pond culture of <i>Arapima gigas</i> in the Peruvian Amazon
Magazine Article
2004
NOP 04-A14 (English)

NOP 04-A14 (English)

In the grow-out phase, twelve (12) 500 m2 ponds were used in the study to determine the growth, yield and survival of Nile tilapia (Oreochromis niloticus L.) in ponds. The treatments consisted of the following: I- direct stocking at size #22; II- stocking at size #14; and III- stocking at size #10. The various treatments and replicates were assigned randomly in the ponds following a completely randomized design. Treatment III gave the highest extrapolated fish yield (3,799 kg ha-1) followed by Treatment II (3,065 kg ha-1) then Treatment I (2,738 kg ha-1). Analysis of variance on fish yield showed significant difference between Treatments I and III (P < 0.05). Specific growth rate likewise significantly differed among treatments (P < 0.01). Survival rate of Nile tilapia was also significantly affected by stocking size of fingerlings. Higher survival rate was obtained with bigger size fingerlings. Introduction

Effect of stocking sizes on the yield and survival of Nile tilapia (<i>Oreochromis niloticus</i> L.) on-grown in ponds
Conference Paper
2004

NOP 87-A02 (English); NOP 04-A09 (English)

A combination of increased human population growth, high fish harvest pressure, and adoption of more technologically advanced fishing equipment by the commercial fleet has generated concerns about the sustainability of fish stocks in the Peruvian Amazon. We assessed the status of the commercial fishery by conducting interviews with officials of the Peruvian Ministry of Fisheries as well as with commercial and artisanal fishers.We also reviewed pertinent publications and agency reports written in one of three languages (Spanish, Portuguese, and English). Based on the trend toward smaller-sized fish and greater effort needed to achieve full capacity catches, we suggest the commercial fishery is beginning to show the classical signs of over fishing. More comprehensive data collection, stringent enforcement of management regulations, research on the influence of flood level on fish production, and development of an ecologically and genetically sound native-species aquaculture program are measures we recommend be adopted to protect and sustain the fishery resources of the Peruvian Amazon.

The Commercial Fishery of The Peruvian Amazon
Journal Article
2004

NOP 04-A10 (English)

Although some methods for determining lime requirement of pond soils are available and commonly used, there is still no consensus on whether it is more effective to apply liming materials to the bottoms of empty ponds or to wait and apply them over the water surface after ponds are filled. There is also little information on how deep lime reacts in pond sediment over time, and whether the depth of reaction is different when liming materials are applied to the water or to the soil. Therefore, three techniques for treating fish ponds with agricultural limestone were evaluated in ponds with clayey soils at a commercial fish farm. Amounts of agricultural limestone equal to the lime requirement of bottom soils were applied to each of three ponds by: direct application over the pond water surface; spread uniformly over the bottom of the empty pond; spread uniformly over the bottom of the empty pond followed by tilling of the bottom. Effectiveness of agricultural limestone applications did not differ among treatment methods. Agricultural limestone also reacted quickly to increase total alkalinity and total hardness of pond water to acceptable concentrations within 2 weeks after application. The reaction of lime to increase soil pH was essentially complete after one to two months, and lime had no effect below a soil depth of 8 cm. Tilling of pond bottoms to incorporate liming materials is unnecessary, and tilling consumes time and is an expensive practice; filled ponds can be limed effectively. 

Lime Application Methods, Water and Bottom Soil Acidity in Fresh Water Fish Ponds
Journal Article
2004
NOP 04-A16 (English)

NOP 04-A16 (English)

The purposes of the study, consisting of two experiments, were to determine the upper limits to tilapia production utilizing supplemental feeding and appropriate fertilization regimes for controlling nutrient addition and maintaining good water quality. In order to test these, Nile tilapia fingerlings were stocked at 3, 6, and 9 fish m-2. The fish were supplementally fed to 50% satiation during culture of 155 and 194 days for experiments 1 and 2, respectively. While ponds were fertilized at fixed rates (4 kg nitrogen and 1 kg phosphorus per hectare per day) throughout experiment 1, ponds in experiment 2 were fertilized at various rates to balance nutrient contents of feeding wastes, bringing nutrient loading to the same levels as in experiment 1. The experiments were conducted at the Ayutthaya Freshwater Fisheries Station, Thailand. Growth, survival, yield, and water quality were evaluated during both experiments. Growth continued in a linear fashion throughout the experiments. Survival also differed significantly among treatments in both experiments, with lowest rate at the highest density. Feeding rates averaged 1.86% and 1.65% of the body weight per day in experiments 1 and 2, respectively, and were not significantly different among treatments in each experiment. Feed conversion rates averaged 1.18 and 1.38 for experiments 1 and 2, respectively, and also were not significantly different among treatments. Most water quality parameters were not significantly different among treatments, and did not deteriorate at least during the initial 155 days. The reduced growth and survival in high density ponds appears to be a behavioral or physiological response to density itself, not to water quality. Partial economic analyses indicated that the 3 fish m-2 treatments were profitable, while the 6 or 9 fish m-2 treatments were unprofitable in both experiments. At present, the best system seems to be culturing at 3 fish m-2 with intensive feeding and balanced fertilization.

Stocking densities and fertilization regimes for Nile tilapia (<i>Oreochromis niloticus</i>) production in ponds with supplemental feeding
Conference Paper
2004

NOP 04-A03 (English)(Spanish)

The digestible energy and apparent nutrient digestibility coefficients of common diet ingredients were determined for pacu Piaractus brachypomus (370.21 +/- 17.56 g). fish were fed with pelleted practical diets to apparent satiation and the feces were collected by siphoning. The digestibility value for each ingredient was determined by comparison of the digestibility of a test diet with a reference diet (24.5% crude protein and 1% chromic oxide). The digestible energy values of soybean meal (SBM), fish meal (m). corn (CN), and wheat bnn (WB) were 2382, 3826, 3353, and 1784 kcal/kg, respectively. The apparent dry matter digestibility coefficients were 83.72, 90.14, 89.13, and 82.05% for SBM, FM, CN, and WB, respectively. The apparent crude protein digestibility coefficients were 75.88, 90.49, 85.06, and 61.62% for SBM, FM, CN, and WB, respectively. The apparent lipid digestibility coefficients were 63.03, 77.00, 83.01, and 82.45% for SBM, FM, CN, and WB, respectively. The digestibility of protein, lipid. and energy from SBM were somewhat low compared to values for other warmwater omnivorous fishes, but similar to values reported for pacu-caranha P. mesoporumirus. Otherwise, the nutrient and energy availability of the ingredients to P. brachypomus was similar to that of other fish. This information will be useful in formulating nutritious, economical diets for pacus.

Apparent Digestible Energy and Nutrient Digestibility Coefficients of Diet Ingredients for Pacu
Journal Article
2004

NOP 04-A05 (English)(Spanish)

Maca tuber meal is used in fish diet formulations in Andean trout culture and knowledge of its effects on fish growth is paramount to healthy human food production. In the first experiment with rainbow trout alevins (0.096 +/- 0.002 g), starter diets were offered from first feeding until 15 weeks. We formulated high protein content (~60%) semi-purified starter diets supplemented with 0%, 5%, 10%, or 15% maca tuber meal (control, M-5, M-10, and M-15 respectively). The second feeding trial was conducted with juveniles (1.56 +/- 0.02 g) fed one of three diets (control, M-15, and commercial) for 8 weeks. In the first experiment, fish fed M-10 and M-15 diets exhibited significantly higher growth rates than the other dietary groups. Survival was significantly improved in the groups fed diets supplemented with maca tuber meal (60.0 - 69.2%) in comparison with the group fed a control diet (21.7%). The second experiment showed a higher growth rate in the M-15 group compared with the control and a commercial diet fed group. Leucocyte numbers were increased by dietary supplementation of maca tuber meal. The findings of the present study suggest that a maca tuber meal inclusion at least 5% improves growth rate, feed utilization, immunity by increased leucocyte number, and survival of rainbow trout alevins and juveniles.

Supplementation of maca (<i>Lepidium meyenii</i>) tuber meal in diets improves growth rate and survival of rainbow trout <i>Oncorhynchus mykiss</i> (Walbaum) alevins and juveniles
Journal Article
2004
Lin, C. K., Y. Yi, and J. S. Diana. 2004. Management of Organic Matter and Nutrient Regeneration in Pond Bottoms. Pp. 763 - 772 in 6th International Symposium on Tilapia Aquaculture, vol. 2, 6th International Symposium on Tilapia Aquaculture, edited by K. Fitzsimmons, Bolivar, R.B., and Mair, G. Manila, Philippines. Retrieved (http://www.was.org/Shopping/ista--6th-international-symposium-on-tilapia-in-aquaculture-proceedings).
NOP 04-A25 (English)

NOP 04-A25 (English)

An experiment was conducted in twelve 200-m2 earthen ponds at the Asian Institute of Technology, Thailand, during November 1997 through April 1998. The experiment was conducted for 149 days to assess effects of aerobic and anaerobic conditions at pond bottom on organic matter decomposition and nutrient release, as well as the effectiveness of common carp (Cyprinus carpio) in removing organic matter from pond sediments and recycling nutrients in Nile tilapia (Oreochromis niloticus) ponds. The experiment consisted of four treatments: (A) tilapia monoculture with water mixing; (8) tilapia monoculture without water mixing; (C) tilapia/carp polyculture with water mixing; and (D) tilapia/carp polyculture without water mixing. Sex-reversed all-male Nile tilapia were stocked at 2 fish m-2 at a size of 8-12 g in all ponds, while common carp fingerlings at 0.3 fish m-2 at a size of 13-17 g. All ponds were fertilized with chicken manure at the rate 1,000 kg ha-l week-I (dry matter basis) to create anaerobic bottoms. Aerobic pond bottoms in water mixing treatments (A and C) were created by fixing a submersible pump (0.5 kW) 30 em above the bottom of each pond to mix, surface and bottom water. Results of the experiments indicate that inclusion of common carp into Nile tilapia ponds was effective in recycling nutrients, and might be effective in removal of organic matter if more common carp are added. Water mixing in the experiments largely reduced phytoplankton growth in both mono- and polyculture ponds. Water mixing did not affect the growth of Nile tilapia in monoculture ponds, but significantly (P < 0.05) reduced the growth of both Nile tilapia and common carp in polyculture ponds.

Management of Organic Matter and Nutrient Regeneration in Pond Bottoms
Conference Paper
2004

NOP 04-A17 (English)

An experiment was conducted in fifteen 5-m2 cement tanks for 91 days to determine the appropriate stocking ratio of Nile tilapia (Oreochromis niloticus) to hybrid catfish (Clarias macrocephalus x C. gariepinus) and effects of stocking ratios on the growth of both Nile tilapia and hybrid catfish, water quality, nutrient utilization efficiency and economic returns. Hybrid catfish fingerlings of 25-26 g size were stocked at 20 fish/m2, while Nile tilapia fingerlings of 20-23 g size were stocked at 0, 1, 2, 3, 4, 5 and 6 fish/m2, giving stocking ratios of Nile tilapia to hybrid catfish of 0:20, 1:20, 2:20, 3:20, 4:20, 5:20, and 6:20, respectively. The control (0:20) had three replicates, while other treatments had two replicates each. No fertilizers were applied to the tanks. Floating pelleted feed (30% crude protein) was given twice daily at 0830 and 1530 h six days per week. Feed rations were calculated based only on hybrid catfish biomass at feeding rates of 5% and 3% body weight per day for hybrid catfish smaller and larger than 100 g, respectively. All tanks were aerated by airstones throughout the experimental period. The addition of Nile tilapia into hybrid catfish tanks did not cause any significant effects on survival, growth and yields of hybrid catfish (P > 0.05). Survival of tilapia was not significantly different in the polyculture treatments (P > 0.05). With increasing stocking ratios of Nile tilapia to hybrid catfish, mean tilapia weights at harvest decreased linearly, while both net and gross tilapia yields increased linearly (P < 0.05). FCRs based on either hybrid catfish alone or combined hybrid catfish and Nile tilapia were not significantly different among all treatments (P > 0.05). Combined net yields were not significantly different among all treatments (P > 0.05), however, combined gross yields increased linearly with increasing stocking ratios of Nile tilapia to hybrid catfish (P < 0.05). The present experiment indicates that intensive polyculture of hybrid catfish and Nile tilapia is feasible technically and economically. However, further research is needed to optimize the stocking ratio of Nile tilapia to hybrid catfish to reduce the nutrient release to the environment. 

Stocking ratios of hybrid catfish (<i>Clarias macrocephalus</i> x <i>c. gariepinus</i>) and Nile tilapia (<i>Oreochromis niloticus</i>) in an intensive polyculture
Conference Paper
2004

NOP 04-A02 (English)(Spanish)

The performance of individual firms often is enhanced by membership in a group or cluster of other firms engaged in similar activities. This paper examines a cluster of Honduran fish farmers in terms of the patterns of relationships that allowed them to initiate and sustain successful tilapia businesses for an extended period of time. Although there are larger, individual production facilities elsewhere in Honduras, the circumstances of the cluster are unique. The cluster of tilapia farms has been in operation in Olancho, Honduras for over 15 years. Financial analysis describes production costs, prices, and profitability in the context of the cluster. The results elucidate the way relationships among coexisting firms provide a source of competitive advantage for the adoption and development of an aquacultural enterprise. Furthermore, the results provide insights into the organizational and contextual factors that facilitate commercial fish culture. As the Olancho model for aquacultural development becomes more widely known, it may be an important means of fostering tilapia culture in other locales. These Honduran producers have been able to sustain the enterprise due to advantages offered by the grower cluster beyond the efficient operation of the individual farms.

Cluster membership as a competitive advantage in aquacultural development: case study of tilapia producers in Olancho, Honduras
Journal Article
2004
Meso, M. B. et al. 2004. Effect of Fish Pond Effluents Irrigation on French Beans in Central Kenya. Communications in Soil Science and Plant Analysis 35(7-8):1021 - 1031. Retrieved (http://www.tandfonline.com/doi/abs/10.1081/CSS-120030578).
NOP 04-A21 (English)

NOP 04-A21 (English)

When fish are recovered from ponds, the effluent is often drained presenting both an environmental challenge and an agricultural opportunity. The effects of irrigation with pond effluent and its interaction with applied fertilizer were assessed in a field experiment using French bean (Phaseoulus vulgaris) over two growing seasons near Sagana, Kenya. Fresh yield of beans was recorded at harvest, and leaf samples were collected for determination of tissue nutrient concentration. In the first season plots receiving canal water and fertilizer at recommended rates had the highest yield (9.1 Mg fresh pod ha-1), while those receiving no fertilizer or irrigation had the least yield (1.3 Mg fresh pod ha-1). In the second season, the highest (4.4 Mg ha-1) fresh pod yield was observed in pond effluent irrigated and fertilized plots, while the lowest (1.3 Mg ha-1) was observed in non-irrigated/unfertilized plots. Low nutrient status in the pond water was responsible for low yield where it was substituted for canal water. Pond water from the Sagana Fish Farm supplied low amounts of nitrogen (N) and phosphorus (P) for crops, indicating that recommended rates of mineral fertilizers should be used when pond water is used for irrigation.

Effect of Fish Pond Effluents Irrigation on French Beans in Central Kenya
Journal Article
2004
NOP 04-A15 (English)

NOP 04-A15 (English)

An experiment was conducted in outdoor concrete tanks (4.9 m x 4.8 m x 1.75 m) at the Institute of Agriculture and Animal Science (IAAS) of Nepal to evaluate the growth of grass carp and Nile tilapia fed with napier grass in polyculture, to evaluate water quality regimes of pond water, to determine the compositions of foods consumed by Nile tilapia, and to determine the optimal ratio of grass carp to Nile tilapia in polyculture. The experiment was laid out in a completely randomized design with five treatments replicated thrice. Five stocking ratios of grass carp to Nile tilapia were tested: (1) grass carp only at 0.5 fish/m2 (control); (2) grass carp at 0.5 fish/m2 plus tilapia at 0.25 fish/m2; (3) grass carp at 0.5 fish/m2 plus tilapia at 0.5 fish/m2; (4) grass carp at 0.5 fish/m2 plus tilapia at 1 fish/m2; and (5) grass carp at 0.5 fish/m2 plus tilapia at 2 fish/m2. Grass carp fingerlings (39.3 ± 2.3 – 46.6 ± 0.2 g) were stocked on 26 May 2002, while mixed-sex Nile tilapia fingerlings (9.0 ± 0.1 – 10.0 ± 0.2 g) were stocked 6 days later. Chopped fresh napier grass leaf was the sole nutrient input and provided ad libitum daily in the morning. Mass mortality of grass carp (100%) occurred in all three replications of the monoculture (treatment 1) during the twelfth week (81 days) of the experimental period, however, survival of grass carp was not significantly different among the polyculture treatments (treatments 2 through 5) (P > 0.05). At harvest, the mean weights and daily weight gains of grass carp in treatment 3 were significantly greater than those in other polyculture treatments (P < 0.05). Net and gross fish yields were highest in treatment 3, intermediate in treatments 4 and 5, and lowest in treatment 2 (P < 0.05). Survival of Nile tilapia was 100% in all polyculture treatments. Mean weights of Nile tilapia at harvest decreased linearly with increased stocking densities of Nile tilapia, while net fish yields of Nile tilapia increased linearly (P < 0.05). The combined net and gross fish yields of grass carp plus both adult and recruited Nile tilapia were not significantly different among all polyculture treatments (P > 0.05). There were no significant differences in all measured water quality parameters. Gut analyses showed that grass carp consumed grass only while Nile tilapia consumed diversified food items including feces of grass carp. The present study has showed that the optimal ratio of grass carp to Nile tilapia in polyculture fed napier grass is 1:1, i.e., grass carp at 0.5 fish/m2 plus Nile tilapia at 0.5 fish/m2. The present study has indicated that the addition of Nile tilapia to the grass carp tanks fed napier grass as the sole nutrient input is a low-cost culture system, which can efficiently utilize available resources, reuse wastes derived from grass carp, augment total fish production.

Polyculture of grass carp and nile tilapia with napier grass as the sole nutrient input in the subtropical climate of Nepal
Conference Paper
2004
Phuong, N. T., Y. Yi, J. S. Diana, C. K. Lin, and T. V. Bui. 2004. Integrated Cage-Cum-Pond Culture: Stocking Densities of Caged Climbing Perch in Nile Tilapia Ponds. Pp. 597 - 598 in Proceedings of the 6th International Symposium on Tilapia in Aquaculture, Proceedings of the 6th International Symposium on Tilapia in Aquaculture. Retrieved (http://www.was.org/Shopping/ista--6th-international-symposium-on-tilapia-in-aquaculture-proceedings).
 NOP 04-A26 (English)

 NOP 04-A26 (English)

An experiment was conducted for 150 days at Cantho of Vietnam to determine the appropriate stocking density of caged climbing perch (Anabas testudineus) in Nile tilapia (Oreochromis niloticus) ponds, to assess the economic and environmental benefits of this integrated cage-cum-pond culture system. One of the 4m3 cage was suspended in each of the twelve 100-m2 earthen ponds, and three ponds of same size served as control without cages. Climbing perch fingerlings 9 g in size were stocked at 50, 100, 150, and 200 fish/m3 in cages, while caged climbing perch to open-pond Nile tilapia ratios of 1:1, 2:1, 3:1 and 4:1, respectively. Caged climbing perch were fed commercial pelleted feed (26-28% crude protein) at rates of 5%, 3% and 2% body weight per day during the first, second and the remaining months, respectively. The control ponds were fertilized weekly with urea and TSP at 28 kg P/ha/week, while no fertilizers were applied in the treatment ponds. Survival of climbing perch in the highest density treatnment (97.1%) was significantly lower than that in other treatments (99.3-99.6%; P < 0.05). Final mean weights of both climbing perch and Nile tilapia were not significantly different among all treatments, ranging from 19.5 to 20.5 g and from 111.5 to 133.9 g, respectively (P > 0.05). Total Harvest weight of climbing perch, ranging from 400 to 15.2 kg/cage, increased significantly with increasing stocking density (P < 0.05), while total harvest weight of Nile tilapia was highest in the 150 fish/m3 treatment (22.7 kg/pond), immediate in other cage treatments (19.0 - 20.7 kg/pond), and lowest in the control (15.8 kg/pond; P < 0.05). The combined total weights of both climbing perch and Nile tilapia in the high density treatments (35.0 kg/pond in 150 fish/m3 treatment and 35.8 kg/pond in 200 fish/m3 treatments) were significantly greater than those in the low density treatments (23.0 kg/pond in 50 fish/m3 treatment and 28.2 kg/pond in 100 fish/m3 treatments; P < 0.05). FCR of climbing perch in all treatments was very high, ranging from 5.05 to 6.00. FCR was lowest in the 150 fish/m3 treatment, intermediate in the 100 and 200 fish/m3 treatment, and highest in the 50 fish/m3 treatment (P < 0.05). The results indicate that caged climbing perch to open-pond Nile tilapia ratio of 3:1 was the best. Further research in feed protein level and feed strategy should be conducted.

Integrated Cage-Cum-Pond Culture: Stocking Densities of Caged Climbing Perch in Nile Tilapia Ponds
Conference Paper
2004

NOP 04-A11 (English)

Tilapia are currently having important impacts on poor people in developing countries, both as cultured species in household-management systems and through access to fish produced in informal and formal fisheries. But in Bangladesh, despite several attempts made by Bangladesh Fisheries Research Institute (BFRI), Department of Fisheries (DoF), and Bangladesh Agricultural University (BAU), dissemination and adoption of this species could not reach any wider scale. The present study was conducted to map out the underlying reasons that constrain the adoption of this species in the country. Results of descriptive statistics, Chi-square test and, correlation and regression analysis indicated that skill training, contact with private fish hatchery, DoF and BFRI, and organizational membership significantly facilitated farmers to adopt this species. On the other hand, non-availability and high price of quality seed, difficult technology, lack of appropriate technical information and technical support, and high price of feed appeared as significant factors that constrained farmers to adopt it. Based on findings of the study, some specific recommendations as well as a broad policy model are suggested, aiming at promoting the dissemination and adoption of tilapia in a wider scale in the country.

Constraints of Tilapia (<i>Oreochromis niloticus</i>) Production in Bangladesh: Looking from Socio-economic Perspective
Journal Article
2004

NOP 04-A07 (English)(Spanish)

The original method for determining the fineness of agricultural limestone was modified for the greater contribution of particles less than 0.25 mm in diameter that is found in the modern agricultural limestone used in aquaculture. Crusher-run limestone was screened to give nine particle size separates. Systems containing 3.0 kg of soil (pH 5 5.21) and 23.5 L of water (total alkalinity 5 0.39 mg/L) were treated with 8.0 g of each separate, and total alkalinity and pH were monitored. After 70 d, total alkalinity equilibrated at 55 mg/L in systems treated with particles less than 0.106 mm. The total alkalinity in systems treated with other particle size separates were as follows: control, 0.52 mg/L; greater than 2.0 mm, 2.28 mg/L; 2.0 – 0.85 mm, 5.75 mg/L; 0.85 – 0.42 mm, 12.25 mg/L; 0.42 – 0.25 mm, 26.8 mg/L; 0.25 – 0.15 mm, 45.62 mg/L; and 0.15 – 0.106 mm, 49.30 mg/L. Water pH exceeded 7.36 after 2 weeks for systems treated with particles less than 0.25 mm. Wet soil samples (2.5 kg) of pH 5.04 were placed in trays and treated with 6.7 g of limestone of different particle size separates. After 1 week, pH was 6.9 – 7.1 in soil treated with particles less than 0.106 mm. By 10 weeks, a pH greater than 6.5 was attained in soils treated with particles less than 0.25 mm. The pH of soil treated with particles greater than 0.25 mm was similar to the control pH. Efficiency factors were assigned to particle size-classes as follows: less than 0.106 mm, 100%; 0.25 – 0.106 mm, 86.7%; 0.42 – 0.25 mm, 49.06%; 0.85 – 0.42 mm, 22.4%; and greater than 0.85 mm, 7.3%. The sum of the products of the proportion of each particle size-class and the corresponding efficiency factor gave the fineness value. Fineness values usually were smaller when determined by the new method instead of the old method.

An Improved Method for Determining the Fineness Value of Agricultural Limestone for Aquaculture
Journal Article
2004

NOP 04-A13 (English)

The present research was conducted in six 280-m2 earthen ponds at Bang Sai, Thailand, to investigate and compare water quality, growth performance, nutrient utilization, and economic return for Nile tilapia culture with two fertilization and feeding strategies. There were two treatments in triplicate each: (A) fertilizing ponds throughout the culture period and feeding Nile tilapia starting from day 80; (B) fertilizing ponds until day 80 and feeding Nile tilapia starting from day 80. Ponds were stocked with sex-reversed all-male Nile tilapia at 3 fish m-2. The study showed that tilapia growth in treatment A was significantly better than that in treatment B. Final mean weight of tilapia in treatment A was 312 ± 1.8 g and mean daily weight gain was 1.8 ± 0.0 g day-1, whereas in treatments B final mean weight was 248 ± 17.5 g and mean daily weight gain was 1.4 ± 0.2 g day-1. Net tilapia yield in treatments A and B was 16.7 ± 0.4 and 13.0 ± 1.4 t ha-1 year-1, respectively. Overall mean concentrations of total alkalinity and total ammonia nitrogen were significantly higher in treatment A than those in treatment B, however, the overall mean values of all other measured water quality parameters were not significantly different between the two treatments. Total inputs of nitrogen and phosphorus through fertilizer and feed over the culture period were significantly higher in treatment A than those in treatment B, however, percentage recovery of N and P in the harvested biomass was higher in treatment B than that in treatment A. Economic analysis showed that tilapia culture practice with fertilization plus feeding (treatment A) generated 50% additional gross revenue as compared to the fertilization followed by feeding (treatment B). Moreover, treatment A showed a positive return, whereas a negative return was observed in treatment B. Apparently, better economic return in treatment A is due to the improved growth performance of Nile tilapia in treatment A than in treatment B, which might have been influenced by the presence of plenty of natural food in the ponds. The results suggest therefore that combination of fertilization and feeding should be a preferred strategy over fertilization followed by feeding for culturing Nile tilapia.

Effects of fertilization and feeding strategy on water quality, growth performance, nutrient utilization and economic return in Nile tilapia (<i>Oreochromis niloticus</i>) ponds
Conference Paper
2004
NOP 04-A22 (English)

NOP 04-A22 (English)

This experiment was conducted in nine 200 m2 earthen ponds at the Asian Institute ef Technology, Thailand for 133 days from 21 May to 2 October 2003, to investigate effects of adding shrimp (Penaeus monodon) into intensive Nile tilapia (Oreochromis niloticus) ponds on the growth performance, water quality and nutrient utilization efficiency in different stocking combinations of tilapia-shrimp polyculture. There were three treatments in triplicate each: tilapia at 11 m2 and shrimp at 151 m2 (low tilapia density), tilapia at 21 m2 and shrimp at 151 m2(medium tilapia density), tilapia at 41 m2 and shrimp at 151 m2 (high tilapia density). Mean daily weight gains and final mean weight of tilapia in the low tilapia density treatment was significantly greater than those in the medium and high tilapia density treatments, between which there was no significant difference. However, total weight gain, and net and gross yields of tilapia were highest in the high tilapia density treatment, intermediate in the medium tilapia density treatment, and lowest in the low tilapia density treatment. Final mean weight of shrimp was not significantly different among all treatments, however, survival and net and gross yields in the high tilapia density treatment were significantly poorer than those in the medium and low tilapia density treatments, between which there were no significant differences. Nutrients incorporated by Nile tilapia biomass accounted far 48.01%, 52.89%, and 48.99% of TN, and 60.55%, 68.47% and 62.25% of TP inputted from fertilizer and pelleted feeds in the low, medium and high tilapia density treatments, respectively, while shrimp recovered only 1.10% and 0.33% of TN, and 0.55% and 0.27% of TP in the low and medium tilapia density treatments. However, nutrients were lost through dead shrimps in the high tilapia density treatment. Overall mean DO concentrations at both surface and bottom were highest in the low tilapia density treatment, intermediate in the medium and lowest in the high tilapia density treatment. Overall mean concentrations of TAN tended to be higher at higher tilapia density. The present experiment indicated that adding shrimp into Nile tilapia ponds is technically feasible, however, more research is needed to optimize the tilapia-shrimp polyculture system.

Effects of adding shrimp (<i>Penaeus monodon</i>) into intensive culture ponds of Nile tilapia (<i>Oreochromis niloticus</i>) at different densities
Conference Paper
2004

NOP 04-A06 (English)(Spanish)

Samples of 45 brands of liming materials were obtained in Thailand and analyzed for chemical and physical properties. Eight of 10 products sold as ground calcium carbonate (calcitic agricultural limestone) were properly identified by vendors and of high quality, that is, neutralizing value and fineness rating above 85%. Seven of 15 products sold as ground dolomite (dolomitic agricultural limestone) were properly identified, seven were ordinary pulverized limestone instead of dolomite, and one was lime. The seven dolomitic agricultural limestone samples were of high quality, that is, fineness ratings above 85% and neutralizing values above 95%. Only two of eight misidentified samples were of high quality. Only one of four products sold as marl had neutralizing value and efficiency rating above 85%, but all were properly identified. Five products sold as crushed seashell had been burned and should have been identified as lime. However, neutralizing values (72-103%) were lower than those of good quality lime. All 13 samples sold as lime were properly identified, and eight were of good quality, that is, neutralizing value above 120% and fineness rating above 85%. The cost of liming materials ranged from US$ 0.01 to 0.02 kg-1 for marl and from US$ 0.10 to 0.14 kg-1 for lime. There was no relationship between product quality and cost. Fish and shrimp farmers\nin Thailand should insist that manufacturers and vendors of liming materials provide data on product composition.

Quality of liming materials used in aquaculture in Thailand
Journal Article
2004

NOP 04-A01 (English)(Spanish)

Bottom soil samples were collected from 35 ponds in the vicinity of Samutprakarn, Thailand. Ponds ranged in age from 3 to 39 years and had been used continuously for production of tilapia. Liming materials had been applied in large amounts, and bottom soils of all ponds had pH above 7, low exchange acidity, and free carbonate. Pond soils often contained between 1% and 2% total sulphur, suggesting that they were potential acid-sulphate soils. However, acidity from sulphide oxidation was not expressed because carbonate in the soil neutralized it. Concentrations of total carbon seldom exceeded 4% and the average for organic carbon was 1.90%. The correlations between pond age and both total carbon and organic carbon concentration were weak (r=0.34 and 0.36 respectively). Concentrations of nitrogen in bottom soils did not differ with pond age and ranged from 0.1% to 0.3% with an average of 0.19%. The average ratio of concentrations of carbon and nitrogen was 11. Acid-extractable phosphorus concentrations averaged 217 mg kg-1, but the phosphorus adsorption capacity averaged 768 mg kg-1 suggesting that soils still have considerable reserve capacity to adsorb phosphorus. Ponds can be used annually for semi-intensive production of tilapia, and presumably other species, for many years without serious deterioration of bottom soil quality.

Bottom soil quality in Tilapia ponds of different age in Thailand
Journal Article
2004

NOP 04-204 (English)(Spanish)

Variable rainfall distribution and terrain make surface water harvesting and storage a challenge in many developing countries. The overall goal of this study is to collect and develop information required to equip extension, non-governmental organization (NGO) agents, contractors and engineers for surface water development and aquaculture enterprise development in Honduras and Latin America. A pond water balance for the levee production pond enabling determination of water flow required to balance seepage, evaporation and direct rainfall was developed in English and Spanish on the Microsoft Excel® platform. The pump-in flow rate can also be determined for reaching a volume change per month target. A second model was formulated for evaluating surface water capture by watershed and/or hillside ponds for meeting the levee pond demand. Using hillside ponds that fill by impounding a fraction of total runoff (e.g., diverting water upstream) from streams appears to have promise for meeting water needs. A systematic approach using both models to reach a sustainable water supply target emerged from this work. Both the levee pond model and the water harvest model are based on balancing inputs and outputs given monthly rainfall patterns. A simple approach to mechanical spillways preliminary design was developed. The models are adaptable to any location if key input data is available, particularly average monthly rainfall and storm frequency–duration data. The models do not address water quality issues. The software is intended for watershed sizes not larger than 500 ha and storage ponds of less than 5 ha surface area—4m depth due to relationship limitations and safety concerns. Coupling with other cooperative development concerns such as marketing association provides a platform for helping groups of people in a watershed to realize further the potential of enlightened self-interest in developing common solutions to water problems.

Spreadsheet tools for developing surface water supplies for freshwater fish production in developing countries
Journal Article
2004

NOP 04-A08 (English)(Spanish)

Taura Syndrome Virus (TSV) and White Spot Syndrome Virus (WSSV) have significantly decreased survival rates of farm-raised penaeid shrimp in Honduras and other shrimp-growing regions of the Western Hemisphere. A dataset of individual records of 1,004 shrimp ponds in Honduras was used to develop a linear programming model to evaluate optimal management strategies if viral disease prevention programs were implemented on shrimp farms. The model selected low and intermediate stocking densities as optimal for most growout cycle alternatives considered, given post-Taura and post-White Spot Syndrome production relationships. Model simulations indicated that the decreased shrimp survival due to viral infections had decreased net farm income by approximately 84% from optimal management plans in the absence of viral diseases. Simulations in which costs of viral disease prevention programs were included resulted in a 47% increase in net farm income above the base scenario. Production activities would need to be re-scheduled and stocking densities adjusted to accommodate disease prevention programs. These results further provide a measure of the value to shrimp farms of new technologies related to either shrimp health or disease-resistant shrimp that increase shrimp survival rates.

Farm-level economic effects of viral diseases on Honduran shrimp farms
Journal Article
2004
Yi, Y., and K. Fitzsimmons. 2004. Tilapia-shrimp polyculture in Thailand. Pp. 777 - 790 in 6th International Symposium on Tilapia Aquaculture, 6th International Symposium on Tilapia Aquaculture, edited by K. Fitzsimmons, Bolivar, R.B., and Mair, G. Manila, Philippines. Retrieved (http://www.was.org/Shopping/ista--6th-international-symposium-on-tilapia-in-aquaculture-proceedings).
NOP 04-A18 (English)

NOP 04-A18 (English)

A survey on tilapia-shrimp polyculture was conducted in Thailand from March until June 2002, to assess the current status of Thai farmers’ practices of tilapia-shrimp polyculture. Sixty-one farmers who culture fish in their shrimp farms in 12 provinces of Thailand were selected and interviewed using a structured checklist and open-ended type of questionnaires. Results showed that three versions of tilapia-shrimp polyculture, namely: a) simultaneous, b) sequential, and c) crop rotation systems, are practiced by Thai shrimp farmers. Among the farmers, 42.6% use a simultaneous polyculture system, while percentages of farmers using sequential and crop rotation systems are 34.4 and 6.6%, respectively. The remaining 16.4% of farmers stock fish in reservoir ponds and use a monoculture system for shrimp. Among the farmers who adopt the simultaneous tilapia- shrimp polyculture system, 76.9% released tilapias directly into shrimp ponds, and 23.1% stocked tilapias in cages suspended in shrimp ponds. Tilapia-shrimp polyculture is practiced in a wide range of salinity levels from 0 to 30 %. Tilapias used in the polyculture include red tilapia (Oreochromis spp.), Nile tilapia (O. niloticus), and Mossambique tilapia (O. mossambicus). The survey revealed that shrimp production and economic returns from the two simultaneous polyculture systems and in sequential polyculture systems were higher than those in their respective shrimp monoculture systems practiced previously. Also shrimp production and economic returns from these polyculture systems were higher than those in the crop rotation polyculture system and in the currently practiced monoculture system. For many farmers, tilapia-shrimp polyculture could improve water quality in shrimp ponds, reduce diseases, and reduce the use of chemicals. In the direct style of tilapia-shrimp polyculture, about 40% farmers believed that tilapias compete for feed with shrimp, while the remaining 60% were not aware of such feed competition. It can be concluded from the survey that polyculture of shrimp with tilapias may provide an alternative approach for shrimp farming, which could ultimately lead to a more sustainable shrimp industry. However, further research is needed on the merits for converting from shrimp monoculture to polyculture with tilapia.

Tilapia-shrimp polyculture in Thailand
Conference Paper
2004
Yi, Y., J. S. Diana, M. K. Shrestha, and C. K. Lin. 2004. Culture of mixed-sex nile tilapia with predatory snakehead. in 6th International Symposium on Tilapia Aquaculture, 6th International Symposium on Tilapia Aquaculture, edited by K. Fitzsimmons, Bolivar, R.B., and Mair, G. Manila, Philippines. Retrieved (http://www.was.org/Shopping/ista--6th-international-symposium-on-tilapia-in-aquaculture-proceedings).
NOP 04-A19 (English)

NOP 04-A19 (English)

An experiment was conducted in eighteen 200-m2 fertilized earthen ponds at the Asian Institute of Technology, Thailand, during March-October 2000. This experiment was designed to assess the efficiency of snakehead (Channa striata) in controlling recruitment of mixed-sex Nile tilapia (Oreochromis niloticus) in ponds and to assess growth and production characteristics of Nile tilapia in monoculture and polyculture with snakehead. There were six treatments: (A) monoculture of sex-reversed all-male tilapia; (B) monoculture of mixed-sex tilapia; (C) polyculture of snakehead and mixed-sex tilapia at 1:80 ratio; (D) polyculture of snakehead and mixed-sex tilapia at 1:40 ratio; (E) polyculture of snakehead and mixed-sex tilapia 1:20 ratio; (F) polyculture of snakehead and mixed-sex tilapia at 1:10 ratio. Both generic types of Nile tilapia were stocked at 2 fish m-2 at sizes of 10.5 - 11.6 g and 7.2 - 8.1 g, respectively. Results show that snakehead were able to completely control Nile tilapia recruitment at all tested predator:stocked-prey ratios and the best predator:stocked-prey ratio was 1:80. The addition of snakehead into Nile tilapia ponds did not result in significantly greater tilapia growth, but significantly lowered total net and gross yields of adult plus recruited tilapia. Snakehead growth was density-dependent, decreasing significantly with increasing stocking densities. While snakehead biomass gain was not significantly different at stocking density from 0.025 to 0.1 fish m-2, the gain was significantly lower at stocking density of 0.2 fish m-2. The present experiment demonstrates that snakehead were able to control Nile tilapia recruitment completely and provide an alternative technique for Nile tilapia culture.

Culture of mixed-sex nile tilapia with predatory snakehead
Conference Paper
2004
Yi, Y., K. Fitzsimmons, W. Saelee, and P. Clayden. 2004. Stocking densities of nile tilapia in shrimp ponds under different feeding strategies. Pp. 402 - 420 in 6th International Symposium on Tilapia Aquaculture, 6th International Symposium on Tilapia Aquaculture, edited by K. Fitzsimmons, Mair, G., and Bolivar, R.B. Manila, Philippines. Retrieved (http://www.was.org/Shopping/ista--6th-international-symposium-on-tilapia-in-aquaculture-proceedings).
NOP 04-A20 (English)

NOP 04-A20 (English)

This study, consisting of two experiments, was carried out at the Asian Institute of Technology (AIT), Thailand, to investigate the growth performance of shrimp (Penaeus monodon) and Nile tilapia (Oreochromis niloticus), water quality and nutrient budget in different stocking combinations of tilapia-shrimp polyculture. Both experiments were conducted in nine 200-m2 earthen ponds with three treatments in triplicate each, namely: a) shrimp alone at 30/m2 (monoculture); b) shrimp at 30/m2 and Nile tilapia at 0.25/m2 (low- density polyculture); c) shrimp at 30/m2 and Nile tilapia at 0.50/m2 (high-density polyculture). In experiment 1, the feed ration was determined daily by feeding-tray method in every pond during the 65-day culture period, while the fixed feed ration for all ponds was determined by a feeding table and estimated mean survival rate in experiment 2 during 75-day culture period. In experiment 1 with varied feed rations, the growth, yield and survival of shrimps were not significantly different among all treatments (P > 0.05). Although the Feed Conversion Ratios (FCR) of shrimps, which ranged from 1.62 - 2.24, were not significantly different among all treatments (P > 0.05), shrimp monoculture had significantly lower feed input than tilapia-shrimp polyculture (P < 0.05). However, in experiment 2 with fixed feed rations, the low-density tilapia polyculture resulted in significantly higher shrimp yield than the monoculture and high-density tilapia polyculture (P < 0.05). FCR in the low-density tilapia polyculture treatment (1.44) was significantly better than those in both monoculture and high-density tilapia polyculture, (1.73 and 1.69, respectively) (P < 0.05). In both experiments, Nile tilapia showed fast growth (3.98-4.70 g/fish/day). There was no significant difference in growth and survival of Nile tilapia between the low- and high-density tilapia polyculture (P > 0.05), while fish yields were significantly higher in the high-density tilapia polyculture than those in the low-density tilapia polyculture (P < 0.05).

Stocking densities of nile tilapia in shrimp ponds under different feeding strategies
Conference Paper
2004
Yi, Y., J. S. Diana, and C. K. Lin. 2004. Supplemental feeding for red tilapia culrure in brackishwater. Pp. 451 - 462 in 6th International Symposium on Tilapia Aquaculture, 6th International Symposium on Tilapia Aquaculture, edited by R.B. Bolivar, Mair, G., and Fitzsimmons, K. Manila, Philippines. Retrieved (http://www.was.org/Shopping/ista--6th-international-symposium-on-tilapia-in-aquaculture-proceedings).
NOP 04-A24 (English)

NOP 04-A24 (English)

An experiment was conducted at the Asian Institute of Technology, Thailand, to investigate effects of feeding regimes on growth of sex-reversed Thai red tilapia (Oreochromis sp.). There were five different supplemental feeding regimes: 0%, 25%, 50%, 75% and 100% of satiation. Red tilapia fingerlings (33.2-33.4 g size) were stocked at 62.5 fish m-3 in fifteen 0.8-m3 net cages suspended in.a 200-m2 earthen pond and cultured for 90 days. The pond was maintained at 10% salinity and fertilized weekly at rates of 4 kg N and 1 kg P ha-l d-1. Growth performance of red tilapia was significantly better in feeding treatments than in the non-feeding treatment. Red tilapia growth and average feeding rate increased but FCR and net economic return decreased with increasing percentages of satiation feeding levels from 25% to 100%. Considering low FCR, good growth and yield performance, high economic return and potential for growing to greater size, 50% satiation feeding was the most efficient feeding rate.

Supplemental feeding for red tilapia culrure in brackishwater
Conference Paper
2004
Yi, Y., K. Fitzsimmons, and P. Clayden. 2004. Stocking Densities of Nile Tilapia in Tilapia-Shrimp Polyculture Under Fixed Feeding Regime. Pp. 100 - 113 in Proceedings: The 5th National Symposium on Marine Shrimp, Proceedings: The 5th National Symposium on Marine Shrimp.
NOP 04-202 (English)(Spanish)

NOP 04-202 (English)(Spanish)

An experiment was carried out in nine 200-m2 earthen ponds at the Asian Institute of Technology, Thailand, to investigate the growth performance of Nile tilapia (Oreochromis niloticus) and shrimp (Penaeus monodon) and water quality in different stocking combinations of tilapia shrimp polyculture under fixed feeding regime. There were three treatments in triplicate each: shrimp alone at 30/m2 (monoculture, control); shrimp at 30/m2 and Nile tilapia at 0.25/m2 (low tilapia density polyculture); shrimp at 30/m2 and Nile tilapia at 0.50/m2 (high tilapia density polyculture). The fixed same feed ration for all ponds was determined by a feeding table during 75-day culture period. Results showed that the low tilapia density polyculture resulted in significantly higher shrimp yield than the monoculture and high tilapia density polyculture (P < 0.05). FCR of 1.44 in the low tilapia density polyculture was significantly better than those (1.73 and 1.69) in both monoculture and high tilapia density polyculture, respectively (P < 0.05). Nile tilapia showed fast growth (4.64-4.70 g/fish/day). There was no significant difference in growth and survival of Nile tilapia between the low and high tilapia density polyculture (P > 0.05), while fish yields were significantly higher in the high tilapia density polyculture than those in the low tilapia density polyculture (P < 0.05). Partial budget analyses indicated that the low tilapia density polyculture gave the highest net return, followed by the high tilapia density polyculture and shrimp monoculture and the ratio of added return to added cost in the low tilapia density polyculture reached 22.69, which is higher than that (5.04) in the high tilapia density polyculture. The present study indicated that the addition of Nile tilapia into shrimp ponds can improve feed utilization efficiency, resulting in better economic returns and less environmental pollution. The present study showed that the tilapia-shrimp polyculture with appropriate feeding strategy is technically feasible, economically attractive and environmentally friendly.

Stocking Densities of Nile Tilapia in Tilapia-Shrimp Polyculture Under Fixed Feeding Regime
Conference Paper
2004

2003

NOP 03-195 (English) (Spanish)

Androgen immersion protocols have been unsuccessful in consistently producing all-male tilapia at a high enough ratio for them to be commercially viable. This study explored the use of ultrasound to improve on the results of previous immersion studies. Variables tested include two hormones (trenbolone acetate-TBA and 17α-methyldihydrotestoterone-MDHT) at two concentrations (100 and 250 μg/L) and with or without ultrasound (cavitation level). All hormone treatments with ultrasound and non-ultrasound resulted in significantly higher masculinization than the appropriate controls (P < 0.05). Among pairs of treatments of the same hormone at the same dose, all ultrasound treatments resulted in significantly higher number of males compared with non-ultrasound treatments with the exception of MDHT 250 μg/L (P < 0.05). Comparing across all ultrasound treatments, TBA 250 μg/L with ultrasound had higher masculinization than all the other ultrasound treatments (P < 0.05). Comparing across all non-ultrasound treatments, TBA 250 μg/L had higher (P < 0.05) masculinization than MDHT 100 μg/L and TBA 100 μg/L with non-ultrasound. Two of the three replicates of TBA 250 μg/L ultrasound treatment resulted in 100% males and the highest mean percentage (98%) of males. This study thus demonstrated the potential of a short-term immersion protocol using ultrasound to more predictably produce all-male, commercially viable tilapia seed.

Ultrasound Enhanced Immersion Protocols for Masculinization of Nile Tilapia, <i>Oreochromis niloticus</i>
Journal Article
2003
Corbin, J. S., J. C. Cato, and C. L. Brown. 2003. Marine Ornamentals Industry 2001: Priority Recommendations for a Sustainable Future. Pp. 3 - 10 in Marine Ornamental Species: Collection, Culture, & Conservation, Marine Ornamental Species: Collection, Culture, & Conservation, edited by J.C. Cato and Brown, C.L. Ames, Iowa, USA: Blackwell Publishing Company. Retrieved (http://doi.wiley.com/10.1002/9780470752722.ch1).
NOP 03-A07 (English)

NOP 03-A07 (English)

The marine ornamentals industry around the world encompasses a broad array of disciplines, interests, and activities. Simply describing the chain of product distribution (chain of custody) includes mention of collectors and culturists, wholesalers and transshippers, distributors and retailers small and large, and of course hobbyists. When we add to this the equipment and supplies manufacturers, government resource managers and regulators, researchers and extension agents, educators and public aquariums, various media and international conservation organizations, the list of stakeholders in the future of the industry becomes daunting. Indeed, as the twenty- rst century dawns, interest in marine ornamentals is growing rapidly but perhaps not for the best of reasons. Reportedly, between 15 and 30 million marine sh from among approximately 1,000 species enter the trade every year, though accurate statistics are lacking (Wood 2001). Hundreds of species of marine invertebrates are also sold. Currently, as much as 98% of the marine ornamental species marketed are wild animals collected from coral reefs, mostly in tropical developing countries, for example, the Philippines and Indonesia (Moe 2001; Dawes 2001 a). Major problems with collecting in the wild have been described by numerous recent reports, including the widespread use of chemicals and other destructive collection methods that damage coral reefs, negative social and economic impacts on rural coastal communities, and inadequate handling and shipping procedures that cause unnecessary stock mortalities (Baquero 1999; Wood 2001; Cruz 2001; Dawes 2001a). Aquacultured sources in the marine ornamentals trade account for less than 2% of the supply, and sources of commercial quantities of product have been slow to develop (Moe 2(01). The life histories of many economically important marine reef sh and invertebrates are extremely complex and dif cult to control (Ziemann 2001; Brown 2001). Moreover, the marketplace has yet to appreciate fully the advantages of cultured species over wild-caught species and there- fore accept the higher prices charged (Stime 2(01).

Marine Ornamentals Industry 2001: Priority Recommendations for a Sustainable Future
Book Chapter
2003

NOP 04-200 (English)(Spanish)

Broodstock pacu Piaractus brachypomus as well as their eggs during their embryonic development were exposed to either normoxia (5.5–7.5 mg O2/L) or hypoxia (2.0–4.5 mg O2/L) conditions. The plasma concentrations of 11-ketotestosterone in males and estradiol-17β in females, as well as that of their precursor testosterone (T) were significantly (P < 0.01) higher in fish maintained under normoxic conditions than in fish exposed to hypoxia. After ovulation and spermiation induced by hormonal treatments, the plasma concentrations of T and 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) significantly (P < 0.05) increased in both sexes under both normoxic and hypoxic conditions. The plasma levels of T and 17,20βP achieved under normoxic conditions were higher than the ones recorded under hypoxia, except for those of 17,20βP in males. Males responded positively to the hormonal treatments, and the concentration of spermatozoa was 10.5 ± 0.8 109/mL under both oxygen conditions. Hypoxia resulted in significantly lower survival of embryos (17.3 ± 28%) in comparison to normoxic conditions (68.5 ± 25%). Moreover, larval deformities were found when exposed to hypoxia (91.6 ± 6%). During embryonic development of this species 4 mg/L of oxygen is tolerated at 26–27 degrees C without negative impact. We conclude that despite the highly adaptable nature of adult pacu to environmental hypoxia, oxygen concentrations below 4 mg/L severely impacted survival of embryos.

Effect of Oxygen Saturation in Water on Reproductive Performances of Pacu <i>Piaractus brachypomus</i>
Journal Article
2003

Nicaraguan tilapia farmers face considerable market risk in attempting to develop export markets for their products. Domestic markets would provide stability by offering additional market alternatives, thereby reducing risks associated with having only one target market. The goal of this project was to assess the domestic market as an alternative tilapia outlet. A complete census of open-air markets was conducted in the major urban and rural population centers. The survey results indicated that tilapia was a common product in Nicaragua, with over 65% of fish market vendors selling tilapia. On average, vendors had been selling tilapia for more than ten years. Tilapia were sold most commonly by vendors with larger stands and those with slightly higher education levels. Inconsistent supplies and insufficient quantities of tilapia have resulted in decreasing sales of tilapia. Sales of freshwater fish in Nicaragua are hampered by fears on the part of consumers over contamination of Lake Managua and the safety of fish supplies as a result. Fear of contamination was the major reason why vendors had either stopped selling or never sold tilapia. Wholesale prices paid by vendors for tilapia are likely to be lower than the price levels that will be necessary to cover production costs of farm-raised tilapia.

Potential for Open-Air Fish Market Outlets for Tilapia in Nicaragua
Report
2003

Development of a domestic market for farm-raised tilapia in Nicaragua could provide an economic incentive for development of a farm-raised tilapia industry in Nicaragua. The goal of this project was to assess the domestic market as an alternative market outlet to the export market. While the overall study includes analyses of supermarket, fish market, and restaurant market outlets, this document will focus on the supermarket segment. A census of the supermarkets listed in telephone books in the major urban areas and small towns in the country resulted in 35 completed supermarket questionnaires. Information was collected on both tilapia and other types of fish and seafood sold, prices, most frequently sold fish products, marketing channels, supplier information, attitudes towards tilapia, and store characteristics. Survey results showed that only one-fourth of supermarkets in the country sold tilapia in spite of the substantial fishery for tilapia in Lake Nicaragua. Tilapia were not sold due to off-flavor (tastes like earth), lack of supply, and fears of selling contaminated fish from Lake Nicaragua. Nevertheless, those supermarkets that sold tilapia indicated that their sales in 2000 were higher than they had been in 1999. A high percentage of supermarkets indicated that they were very likely to begin selling tilapia in the coming year. Inconsistent supplies and insufficient quantities were the greatest supply problems. Fresh filets were preferred but quality and availability needed to be improved. For a domestic market for farm-raised tilapia to develop in Nicaragua, the issue of consumer fears of contamination must be addressed. Broad-based consumer education, third-party certification, and labeling programs may be needed to assist consumers to differentiate between farm-raised and wild-caught tilapia. Tilapia farms and processors in Nicaragua will need to guarantee and ensure a consistent supply of good-flavor, high-quality, and safe tilapia products.

Potential for Supermarket Outlets for Tilapia in Nicaragua
Report
2003

Honduran tilapia farmers currently face several problems regarding product size and export-quota requirements. One major obstacle is the production of undersized fish not suitable for the export market. Domestic markets would provide stability by offering additional market alternatives, thereby reducing risks associated with having only one target market. The goal of this project was to assess the domestic market as an alternative tilapia outlet. While the overall study includes analyses of supermarket, fish market, and restaurant market outlets, this document will focus on the supermarket segment. A census of the supermarkets listed in telephone books in the major urban areas and eight small towns in Honduras resulted in 54 completed supermarket questionnaires. The analysis provides important insights into supply characteristics, buyer patterns and preferences, and trends in the domestic market. The survey showed that tilapia is a well-known product in Honduran supermarkets. More than 40% of the supermarkets in the country sold tilapia, and 50% of supermarket managers responded that they were either somewhat or very likely to sell tilapia the next year. However, lack of demand, freshness, and seasonal availability were mentioned as primary reasons for not selling the product. Short-term strategies would focus on larger supermarkets catering to international, high-, and middle-income clientele groups. The presence of a specialized seafood section contributes to tilapia sales. Low daily volumes and lack of demand could be addressed through in-store demonstrations, samples, and point- of-purchase information. These results suggest that, provided tilapia farmers combine adequate marketing strategies with availability of high-quality tilapia, it may be possible to further develop the domestic market for tilapia in Honduras.

Potential for Supermarket Outlets for Tilapia in Honduras
Report
2003
NOP 03-198 (English)(Spanish); NOP 03-A09 (English)

NOP 03-198 (English)(Spanish); NOP 03-A09 (English)

This study was conducted in Dai Tu district of Thai Nguyen province during November 2001 - January 2003 to assess the aquaculture development potential for watershed ponds by integrating socio-economic and environmental data into GIS database, detecting land use change, and identifying and estimating potential areas for aquaculture development in watershed ponds. The socio-economic and environmental data were collected using pre-test questionnaires and field measurements. Three SPOT multi-spectral band satellite images were used to detect land use change during three periods of 1994-1998, 1994-2002, and 1998-2002. For land suitability evaluation, the suitability ratings were established according to FAO classification in terms of suitability of land for defined uses. Aquaculture production and economic returns from interviewed farmers were used to verify the results and comparisons among different land suitability levels. The present study has predicted that about 4.7% (2,725 ha) of the total land area of 57,618 ha in Dai Tu district are suitable sites for watershed pond construction, compared to the existing 404-ha watershed ponds. The present study has demonstrated the usefulness of integration of remote sensing, GIS and attribute data to select suitable sites for the development of watershed ponds, and the importance to be a useful tool for planners to develop strategic plans for aquaculture development.

Application of GIS and Remote Sensing for Assessing Watershed Ponds for Aquaculture Development in Thai Nguyen, Vietnam
Conference Paper
2003

NOP 03-197 (English)(Spanish); NOP 03-A04 (English); NOP 03-A06 (English)

This paper compares three different strategies/treatments for determining fertilization rates for producing natural foods in semi-intensive aquaculture ponds. The first strategy used a predetermined, fixed-input rate of nitrogen (N) and phosphorus (P) based on results from previous yield trials. The second strategy was based on algal nutrient concentrations, and used biweekly water quality measurements in combination with a microcomputer-based expert system, PONDCLASS©, to determine fertilization rates. The third approach, the algal bioassay fertilization strategy (ABFS), was based on algal growth responses to nutrient [i.e., N, P, and carbon (C)] enrichment, and used weekly, pond-specific algal bioassays to determine both nutrient requirements and associated rates of nutrient inputs. The three fertilization strategies were applied to Nile tilapia (Oreochromis niloticus) growout ponds over a 120-day period, with five ponds per treatment. All ponds were fertilized weekly with urea, triple superphosphate, agricultural lime, and/or chicken manure in amounts determined by each strategy. Results indicated that net fish yields (NFYs) were not significantly different (P = 0.094) between treatments, with the fixed-input treatment giving the highest but most variable yields. Average NFYs ± S.E. (standard error) for the 120-day growout period were 2124 ± 276, 1476 ± 151, and 1651 ± 133 kg ha-1 for the fixed-input strategy, PONDCLASS©, and ABFS treatments, respectively. The relatively lower NFYs for PONDCLASS© and ABFS indicate that neither approach maximized fish production. Nitrogen utilization efficiencies of fertilizer inputs were similar for all three strategies. Although the fixed-input approach used approximately 20% more N than the other two approaches, mean algal productivities and NFYs were also proportionally higher with this treatment. This result is consistent with the observation that algal productivities in PONDCLASS© and ABFS ponds were nearly always limited by N availability. However, both P utilization and fertilization cost efficiencies were significantly better with PONDCLASS© and ABFS than with the fixed-input treatment. The fixed-input approach not only used a higher P input rate than necessary, it did not account for ecological differences between ponds within the same treatment (e.g., nutrient and light limitation of algal productivity, inorganic turbidity, etc.), which can affect a pond's response to fertilization. In particular, the fixed-input treatment did not add carbon to compensate for nonuniform losses in alkalinity, which resulted in relatively high soluble P concentrations in treatment ponds where C availability apparently limited algal productivity. Including C fertilization in the fixed-input treatment would have likely reduced NFY variability and improved P utilization efficiency in those ponds. Because both PONDCLASS© and the ABFS adjusted pond-specific fertilization requirements throughout the study, they provided increased fertilization efficiencies and profitability over the fixed-input strategy. However, the ABFS is more practical than PONDCLASS© for rural application because it is far simpler and does not require water chemistry, computers, laboratory equipment, technical expertise, or electricity to implement. Based on this study, the recommended fertilization strategy designed to achieve cost-efficient, consistently high yields is a modified ABFS approach that uses a fixed-input fertilization rate for N, and algal bioassays to determine time-specific and pond-specific fertilization requirements for P and C. © 2003 Elsevier Science B.V. All rights reserved.

A comparative analysis of the fixed-input, computer modeling, and algal bioassay approaches for identifying pond fertilization requirements for semi-intensive aquaculture
Journal Article
2003

NOP 03-196 (English)(Spanish); NOP 03-A03 (English)(Spanish)

A wide range of aquaculture systems is practiced in Asia, predominantly in semi-intensive systems with fertilization and intensive systems with formulated feeds in pond culture. This paper describes various means to minimize environmental impacts and reuse pond effluents and bottom mud, based on a series of pond experiments of the most commonly cultured species in Thailand, hybrid catfish (Clarias macrocephalus x Clarias gariepinus) and Nile tilapia (Oreochromis niloticus). Experiment 1 was designed to improve feeding efficiency through optimization of feeding regime to reduce nutrient inputs in Nile tilapia culture; the results show that there were no significant differences in fish yield among daily feed rations at 50%, 75%, and 100% satiation, but the nutrient loading was escalated with increasing rations. The second experiment on hybrid catfish and Nile tilapia culture in cage-cum-pond systems shows that major nutrient input from formulated feed could be effectively recycled in a closed pond where hybrid catfish were cultured intensively with formulated feed in cages and Nile tilapia with natural food in an open pond. The third experiment was conducted to determine appropriate harvest methods and draining treatments for reducing pollutants from Nile tilapia ponds; the results show that liming pond water a day before draining and gradually draining ponds to a 25-cm depth during harvest was most effective. An experiment conducted to reuse effluents from hybrid catfish culture to fertilize rice crops demonstrated that the rice crop removed 32% total nitrogen (TN) and 24% total phosphorus (TP) from the effluents, with rice production comparable to that which received regular fertilization regime. The last experiment was to determine the efficiency of rooted aquatic plants in extracting nutrients from pond mud. The results show that the economic aquatic plants, such as lotus (Nelumbo mucifera), were able to remove 300 kg N and 43 kg P/ha/year from pond substrates. © 2003 Elsevier B.V. All rights reserved.

Minimizing environmental impacts of freshwater aquaculture and reuse of pond effluents and mud
Journal Article
2003

NOP 03-A01 (English)(Spanish)

Coastal aquaculture can contribute to eutrophication of receiving waters. New technologies and improved management practices allow the aquaculture industry to be more sustainable and economically viable. Current practices, however, do not provide an additional use for effluent water. Nitrogen, phosphorus and other effluent compounds could be valuable plant nutrients. Inflow and effluent water from an inland, low-salinity shrimp farm, were monitored. Bi-weekly analysis included total nitrogen, ammonia-nitrogen, nitrite-nitrogen, nitrate-nitrogen, total phosphorus, reactive phosphorus, alkalinity, chemical oxygen demand (COD), biochemical oxygen demand (BOD), total suspended solids (TSS) and volatile suspended solids (VSS), as well as temperature, salinity, dissolved oxygen and pH. Alkalinity and total nitrogen decreased during the in-pond residency. The other parameters increased while in the ponds. The potential benefit of having nutrient enriched wastewater to irrigate field crops was substantial, supplying between 20 and 31% of the necessary nitrogen fertilizer for wheat production. 2002 Elsevier Science B.V. All rights reserved.

Characterization of effluent from an inland, low-salinity shrimp farm: What contribution could this water make if used for irrigation
Journal Article
2003

NOP 03-A05 (English)(Spanish)

Organic fertilizers are phosphorus rich and nitrogen poor relative to the 1:7 ratio of P:N required by pond algae for growth. During experiments in Thailand, nitrogen deficiency occurred in Nile tilapia ponds where chicken manure was used at a rate of 500 kg/ha/wk. Ponds in this treatment has the same microflora/fauna production and fish yields as ponds treated at 1/10 the rate of chicken plus a urea supplement that provided a 1:7 ratio of P:N in the fertilizers. Rates of net primary productivity were 2.23 and 2.24 g C/m2/day in these treatments respectively. Fish yields obtained from 25 g fingerlings at two fish m2 with a four month growout were close to 4,000 kg/ha/yr in both treatments. Fertilizer cost per kg of fish yield was $US 0.05 in both treatments. Data from our work suggest that Nile tilapia yields close to those obtained with feeds will result from increasing chicken manure to a range of 50 to 200 kg/ha/wk and adding urea to make the fertilizer P:N ratio 1:5. We are testing this approach with consideration of economics.

Fish Yield with Nitrogen Supplemented Organic Fertilizers
Journal Article
2003

This report is part of a series of studies conducted during the third quarter of 1999 in Honduras. The project was designed to assess the Honduran market to determine the potential market for tilapia. Three different surveys were conducted: a supermarket survey, and open air fish market survey, and a full-service restaurant survey. This report will focus on the latter. A random sample and a census of full-service restaurants were taken in all major urban and selected rural areas of the country. The survey resulted in 72 completed questionnaires by restaurants randomly selected throughout the urban and selected rural areas. While the vast majority of restaurants were familiar with tilapia, only 30% sold tilapia. While tilapia sales were increasing, less than half of the restaurants promoted tilapia entrees. Restaurants that did not sell tilapia still rated it favorably on many attributes but had difficulty obtaining reliable supplies. These restaurant managers also were hesitant about customer reactions to tilapia. Reliable supplies, samples, and catch-of-the-day promotions in restaurants would likely be effective in creasing sales of tilapia. An emphasis on quality and year-round availability of fresh filets will be critical factors to encourage more restaurants to experiment with tilapia.

Potential for Restaurant Markets for Tilapia in Honduras
Report
2003

Honduran tilapia farmers face several problems regarding product size and export-quota requirements. One major obstacle is the significant production of undersized fish not suitable for the export market. Domestic markets would provide stability by offering additional market alternatives, thereby reducing risks associated with having only one target market. The goal of this project is to assess the domestic market as an alternative tilapia outlet. While the overall study includes analyses of open-air fish market, supermarket, and restaurant market outlets, this document will focus on open-air fish markets. A random sample of all open-air fish market vendors in the major urban areas and census of the fish market vendors in the small towns in the country resulted in 66 completed fish market questionnaires. The survey showed that tilapia is a well-known product in Honduran open-air markets. Overall, 70% of open-air market vendors sold tilapia, and over half of the open-air market vendors not currently selling tilapia responded that they were very likely to sell tilapia the next year. Approximately 25% of tilapia sold was from Lake Nicaragua. However, lack of demand, high wholesale prices, and off-flavor were mentioned as primary reasons for not selling or not continuing to sell the product. Results indicated relatively stable tilapia sales in recent years; however, inconsistency in supply was a major obstacle for further market growth. The survey results appeared to indicate potential to increase tilapia sales if a consistent supply can be maintained. Nevertheless, careful attention needs to be paid to the costs of production of farm-raised fish versus wholesale prices of wild-caught tilapia. Wholesale prices of tilapia ranged from US$0.20 to $0.61 lb-1 and averaged $0.51 lb-1. It is unlikely that many tilapia farms would be able to produce and transport tilapia to open-air markets at these wholesale prices. Open-air markets do not appear to represent a profitable market outlet for farm-raised tilapia.

Potential for Open-Air Fish Markets Outlets for Tilapia in Honduras
Report
2003

Domestic markets for tilapia production can diversify for Nicaraguan tilapia producers. The availability of export alternatives to the US market can reduce market-related risks. Three surveys were conducted in Nicaragua from August to September 2000. Although the study includes surveys of supermarkets and fish market sellers, this report emphasizes in surveys of the restaurant market. A random sample of restaurants in urban and rural areas resulted in 118 completed questionnaires. Information was collected in aspects such as: supply characteristics, supply channels, characteristics of demand preferences and patterns of consumption. The results indicated increased sales of tilapia, but also revealed problems such as: negative perceptions by consumers of tilapia for having a rare taste, contaminated fish from capture and inconsistency of supply. Tilapia is very well known in Nicaragua. It was considered the fourth most important in fish sales, but the restaurants were reluctant to admit the sale of tilapia because of the lack of flavor and fears of the consumer related to the capture of Lake Managua tilapia. The education of the product labeling programs would be necessary to deal with perceptions of pollution. Tilapia farms and processors will need to ensure the taste, quality and safety of the product. Promotional efforts that emphasize these attributes will become essential.

Potential for Restaurant Markets for Tilapia in Nicaragua
Report
2003

NOP 03-A02 (English)(Spanish); NOP 03-A08 (English)

This study assessed the potential to increase sales of farm‐raised tilapia through domestic restaurants in Nicaragua. Direct personal interviews were conducted with 118 restaurant managers. Information was collected on tilapia and other seafood sales, restaurant and market characteristics, attitudes towards tilapia characteristics, and willingness to add tilapia to the menu. The results from logistic analyses suggest that the most promising restaurant markets for tilapia are older restaurants that offered a variety of food and those that served steaks. Larger restaurants that considered tilapia to be a high‐quality product and that offered “ceviche” (fish marinated in lime juice) on the menu were those that tended to sell tilapia. Tilapia farmers and processors in Nicaragua will need to guarantee and ensure the flavor, quality, and safety of their product, and promote these attributes.

Potential restaurant markets for farm‐raised tilapia in Nicaragua
Journal Article
2003
Yi, Y., C. K. Lin, and J. S. Diana. 2003. Waste recycling in fishpond culture through integrated culture systems. Pp. 265 - 270 in Proceedings of the Third World Fisheries Congress: Feeding the World with Fish in the Next Millenium - the Balance Between Production and Environment, vol. Symposium, Proceedings of the Third World Fisheries Congress: Feeding the World with Fish in the Next Millenium - the Balance Between Production and Environment, edited by B. Phillips, Megrey, B.A., and Zhou, Y. American Fisheries Society. Retrieved (https://www.researchgate.net/publication/242468720_Waste_Recycling_in_Fish_Pond_Culture_through_Integrated_Culture_Systemshttp://fisheries.org/bookstore/all-titles/afs-symposia/x54038xm/).
NOP 04-201 (English)(Spanish)

NOP 04-201 (English)(Spanish)

Two new culture strategies, have been developed to recycle feeding waste derived from intensive aquaculture within a single pond, enhance nutrient utilization efficiency, reduce the nutrient contents in effluents discharged from intensive culture ponds, and mitigate eutrophication in receiving waters. In the integrated cage-cum-pond culture system, high value species are stocked in cages suspended in ponds, and filter-feeding species are stocked in open water outside the cages. While in the integrated pen-cum-pond culture system, high valued species and filtering-feeding species are segregated by plastic netting, which partitions a pond into two compartments. High-value species in both systems are fed a high protein diet, while the filtering feeding species depend solely on natural foods generated from feeding wastes. In the integrated culture systems, nutrients contained in wastewater of intensive fish culture can be effectively reused by filtering-feeding species, giving compatible yields with those achieved in organically or inorganically fertilized ponds. The integrated culture systems recycle wastes from intensive culture into semi-intensive culture, thereby reducing the nutrient input for pond fertilization, and minimize the impacts of pond effluents on environments. The integrated culture systems can also be used in polyculture ponds to confine costly high protein diets to the high valued species to achieve higher economic returns. The integrated culture systems can be adapted by small-scale farmers, especially suitable for low capital investment.

Waste recycling in fishpond culture through integrated culture systems
Conference Paper
2003

NOP 03-188 (English)(Spanish)

Two experiments were conducted in 200-m2 earthen ponds at Asian Institute of Technology, Thailand, for 87 days to test the feasibility of an integrated pen-cum-pond system, which utilizes wastes from intensive culture of hybrid catfish (Clarias macrocephiilus x C. gariepinus) as nutrients for semi-intensive culture of Nile tilapia (Oreochromis niloticus). This integrated pen-cum-pond system enhances nutrient utilization efficiency, minimizes environmental impacts of pond effluents, and gains extra fish production at low cost. Experiment 1 was designed to compare the integrated pencum-pond systems with natural and artificial water circulation. Six randomly selected 200-m2 ponds were partitioned by 1.0-cm mesh plastic net into two compartments: 1/3 of pond area (67 m2) for hybrid catfish and 2/3 (133 m2) for Nile tilapia. In experiment 2, one additional pond was partitioned by 1.0 - cm mesh plastic net into three equal compartments with 67 m2 each. The mesh was not cleaned and thus partitions serve as three replicates for hybrid catfish culture alone (non-integrated system). Experiment 2 was designed to compare growth performance of hybrid catfish and effluent quality from intensive culture of hybrid catfish among the non-integrated system with hybrid catfish alone (non-integrated treatment) and the integrated pen-cum-pond systems (natural and artificial water circulation treatments) in the 67-m2 compartments. The nutrient budgets were also compared among the three culture systems. Sex-reversed all-male Nile tilapia were stocked at 2 fish/m2, and hybrid catfish at 25 fish/m2. Hybrid catfish were fed floating pelleted feed twice daily at rates of 3-10% body weight per day. During the first month, tilapia compartments were fertilized weekly using urea and triple superphosphate (TSP) at rates of 28 kg N and 7 kg P/ha/week. In the artificial water circulation treatment, the water in the catfish compartment was continuously circulated by a submersed pump to the tilapia compartment at a rate of one exchange per week, starting the second month. There were no significant differences in growth performance of hybrid catfish among all treatments (P > 0.05). Extrapolated net tilapia yields obtained by using hybrid catfish wastes in this study were comparable to those achieved in organically and inorganically fertilized tilapia ponds. The results indicated that neither natural nor artificial water circulation between catfish and tilapia compartments improved the growth of hybrid catfish. Nile tilapia growth was not significantly different between the natural and artificial water circulation treatments (P > 0.05). However, the artificial water circulation caused mass mortality of Nile tilapia due to heavy loading of wastes. Nutrient budgets showed that total nitrogen JN) and total phosphorus (TP) levels in pond effluents in the natural and artificial water circulation treatments were significantly lower than those in the non-integrated treatment (P < 0.05). Nile tilapia recovered 3.30% and 2.12% of TN, and 1.29% and 0.84% of TP from feed wastes and fertilizer inputs in natural and artificial water circulation treatments, respectively. Concentrations of TKN, TP and SRP were significantly lower in the natural and artificial water circulation treatments than in the non-integrated treatment (P < 0.05). This study demonstrates that the integrated pen-cum-pond system is feasible, indicates that Nile tilapia can effectively recover nutrients contained in wastewater of intensive catfish culture, and suggests that natural water circulation between catfish and tilapia compartments can reduce nutrient contents in pond effluents and is cost-effective. (C) 2003 Elsevier Science B.V. All rights reserved.

Hybrid catfish (<i>Clarias macrocephalus</i> x <i>C-gariepinus</i>) and Nile tilapia (<i>Oreochromis niloticus</i>) culture in an integrated pen-cum-pond system: growth performance and nutrient budgets
Journal Article
2003

NOP 03-187 (English)(Spanish)

An experiment was conducted in fifteen earthen ponds at the Asian Institute of Technology (AIT), Thailand, during June to November 1998 to identify the source of clay turbidity, to evaluate several clay turbidity mitigation techniques and their effects on fish growth and water quality, and to find a suitable approach for turbidity mitigation during the rainy season. There were five treatments: (A) control; (B) covering upper 50 cm pond dikes with black plastic material to prevent turbidity from run-off (edge-covered); (C) covering pond bottoms with green manure (terrestrial weeds) to alter soil texture (weed-covered); (D) covering pond bottoms with small mesh (1 cm) net to prevent turbidity from fish disturbance (bottom-covered); and (E) covering pond dikes with rice straw (straw-covered). All ponds were fertilized weekly with chicken manure at a rate of 500 kg ha-1 (dry matter basis) supplemented with urea and triple superphosphate (TSP) to provide 28 kg N per ha per week and 7 kg P per ha per week. Sex-reversed all-male Nile tilapia (Oreochromis niloticus) were stocked at two fish per square meter at a size of 19.0 ± 1.0 g. Results showed clearly that clay turbidity was mainly from the run-off of pond dikes but not from fish disturbance of pond bottom during the rainy season and indicated that covering pond dike was effective in mitigating clay turbidity caused by the run-off in fish ponds. No significant differences of fish survival were found among all treatments. The straw- and weed-covered treatments resulted in significantly higher fish growth and yield. In contrast, the edge- and bottom-covered treatments did not increase fish yield, compared with the control. Covering pond dikes with rice straw not only reduces clay turbidity caused by run-off but also enhance Nile tilapia growth probably through microbial biofilm developed on the rice straw. Therefore, covering pond dikes with rice straw is a cost-effective technique for clay turbidity mitigation in fish ponds during the rainy season. © 2002 Elsevier Science B.V. All rights reserved.

Techniques to mitigate clay turbidity problems in fertilized earthen fish ponds
Journal Article
2003

2002

NOP 03-186 (English)(Spanish)

Five pond management strategies for Nile tilapia Oreochromis niloticus L. production were evaluated in 0.1-ha earthen ponds in Egypt during a 145-day production cycle. Pond management strategies developed by the Pond Dynamics/Aquaculture Collaborative Research Support Programme (PD/A CRSP) were compared with a traditional and a modified Egyptian pond management strategy. Young-of-year Nile (mixed-sex or sex-reversed) tilapia were stocked into ponds at 20,000 fish ha-1. Sex-reversed tilapia were stocked into chemical fertilization, organic fertilization plus formulated feed and feed only treatment ponds, whereas mixed-sex tilapia were stocked into organic fertilization plus formulated feed and chemical plus organic fertilization plus formulated feed treatment ponds. Nile tilapia yields ranged from 1,274 to 2,929 kg ha-1. Nile tilapia yields in organic fertilization plus formulated feed treatments were significantly greater than the yield from chemical fertilization ponds. PD/A CRSP pond management strategies did not produce significantly greater Nile tilapia yields than the traditional Egyptian system, but a larger percentage of harvested tilapia in the organic fertilization plus feed treatments were classified in the first and second class size categories compared with the traditional Egyptian system. Organic fertilization plus formulated feed pond management strategies had the highest net returns, average rate of return on capital and the highest margin between average price and break-even prices to cover total variable costs or total costs.

Evaluation of Nile tilapia pond management strategies in Egypt
Journal Article
2002

NOP 02-A03 (English)(Spanish)

A dynamic and mechanistic mass balance model (Integrated Aquaculture/Agriculture System model, or IAAS) for predicting nitrogen and organic matter outputs from aquaculture ponds and their subsequent recycling in conventional agriculture practices has been developed and calibrated using data from Honduras, Thailand and Malawi. The model, developed using Stella™ modeling software (High Performance Systems, Inc. Hanover, New Hampshire), simulates individual fish growth, organic matter, nitrogen (organic, total ammonia and nitrate), dissolved oxygen and phytoplankton, crop growth, soil nitrogen concentrations and soil water balance. Processes included in the model are fish growth, crop biomass growth, allochthonous and autochthonous organic matter production, organic matter decomposition, nitrogen input, nitrogen mineralization, nitrification, denitrification, diffusion, uptake and leaching. The model has been calibrated using literature and observed parameter values from experiments. The calibration procedure involves running the model using inputs from observed data, comparing the model output to observed data, and making appropriate adjustments to parameter values until a general fit between the model and observed values is observed. The structure of the model allows users to modify parameter values to suit different simulation scenarios via a user interface display that also includes graphs and tables for model output.

An organic matter and nitrogen dynamics model for the ecological analysis of integrated aquaculture/agriculture systems: I. model development and calibration
Journal Article
2002

NOP 02-A04 (English) (Spanish)

The performance of a model developed to simulate organic matter and nitrogen dynamics in integrated aquaculture/agriculture systems was evaluated using sensitivity analysis and model verification procedures with data from three sites. The model sensitivity analysis results were used to identify parameters that required high accuracy in measurement, and to suggest areas of future research in integrated aquaculture/agriculture systems. Model sensitivity analysis results showed that research on stocking density, sediment processes and water management practices was required, in order to improve the overall understanding of the functioning of the integrated aquaculture/agriculture system. Results from model verification runs showed that the model performance was satisfactory with respect to fish growth, crop growth, pond and terrestrial nitrogen and organic matter simulations. However, the modeling of phytoplankton biomass was less satisfactory and the results suggested the need for more site-specific calibration of exogenous factors and the consideration of phytoplankton species composition in simulating grazing preferences by fish. Application of the model to investigate the effects of different cycling pathways on nitrogen retention and productivity showed that the recycling of plant wastes to aquaculture ponds had a major effect in reducing system nitrogen losses and increasing system productivity. Sediment organic matter processes were identified as the major determinants of system nitrogen retention, as measured by the nitrogen retention index. The modeling study also showed that the number of linkages between the aquaculture and agriculture components was not directly related to nitrogen retention and productivity in the system. The results of the modeling study suggest that the system nitrogen status may be more important than the number of pathways in determining the number and type of cycling pathways that should be incorporated in integrated aquaculture/agriculture system.

An organic matter and nitrogen dynamics model for the ecological analysis of integrated aquaculture/agriculture systems: II. Model evaluation and application
Journal Article
2002

NOP 02-A01 (English)(Spanish)

A profit-maximizing linear programming model with a risk programming component was developed to identify sets of optimal management strategies and outline an annual schedule of production activities for shrimp farming in Honduras. A database of 912 complete pond production records was used to define technical relationships between stocking density and survival and growth rates and to develop net return coefficients for the mathematical model. Separate matrices were developed for three farm-size scenarios to account for economies of scale. Results indicated that, in spite of recent viral epizootics, shrimp farming continues to be a profitable economic activity. Stocking density was found to have a negative effect on growth rate, but not on survival rate. As a consequence, low and intermediate stocking rates were most commonly selected, but high stocking densities were recommended in certain periods of the dry season. Results demonstrated some economic advantages of reducing the traditional levels of water exchange with supplemental aeration. The risk programming analysis indicated that the selection of low and intermediate stocking rates resulted in overall annual risk levels that were relatively low.

Economic Optimization of Shrimp Farming in Honduras
Journal Article
2002

NOP 02-185 (English)(Spanish); NOP 02-A02 (English)

An experiment was conducted in nine 200-m2 fertilized earthen ponds at the Asian Institute of Technology, Thailand, during January-September 2000. This experiment was designed to assess the recovery of nutrients from pond mud by lotus (Nelumbo nucifera), to assess pond mud characteristics after lotus-fish co-culture, and to compare fish growth with and without lotus integration. There were three treatments in triplicate: (A) lotus-tilapia co-culture; (B) tilapia alone; (C) lotus alone. Seedlings (0.39 +/- 0.09 kg) of Thai lotus variety were transplanted to ponds of the treatments with lotus (treatments A and C) at a density of 25 seedlings pond-1, while sex-reversed all-male Nile tilapia (Oreochromis niloticus) fingerlings (8.6 - 10.3 g) were stocked at two fish per square meter in ponds of the treatments with tilapia (treatments A and B) when the water depth had been increased to 50 cm due to increasing lotus height. Ponds stocked with tilapia (treatments A and B) were fertilized weekly with urea and triple super phosphate (TSP) at a rate of 4 kg nitrogen (N) and 1 kg phosphorus (P)/ha/day after tilapia stocking. There was no fertilization in ponds of the lotus alone treatment, Lotus co-cultured with tilapia or cultured alone in ponds was able to effectively remove nutrients from old pond mud. Annual nutrient losses from mud in a 1-ha pond was about 2.4 ton N, and 1 ton P, among which about 300 kg N and 43 kg P were incorporated in lotus biomass. There were no significant differences in lotus growth performance between the lotus-tilapia and lotus alone treatments, while Nile tilapia cultured alone grew significantly better than when co-cultured with lotus. The present experiment has demonstrated the effectiveness of nutrient removal from old pond mud by lotus and the feasibility of rotation and co-culture of lotus and Nile tilapia. Both systems can recycle nutrients effectively within ponds and are environmentally friendly culture systems. 

Recycling pond mud nutrients in integrated lotus-fish culture
Journal Article
2002

2001

NOP 01-A01 (English)(Spanish)

Fish culture is a rapidly growing industry. Even faster growth can be expected if we have better control over reproduction, seed storage, growth, and diseases. Despite an availability of a variety of substances with the potential to allow control over processes that facilitate sexual differentiation, preservation of embryos, reproduction, and disease prevention, there is no reliable and efficient method to deliver these substances. Novel techniques such as ultrasound have shown to enhance transport of substances through the skin of both, mammals and fish. This paper summarizes results of some of our original studies to deliver calcein into fish larvae for marking and quantification, to enhance delivery of androgen for sex reversal of tilapia and to enhance permeation of cryoprotectants into embryos for cryopreservation using cavitation level ultrasound.

The use of ultrasound to enhance transport of compound into fish and fish embryos
Journal Article
2001
Corrales, H. L., C. A. Lara, J. E. Heerin, J. M. Wigglesworth, and B. W. Green. 2001. A sustainable shrimp aquaculture system from Honduras. edited by W.A. Payne, Keeney, D.R., and Rao, S.C. Madison, Wisconsin: American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. Retrieved (https://dl.sciencesocieties.org/publications/books/tocs/asaspecialpubli/sustainabilityo).
NOP 02-184 (English)(Spanish)

NOP 02-184 (English)(Spanish)

Annual global capture fisheries destined for human consumption have leveled off at around 60 million metric tons in recent years. Additional supplies from aquaculture are important to provide for future demand for seafood. Shrimp aquaculture is a relatively new activity that has grown significantly since the 1980's. Compared with development of traditional agriculture practices, there is a great potential for improvement in shrimp cultivation techniques that must come from research and development. Producers, producer organizations, and other development agencies must take a more active role in research activities. A program of field research was established during the last several years to determine and optimize production practices to achieve an environmentally sustainable system in Honduras. To assure sustainability of the activity, water quality trends will guide how much additional production area should be developed based on the elaboration of models to estimate the carrying capacity of individual estuaries. Honduras is a good example of producers, researchers, and government working together to define and optimize sustainable shrimp farming practices. There are substantial improvements to be made in decades to come. Continued support in the areas of water quality, health management, nutrition, and genetics is essential to assure the long-term viability of shrimp farming for producers and the environment.

A sustainable shrimp aquaculture system from Honduras
Book
2001
Egna, H. S. 2001. Environment, aquaculture, and food policy nexus; Case study of two USAID aquaculture projects in Rwanda. Pp. 281 - 314 in Handbook of Global Environmental Policy and Administration, Handbook of Global Environmental Policy and Administration, edited by D.L. Soden and Steel, B.S. New York: Marcel Decker, Inc. Retrieved (https://www.crcpress.com/Handbook-of-Global-Environmental-Policy-and-Administration/Soden-Steel/p/book/9780824719890).
NOP 01-167 (English) (Spanish)

NOP 01-167 (English) (Spanish)

This case study centers on some of the institutional networks that evolved in Rwanda around aquatic food resources and how these networks acted as microcosms of the larger system being played out at the national level. The majority of aquaculture activity throughout the 1980's was led by two US Agency for International Development funded projects, the Pond Dynamics/ Aquaculture Collaborative Research Support Program and an extension project, the Projet Pisciculture Nationale. Changes brought about by project networks became embedded in Rwanda's cultural, economic, and political structures. Through 15 years of promotion by donors, nontraditional farming technology was gaining a foothold in Rwanda. The case study demonstrates that institutional networks arose not through organizational preplanning but by default. This resulted in few of the planned objectives being as successful as unanticipated outcomes, such as the emergence of women as new technology adopters, the development of a highly successful water quality laboratory, and the inclusion of aquaculture into national policy. Many of the unanticipated results derived from the efforts of expatriates, who promoted aquaculture both actively and passively. While the expatriates were effective, the study questions whether a few external actors should accumulate so much power and influence over development agendas.

Environment, aquaculture, and food policy nexus; Case study of two USAID aquaculture projects in Rwanda
Book Chapter
2001
Fitzsimmons, K. 2001. Tilapia markets in the Americas, 2001 and beyond. Pp. 72 - 81 in Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, edited by D. Meyer. Tegucigalpa, Honduras.
NOP 02-176 (English)(Spanish)

NOP 02-176 (English)(Spanish)

The total market for tilapia in the Americas was almost 300,000 metric tons of live weight fish in 2000. Production in the Americas was approximately 257,000 mt and the US imported filets and frozen tilapia representing more than 30,000 mt of harvested fish from Eastern Hemisphere producers. Expanding demand sufficiently to absorb the rapidly expanding supply has become a critical task to support the current prices for tilapia products.

During the 1980's and 90's several different seafood publications declared tilapia to be the "new fish of the year". Since then tilapia has become one of the more popular seafood entrees in the Americas. As high quality tilapia products began to appear, its recognition as a quality seafood product has increased from Canada to Chile. Tilapia are not truly a new product in the Americas. Mossambique Tilapia, Oreochromis mossambicus were first introduced to the Caribbean by C.F. Hickling in 1947. They were quickly introduced throughout Central and South America. O. aureus, O. niloticus and several hybrid red strains were introduced in the 1960's and 1970's. 

Mexico currently produces and consumes (=100,000 mt) more tilapia than any other country in the Americas. The US is the next biggest consumer (>90,000 mt) but just a minor producer (<9,000 mt). Brazil and Cuba are the next largest producers / consumers. Costa Rica, Honduras, Ecuador, and Jamaica are the major exporting countries. Each has a well-developed infrastructure of production, processing and export, with Honduras being the most recent. Each of these exporting countries has some domestic consumption, but the relatively small population base and high level of investment required for large-scale production has driven them to look toward US and European markets. 

As supply continues to expand, consumer demand must also increase. "Push" and "pull" strategies are used by marketers to increase demand. Examples of these techniques are described as well as advertising and sales tools. One example of the efforts made by some producers to increase demand was the creation of a marketing entity. Several of the largest tilapia producers and importers/exporters to the U.S. have jointly funded the Tilapia Marketing Institute (TMI). The TMI has begun a broad ranging program to increase U.S. demand for tilapia products. The Institute is pursuing a generic campaign to increase demand for all product forms of tilapia. 

Tilapia markets in the Americas, 2001 and beyond
Conference Paper
2001
Funez, O., I. Neira, and C. R. Engle. 2001. Super market outlets for tiiapia in Honduras : an overview of survey results. Pp. 82 - 86 in Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, edited by D. Meyer. Tegucigalpa, Honduras. Retrieved (https://bdigital.zamorano.edu/handle/11036/3998%0D).
NOP 02-177 (English)(Spanish)

NOP 02-177 (English)(Spanish)

Tilapia culture was initiated in Honduras in the late 1970's (Teichert-Coddington and Green 1997). In the early years, tilapia production was primarily characterized by small-scale, family operations that were managed either extensively or semi-extensively as a supplemental agricultural activity. However in the last decade, tilapia production in Honduras has grown rapidly because of market expansion for fresh tilapia filets in the United States. Additionally, uncertain prices and disease problems that have struck the shrimp farmers to raise tilapia (Engle 1997a).

Super market outlets for tiiapia in Honduras : an overview of survey results
Conference Paper
2001

NOP 01-A08 (English) (Spanish)

The accumulation rate of organic matter has been used to develop guidelines on sediment management in tropical aquaculture ponds. However, there is conflicting evidence as to the rate of sediment organic matter accumulation and whether steady state concentrations are achieved in the short term (< 10 years) in aquaculture ponds. A simulation study using the multiple pool modeling approach (Multi-G model) was conducted to determine the long-term dynamics of sediment organic matter and to establish whether steady state concentrations could be achieved in tropical aquaculture ponds. The Multi-G model, which recognizes the existence of different organic matter pools, each with its own decay rate constant was run as a sub-model of an integrated aquaculture-agriculture system (IAAS) model. The simulation study was conducted for representative management scenarios for new integrated ponds receiving artificial feed, chicken manure, or a combination of chicken manure and crop wastes. The model was run for 10 years using a 0.125 day time step, and each year's simulation consisted of a wet and a dry season, and fallow periods between crops that totaled 121 days for the year. Pond sediment organic matter concentrations increased over time for all input regimes in the following order: chicken manure x plant waste > chicken manure > artificial feed. Simulated organic matter concentration decreased in the first 4-5 years in ponds receiving chicken manure and artificial feed. Contrary to predictions of models that used a single decay rate constant for the organic matter, steady state sediment organic matter were not achieved within the first 5 years of production. These results were consistent with those obtained from long term sediment organic matter experiments in tropical aquaculture ponds. The results show that the multiple pool modeling approach may be more applicable to the simulation of pond sediment organic matter dynamics than those that assume organic matter to consist of a single pool decaying at a single rate. ?? 2001 Published by Elsevier Science B.V.

Ten-year simulations of organic matter concentrations in tropical aquaculture ponds using the multiple pool modeling approach
Journal Article
2001
Lin, C. K., and Y. Yi. 2001. Developments in Integrated Aquaculture in Southeast Asia. Pp. 77 - 88 in Responsible aquaculture development in Southeast Asia : proceedings of the seminar-workshop on aquaculture development in Southeast Asia, Responsible aquaculture development in Southeast Asia : proceedings of the seminar-workshop on aquaculture development in Southeast Asia, edited by L.M.B. Garcia. Tigbauan, Iloilo, Philippines: Aquaculture Department, Southeast Asian Fisheries Development Center.
NOP 01-173 (English) (Spanish)

NOP 01-173 (English) (Spanish)

Integrated aquaculture is inclusive of interactive utilization of resources and ecosystems in the artificial rearing of aquatic animals and plants. By the nature, purpose and scale of the operation, integrated fish culture can be categorized into five major modes. One is the traditional small-scale subsistence farming where fish are produced by recycling on-farm wastes in ponds or rice field, two is recycling of human excreta, three is the “industrialized” commercial operation by integrating medium and large-scale poultry or livestock farms with ponds for fish production, four is integration of aquaculture with natural ecosystems, e.g., shrimp culture with mangroves, cage and pen culture in lakes, cove culture in reservoirs. The fifth is environmental-oriented integration, where waste effluents from intensive aquaculture ponds are recycled to improve water quality and to grow filter feeder/ herbivores or macrophytes as secondary crops. This paper presents concepts and practical examples for some of these systems.

Developments in Integrated Aquaculture in Southeast Asia
Conference Paper
2001

NOP 01-172 (English) (Spanish); NOP 01-A04 (English)

An experiment was conducted to evaluate the amount of wastes discharged from fish ponds during harvest and to assess pond draining schemes and harvest techniques that may reduce waste loading in effluent water. Nile tilapia (Oreochromis niloticus) were cultured for 113-119 days in twelve 200 m2 ponds with fertilization and supplementary pelleted feed. There were four treatments with three replicates each: (A) ponds were treated with teaseed cake at a rate of 10 ppm to partially anesthetize tilapia 1.5 h prior to harvest by three seinings without draining ponds; (B) ponds were limed at a rate of 75 ppm calcium hydroxide 24 h prior to harvest and drained by sequential complete draining, and then tilapia were collected from a harvesting pit; (C) ponds were drained by sequential complete draining and tilapia were collected from a harvesting pit; and (D) ponds were drawn from 100 to 50 cm and tilapia were harvested by two seinings, followed by complete draining and collection of the remaining tilapia from a harvesting pit. Treatment D is the common practice in Thailand. The harvest efficiency was 97% in treatment A. Comparing the harvest efficiency for the first two seinings, there were no significant differences between treatments A and D. Liming in treatment B resulted in significantly higher concentrations of 5 day biochemical oxygen demand, total settable matter, total solids and total phosphorus (TP) in the water discharged from the last 25 cm depth than those at both 100-50 and 50-25 cm depths, while there were no significant differences in effluent quality parameters among different depths in both treatments C and D. Concentrations of all effluent quality parameters in the water discharged from the last 25 cm depth in treatment B were higher than those in treatments C and D. Seining in treatment D resulted in the highest concentrations of all effluent quality parameters except TP at middle depth. Compared with the common draining practice, adoption of the sequential complete draining schemes (treatments B and C) caused 33-86% reductions for different effluent quality parameters except total nitrogen and TP in the discharged wastes. The present experiment showed that the use of teaseed cake to anesthetize tilapia could allow effective harvest by seining, without draining the pond. Alternatively, the discharge of potential pollutants from ponds into the environment could be reduced by sequential complete draining of ponds and collecting fish from harvesting pit (treatments B and C), and can be further reduced by modification of sequential partial draining of pond water level to 25 cm above pond bottom and seining fish without further draining. The present experiment demonstrated that appropriate management in pond draining and fish harvest could minimize the environmental impacts of pond effluents. 

Management to minimize the environmental impacts of pond effluent: Harvest draining techniques and effluent quality
Journal Article
2001
Meyer, D. E. 2001. Technology for successful small-scale tilapia culture. Pp. 97 - 106 in Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, edited by D. Meyer. Tegucigalpa, Honduras. Retrieved (https://bdigital.zamorano.edu/handle/11036/3998%0D).
NOP 02-179 (English)(Spanish)

NOP 02-179 (English)(Spanish)

Tilapia are tropical African fish that adapt well to the artificial conditions of the culture environment. These fish are hardy and resistant to diseases. They gain weight quickly at temperatures between 25 and 30 degrees Celsius and they reproduce on the farm without special management or infrastructure. Tilapia feed primarily on algae, other small organisms, and organic matter present in pond water and sediments. They quickly learn to consume artificial diets and can adapt to saltwater. Tilapia flesh is firm and white, and has an excellent flavor. In spite of all the advantages of tilapia, most small-scale fish culture projects established in Central America during the past 30 years have failed These failures are often related to several fundamental errors committed when establishing objectives for rural development projects, in the site selection process for building new ponds, and in the implementation of fish culture projects in rural areas. In many instances the aim of the extension or development program is to improve the nutritional status of the rural family by providing techniques for culturing fish. Fish are an excellent source of animal protein for humans. Historically, the emphasis on improved family nutrition has not been sufficient motivation to make tilapia culture a part of traditional agriculture production in rural Central America. There has been too little emphasis on establishing fish culture to improve the economic status of rural families in the region. We often make the mistake of constructing ponds at high elevation or in situations lacking adequate water resources. A warm climate and a year-round supply of adequate water are requirements for successful culture of tilapia. Often farmers are unable to obtain fingerlings to continue culturing tilapia in subsequent cycles following the first harvest. Many extension agents promoting tilapia culture do not have adequate knowledge to advise and assist farmers in this new technology. Most farmers do not have the knowledge and skills to manage the use of basic inputs (fertilizers and feeds) for successful fish culture. Small-scale tilapia production is not a panacea for rural poverty. Fish culture can provide high quality animal protein to improve the diet of rural families. The sale of fish can also contribute to improving the economic status of rural families in the region.

Technology for successful small-scale tilapia culture
Conference Paper
2001
Meyer, D. E. 2001. Nutrition and feeding of tilapia. Pp. 61 - 140 in Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, edited by D. Meyer. Tegucigalpa, Honduras. Retrieved (https://bdigital.zamorano.edu/handle/11036/3998%0D).
NOP 01-175 (English) (Spanish)

NOP 01-175 (English) (Spanish)

According to the most recent estimates, world production of cultured tilapia (Oreochromis sp.) is in excess of 1 million metric tons. Tilapia are cultured in a great variety of aquatic environments and with many different management protocols. The management of modern commercial tilapia production systems is an aquatic analog to North American feedlots used for beef production. The fish are held in cages and raceways at stocking densities that can exceed 100 fish/m3. The fish are fed to satiation several times each day using specially formulated feeds, and then promptly sacrificed and fileted, for shipment to market. Modern manufactured fish feeds are not well assimilated by tilapia. Typically only a small fraction (<30%) of the total content of N and P in the diet is incorporated into the fish’s biomass (= growth). The remaining amounts of each macronutrient are never ingested (feed not consumed), excreted into the pond water, lost as part of fecal material, or used for maintenance. There are several commercial farms in Central America that are successfully growing tilapia to export fresh filets to North America. Additional farms are coming online in the region. In Honduras the demand for tilapia has increased in the past few years and several farms are focusing on local markets. No matter where they are sold, the purchase of feed for fattening these fish is the largest cost in the production budget for commercial tilapia farmers regionally. Small-scale tilapia culture has not prospered locally. Fish culture is not a part of traditional agriculture in Central America. Local NGO run extension programs have had limited success in assisting rural farmers in growing tilapia. One important problem is the lack of knowledge in the proper management of costly inputs such as fish feed. How farmers manage the feeding of their fish is often the key to success, or reason for the failure, of a particular farm. This paper discusses some of the biological aspects of tilapia in relation to its nutritional needs and practical feeding of fish in the culture environment.

Nutrition and feeding of tilapia
Conference Paper
2001
Neira, I., and C. R. Engle. 2001. Markets for tilapia (Oreochromis sp.) in Nicaragua: a descriptive analysis of restaurants, supermarkets and stands in open markets. Pp. 87 - 91 in Simposio Centroamericano de Acuacultura, Simposio Centroamericano de Acuacultura, edited by D.E. Meyer. Tegucigalpa, Honduras. Retrieved (https://bdigital.zamorano.edu/handle/11036/3998%0D).
NOP 02-178 (English)(Spanish)

NOP 02-178 (English)(Spanish)

Commercial aquaculture has developed slowly in Nicaragua. Presently there are 2,407 ha of reservoirs utilized for tilapia production. However, low technology and poor management have resulted in inconsistent harvests; a restocking program maintains fish populations for villagers' subsistence (Durand 1997). Most of the tilapia farms in Nicaragua are small, approximately 0.01 ha, and are used primarily to produce fish extensively in low volumes for subsistence. Nicaragua is a country with ample resources to develop a farm-raised tilapia culture industry in ponds or cages in lakes and reservoir. No marketing studies, either qualitative or quantitative, have been done on the potential to develop a domestic market for farm-raised tilapia in Nicaragua. Domestic markets would provide stability by offering additional market alternatives that reduce risks associated with one target market. Development of a domestic market would also provide protein sources for Nicaraguans. The purpose of this research is to perform qualitative analyses of fish buyers such as stands in open markets, supermarkets, and restaurants.

Markets for tilapia (<i>Oreochromis</i> sp.) in Nicaragua: a descriptive analysis of restaurants, supermarkets and stands in open markets
Conference Paper
2001
Phelps, R. P. 2001. Sex Reversal : the directed control of gonadal development in tilapia. Pp. 35 - 60 in Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, edited by D. Meyer. Tegucigalpa, Honduras. Retrieved (https://bdigital.zamorano.edu/handle/11036/3998%0D).
NOP 01-174 (English) (Spanish)

NOP 01-174 (English) (Spanish)

Tilapia are becoming the most widely produced species of freshwater fish in the world. They can be produced in a variety of settings using a range of nutrient inputs. Males are the preferred sex to culture as they grow faster and divert less energy into reproduction. Males can be obtained using a variety of procedures but the most practical is through controlling gonadal development. Recently hatched tilapia fry have gonads that have not differentiated into ovaries or testes. It is possible to give such fish an exogenous source of hormone (androgen or estrogen) to control the development of the gonad. Fry less than 12 mm long can be harvested by seining along the edge of a spawning pond or from specialized spawning ponds where the pond is drained and harvested after 16-21 days. Proper size fish can also be obtained through a more intensive management approach where eggs are collected from the mouths of incubating females. Most commonly used approach to obtain male tilapia is to feed fry for 28 days or less a feed containing the androgen methyltestosterone. When fed properly the frequency of females in the population can be reduced to less than 5%. The short treatment duration very early in the fish's life history and rapid metabolism of methyltestosterone helps insure that tilapia are free of MT before fish reach the consumer. The production techniques associated with sex reversal are efficient and straight forward enough so that sex reversal has become the commercial procedure of choice to produce male tilapia fingerlings and has been a significant factor in the rapid growth of the tilapia industry.

Sex Reversal : the directed control of gonadal development in tilapia
Conference Paper
2001
Popma, T. J. 2001. Production and marketing strategies used by small and medium-scale fish farmers. Pp. 107 - 155 in Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, edited by D. Meyer. Tegucigalpa, Honduras. Retrieved (https://bdigital.zamorano.edu/handle/11036/3998%0D).
NOP 02-180 (English)(Spanish)

NOP 02-180 (English)(Spanish)

This report examines samples of farms from Honduras departments have and do not have tilapia ponds as part of their farming systems. Data were obtain through personal interviews with 128 farmers, including 64 tilapia producers, in five departments: Olancho, Intibuca, El Paraiso, Fransisco Morazan, and Santa Barbara. To obtain information about farms without tilapia, farmers were selected at random within the same community as the identified tilapia producers. Interviews were conducted in communities where the small-scale farmers with production of tilapia were located (Casley and Kumar 1988). The data are intended to constitute a representative sample of the population of the Honduran small aquaculture farmers in these departments. The analysis presents basic comparisons of landholding, farm, and personal characteristics of tilapia producers with the mirror sample of the farmers without tilapia. The analysis profiles basic differences between the two categories of farms, the operators, and their households. Younger farmers were more likely to become involved with tilapia farming. Those farmers more dedicated to their work inside their farm from which they obtain all their income, and whose principal occupation is being a farmer, were more inclined to adopt farming of tilapia. Farmers that use of their land more intensively and who dedicate themselves more to the farming of basic grains were more likely to adopt the farming of tilapia. Since Honduran small farmers tend to be a depressed segment economically, they tend to satisfy first their subsistence necessities by maximizing the use of their resources. The financing for both tilapia growers and non-growers tends to be a limiting factor because more than 80% of the population works without financing, a clear barrier to farm investments. Tilapia growers participated more in development projects.

Production and marketing strategies used by small and medium-scale fish farmers
Conference Paper
2001
Popma, T. J., and D. E. Meyer. 2001. Training and technical assistance in warm-water fish culture. Pp. 118 - 125 in Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, edited by D. Meyer. Tegucigalpa, Honduras. Retrieved (https://bdigital.zamorano.edu/handle/11036/3998%0D).
NOP 02-182 (English)(Spanish)

NOP 02-182 (English)(Spanish)

A central issue for aquaculture development in Honduras is fingerling supply. Previous PD/A CRSP research reported that farmers in remote places found that fingerlings were difficult to obtain but did not consider this sufficient reason for withdrawing from fish farming. The Zamorano Pl and his technician in this project confirmed that the Comayagua research station "El Carao" was not a reliable supplier of fingerlings for producers. Private fingerling producers are few and generally geared to supply large-scale commercial operations. The overriding objective of our work was to provide technical assistance and training to current and potential fingerling suppliers to small- and medium-scale tilapia producers in Honduras.

A Peace Corps program of technical support to fish farmers was possibly the most focused on-farm assistance to small-scale fish farmers in Honduras, but this program ended in 1995. The national extension program in aquaculture has a presence in many regions, but the effort is fragmented and under-funded. A large number of nongovernmental organizations promoting fish farming, but expertise in this activity is often insufficient to provide critical technical information required for proper pond management.

During November 1999, we consulted with 13 representatives of national and international, government and non-government organizations. From these consultations, a strategy and timetable were developed for implementing technical assistance and training of fingerling suppliers and technicians working with NGOs currently, or potentially involved in small- and medium-scale fish culture development. At least 33 small- and medium-scale tilapia producers (each with 150 - 12,000 m2 of water surface) and 26 restaurants were subsequently interviewed by the technical team to assess the production and marketing demands for tilapia in Honduras. With the collaboration of a local NGO, we invited representatives of NGOs with actual or potential interest in aquaculture development to a one-day seminar to describe opportunities and constraints for family-scale fish culture in Honduras. The Zamorano team continues to identify and provide technical assistance to regional fingerling producers and organizations involved in aquaculture extension. During the life of this activity three technical workshops were provided by Zamorano and Auburn for actual and prospective fingerling producers and extensionists. More than 30 publications on fingerling production and pond management practices have been incorporated in a web-based information system developed by a local NGO, primarily in response to needs of local NGOs.

 

Training and technical assistance in warm-water fish culture
Conference Paper
2001
NOP 01-169 (English) (Spanish)

NOP 01-169 (English) (Spanish)

Soil pH often is measured in samples from the bottoms of aquaculture ponds. Several different techniques for soil pH are used. This study considered the differences in pH obtained by the different methods and determined which methods appeared most useful. Dual electrodes (indicating and reference) and a single-probe combination electrode gave similar pH values when inserted into 1:l mixtures of dry soil and distilled water. There were slight differences in pH between readings with dual and combination electrodes when the dual electrodes were arranged with the indicating electrode in the sediment phase and the reference electrode in the supernatant phase of the mixture. The two-phase method with the dual electrode does not appear warranted because of greater difficulty in making measurements. Dry soil : distilled water ratios of 1:2.5, 15, and 1:lO had progressively greater pH readings than obtained at a 1:1 ratio. Measurements made in 0.01 M CaCI, and 1.0 M KCI had much different values than those made in distilled water. Higher pH resulted when pH was measured without stirring or in filtrates of soil-water mixtures. A 20-min period of intermittent stirring before making measurements was necessary for a stable pH value. Particle size did not influence pH in aliquots passing 0.053 to 2.36-mm sieves. Drying temperature had a strong influence on pH, and measurements made on samples dried at 40 to 60 degrees C are probably most reliable. Measurements of in situ pH in wet soil with standard pH electrode or a portable acidity tester differed greatly from those made in 1:l dry soil to distilled water mixtures. Pond bottom soil pH measurement should be standardized. Based on findings of this study, the following method is suggested: dry soil at 60 C in a forced-draft oven; pulverize soil to pass a 2-mm sieve; mix soil and distilled water in a 1:1 ratio (weight : volume); stir intermittently with glass rod for 30 min; insert dual electrodes or a combination electrode into the mixture; measure pH while stirring.

Pond Soil pH Measurement
Journal Article
2001
Tollner, E. W. 2001. Levee pond design model. Pp. 116 - 117 in Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, edited by D.E. Meyer. Tegucigalpa, Honduras. Retrieved (https://bdigital.zamorano.edu/handle/11036/3998%0D).
NOP 02-181 (English)(Spanish)

NOP 02-181 (English)(Spanish)

The levee pond model is an Excel spreadsheet that computes a volume balance on a levee pond. The model is organized into the following pages: Directions and overview, tables of contents, input, pond model, results and principal spillway. The design is based on answers to 15 key questions on the input page. Each question has guidance in the form of a comment that becomes visible when clicked upon. The model computes a volume balance on the pond as shown in a drawing on a "Drawings" page. The model is designed to assist competent NGO personnel in helping small to medium producers.

Levee pond design model
Conference Paper
2001

NOP 01-171 (English) (Spanish)

Honduras is the leading producer of pond‐raised shrimp in Central America, but profitability of operations is affected by fluctuating yields and prices which generate economic risk. An analysis of the financial risks associated with different management strategies would provide useful management guidelines. Data from a 1997 survey were used to develop enterprise budgets and a risk analysis for three farm‐size scenarios (73, 293, and 966 ha) and for a group of farms exhibiting an alternative, more intensive level of semi‐intensive technology (AST farms). Economies of size related to fixed costs and to feed, repair, and interest costs were identified. Net returns/ha were highest for the AST farms while low net returns/ha reported by the other farm groups were connected with low yields, conservative input usage rates, poor survivals, and economies of size. To minimize potential for loss, farms should target a minimum acceptable yield that would vary with farm size.

Risk analysis of shrimp farming in Honduras
Journal Article
2001

NOP 01-A02 (English) (Spanish)

Honduras is the most important cultivated shrimp producer among the Isthmus Central American countries, with a total production volume of 12,000 MT from an area of 14,000 ha during 1998. The shrimp industry observed the drop in production levels in 1994 and 1995, due to the presence of the Taura virus (TSV). Even though production levels partially recovered in 1997 and 1998, the introduction of the White Spot virus (WSSV) in the first months of 1999. resulted in a further decline in the production capacity of the farms.

Effects on yield and management strategies of farms in Honduras, by the survival rates of White Shrimp
Journal Article
2001
Verma, B. P. 2001. Web-based information delivery system for tilapia for sustainable development of aquaculture in Honduras. Pp. 126 - 134 in Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, Proceedings: Tilapia Sessions, 6to. Simposio Centroamericano de Acuacultura, edited by D. Meyer. Tegucigalpa, Honduras. Retrieved (https://bdigital.zamorano.edu/handle/11036/3998%0D).
NOP 02-183 (English)(Spanish)

NOP 02-183 (English)(Spanish)

The project was focused on identifying and developing methods to create an enabling environment for sustainable development of aquaculture on Honduras. Honduras has large network of NGOs operating at village level, an exceptional educational institution in Zamorano with commitment to extend training and knowledge in aquaculture and an established in-country sustainable development electronic network operated by Red de Desarrollo Sostenible-Honduras (RDS-HN). We develop the concept of training the trainers (NGOs working with farmers at village level) by bringing together Zamorano and RDS-HN and developing a Web-based Information Delivery System for Tilapia (WiDeST). In this approach WIDeST capture on the developed electronic information technology network and capacity of RDS-HN while providing a means to provide easy to use information developed by Zamorano. Furthermore, it provides a way to connect local NGOs, farmers, decision-makers for exchanging information and enabling them to make informed decisions. The WIDeST provides information in Tilapia production and related topics, natural resources of Honduras, contact information of NGOs, and chat room facilities for conducting virtual forums and discussions. The email facility enables the user to ask questions which is answered by an expert. Since the inauguration session in March 2001, the Website has had more than 6800 hits, and more than 300 individuals formally registered to receive information. The participants at training and workshop sessions have found this to be an easy and useful approach and have provided strong encouragement for adding new information. The number of individuals already reached as evidenced from the numbers of visits to the Website provide a strong evidence that is may be a way to build capacity of local institutions in developing and environment that enables farmers to adopt aquaculture as an alternative in their farms.

Web-based information delivery system for tilapia for sustainable development of aquaculture in Honduras
Conference Paper
2001
Yakupitiyage, A., and Y. Yi. 2001. Feeds in small-scale aquaculture. Pp. 263 - 268 in Utilizing Different Aquatic Resources for Liveliboods in Asia: A Resource Book, Utilizing Different Aquatic Resources for Liveliboods in Asia: A Resource Book. Cavite, Philippines: International Institute of Rural Reconstruction. Retrieved (https://www.worldfishcenter.org/content/utilizing-different-aquatic-resources-livelihoods-asia-resource-book).
NOP 01-A07 (English)

NOP 01-A07 (English)

Carp and tilapia are dominant species in freshwater fish culture in many Asian countries. Majority of carps and tilapias are produced by utilizing natural foods resulting from proper pond fertilization, often supplemented by artificial feeds to enhance fish yield and raise fish to a larger size than is possible with natural foods. Artificial feeds range from farm products such as grass and rice bran to farm-made, formulated feeds and commercial feeds. The choice of artificial feeds depends mainly on the cost and availability of resources to small-scale farmers.

Feeds in small-scale aquaculture
Book Chapter
2001
Yi, Y., C. K. Lin, and J. S. Diana. 2001. Integrating intensive and semi-intensive culture systems to utilize feeding waste. Pp. 250 - 253 in Utilizing Different Aquatic Resources for Liveliboods in Asia: A Resource Book, Utilizing Different Aquatic Resources for Liveliboods in Asia: A Resource Book, edited by J.T. Oliver, Nasar, S.S. Tabrez, Gonsalves, J.F., and Rivaca-Caminade, J.. Retrieved (https://www.worldfishcenter.org/content/utilizing-different-aquatic-resources-livelihoods-asia-resource-book).
NOP 01-A06 (English)

NOP 01-A06 (English)

In intensive fish culture, fish are generally fed with high protein diets. The nutrient-rich wastes derived from feeding are often directly or indirectly released to the surrounding environment, becoming a source of pollution. The wastes from intensive fish culture can be used for culturing filter-feeding fish species such as Nile tilapia (Oreochromis niloticus) at low cost. Dual integrated culture systems, namely cage-cum-pond and pen-cum-pond culture systems, have been developed to maximize fish production and profitability from given inputs and to minimize the environmental impact of intensive fish culture.

Integrating intensive and semi-intensive culture systems to utilize feeding waste
Book Chapter
2001
Yi, Y., and C. K. Lin. 2001. Low-cost fertilization in inland pond aquaculture. Pp. 250 - 253 in Utilizing Different Aquatic Resources for Liveliboods in Asia: A Resource Book, Utilizing Different Aquatic Resources for Liveliboods in Asia: A Resource Book. Cavite, Philippines: International Institute of Rural Reconstruction. Retrieved (https://www.worldfishcenter.org/content/utilizing-different-aquatic-resources-livelihoods-asia-resource-book).
NOP 01-A05 (English)

NOP 01-A05 (English)

The introduction and/or improvement of aquaculture in small-scale aquaculture in small-scale agriculture systems is constrained by the limited availability of on-farm resources for use in fish culture. However, pond fertilization, using animal manure, has long been practiced in many Asian countries. The general goal of pond fertilization involves: increasing natural food production, optimizing nutrient utilization efficiency and cost efficiency, and maintaining a favorable growth environment for culture species.

Low-cost fertilization in inland pond aquaculture
Book Chapter
2001

NOP 01-168 (English); NOP 01-A03 (English)

An experiment was conducted to determine the appropriate biomass of caged Nile tilapia (Oreochromis niloticus) supporting maximum production of small tilapia in open water and maintaining acceptable water quality, and to investigate effects of aeration on the growth of both caged and open-pond tilapia and water quality in an integrated cage-cum-pond system. One, two, three or four cages were suspended in un-aerated ponds as experimental treatments with three replicates each. An additional treatment with four cages in aerated ponds was also tested. Large tilapia (91 ± 2.6-103 ± 2.8 g) were stocked in 4-m3 net cages at 50 fish/m3, while tilapia fingerlings (13 ± 0.2-16 ± 0.8 g) were stocked at 2 fish/m3 in open water of all ponds. Caged tilapia were fed with floating pelleted feed twice daily at 3%, 2.5%, and 2% body weight/day during the first, second and third month, respectively. Important water quality parameters, such as dissolved oxygen, unionized ammonia nitrogen and chlorophyll a, were analyzed biweekly. The biomass of caged tilapia had significant (P < 0.05) effects on the growth of both caged and open-pond tilapia. Survival of caged tilapia decreased with increasing biomass of caged tilapia per pond, while survival of open-pond tilapia in the treatment with one cage was significantly (P < 0.05) lower than that in treatments with more cages. Final mean weight of caged tilapia decreased significantly (P < 0.05) from 478 ± 20.0 g in the treatment with one cage to 261 ± 10.0 g in the treatment with four cages. However, the growth of open-pond tilapia (0.74 ± 0.02-1.57 ± 0.10 g/fish/day) increased significantly (P < 0.05) with the increased biomass of caged tilapia per pond, in response to the increased feed inputs to cages. Total extrapolated net yield, including both caged and open-pond tilapia, was highest (6.20 ± 0.36 t/ha/crop) in the treatment with four cages; however, the treatments with one or two cages gave significantly (P < 0.05) better overall feed conversion ratio (0.82 ± 0.02-0.98 ± 0.02). Nighttime aeration for 5 h enhanced the growth of tilapia in the treatment with 4 cages/pond, and increased the carrying capacity in the integrated cage-cum-pond system. Net yield of caged tilapia in aerated ponds averaged 6.92 ± 0.60 t/ha/crop, which was significantly (P < 0.05) higher than that (3.65 ± 0.22 t/ha/crop) in un-aerated ponds with four cages each. However, the growth of open-pond tilapia in aerated ponds was significantly (P < 0.05) lower than that in un-aerated ponds. Further study should focus on determining the appropriate stocking density of open-pond tilapia to optimize the harvested tilapia size both from cages and open ponds in order to develop an integrated cage-cum-pond system for tilapia rotation culture. © 2001 Elsevier Science B.V.

Effects of biomass of caged Nile tilapia (<i>Oreochromis niloticus</i>) and aeration on the growth and yields in an integrated cage-cum-pond system
Journal Article
2001

2000

Bolivar, R. B., and G. F. Newkirk. 2000. Response to selection for body weight of Nile Tilapia (Oreochromis niloticus) in different culture environments. Pp. 12 - 23 in Tilapia Aquaculture in the 21st Century, Proceedings of the Fifth International Symposium on Tilapia Aquaculture, Tilapia Aquaculture in the 21st Century, Proceedings of the Fifth International Symposium on Tilapia Aquaculture, edited by K. Fitzsimmons and Filho, J.C. Rio de Janeiro. Retrieved (https://cals.arizona.edu/azaqua/ista/order.html).
NOP 00-156 (English) (Spanish)

NOP 00-156 (English) (Spanish)

Within-family selection was practiced in Nile tilapia (Oreochromis niloticus) for 12 generations to increase body weight at 16 weeks of age. Response to selection was evaluated based on the progenies from two selected generations (S10, S13). Two variants of control lines (random-bred control and mean selected control) were used to account for environmental changes during the course of the selection experiments. A genetically improved strain (GIFT strain) and a commercial strain (Israel strain) were included in the performance evaluation. Eight experiments were conducted between 1993 and 1997. The different test groups were stocked communally in tanks, hapas, and ponds. Results showed that the selected group consistently had higher final body weights in the three test culture environments. The highest response was observed in the selection environment (tanks). A higher response occurred in the tanks for S10 (68% as deviation from the RBC group) and the response was still substantial at S13. A significant interaction was observed in the 1996 GxE study but this can be attributed to a scale effect, a change in the magnitude of growth difference within group from one environment to another. In this study, the pond environment provided more optimal condition for growth than the tank and hapa environments. The results of 1993 and 1997 GxE analyses did not show significant test group x environment interaction. Overall, the results of these growth evaluations showed that the selected group produced from within-family selection had improved growth performance and the selection response achieved in the tanks was apparent in hapa and pond environments.

Response to selection for body weight of Nile Tilapia (<i>Oreochromis niloticus</i>) in different culture environments
Conference Paper
2000

NOP 00-153 (English) (Spanish)

Decision support systems (DSS) are potentially valuable tools for assessing the economic and ecological impacts of alternative decisions on aquaculture production. In this paper, we discuss the philosophy of design, functional modules and application areas of POND, a decision tool that has been developed to allow analysis of pond aquaculture facilities by the use of a combination of simulation models and enterprise budgeting. We focus less on the details of POND's internal models, and more on the experiences we have gained from going through the process of the designing, developing and using the POND software. POND was designed and implemented using object-oriented programming principles. The software makes use of a simulation framework to provide much of the generic simulation, data handling, time flow synchronization and communication features necessary for complex model-based DSSs. Additionally, an architecture suitable for representing and manipulating pond aquaculture facilities was developed in order to meet the design specifications of POND. This architecture includes a series of mini-databases, a number of knowledge-based components ('experts'), models of the pond ecosystem, and various decision support features (e.g. assembling alternate management scenarios, economic analysis, and data visualization). A typical POND simulation consists of assembling a number of appropriate objects or entities (e.g. multiple ponds and fish lots), their management settings together with appropriate experts (e.g. an aquaculture engineer, an aquatic biologist, an economist, etc.), and projecting changes in the facility over time. Our experience with the development of POND and other simulation-based tools indicates that the object-based approach provides a robust foundation for developing tools which allow code reusability, facilitate maintenance of complex software, and enable partition of program development among multiple programmers. Experience gained with POND users suggests that there are largely two groups of aquaculture personnel interested in such applications, namely commercial growers and educators. These two groups have substantially different interests and needs. Consequently, a single tool such as POND may not optimally meet the requirements of both groups. Recent development work on POND, and the need to involve users in the design process of such tools are discussed. (C) 2000 Elsevier Science B.V.

Development of decision support tools for aquaculture: The POND experience
Journal Article
2000

NOP 00-152 (English) (Spanish)

Total carbon concentrations and respiration rate were greater in the upper 0.5-cm or 1.0-cm layers of pond soil than in deeper layers. The respiration rate expressed on either a dry soil weight basis or a soil carbon basis decreased with increasing soil depth. This suggests that the ratio of labile to refractory organic matter also declines with increasing soil depth. Variation in soil properties with depth should be considered in pond bottom soil sampling programs.

Vertical gradients of organic matter concentration and respiration rate in pond bottom soils
Journal Article
2000

NOP 00-151 (English) (Spanish)

Chemical and physical analyses were conducted on bottom soil samples from 74 brackish- water ponds representing 40 shrimp farms in Ecuador. Most ponds had soils with pH > 6 and total carbon concentrations < 2.5%. Carbon was mostly in organic form, for the average concentration of carbonate carbon was 0.06%. The C:N ratio was 8 to 10 in soils with < 2.5% carbon. In ponds built in former mangrove areas, soil carbon was > 2.5% and C:N ratios were 25 to 30. Ponds soils in former mangrove areas also tended to be high in total sulfur and low in pH. Lack of correlation between carbon and sulfur in mangrove soils suggested that most of the sulfur was inorganic and presumably in sulfides. Soils containing above 0.4% free carbonate (as equivalent CaCO,) had pH values > 7. Although carbonate concentration was a major factor controlling soil pH, calcium hardness of pond waters was strongly influenced by salinity (and calcium) in the water supply. Total phosphorus concentrations averaged 898 mg/kg, and dilute acid extractable phosphorus usually accounted for 25-35% of the total. Concentrations of major cations and minor elements varied greatly in soils and exhibited ranges of up to three orders of magnitude. Contrary to opinions of shrimp producers, many pond soils in Ecuador are not acidic and few soils have a high organic matter content. Proper use of soil and water testing could greatly improve the efficiency of liming and other soil management practices.

Chemical and physical properties of shrimp pond bottom soils in Ecuador
Journal Article
2000
Brown, C. L., R. B. Bolivar, E. T. Jimenez, and J. P. Szyper. 2000. Timing of the onset of supplemental feeding of Nile tilapia (Oreochromis niloticus) in ponds. Pp. 237 - 240 in Tilapia Aquaculture in the 21st Century, Proceedings of the Fifth International Symposium on Tilapia Aquaculture, Tilapia Aquaculture in the 21st Century, Proceedings of the Fifth International Symposium on Tilapia Aquaculture, edited by K. Fitzsimmons and Filho, J.C. Rio de Janeiro. Retrieved (https://cals.arizona.edu/azaqua/ista/order.html).
NOP 00-158 (English) (Spanish)

NOP 00-158 (English) (Spanish)

An on-farm trial was conducted in seven (7) farms in Nueva Ecija, Philippines, to investigate the effect of two onsets of feeding on the growth, yield, and survival of Nile tilapia. There were no significant differences on the performance data (final mean weight, daily weight gain, extrapolated gross fish yield, and survival rate) that were recorded in this study. The only statistically significant difference observed was in the total quantities of feed used in the trial. The 45-day onset in feeding produced a slightly higher mean gross value of the crop (P205,617 ha-1) compared with the 75-day delay (P197,063 ha-1) but by delaying the start of feeding to 75 days, the costs were reduced such that the net value of the crop was improved (P124,242 ha-1 in 75-day delay vs. P106,026 ha-1 in 45-day delay).

Timing of the onset of supplemental feeding of Nile tilapia (<i>Oreochromis niloticus</i>) in ponds
Conference Paper
2000
Contreras-Sánchez, W. M., M. S. Fitzpatrick, R. H. Milston, and C. B. Shreck. 2000. Masculinization of Nile tilapia with steroids: alternate treatments and environmental effects. Pp. 250 - 252 in Proceedings of the 6th International Symposium on the Reproductive Physiology of Fish, Proceedings of the 6th International Symposium on the Reproductive Physiology of Fish, edited by B. Norberg, Kjesbu, O.S., Taranger, G.L., Anderson, E., and Stefansson, S.O. Bergen, Norway: University of Bergen. Retrieved (http://www.worldcat.org/title/proceedings-of-the-6th-international-symposium-on-the-reproductive-physiology-of-fish-institute-of-marine-research-and-university-of-bergen-4-9-july-1999/oclc/45613554).
NOP 01-165 (English) (Spanish)

NOP 01-165 (English) (Spanish)

Steroid-treated food is widely used to masculinize tilapia. We have previously shown that short-term immersion in steroids can also masculinize Nile tilapia. In the following study, we determined that a single immersion of tilapia fry in Trenbolone Acetate for 3 hr on 12, 13, or 14 days post-fertilization (dpf) or multiple immersions in combinations of days between 12 and 15 dpf, can result in masculinization. However, effectiveness of immersion treatment varied between experiments, suggesting that sensitivity to treatment may differ between individual broods. We also found that the use of 17α-methyltestosterone (MT)-treated food to masculinize Nile tilapia results in accumulation of MT in sediments even after cessation of treatment.

Masculinization of Nile tilapia with steroids: alternate treatments and environmental effects
Conference Paper
2000

NOP 00-A03 (English); NOP 01-170 (English)(Spanish)

Economic returns to the investment in shrimp research in Honduras by Auburn University researchers, as a part of the Pond Dynamics/Aquaculture Collaborative Research Support Program (1993 to 1998), were estimated using a nonparametric approach. A survey of shrimp growers in Honduras provided dada on yield, input application, and prices for their first year of production and for the year 1997. Research investment data included funding from both public and private sectors. Results showed that total factor productivity indices increased from 1995 to 1997 indicating technical progress due to research. When both private and public investment were considered, the internal rate of return to the investment in research was 46%. However, the internal rate of return to public-sector investment alone was above 6,681%. This indicated that the public funds invested in shrimp research in Honduras have been leveraged effectively with private-sector capital to generate technological progress.

Nonparametric Estimation of Returns to Investment in Honduras Shrimp Research
Journal Article
2000
Edwards, P., C. K. Lin, and A. Yakupitiyage. 2000. Semi-intensive pond aquaculture. Pp. 377 - 403 in Tilapias: Biology and Exploitation, Tilapias: Biology and Exploitation, edited by M. Beveridge and McAndrew, B.J. Springer Netherlands. Retrieved (http://link.springer.com/chapter/10.1007/978-94-011-4008-9_10).
NOP 00-A05 (English)

NOP 00-A05 (English)

Semi-intensive production of tilapia in ponds using fertilizers and supplementary feeds is a means to produce low-cost fish which contributes to national food security in many developing countries. Culture of herbivorous and omnivorous tilapias feeding low down on the food chain provides produce that is potentially available to a wide range of consumers as a staple food. This feature led to tilapia being referred to as an ’aquatic chicken’ (Maclean, 1984). Indeed, global production and value of farmed tilapias increased at a recorded average rate of 11.4 and 15.5% between 1986 and 1995, respectively (FAO, 1997). The rate of increase has probably been higher because of considerable underestimation of farmed tilapia production, particularly in Asia which dominates production, because of the difficulty of collecting statistics from diverse and widely scattered farms in developing countries. Using hatchery data as a proxy for output may be useful for carps and other species produced in conventional hatcheries but as tilapia can breed in food fish production systems this method cannot be used (Little and Hulata, this volume). Tilapias are currently farmed commercially or experimentally in at least 75 countries (Pullin et al, 1994). Over the past decade a low-tech/high-tech 'divide' has developed in tilapia culture similar to that which occurred with poultry (Pullin et al., 1994). At the same time that small-scale farmers in developing countries in Asia are introducing tilapias into traditional carp polycultures, entrepreneurs are exploring ways to farm tilapia as an international commodity, usually rising demand for high quality 'white fish' products in the developed world, especially in Europe and North America. However, the major factor inhibiting the purchase of more tilapia in North America is price; tilapia is overpriced compared to chicken and most other forms of animal protein using current, largely intensive methods of aquaculture (Smiley, 1995). The case is made in this chapter that a semi-intensive mode of pond culture can be used effectively to satisfy both the subsistence needs and growing desire of small-scale farmers to intensify production to generate and to lower the cost of production of industrial scale farming. The current status of production and regional evolution of culture of tilapias is compared with carps, the major group of inland herbivorous / omnivorous finfish. Culture systems of tilapias in three major resource zones (inland, rural areas; wastewater-fed culture in periurban areas; and in coastal areas) are discussed. The scientific basis of pond fertilization and supplementary feeding strategies are reviewed, followed by consideration of environmental and long term sustainability of semi-intensive pond culture of tilapias. 

Semi-intensive pond aquaculture
Book Chapter
2000

NOP 00-154 (English) (Spanish) and NOP 00-A02 (English)

Development and application of a software product for aquaculture facility design and management planning are described (AquaFarm, Oregon State University©). AquaFarm provides: (1) simulation of physical, chemical, and biological unit processes; (2) simulation of facility and fish culture management; (3) compilation of facility resource and enterprise budgets; and (4) a graphical user interface and data management capabilities. These analytical tools are combined into an interactive, decision support system for the simulation, analysis, and evaluation of alternative design and management strategies. The quantitative methods and models used in AquaFarm are primarily adapted from the aquaculture science and engineering literature and mechanistic in nature. In addition, new methods have been developed and empirically based simplifications implemented as required to construct a comprehensive, practically oriented, system level, aquaculture simulator. In the use of AquaFarm, aquaculture production facilities can be of any design and management intensity, for purposes of broodfish maturation, egg incubation, and/or growout of finfish or crustaceans in cage, single pass, serial reuse, water recirculation, or solar-algae pond systems. The user has total control over all facility and management specifications, including site climate and water supplies, components and configurations of fish culture systems, fish and facility management strategies, unit costs of budget items, and production species and objectives (target fish weights/states and numbers at given future dates). In addition, parameters of unit process models are accessible to the user, including species-specific parameters of fish performance models. Based on these given specifications, aquaculture facilities are simulated, resource requirements and enterprise budgets compiled, and operation and management schedules determined so that fish production objectives are achieved. When facility requirements or production objectives are found to be operationally or economically unacceptable, desired results are obtained through iterative design refinement. Facility performance is reported to the user as management schedules, summary reports, enterprise budgets, and tabular and graphical compilations of time-series data for unit process, fish, and water quality variables. Application of AquaFarm to various types of aquaculture systems is demonstrated. AquaFarm is applicable to a range of aquaculture interests, including education, development, and production.

AquaFarm: simulation and decision support for aquaculture facility design and management planning
Journal Article
2000
Jamu, D. M. 2000. A pilot study on the spatial and temporal soil moisture distribution in integrated crop-fish-wetland and crop-wetland agroecosystems in Zomba-East, Malawi. Pp. 582 - 587 in Tilapia in the 21st Century: Proceedings of the Fifth International Symposium on Tilapia in Aquaculture, Tilapia in the 21st Century: Proceedings of the Fifth International Symposium on Tilapia in Aquaculture, edited by K. Fitzsimmons and Filho, J.C. Rio de Janeiro. Retrieved (https://cals.arizona.edu/azaqua/ista/order.html).
NOP 00-163 (English) (Spanish)

NOP 00-163 (English) (Spanish)

Integration of aquaculture into existing agricultural systems has been reported to improve productivity and ecological sustainability through better water management, improved soil fertility arising from waste recycling and synergies occurring between the aquaculture and agricultural components, and extension of the crop growing season. While information is available on the role of integrated systems in improving soil fertility and waste recycling, quantitative data on the influence of fishponds on the length of the crop growing season, and the temporal and spatial distribution of soil moisture around fishponds is not available. I therefore quantified the influence of fishponds on soil moisture regimes on six farm systems in Zomba district by comparing the spatial and temporal distribution of soil moisture between farm subsystems with fishponds (integrated crop-fish-wetland) with that from adjacent sites without fishponds (crop-wetland). Four sampling transects, each with five sampling sites placed at 2, 4, 6, 8 and 10m from the pond dike were established at four cardinal points of the pond. Soil samples were obtained biweekly from each sampling site for gravimetric soil moisture determination. Sampling was terminated when soil moisture content fell below the permanent crop wilting point, which for this study was 13%. A similar procedure was adopted for the crop-wetland subsystem; however, a predetermined axis in the subsystem was used as a reference point for the placement of transects. Soil moisture content was measured gravimetrically. A paired t-test was used to determine differences in soil moisture content between the integrated crop-fish-wetland and crop-wetland subsystem. The length of the crop-growing season was defined as the period during which soil moisture content was above the permanent wilting point and below field capacity (23% moisture content). One-way ANOVA was used to determine significant differences (P < 0.05) in the spatial distribution of soil moisture between the four cardinal points of each subsystem. Significant differences (P < 0.05) in soil moisture content between the two subsystems were detected at five of the six farms sampled. At two of the sites where significant differences were detected, the crop-wetland subsystem. Placement of a fishpond in a seasonal wetland did not influence the length of the crop-growing season. These initial results appear to suggest that although integration of fishponds in crop-wetland systems may significantly affect soil moisture regimes, these differences are not important in so far as the extension of the crop-growing season is concerned. Since the study used a small sample size and soil samples from the top 15 cm of the soil, and the fishpond may influence soil moisture below this zone, further studies that incorporate more farms and sample at depths greater than 15 cm are needed before definitive conclusions on the influence of fishponds on soil moisture regimes in seasonal wetlands are drawn.

A pilot study on the spatial and temporal soil moisture distribution in integrated crop-fish-wetland and crop-wetland agroecosystems in Zomba-East, Malawi
Conference Paper
2000
Lin, C. K., and K. Kaewpaitoon. 2000. An overview of freshwater cage culture in Thailand. Pp. 237 - 242 in Proceedings of the First International Symposium on Cage Aquaculture in Asia, Proceedings of the First International Symposium on Cage Aquaculture in Asia, edited by I.C. Liao and Lin, C.K. Manila, Philippines: Asian Fisheries Society. Retrieved (http://agris.fao.org/agris-search/search.do?recordID=PH2002001163).
NOP 00-149 (English)(Spanish)

NOP 00-149 (English)(Spanish)

Despite its long history and a large number of rivers and reservoirs in Thailand, cage culture contributed only 0.3% of 200,000 tons in total fish production from freshwater aquaculture. Over the last decade, the peak of annual fish production from freshwater cages reached 2,700 tons in 1991 and declined since to a minimum of 600 tons in 1995. Although cage culture takes place in various habitats such as river, reservoirs, irrigation canals and large ponds, its predominant habitats are in flowing waters. Among a dozen of cultured species, red snakehead (Channa micropeltes), catfish (Pangasius spp.), marble goby (Oxyeleotris marmoratus) and tilapia (Oreochromis spp.) topped the list. The production of those species fluctuated drastically resulting mainly from deteriorating water quality, competing for trash fish feed, changing market value, and shifting culture practices. However, disease and fingerling supply caused the reduction and limitation in culture of the most valued marble goby. Recently, the cage culture of tilapia has gained great popularity in certain parts of the country. Cage culture has been a small-scale, artisanal operation with little research and technical innovation. Further development of cage cultures in freshwater lies on ecologically sound multiple uses of reservoirs and flowing waters. In addition, integration of intensive cage culture with semi-intensive species in ponds should also be promoted.

An overview of freshwater cage culture in Thailand
Conference Paper
2000
Lovshin, L. L. 2000. Criteria for Selecting Nile Tilapia and Red Tilapia for Culture. Pp. 49 - 57 in Tilapia Aquaculture in the 21st Century, Proceedings of the Fifth International Symposium on Tilapia Aquaculture, Tilapia Aquaculture in the 21st Century, Proceedings of the Fifth International Symposium on Tilapia Aquaculture, edited by K. Fitzsimmons and Filho, J.C. Rio de Janeiro. Retrieved (https://cals.arizona.edu/azaqua/ista/order.html).
NOP 00-157 (English) (Spanish)

NOP 00-157 (English) (Spanish)

Tilapia farmers often have problems deciding if Nile tilapia or red tilapia is the proper choice for culture. Nile tilapia is the most widely farmed tilapia world-wide but interest in red tilapia culture is growing rapidly. Nile tilapia are more dependable spawners and produce more consistent quantities of fry than red tilapia. Survival of eggs, fry and juveniles is higher for Nile tilapia and Nile tilapia are more tolerant of low water temperatures than most strains of red tilapia. Red tilapia often have higher market value, are more appropriate for culture in salinities above 10 g/l, and are easier to seine harvest from earthen ponds and transport live than Nile tilapia. Red tilapia need continual selection to retain their red color and pass the red color from generation to generation. Farmers should evaluate environmental conditions, culture system and markets before selecting either Nile tilapia or red tilapia for culture.

Criteria for Selecting Nile Tilapia and Red Tilapia for Culture
Conference Paper
2000
Lovshin, L. L. 2000. Evaluation of tilapia culture by resource limited farmers in Panama and Guatamala. Pp. 633 - 638 in Tilapia in the 21st Century: Proceedings of the Fifth International Symposium on Tilapia in Aquaculture, Tilapia in the 21st Century: Proceedings of the Fifth International Symposium on Tilapia in Aquaculture, edited by K. Fitzsimmons and Filho, J.C. Rio de Janeiro. Retrieved (https://cals.arizona.edu/azaqua/ista/order.html).
NOP 00-164 (English) (Spanish)

NOP 00-164 (English) (Spanish)

Mixed-sex and male Nile tilapia, Oreochromis niloticus, were cultured in family and communally managed fish-ponds in Guatemala and Panama in the 1980's. Fish were used to improve family nutrition and meager incomes of the pond managers. Tilapia culture systems were designed to permit farmers with no fish culture experience to produce their own tilapia fingerlings on-farm and grow the fingerlings using available household by-products and animal manures to sizes required for home consumption and sale. The author returned to Guatemala and Panama in 1998 to evaluate the ability of pond managers to learn and sustain tilapia culture as a farm activity. Mixed-sex culture of Nile tilapia was the culture system introduced to Guatemalan pond managers in the 1980's and continues as the only culture system employed by those farmers still growing fish. Forty-three percent of the pond projects were abandoned between 1989 and 1998. Seventy-two percent of Guatemalan farmers produced small tilapia for pond stocking on-farm or obtained them for neighbors. Use of the predacious guapote tigre, Cichlasoma managuense, to control tilapia offspring in grow-out ponds increased from 14% in 1989 to 36% in 1998. Pond managers in Panama were shown how to grow either mixed-sex Nile tilapia with the guapote tigre or monosex male Nile tilapia to reduce tilapia offspring during grow-out and permit harvest of a 200 to 400 g fish. Twenty-nine percent of the pond projects polycultured mixed-sex tilapia with a predator and 71% grew male tilapia in 1984. Forty-eight percent of the pond projects were abandoned between 1984 and 1998. Of the projects still culturing tilapia in 1998, 36% cultured mixed-sex tilapia with a predator and 64% cultured male tilapia. Sixty-four percent of the projects still growing fish in 1998 stocked guapote tigre, indicating that some of the projects stocking male tilapia were also stocking guapote to control tilapia offspring. Most pond managers did not produce tilapia fingerlings on-farm as 82% of the fishpond projects received their tilapia fingerlings from the government hatchery. Economic and nutritional impacts from fish culture as documented for Panama in 1984 and Guatamala in 1989 were not sustained. The failure of fish culture in Guatamala and Panama does not rest solely with tilapia but with a complex of economic, social, technical and political issues that combined to limit the intended impact of fish culture on impoverished pond managers and their families.

Evaluation of tilapia culture by resource limited farmers in Panama and Guatamala
Conference Paper
2000
Mckeon, C., E. Glenn, C. P. Gerba, and K. Fitzsimmons. 2000. Microbiological Hazards of Tilapia Culture Systems. Pp. 479 - 485 in Tilapia in the 21st Century: Proceedings of the Fifth International Symposium on Tilapia in Aquaculture, Tilapia in the 21st Century: Proceedings of the Fifth International Symposium on Tilapia in Aquaculture, edited by K. Fitzsimmons and Filho, J.C. Rio de Janeiro. Retrieved (https://cals.arizona.edu/azaqua/ista/order.html).
NOP 00-161 (English) (Spanish)

NOP 00-161 (English) (Spanish)

Fecal coliform levels were measured in seven freshwater fish culture systems to assess potential microbiological hazards. Over a two month period, fecal coliform concentrations in two tilapia research facilities varied from 1 to 104 colony forming units (CFU) per 100 ml of water, at a mean level that could indicate the presence of human pathogens that may be hazardous to fish handlers and consumers. Over a one-month period, five commercial systems were found to contain Escherichia coli, Clostridium perfringens, Enterococci, and fecal coliforms. The concentration of fecal coliforms at the commercial sites was higher than the level found at the research facility. The presence of such organisms creates a potential for microbiological hazards in these systems. No Salmonella was detected in the systems. The source of these indicator organisms was not determined, nor were any host organisms obvious in the system. The findings in this study indicate that monitoring fish culture facilities for microbiological safety should be considered. In addition, workers should be aware of personal hygiene when entering, while working in, and when departing fish culture facilities.

Microbiological Hazards of Tilapia Culture Systems
Conference Paper
2000

NOP 00-155 and NOP 00-A01 (English) (Spanish)

Geographical information systems (GIS) are becoming an increasingly integral component of natural resource management activities worldwide. However, despite some indication that these tools are receiving attention within the aquaculture community, their deployment for spatial decision support in this domain continues to be very slow. This situation is attributable to a number of constraints including a lack of appreciation of the technology, limited understanding of GIS principles and associated methodology, and inadequate organizational commitment to ensure continuity of these spatial decision support tools. This paper analyzes these constraints in depth, and includes reviews of basic GIS terminology, methodology, case studies in aquaculture and future trends. The section on GIS terminology addresses the two fundamental types of GIS (raster and vector), and discusses aspects related to the visualization of outcomes. With regard to GIS methodology, the argument is made for close involvement of end users, subject matter specialists and analysts in all projects. A user-driven framework, which involves seven phases, to support this process is presented together with details of the degree of involvement of each category of personnel, associated activities and analytical procedures. The section on case studies reviews in considerable detail four aquaculture applications which are demonstrative of the extent to which GIS can be deployed, indicate the range in complexity of analytical methods used, provide insight into issues associated with data procurement and handling, and demonstrate the diversity of GIS packages that are available. Finally, the section on the future of GIS examines the direction in which the technology is moving, emerging trends with regard to analytical methods, and challenges that need to be addressed if GIS is to realize its full potential as a spatial decision support tool for aquaculture.

Applications of geographical information systems (GIS) for spatial decision support in aquaculture
Journal Article
2000
Phelps, R. P., and T. J. Popma. 2000. Sex reversal of tilapia. Pp. 34 - 59 in Tilapia Aquacultue in the Americas, vol. 2, Tilapia Aquacultue in the Americas, edited by B.A. Costa-Pierce and Rakocy, J.E. Baton Rouge, Louisiana: World Aquaculture Society. Retrieved (http://www.was.org/Shopping/tilapia-aquaculture-in-the-americas-volume-two).
NOP 00-A04 (English)

NOP 00-A04 (English)

Early maturation and frequent spawning are management challenges when working with tilapia. Male tilapia are preferred for culture because of their faster growth. Of the various techniques that have been developed to provide male tilapia for culture, sex reversal is the most commonly used procedure. Recently hatched tilapia fry do not have developed gonads. It is possible to intervene at this early point in the life history and direct gonadal development to produce monosex populations. Exogenous steroids given during the gonadal development period can control the phenotype overriding the expression of the genotypically determined sex. This process is commonly referred to as sex reversal. Androgens direct the development to males and estrogens to females. Methyltestosterone is the most commonly used androgen to direct the sex of tilapia. Various protocols regarding dose rate and treatment duration have been evaluated. All depend on hormonal treatment with sexually undifferentiated fry. Fry may be obtained by partial or complete harvests of spawning containers. Containers used for tilapia spawning include indoor and outdoor tanks, earthen ponds and fine mesh net enclosures (hapas). When fish are treated from the beginning to end of the gonadal differentiation period with a proper dose of androgen the resultant fish population will be highly skewed to males.

Sex reversal of tilapia
Book Chapter
2000

NOP 01-166 (English) (Spanish)

Accumulation of organic matter increases oxygen demand and the development of reducing and acidic conditions in bottom soils. Deterioration of soil and water quality in aquaculture systems is often associated with decomposition of organic matter over time. Several commercial products currently used in shrimp ponds in Ecuador to accelerate decomposition of organic matter during the fallow period were evaluated. Two ponds were used, one with a salinity of 10 - 20 ppt and the other with 30 ppt. Soil respiration rates were evaluated in situ and in the laboratory. Each treatment was replicated four times. All experiments resulted in a similar drop in soil pH, although differences in soil moisture content occurred for the different evaluations. No statistical differences were found among treatments. No benefits were found by applying bacterial inocula or enzymatic suspension to enhance organic matter decomposition probably resulted because soils were not extremely high in organic matter content or deficient in microorganisms or extracellular enzymes.

Managing the accumulation of organic matter deposited on the bottom of shrimp ponds... Do chemical and biological probiotics really work?
Journal Article
2000

NOP 00-A06 (English)

Shrimp farms in Latin America typically have relatively low stocking rates and are managed without aeration. Nutrient budgets for these farms have not been well established. Intake and discharge from 21 ponds on six shrimp farms located on estuaries or embayments of the Gulf of Fonseca in Honduras were characterized during rainy and dry seasons. Mean shrimp stocking rate, yield, and feed conversion ratio (FCR) for these ponds were 8.2/m2, 633 kg/ha, and 2.74, respectively. Mean intake values of soluble reactive phosphate (SRP), dissolved inorganic nitrogen (DIN), total nitrogen (TN), total phosphorus (TP) and BOD5 were significantly higher in estuaries than in embayments during both seasons. Water exchange produced a mean net discharge of TN, TP, BOD5, chlorophyll a, COD, total alkalinity and salinity, and a mean net intake of DIN; mean SRP was practically equal in discharge and intake water. Each kilogram of feed nitrogen and phosphorus applied to ponds resulted in 0.21 kg of net nitrogen discharge and 0.16 kg of net phosphorus discharge by water exchange. Use of inorganic fertilizers promoted net discharge of phosphorus and nitrogen. Net nitrogen discharge by water exchange significantly increased as nitrogen input by feed increased (P < 0.01). Ponds gained nitrogen primarily from intake water (63%) and feed (36%), and nitrogen was lost primarily from water exchange (72%) and harvested shrimp (14%). Ponds gained phosphorus mostly from intake water (51%) and feed (47%), and phosphorus was lost primarily from water exchange (56%) and harvested shrimp (9%). About 7% of input nitrogen and almost a third (31%) of input phosphorus were not accounted for in measured losses, and presumably were fixed or metabolized in ponds. Mean conversion of feed nitrogen and phosphorus to shrimp flesh averaged 41% and 20%, respectively. Each kilogram of shrimp production resulted in 16.8 g of net nitrogen loss and 2.3 g of net phosphorus loss by water exchange. (C) 2000 Elsevier Science B.V.

Partial nutrient budgets for semi-intensive shrimp farms in Honduras
Journal Article
2000
Verdegem, M. C. J., I. A. A. VanDam, A. A. Cabarcas-Nuñez, and L. Oprea. 2000. Bio-energetic Modeling of Growth and Waste Production of Nile Tilapia (Oreochromis niloticus L.) in Ricurculation Systems. Pp. 368 - 381 in Tilapia in the 21st Century: Proceedings of the Fifth International Symposium on Tilapia in Aquaculture, Tilapia in the 21st Century: Proceedings of the Fifth International Symposium on Tilapia in Aquaculture, edited by K. Fitzsimmons and Filho, J.C. Rio de Janeiro. Retrieved (https://cals.arizona.edu/azaqua/ista/order.html).
NOP 00-162 (English) (Spanish)

NOP 00-162 (English) (Spanish)

A bio-energetic fish growth simulation (FGS) model was developed for Clarias gariepinus and subsequently adjusted for the culture of Oreochromis niloticus, Oncorhynchus mykiss and Colossoma macropomum. The FGS model was extended with a fish waste module (FWM) to calculate the total waste production due to feeding by tilapias grown in indoor recirculation systems. Wastes calculated included the amount of uneaten feed, feces and NH4+ production. The amounts of wastes produced were expressed as g nitrogen (N). The model was calibrated and validated using 3 independent data sets, together comprising 175 aquarium experiments, monitoring growth in all cases and changes in proximate body composition of O. niloticus between stocking and harvesting in 51 cases. Fishes were grown in the individual weight range of 1 – 290 g using 32-54 % protein diets and feeding levels between 5 and 35 g kg-0.8 d-1. The principal read-out parameters for calibration and validation of the model were final weight and final body fat level. Because waste production is the result of the same metabolic processes that lead to protein and fat deposition, it was assumed that waste production was simulated well when protein and fat deposition are. The calibrated model was used to review the effect of feeding level and dietary protein level on N-waste production per kg tilapia produced. Finally, tilapias were grown in 2 different types of recirculation systems and stagnant water ponds, quantifying N-inputs and the amount of N-wastes recovered from each system. The latter was defined as the sum of N-waste discharged (sludge and sludge water drained) and within system accumulation of N-wastes (organic and inorganic nutrients) during culture. After model calibration, the agreement between simulated and observed final weight and body fat level for all data sets was visualized. In recirculation systems different types of N-wastes were estimated well by the model. Care must be taken when applying the model to pond systems. More insight is needed on feeding ecology of tilapias in these systems.

Bio-energetic Modeling of Growth and Waste Production of Nile Tilapia (<i>Oreochromis niloticus</i> L.) in Ricurculation Systems
Conference Paper
2000
Verma, B. P. et al. 2000. Concurrent Design of Hillside Ponds for Tilapia Production. Pp. 311 - 315 in Tilapia Aquaculture in the 21st Century, Proceedings of the Fifth International Symposium on Tilapia Aquaculture, Tilapia Aquaculture in the 21st Century, Proceedings of the Fifth International Symposium on Tilapia Aquaculture, edited by K. Fitzsimmons and Filho, J.C. Rio de Janeiro. Retrieved (https://cals.arizona.edu/azaqua/ista/order.html).
NOP 00-160 (English) (Spanish)

NOP 00-160 (English) (Spanish)

Farming on hillsides in Latin America has resulted in progressive deterioration of natural resources due to a combination of overgrazing, poor farming practices, deforestation, and poor water management. The introduction of tilapia production could improve the nutrition of farm families and local communities and provide a means of additional earning for improving economic status. An important aspect of designing and successfully introducing tilapia in Honduras and the adjoining regions is to have all stakeholders identify needs that include technical requirements as well as social and environmental issues important in the design of ponds and the production of tilapia. The fundamental method of pond design used here was based on the principles of concurrent engineering design methodology. In this method all stakeholders, hereafter referred to as "customers" (a person or entity that can impact the building, maintenance, and use of ponds for tilapia production), are identified. Our customer list included Honduras farmers, extension agents, government agencies, nongovernmental organizations, builders, and design engineers. Customer needs were identified and prioritized based on information from literature and input from experts representing perspectives of the identified customers. Design concepts were then tested using a US National Resource Information System. Concurrently considering needs of all customers in the design and selection of construction method provides a powerful method to have the user educated and invested in the design. This approach presents an increased possibility of introducing acceptable pond design and tilapia production as an economic enterprise in Honduras and Central America. 

Concurrent Design of Hillside Ponds for Tilapia Production
Conference Paper
2000

Intensive data collection and a modeling study have been underway for the past several years addressing two of the channel estuaries draining into the Gulf of Fonseca, Estero El Pedregal and Estero San Bernardo. Data have been compiled on the shrimp farm configurations, exchange rates, and effluent chemistry. Temperature, salinity, and dissolved oxygen profiles have been measured in the estuary channels during both rainy and dry seasons. Physiographic, hydrographic, and meteorological data have been obtained to supplement the estuary data. This report examines the assimilative capacity of these estuaries with respect to dissolved oxygen (DO). The oxygen demand of organics is measured by biochemical oxygen demand (BOD). Shrimp farm BOD loadings were estimated from effluent data and exchange. A transport model for salinity and DO in the estuaries was applied to predict the tidal-mean and section-mean concentrations of salinity and DO. The model predictions of DO—based on 1995 BOD loadings—were satisfactory. Future loadings based upon full shrimp farm development along these two estuaries were then input to determine the resulting DO under these conditions. It was found that the 1995 configuration is already pressing the carrying capacity of both systems, and the DO will be worse at full development. Shrimp farms placed farther upstream than about 20 km from the mouth will most likely have excessive impact on the DO in the estuary, which is exacerbated under dry-season conditions. Negative impacts of a specific farm can be ameliorated by reducing or eliminating pond discharges during the dry season and by reducing the level of water exchange employed. This work needs to be extended to address additional water quality parameters and to incorporate larger spatial scales, especially to establish the interaction between different estuaries draining into Fonseca. 

Effects of Shrimp Farming on the Hydrography and Water Quality of El Pedregal and San Bernardo Estuaries, Gulf of Fonseca, Honduras
Report
2000
Yi, Y., and C. K. Lin. 2000. Integrated Cage Culutre in Ponds: Concepts, Practice, and Perspectives. Pp. 233 - 240 in Cage Aquaculture in Asia: Proceedings of the First International Symposium on Cage Aquaculture in Asia, Cage Aquaculture in Asia: Proceedings of the First International Symposium on Cage Aquaculture in Asia, edited by I.C. Liao and Lin, C.K. Bangkok. Retrieved (http://www.was.org/Shopping/proceedings-of-the-first-international-symposium-on-cage-culture-in-asia).
NOP 00-148 (English) (Spanish)

NOP 00-148 (English) (Spanish)

The integrated cage culture in ponds refers to the system in which high valued species are stocked in cages suspended in ponds while filter-feeding species are stocked in open water outside the cages. While the caged fish are fed with high protein diets, the open-pond fish are solely dependent on the natural foods generated from cage wastes.

The following advantages make the integrated cage culture in ponds attractive and promising:

(1) Wastes derived from high protein diets of caged fish are reused as a valuable nutrient source to generate natural foods for open pond fish.

(2) Nutrients in wastes derived from cages are recovered thus reducing nutrients contained in effluents, which are usually released directly or indirectly to the surrounding environment, causing accelerated eutrophication in those waters.

(3) It is used in polyculture ponds to confine costly high protein diets to caged high valued species to achieve higher economic returns.

(4) It is used in sub-tropical or temperate regions, where tropical fish species cannot overwinter, to make full use of growing seasons and make management such as fish harvest easy and convenient.

(5) This system makes it possible to fatten large fingerlings with high protein diets in cages and nurse fry with natural foods derived from cages wastes in open water in a single pond, which could allow small-scale farmers with one pond to maximize fish production and profitability.

The integrated cage culture in ponds has been practiced in caged catfish-open pond tilapia and caged large tilapia-open pond small tilapia. Encouraging results have been achieved from the above trials.

Integrated Cage Culutre in Ponds: Concepts, Practice, and Perspectives
Conference Paper
2000
Yi, Y., and C. K. Lin. 2000. Analyses of various inputs for pond culture of nile tilapia (Oreochromis niloticus): profitability and potential environmental impacts. Pp. 247 - 257 in Tilapia Aquaculture in the 21st Century, Proceedings of the Fifth International Symposium on Tilapia Aquaculture, Tilapia Aquaculture in the 21st Century, Proceedings of the Fifth International Symposium on Tilapia Aquaculture, edited by K. Fitzsimmons and Filho, J.C. Rio de Janeiro. Retrieved (https://cals.arizona.edu/azaqua/ista/order.html).
NOP 00-159 (English) (Spanish)

NOP 00-159 (English) (Spanish)

This paper presents profitability analyses and potential environmental impacts for Nile tilapia culture in ponds with a series progressive inputs. The sequential experimental stages to increase fish production through intensification were: 1) TSP only; 2) chicken manure only; 3) chicken manure supplemented with urea or urea and TSP; 4) urea and TSP; 5) continually supplemental feeding; 6) staged supplemental feeding; 7) feed alone.

Profitability analyses showed that the choices of input regimes with increasing economic gains are: 1) fertilizing ponds with moderate loading of chicken manure; 2) fertilizing ponds with chicken manure supplemented with urea and TSP to balance nutrient loading and maintain water quality; 3) fertilizing ponds with urea and TSP at appropriate rates; 4) fertilizing ponds initially with urea and TSP, in combination of supplemental pelleted feed at 50% satiation level at later stage of grow-out cycle.

The analyses indicated that intensification of tilapia culture through staged inputs in ponds improved efficiency in land use and water consumption. The analyses also showed that the rate of nutrient loss as wastes and the nutrients required to produce 1 kg tilapia were markedly less in ponds with supplemental feed than those with high rate of fertilizer inputs.

Analyses of various inputs for pond culture of nile tilapia (<i>Oreochromis niloticus</i>): profitability and potential environmental impacts
Conference Paper
2000

1999

NOP 99-134 (English) (Spanish)

The most common substances used in pond aquaculture are fertilizers and liming materials. Fertilizers are highly soluble and release nutrients that can cause eutrophication of natural waters. Fertilizers are also corrosive and some are highly explosive, so proper handling is necessary to prevent accidents. Some liming materials are caustic and can be hazardous to workers if proper precautions are not exercised. Liming materials do not cause environmental problems, and liming and inorganic fertilizer compounds do not present food safety concerns. An array of other substances is used less frequently in aquaculture including: oxidants, disinfectants, osmoregulators, algicides, coagulants, herbicides, and probiotics. These compounds or biological products quickly degrade or precipitate. They are not bioaccumulative and do not cause environmental perturbations in natural waters receiving pond effluents. Accidental spills of some substances could cause environmental damage. Most substances used in pond aquaculture to improve soil or water quality present little or no risk to food safety. The use of human wastes in aquaculture or the contamination of aquaculture systems with agricultural or industrial pollution could result in product contamination and food safety concerns. Some substances pose safety risks to workers, explosion or fire hazards, or cause mild pollution.

Risks associated with the use of chemicals in pond aquaculture
Journal Article
1999
Boyd, C. E., and M. C. Haws. 1999. Good management practices (GMPs) to reduce environmental impacts and improve efficiency of shrimp aquaculture in Latin America. Pp. 9 - 33 in V Central American Symposium on Aquaculture, V Central American Symposium on Aquaculture, edited by B.W. Green, Clifford, H.C., McNamara, M., and Montano, G.M. Choluteca, Honduras: Asociacion Nacional de Acuicultores de Honduras, Latin American Chapter of the World Aquaculture Society, and Pond Dynamics/ Aquaculture Collaborative Research Support Program.
NOP 99-136 (English) (Spanish)

NOP 99-136 (English) (Spanish)

A list of practices that can be used to improve the efficiency and reduce the negative environmental impacts of shrimp farming is presented. The practices are called good management practices (GMP's) instead of best management practices (BMP's), because the best ways of reducing environmental impacts in shrimp farming are still evolving. The practices were developed specifically for shrimp culture in Latin America countries with the assistance of the Honduran Shrimp Producer’s Association, but many of the practices are applicable to shrimp farming anywhere in world and to most other types of pond aquaculture. Further modifications and refinements are anticipated for these GMP's as a result of continued collaboration with shrimp producers and aquacultural scientists.

Good management practices (GMPs) to reduce environmental impacts and improve efficiency of shrimp aquaculture in Latin America
Conference Paper
1999
Contreras-Sánchez, W. M., M. S. Fitzpatrick, G. Marquez-Couturier, and C. B. Schreck. 1999. Masculinization of Nile tilapia (Oreochromis niloticus) by immersion in synthetic androgens: timing and efficacy. Pp. 246 - 248 in V Central American Symposium on Aquaculture, V Central American Symposium on Aquaculture, edited by B.W. Green, Clifford, H.C., McNamara, M., and Montano, G.M. Choluteca, Honduras: Asociacion Nacional de Acuicultores de Honduras, Latin American Chapter of the World Aquaculture Society, and Pond Dynamics/ Aquaculture Collaborative Research Support Program.
NOP 99-140 (English) (Spanish)

NOP 99-140 (English) (Spanish)

A variety of methods have been developed for producing single-sex populations of tilapia; however, dietary treatment with synthetic androgens such as 17α-methyltestosterone is the most common technique. The objectives of our study were to determine the period at which masculinization via immersion can be accomplished, and to determine if multiple immersions during critical days can produce all-male populations. We also wanted to determine if masculinization via immersion can be accomplished on a large scale using fry collected from multiple families in spawning tanks. Fry were immersed in 500 µg l-1 of trenbolone acetate (TA) for 3 h on days 12, 13, or 14 after fertilization (experiment 1) or in combinations of days between 12 and 15 days postfertilization (dpf; experiment 2). The results of these experiments confirm that significant masculinization of tilapia can be achieved through short-term immersion of fry in water containing synthetic androgens. Multiple immersions during the critical period of sensitivity consistently achieved greater than 80% masculinization. The results indicate that 3-h immersions are sufficient, and suggest that including an immersion on 15 dpf does not improve masculinization.

Masculinization of Nile tilapia (<i>Oreochromis niloticus</i>) by immersion in synthetic androgens: timing and efficacy
Conference Paper
1999
Dasgupta, S., and C. R. Engle. 1999. Non-Parametric Estimation of Returns to Investment in Honduras Shrimp Research. Pp. 201 - 203 in V Central American Symposium on Aquaculture, V Central American Symposium on Aquaculture, edited by B.W. Green, Clifford, H.C., McNamara, M., and Montano, G.M. Choluteca, Honduras: Asociacion Nacional de Acuicultores de Honduras, Latin American Chapter of the World Aquaculture Society, and Pond Dynamics/ Aquaculture Collaborative Research Support Program. Retrieved (http://www.tandfonline.com/doi/abs/10.1080/13657300009380266).
NOP 99-138 (English) (Spanish)

NOP 99-138 (English) (Spanish)

This paper reports the results of a study to evaluate the economic returns on the investment in shrimp research in Honduras. The goal of this study was the estimate the economic returns to shrimp research investment by the Pond Dynamics / Aquaculture CRSP, a USAID-funded program involved in global pond aquaculture research in Honduras since 1993. The research program was implemented by Auburn University researchers under the auspices of the PD/A CRSP in order to improve shrimp production efficiency. The analytical technique used in this study is a non-parametric approach to estimate the returns to research investment, based on Varian's Weak Axiom of Profit Maximization (WAPM). Shrimp production data from 21 farms in Honduras were collected by survey techniques. Each farm indicated yield, post-larva (PL) stocking rate, and feeding rate during its first production year and 1997 (the survey year). For the combined investments, the Internal Rate of Return (IRR) was 17% (45% with Taura Syndrome Virus (TSV) correction); considering only public-sector investment gave an IRR of 6,532% (13, 412% with TSV correction). These results suggest a very effective leveraging of US federal research funds with private-sector capital. Results from this study clearly point toward technical progress in Honduran shrimp cultivation. Non-parametric total productivity indices evaluated from the output technological indices indicated proportionately higher yields in the post-research years. This study also illustrates the importance that commercial shrimp farms place on the Auburn University PD/A CRSP research program, which is evident from the significantly higher private-sector over public-sector investment. 

Non-Parametric Estimation of Returns to Investment in Honduras Shrimp Research
Conference Paper
1999
Fitzpatrick, M. S., W. M. Contreras-Sánchez, R. H. Milston, and C. B. Schreck. 1999. Fate of the masculinization agent methyltestosterone in the pond environment. Pp. 249 - 250 in V Central American Symposium on Aquaculture, V Central American Symposium on Aquaculture, edited by B.W. Green, Clifford, H.C., McNamara, M., and Montano, G.M. Choluteca, Honduras: Asociacion Nacional de Acuicultores de Honduras, Latin American Chapter of the World Aquaculture Society, and Pond Dynamics/ Aquaculture Collaborative Research Support Program.
NOP 99-141 (English) (Spanish)

NOP 99-141 (English) (Spanish)

Use of all-male tilapia populations prevents unwanted reproduction and produces the sex with the greatest growth potential. One common method for producing all-male populations is to feed developing fry with food impregnated with the synthetic androgen 17α- methyltestosterone (MT). Although previous studies have shown that MT is rapidly cleared from the fish, little attention has been paid to the possible contamination of the environment by steroid-treated food. Such contamination could pose an exposure risk to workers as well as to other organisms in and around the pond environment. We tested the hypothesis that MT persists in the environment after its use for masculinizing Nile tilapia. Fry were treated with a masculinizing dose of MT (60 mg kg-1) for four weeks beginning at the initiation of feeding in model ponds. Water and soil samples were taken before the onset of treatment and weekly beginning on the last day of treatment (water samples were also taken weekly during the four-week treatment period). The concentrations of MT in water and soil were measured by radioimmunoassay. Concentration of MT in water decreased to background level by 35 days after the onset of feeding (one week after the end of treatment with MT-impregnated food). In contrast, the levels in the soil were 1.4 to 1.7 μg kg-1 at 28 days after the onset of feeding with MT-impregnated food and remained detectable in the soil at between 0.8 and 1.6 μg kg-1 through 49 days (three weeks after ending treatment with MT-impregnated food). These results suggest that MT persists in sediments for at least weeks after cessation of MT treatment, which indicates that unintended exposure to MT may occur.

Fate of the masculinization agent methyltestosterone in the pond environment
Conference Paper
1999

NOP 99-133 (English) (Spanish); NOP 99-A01 (English) (Spanish)

The use of all-male populations increases the efficiency and feasibility of tilapia aquaculture. The objective of this study was to determine the efficacy of a short-term immersion procedure for masculinizing Nile tilapia (Oreochromis niloticus). Two synthetic androgens were evaluated: 17α-methyldihydrotestosterone (MDHT) and 17α-methyltestosterone (MT). Exposure (3 h) on 10 and again on 13 days post-fertilization to MDHT at 500 μg/l successfully masculinized fry in all experiments, resulting in 100, 94 and 83 ± 2% males in Experiments 1, 2 and 3, respectively. Immersions in MDHT or MT at 100 μg/l resulted in significantly skewed sex ratios in Experiments 1 and 3 (MT resulted in 73 and 83 ± 3% males; and MDHT resulted in 72 and 91 ± 1% males) but not in Experiment 2. Immersion in MT at 500 μg/l only caused masculinization in Experiment 3. Although further research and refinement is needed, immersion of Nile tilapia in MDHT may provide a practical alternative to the use of steroid-treated feed. Furthermore, when compared with current techniques for steroid-induced sex inversion of tilapia, short-term immersion reduces the period of time that workers are exposed to anabolic steroids.

Masculinization of Nile tilapia (<i>Oreochromis niloticus</i>) by immersion in androgens
Journal Article
1999
Green, B. W. et al. 1999. Effect of water exchange on semi-intensive production of Penaeus vannamei. Pp. 209 - 212 in V Central American Symposium on Aquaculture, V Central American Symposium on Aquaculture, edited by B.W. Green, Clifford, H.C., McNamara, M., and Montano, G.M. Choluteca, Honduras: Asociacion Nacional de Acuicultores de Honduras, Latin American Chapter of the World Aquaculture Society, and Pond Dynamics/ Aquaculture Collaborative Research Support Program.
NOP 99-144 (English) (Spanish)

NOP 99-144 (English) (Spanish)

Daily water exchange at 10% of pond volume is common practice in semi-intensive shrimp culture in Central America. Rationales for water exchange are to improve dissolved oxygen concentrations in the pond and to remove nutrients before they reach toxic levels. However, the benefit of water exchange in semi-intensive shrimp culture has been poorly demonstrated. Two experiments were conducted on a commercial shrimp farm in Honduras to determine the effects of daily water exchange and emergency water exchange on shrimp production. Ten 0.93-ha ponds stocked with hatchery-spawned post-larval (PL) Penaeus vannamei at 150,000 PL ha-1 were used for this completely randomized design study to test two water exchange regimes: daily water exchange at 10% pond volume, six days per week; and water exchanged at up to 25% pond volume when early morning dissolved oxygen concentrations were ≤ 2.0 mg l-1. The above experiments were conducted in both the rainy and dry seasons. Gross shrimp yields, shrimp survival, and individual growth and weight showed no difference between water exchange regimes for both seasons considered.

Effect of water exchange on semi-intensive production of <i>Penaeus vannamei</i>
Conference Paper
1999
Green, B. W. 1999. Tilapia production systems in Honduras. Pp. 254 - 257 in V Central American Symposium on Aquaculture, V Central American Symposium on Aquaculture, edited by B.W. Green, Clifford, H.C., McNamara, M., and Montano, G.M. Choluteca, Honduras: Asociacion Nacional de Acuicultores de Honduras, Latin American Chapter of the World Aquaculture Society, and Pond Dynamics/ Aquaculture Collaborative Research Support Program.
NOP 99-142 (English) (Spanish)

NOP 99-142 (English) (Spanish)

Following a period of rapid expansion in the early 1990s, tilapia farming in Honduras continues to be a growing industry. This survey of management systems employed at tilapia farms in Honduras, based on interviews conducted between July and September 1998 with managers from 11 farms that supply both domestic and export markets, examines the species cultivated in largest quantity—a hybrid of Oreochromis mossambicus, O. urolepis hornorum, O. aureus, and O. niloticus known as Jamaican red tilapia. The survey revealed that while many farms originally harvested production for the export market, limited and/or irregular production necessitated a scaling back to local distribution. Large farms were found to contain an average of 54 ponds compared with small farms, which operated an average of 33 ponds. In general, ponds in a farm were distributed by total area in the following manner: 5.9% for reproduction and sex inversion, 21% for pre-grow-out, 31.8% for grow-out I, and 41.1% for grow-out II. Sex inversion of fry was practiced on all farms, with varying degrees of success, using daily treatments of 17α-methyltestosterone administered through feed. For most farms, water exchange was the primary method of maintaining water quality during grow-outs I and II. Farms that also implemented water exchange during pre-grow-out reported larger biomasses at the end of this stage of production.

Tilapia production systems in Honduras
Conference Paper
1999
Jamu, D. M., Z. Lu, and R. H. Piedrahita. 1999. Secchi disk visibility and chlorophyll a relationship in aquaculture ponds. Pp. 205 - 214 in Advances in Aquaculture Engineering, Proceedings from the Aquacultural Engineering Society (AES) Technical Sessions at the Fourth International Symposium on Tilapia in Aquacullture, vol. 170, Advances in Aquaculture Engineering, Proceedings from the Aquacultural Engineering Society (AES) Technical Sessions at the Fourth International Symposium on Tilapia in Aquacullture. Orlando, Florida. Retrieved (http://www.worldcat.org/title/advances-in-aquacultural-engineering-proceedings-from-the-aquacultural-engineering-society-aes-technical-sessions-at-the-fourth-international-symposium-on-tilapia-in-aquaculture-coronado-springs-resort-walt-disney-world-orlan).
NOP 98-120 (English) (Spanish)

NOP 98-120 (English) (Spanish)

The application of Secchi disk visibility measurements (SDV) measurements in modeling phytoplankton productivity and management in aquaculture ponds requires a quantitative treatment of the relationship between SDV measurements and chlorophyll a (chla) concentrations. Almazan and Boyd (1978) produced one such relationship for aquaculture ponds where phytoplankton was the major source of turbidity. However, in aquaculture ponds, organic matter, color of humic substances and inorganic materials like suspended clay may also be significant sources of turbidity. A majority of aquaculture ponds receive high inputs of organic matter in the form of food or organic fertilizers (Edwards, 1987; Shroeder et al., 1991; Chien, 1992). In such systems, non phytoplankton sources of turbidity can be significant and the Almazan and Boyd (1978) relationship to allow its applicability in waters with high algal turbidity by including a non algal turbidity parameter.

A method for estimating chla from SDV and for partitioning SDV has been proposed for natural freshwater systems (Bannister, 1974; Megard et al., 1980; Lorenzen, 1980). The linear relationship between the overall light extinction coefficient (kw), the light extinction due to chla (kcc, where kc is the light extinction coefficient due to chla and c is the chla concentration) and the light extinction due to non-phytoplankton particulate and dissolved material (kt) was expressed as (Bannister, 1974; Megard et al., 1980): kt=kw+kcc where kt and kw have units of m-1 and kc has units m-1(mg.m-3)-1. The general applicability of this method to aquaculture has not been evaluated. The aim of this study was to evaluate the applicability of Bannister's approach (1974) to aquaculture ponds by partitioning sources of turbidity and determining the relative importance of phytoplankton and non phytoplankton turbidity.

Secchi disk visibility and chlorophyll a relationship in aquaculture ponds
Conference Paper
1999

NOP 99-132 (English) (Spanish)

The potential of using Bannister's linear equation (k(t) = k(w) + k(c)c) (where k(t) is the overall light extinction coefficient, k(w) represents the non-phytoplankton light extinction, k(c) is the specific light extinction coefficient due to chlorophyll a (chla), c is the chla concentration, and k(c)c represents the light extinction due to chla) to partition sources of turbidity in Secchi disk visibility (SDV) measurements in aquaculture ponds was evaluated. Eight data sets from five sites around the world were used in the study. Chlorophyll a data were regressed against the overall light extinction coefficient determined from SDV measurements. The relationship between chla and overall light extinction coefficient was linear for seven of the eight data sets. The contribution of non-phytoplankton turbidity to SDV measurements was estimated by the intercept of the linear regression line (equivalent to k(w)). The values obtained (range = 3.61-8.91 m-1) were variable and unpredictable between replicate ponds at all sites, but did not vary significantly over time (P < 0.05). Because chla concentration serves as an indicator of phytoplankton concentration, the contribution of phytoplankton turbidity to SDV measurements was estimated by the slope of the linear regression line (equivalent to k(c)) multiplied by the chla concentration. The slope of the regression line (0.014 ± 0.006 m-1 (mg m-3) -1) was similar to values reported for natural freshwater systems. The partitioned light extinction coefficients and chla concentrations were also used to determine the threshold chla concentration above which SDV measurements are determined primarily by chla. The threshold chla concentrations (177-980 mg m-3) above which phytoplankton biomass becomes the primary determinant of SDV were higher than observed chla concentrations. The results indicate that Bannister's linear equation can generally be used to partition and quantify the sources of turbidity in aquaculture ponds. The results also suggest that the contribution of non-phytoplankton turbidity to SDV measurements in fertilized and fed aquaculture ponds can be more important than phytoplankton turbidity.

Relationship between Secchi disk visibility and chlorophyll a in aquaculture ponds
Journal Article
1999
Lovshin, L. L., and S. N.B. 1999. Evaluation of Tilapia Culture by Resource Limited Farmers in Panama and Guatemala. Pp. 258 - 261 in V Central American Symposium on Aquaculture, V Central American Symposium on Aquaculture, edited by B.W. Green, Clifford, H.C., McNamara, M., and Montano, G.M. Choluteca, Honduras: Asociacion Nacional de Acuicultores de Honduras, Latin American Chapter of the World Aquaculture Society, and Pond Dynamics/ Aquaculture Collaborative Research Support Program.
NOP 99-143 (English) (Spanish)

NOP 99-143 (English) (Spanish)

The purpose of this study was to evaluate the current status of tilapia pond projects initiated in the 1980's by the governments of Panama and Guatemala, with financial support from the United States Agency for International Development (USAID) and technical support provided by Auburn University. Projects in both countries were designed to improve the nutrition and increase the income of poor farmers by teaching them the skills required to become self-sufficient pond managers. During June and July 1998 the authors visited 21 cooperatively managed fish pond projects in Panama, and 37 family and 2 cooperatively managed fish ponds in Guatemala. The evaluation team found that in Panama, 6 of the cooperative projects were abandoned and the remaining 15 were being used to grow rice and/or fish, while in Guatemala, 39% of the ponds were abandoned, 48% were underutilized, and 13% were well managed. Fish ponds did not have the intended impact on household nutrition and income for a combination of technical, economic, social, and political reasons. However, participants found ways to profit from the existence of ponds as 15 of 21 cooperatively managed pond projects in Panama and 28 of 46 individual household pond projects in Guatemala were still used at some level of proficiency.

Evaluation of Tilapia Culture by Resource Limited Farmers in Panama and Guatemala
Conference Paper
1999

NOP 00-147 (English) (Spanish)

Culture conditions the ability to organize to provide food security but social organization is the immediate source of policies that prevent food insecurity or determine what happens when it does occur. Weather, war, terrorism, conflict, overpopulation, environmental degradation, corruption, and faulty policies have been identified as causes of food insecurity. Perhaps most of the blame for food insecurity should go to faulty policies or poor implementation of sound policy. This article identifies reasons for both kinds of failure that are linked to culture and social organization. The central task of government is to allow the food system to manage its own affairs, but policies must be ready to guide action when market, crop, or policy failures create food insecurity among those with no other means of coping with adversity.

Sound policies for food security: the role of culture and social organization
Journal Article
1999

NOP 00-146 (English) (Spanish)

Effects of pelleted versus non-pelleted defatted rice bran on fish production and water quality were evaluated at the Aquaculture Research Station, University of Arkansas at Pine Bluff. Mixed-sex Nile tilapia (Oreochromis niloticus) were stocked at 2.3/m-2 into each of six 0.04-ha earthen ponds. Largemouth bass (Micropterus salmoides) were added at 0.17/m-2 for population control. Defatted rice bran was fed to fish at 2% body weight daily. After 169 days, tilapia harvests averaged 2,924 kg/ha in pellet-fed and 3,031 kg/ha in loose bran-fed treatments (a non-significant difference). Stocked fish comprised an average of 52% and 39%, respectively, in these treatments, and approached a significant difference (P = 0.2). Average amounts of inorganic fertilizer required to maintain chlorophyll a levels of 100 - 150 mg/m-3 were significantly different at 736 and 1,108 kg/ha in pelleted and loose bran treatments, respectively.

Effects of feeding pelleted versus non-pelleted defatted rice bran on Nila tilapia <i>Oreochromis niloticus</i> production and water quality in ponds
Journal Article
1999

NOP 99-135 (English) (Spanish)

A stochastic model has been developed for generation of daily and hourly solar radiation values that can be used as inputs in a water quality model for aquaculture ponds. The daily solar radiation values are generated based on the monthly probability distribution of the daily clearness index. The monthly probability distributions are obtained from an incomplete historical daily solar radiation data set collected from fish pond sites. The hourly solar radiation values are estimated by breaking down the generated daily value using an empirical equation from the literature. The model has been applied to locations in Thailand, Honduras, and Rwanda. The length of historical data for the different locations ranged between six and eight years. The generated values show good agreement with the measured data. This model can be used to generate solar radiation values for locations having scant historical information.

Generation of daily and hourly solar radiation values for modeling water quality in aquaculture ponds
Journal Article
1999
Teichert-Coddington, D. R. 1999. Shrimp Farming in Southern Honduras: A Case for Sustainable Production. Pp. 222 - 230 in Managed Ecosystems: The Mesoamerican Experience, Managed Ecosystems: The Mesoamerican Experience, edited by L.U. Hatch and Swisher, M.E. New York: Oxford University Press. Retrieved (https://catalyst.library.jhu.edu/catalog/bib_2062892).
NOP 99-A02 (English)

NOP 99-A02 (English)

Commercial shrimp farming in southern Honduras began in 1972 with the establishment of Sea Farms of Honduras near Punta Raton on the Gulf of Fonseca. Sea Farms was located on playon (salt flats) and private land shared with cattle ranchers. Water was pumped from Estero Los Butus, an embayment off the Gulf of Fonseca. Sea Farms expanded from 45 to about 300 hectares during the decade that followed, accounting for almost all shrimp production in Honduras.

Shrimp Farming in Southern Honduras: A Case for Sustainable Production
Book Chapter
1999
Valderrama, D., and C. R. Engle. 1999. Risk analysis of shrimp farming in Honduras. Pp. 236 - 239 in V Central American Symposium on Aquaculture, V Central American Symposium on Aquaculture, edited by B.W. Green, Clifford, H.C., McNamara, M., and Montano, G.M. Choluteca, Honduras: Asociacion Nacional de Acuicultores de Honduras, Latin American Chapter of the World Aquaculture Society, and Pond Dynamics/ Aquaculture Collaborative Research Support Program.
NOP 99-139 (English) (Spanish)

NOP 99-139 (English) (Spanish)

Current realities (disease issues, environmental concerns, unstable market) are encouraging shrimp farmers world-wide to review traditional management strategies and look for tools that help optimize current practices. Uncertainties and risks associated with shrimp production also need to be recognized. The present study is a risk analysis of activities carried out by shrimp farmers in Honduras. Results of the analysis are intended to provide the farm manager–decision maker with a compendium of possible outcomes that could be obtained under different scenarios, which are modeled according to the characteristics of the Honduran shrimp industry. A survey was conducted to obtain information on production parameters and costs of shrimp farms in Honduras. Data were collected from 21 farms ranging in size from 20 to 1,800 hectares. The survey was aimed at obtaining information on stocking densities, feeding rates, and other production parameters in addition to operational costs. Collected data correspond to the production of 1997. Data from the survey showed that large farms (more than 400 ha) typically produce less than 1,000 lb ha-1 yr-1 and have the lowest costs per unit area and break-even yields. Yields are higher for medium farms (150 to 300 ha) than for large farms. Results of the analysis suggest that under current strategies followed by farm managers in Honduras, there is more risk associated with adopting conservative practices and a low-cost-per-hectare approach than with intensifying shrimp culture by increasing stocking densities and feeding rates.

Risk analysis of shrimp farming in Honduras
Conference Paper
1999

This report discusses the first phase of the National Fish Culture Project in Rwanda that extended from 1983 through 1988. The project focused solely on fish culture and endeavored to improve fish production in existing ponds through a dynamic extension service. Physical, social, and economic constraints to fish culture in Rwanda are presented in addition to background on the project’s extension strategy and a description of the extension agent training. Fifty-five extension agents were trained and upon completion of the project, approximately 3,000 ponds had been covered through the project’s extension efforts. Through the four-year duration of the project, average pond productivity increased 3.4 to 14.5 kg are-1 yr-1. A 41% internal rate of return was calculated for fish culture as a farm enterprise. The increased cost to maintain the extension program in comparison with the increase in fish production resulted in a 27% internal rate of return to the government of Rwanda. Finally, recommendations for future fish culture projects are discussed in addition to a five-phase aquaculture development plan.

Aquaculture Extension in Rwanda
Report
1999
Ward, G. H., B. W. Green, and D. R. Teichert-Coddington. 1999. Estimation of carrying capacity for shrimp aquaculture in the eastern estuaries of the Gulf of Fonesca. Pp. 34 - 63 in V Central American Symposium on Aquaculture, V Central American Symposium on Aquaculture, edited by B.W. Green, Clifford, H.C., McNamara, M., and Montano, G.M. Choluteca, Honduras: Asociacion Nacional de Acuicultores de Honduras, Latin American Chapter of the World Aquaculture Society, and Pond Dynamics/ Aquaculture Collaborative Research Support Program.
NOP 99-137 (English) (Spanish)

NOP 99-137 (English) (Spanish)

An intensive data collection and modeling study has been underway for the past several years addressing two of the channel estuaries draining into the Gulf of Fonseca, namely Estero El Pedregal and Estero San Bernado. Data have been compiled on the shrimp farm configurations, exchange rates, and effluent chemistry. Temperature/salinity/dissolved oxygen profiles have been measured in the estuary channels in both rainy and dry seasons. Physiographic, hydrographic and meteorological data have been obtained to supplement the estuary data. We examine the assimilative capacity of these estuaries with respect to dissolved oxygen (DO). The oxygen demand of organics is measured by biochemical oxygen demand (BOD). Shrimp farm BOD loadings were estimated from effluent data and exchange. A transport model for salinity and DO in the estuaries was applied to predict the tidal-mean, section-mean concentrations of salinity and DO. The model predictions of DO given 1995 BOD loadings were satisfactory. Future loadings based upon full shrimp farm development along these two estuaries were then input to determine the resulting DO under these conditions. It was found that the 1995 configuration is already pressing the carrying capacity of both systems, and the DO will be worsened at full development. Shrimp farms placed farther upstream than about 20 km from the mouth will most likely have excessive impact on the DO in the estuary. The impact is exacerbated under dry season conditions. Negative impacts of a specific farm can be ameliorated by reducing or eliminating pond discharges during the dry season, and by reducing the level of water exchange employed. This work needs to be extended to address additional water-quality parameters, and to incorporate larger spatial scales, especially to establish the interaction between different estuaries draining into Fonseca.

Estimation of carrying capacity for shrimp aquaculture in the eastern estuaries of the Gulf of Fonesca
Conference Paper
1999

NOP 99-145 (English) (Spanish)

A bioenergetics model was developed to simulate growth of both caged and open-pond Nile tilapia in a cage-cum-pond integrated culture system. The model incorporated six key variables affecting Nile tilapia growth in the cage-cum-pond integrated culture system: body size, water temperature, photoperiod, dissolved oxygen, unionized ammonia and food availability. Caged tilapia were given artificial feed, while growth of open-pond tilapia was dependent on uneaten artificial feed from the caged tilapia and natural foods derived from cage wastes. In the model, availability of natural foods was estimated by a relative feeding level parameter, which was a function of potential net primary productivity based on fish standing crop and the limiting nutrients in the ponds. The model was validated using growth data for both caged and open-pond tilapia in 28 ponds. The model described 96 and 85% of the variance in growth of caged and open-pond tilapia, respectively. Statistical analyses indicated significant agreements between predicted and observed values for both cage and open-pond systems. The model showed that the growth of open-pond tilapia was limited by phosphorus limiting primary production when the total number of tilapia stocked in cages was not greater than 200 fish pond-1, beyond which the limiting nutrient was phosphorus at the beginning of experiments and then shifted to nitrogen. The percentages of the culture period during which nitrogen limitation occurred increased from 0 to 84.4% with the increase of artificial feed inputs. The model revealed nitrogen from biological nitrogen fixation accounted for 44.2–74.8% of total nitrogen available for primary production. Under the model assumptions, pelleted feed accounted only for 13.8–14.6% growth of open-pond tilapia when dissolved oxygen was above the critical limit (1.2 mg l-1) for caged tilapia during entire experimental period, however, the percentages ranged from19.0 to 51.0% when dissolved oxygen was below this critical limit. Sensitivity analysis showed that parameters for caged tilapia affected growth of open-pond tilapia but not the reverse, and lowering water quality by decreasing dissolved oxygen or raising unionized ammonia for 10% further reduced growth of caged tilapia, but increased growth of open-pond tilapia.

Modeling growth of Nile tilapia (<i>Oreochromis niloticus</i>) in a cage-cum-pond integrated culture system
Journal Article
1999

1998

Abdalla, A. A. F., and C. D. McNabb. 1998. Acute and sublethal growth effects of un-ionized ammonia to nile tilapia Oreochromis niloticus. Pp. 35 - 48 in Nitrogen Production and Excretion in Fish, Symposium Proceedings of the International Congress on the Biology of Fish, Nitrogen Production and Excretion in Fish, Symposium Proceedings of the International Congress on the Biology of Fish, edited by D. Randall and MacKinlay, D. American Fisheries Society. Retrieved (http://fishphysiology.org/wp-content/uploads/2014/02/Nitroint.pdf).
NOP 98-125 (English) (Spanish)

NOP 98-125 (English) (Spanish)

This study investigated the acute effects of un-ionized ammonia (NH3-N) on 11 g fingerlings of Nile tilapia Oreochromis niloticus at two temperatures (23 and 33°C); and at 28 degrees C with two sizes of fish, 3 and 45 g. In addition, sublethal effects of un-ionized ammonia on.growth of Nile tilapia at 28 degrees C were evaluated. All tests were conducted in flow-through bioassay system.

In acute toxicity tests at 23 and 33°C, the 96-h LC50's (±SD) were 2.25 ± 0.07 and 2.51 ± 0.16 mg/L NH3 -N, respectively. There was not a significant effect between the two temperatures on acute toxicity of NH3- N in these tests (P 0.05). Estimates of the 96-h LC50's (±SD) at 28°C were 1.36 ± 0.45 mg/L NH3-N for the small fish and 2.65 ± 0.09 mg/L NH3-N for the large fish. In these tests, there was a significant difference between the two sizes of fish tested (P 0.05). In 35-day study of the effects of sublethal concentrations of NH3-N at 28°C, there was a linear decrease in fish weight gain with increasing un-ionized ammonia concentrations (r2 = 0.90, P 0.001). The concentrations of un-ionized ammonia that cause no reduction in growth, 50% reduction in growth, and 100% reduction in growth were 0.06, 0.73, and 1.46 mg/L NH3-N, respectively. These data suggest that Nile tilapia has a tolerance to un- ionized ammonia similar to that of tilapia species, somewhat greater than that of channel catfish, and greater than that of many other warmwater fish and salmonids.

Acute and sublethal growth effects of un-ionized ammonia to nile tilapia <i>Oreochromis niloticus</i>
Conference Paper
1998

NOP 98-127 (English) (Spanish)

The present study is an update of an earlier assessment of warm-water fish farming potential in Africa, by Kapetsky (1994). The objective of this study was to assess locations and areal expanses that have potential for warm-water and temperate-water fish farming in continental Africa.

The study was based on previous estimates for Africa by the above author, and on estimates of potential for warm-water and temperate-water fish farming in Latin America by Kapetsky and Nath (1997). However, a number of refinements have been made. The most important refinement was that new data allowed a sevenfold increase in resolution over that used in the previous Africa study, and a twofold increase over that of Latin America (i.e. to 3 arc minutes, equivalent to 5 km x 5 km grids at the equator), making the present results more usable in order to assess fish farming potential at the national level.

A geographical information system (GIS) was used to evaluate each grid cell on the basis of several land-quality factors important for fish-farm development and operation regardless of the fish species used. Protected areas, large inland water bodies and major cities were identified as constraint areas, and were excluded from any fish farming development altogether. Small-scale fish farming potential was assessed on the basis of four factors: water requirement from ponds due to evaporation and seepage, soil and terrain suitability for pond construction based on a variety of soil attributes and slopes, availability of livestock wastes and agriculture by-products as feed inputs based on manure and crop potential, and farm-gate sales as a function of population density. For commercial farming, an urban market potential criterion was added based on population size of urban centres and travel time proximity. Both small-scale and commercial models were developed by weighting the above factors using a multi-criteria decision-making procedure.

A bioenergetics model was incorporated into the GIS to predict, for the first time, fish yields across Africa. A gridded water temperature data set was used as input to a bioenergetics model to predict number of crops per year for the following three species: Nile tilapia (Oreochromis niloticus), African catfish (Clarias gariepinus) and Common carp (Cyprinus carpio). Similar analytical approaches to those by Kapetsky and Nath (1997) were followed in the yield estimation. However, different specifications were used for small-scale and commercial farming scenarios in order to reflect the types of culture practices found in Africa. Moreover, the fish growth simulation model, documented in Kapetsky and Nath (1997), was refined to enable consideration of feed quality and high fish biomass in ponds.

The small-scale and commercial models derived from the land-quality evaluation were combined with the yield potential of each grid cell for each of the three fish species to show the coincidence of each land-quality suitability class with a range of yield potentials. Finally, the land quality-fish yield potential combinations were put together to show where the fish farming potential coincided for the three fish species.

The results are generally positive. Estimates of the quality of land show that about 23% of continental Africa scored very suitable for both small-scale and commercial fish farming. For the three fish species, 50-76% of Africa’s land has the highest yield range potential, and the spatial distribution of this yield is quite similar among the species and farming systems. However, the spatial distribution of carp culture potential was greater than for Nile tilapia and African catfish. Combining the two farming system models with the favorable yields of the three fish species suggest that over 15% of the continent has land areas with high suitability for pond aquaculture.

The final fish farming potential estimates for the three species together show that about 37% of the African surface contains areas with at least some potential for small-scale farming, and 43% for commercial farming. Moreover, 15% of the same areas have the highest suitability score, and suggest that for small-scale fish farming, from 1.3 to 1.7 crops/y of Nile tilapia, 1.9 to 2.4 crops/y of Africa catfish and 1.6 to 2.2 crops/y of Common carp can be achieved in these areas.

Estimates for commercial farming range from 1.6 to 2.0 crops/y of Nile tilapia, 1.3 to 1.7 crops/y of Africa catfish and 1.2 to 1.5 crops/y of Common carp.

From a country viewpoint, the results are also generally positive. For small-scale farming of the three species, 11 countries scored very suitable in 50% or more of their national area. The corresponding results for commercial farming were that 16 countries scored very suitable in 50% or more of their national area.

Farm location data from Zimbabwe, Kenya, Uganda and Malawi were used to verify the GIS-based predictions of fish farming potential, from the standpoint of the farming system models combined with fish yields. This verification procedure indicated that the models used in the study are in general fairly accurate for strategic planning of aquaculture development.

A strategic reassessment of fish farming potential in Africa
Report
1998

NOP 99-130 (English) (Spanish)

This study was conducted to determine the dry matter and elemental composition of two species of tilapia, Oreochromis aureus and O. niloticus. Thirty-two O. aureus (total length, 85–223 mm; live weight, 10.2–210 g) and 34 O. niloticus (total length, 61–282 mm; live weight, 13.7–282 g) were dried, cooled, and weighed to the nearest 0.01 g to calculate the percentage dry weight. From these samples, carbon and nitrogen analyses were made and ash content was determined. To calculate the concentrations of phosphorus, calcium, magnesium, sodium, potassium, iron, manganese, zinc, and copper, five ml of a 2 N acid solution were added to the ash. The mixture was dried and the remaining residue was diluted to volume with the 2 N acid solution in a 100 ml volumetric flask and filtered through acid-washed filter paper. Element concentrations of the two species of tilapia were calculated. Though fish samples represented a wide range in total length and total weight, regression analyses of concentrations of dry matter, ash, and individual elements (Y) on total length (X) did not reveal an influence of fish size on composition. Minor elements such as iron showed greater variation whereas major elements, ash, and dry matter showed less variation. Tilapia are comprised of approximately 25% dry matter—which consists of approximately 20% inorganic matter (ash), 80% organic matter, and 44% carbon—and 75% water. The average nitrogen concentration for both species combined was 8.7% and the protein content of the whole fish was approximately 56.6%. A correlation matrix was developed from simple linear regressions conducted between all combinations of individual elements in each species. Significant correlations among the elements were found, indicating that fish probably have a fairly consistent proportion of the different elements contained in their bodies. Two examples are provided illustrating how the data compiled in this study were used to compute efficiencies of nutrient utilization and potential nutrient loading in aquaculture ponds.

Dry Matter, Ash, and Elemental Composition of Pond-Cultured Tilapia <i>Oreochromis aureus</i> and <i>O. niloticus</i>
Journal Article
1998

NOP 98-A01 (English); NOP 99-131 (English) (Spanish)

Fertilization guidelines developed for shallow ponds (1 m) with controlled depths were tested in deeper (2.5 m) ponds to determine effectiveness of these guidelines for culture of Nile tilapia Oreochromis niloticus. Twelve ponds of 2.5-m depth were used in four treatments: (A) weekly fertilization with water addition; (B) weekly fertilization without water addition; (C) one early fertilization without water addition; and (D) fertilization frequency dependent on nutrient concentrations, without water addition. Sex-reversed Nile tilapia were stocked at 2 fish/m2 with an initial weight of 15 g, and harvested after 234 d. Depth of water declined from 2.4 m to 1.6 m over the experiment in ponds without water addition. Fish growth rate was significantly higher in treatments A and B (0.86 g/d), than in other treatments, as was yield (3,830 kg/ha). Treatment C was lowest in growth (0.086 g/d) and yield (168 kg/ha), with treatment D intermediate. Fish growth rates and yields were strongly correlated to manure input (R2= 0.89 and 0.94, respectively), and residuals were not correlated to any physical or chemical variables. Growth and yield in these deep ponds were somewhat lower than those in previous experiments for shallow ponds with regular water inputs. However, stagnant ponds did not accumulate nutrients and metabolites at rates higher than ponds with controlled water depths.

The Effects of Fertilization and Water Management on Growth and Production of Nile Tilapia in Deep Ponds During the Dry Season
Journal Article
1998

NOP 98-124a (English) (Spanish) (CRSP Research Report)

This data report presents information collected in a survey of 267 fish farmers in Rwanda in September 1991. The findings are discussed in CRSP Research Report 98-124 entitled, "Small-Scale Fish Farming in Rwanda: Economic Characteristics" (Hishamunda et al., 1998). The Research Report contains enterprise budgets for individual and cooperative enterprises that raised fish and alternative crops. These enterprise budgets demonstrate that fish production yielded the highest net returns to land, labor, and management. Additionally, the Research Report compares the carbohydrate yield and protein costs of fish with those of alternative crops, and concludes that sweet potatoes produced the highest yield of carbohydrates and that soybeans were the least expensive protein source. The results of the study demonstrate that fish culture is a superior production system in terms of cash income per unit of land when compared with other crops raised in the marais, or valley lowlands, in Rwanda. This data report presents information collected in the survey that, while supplemental to the original research objectives, may be of interest. Section 1 contains 15 tables and 3 figures, which summarize the supplemental data collected by the survey instrument. The questionnaire itself comprises Section 2. Section 3 contains the criteria which were used to classify survey responses as unreliable, factors for converting various measures of crops and inputs into kilograms, and secondary data from the literature which were used to compare the nutritional values of various crops in the Research Report. Sources of secondary data used in the study are listed in the Literature Cited section.

Small-Scale Fish Farming in Rwanda: Data Report
Report
1998

A survey was conducted of 156 cooperative and 111 individual Rwandan fish farmers to estimate the costs and returns of aquacultural and agricultural crops. Enterprise budgets were developed for both individually and cooperatively produced fish, sweet potatoes, Irish potatoes, cassava, taro, sorghum, maize, peas, beans, soybeans, peanuts, rice, and cabbage. With the exception of Irish potatoes, all enterprises showed positive income above variable costs and positive net returns to land, labor, and management. Fish production yielded the highest income above variable costs and the highest net returns if fingerlings could be sold. If only food fish could be sold, cabbage was the most profitable crop. Sweet potatoes produced the highest yield of carbohydrates and soybeans were the least expensive source of protein. This study demonstrated that the cash income per unit of land generated by fish production is superior to other crops raised in the marais in Rwanda. While aquaculture is often considered a source of animal protein for household consumption, a high potential also exists for cash income generation.

Small-Scale Fish Farming in Rwanda : Economic Characteristics
Report
1998

NOP 98-126 (English) (Spanish)

A water budget simulation model that can be used for forecasting water requirements for aquaculture ponds has been developed. Water sources considered in the model include regulated inflow, precipitation and runoff, whereas water losses include evaporation, seepage, effluent discharge, and overflow. The model has been validated for ponds located at the Asian Institute of Technology (AIT), Thailand and at El Carao, Honduras which are, respectively, located in the humid and dry tropics. Simulation results indicate that precipitation accounted to 69.8% of the total water gains for AIT and 43.2% for El Carao. Regulated inflow provided 27% of the gains for AIT and 52.8% for El Carao. Runoff gains were minimal at both locations due to small watershed areas. Evaporation accounted fro 54.9 and 40.1% of the overall water loss predicted for the AIT and El Carao locations, with seepage accounting for the remaining loss. Predicted water requirements at AIT over a five-m period exceeded actual amounts by 14.9% apparently because seepage loss was over-estimated. For El Carao, however, predicted water requires were only 78.2% of the amount actually added, apparently due to poor estimates of evaporative water loss which averaged 0.32 cm day-1 compared to pan evaporative measurements of 0.43 cm day-1. In contast, the predicted evaporative water loss for the AIT pond (0.47 cm day -1) closely matched pan evaporation measurements (0.45 cm day-1). The availability of relative humidity and cloud cover data for AIT explain the higher accuracy in evaporative water loss estimates, and therefore water requirements, compared to EL Carao. If comprehensive weather datasets are available, the water budget model developed herein is a useful tool for estimating pond water requirement sat individual facilities located in different geographical regions.

A water budget model for pond aquaculture
Journal Article
1998

NOP 98-128 (English)(Spanish)

A bioenergetics growth model for Nile tilapia in fertilized ponds, which linked Nile tilapia growth with limiting nutrients in pond water, was developed. The model incorporated six key variables affecting Nile tilapia growth in fertilized ponds: body size, water temperature, photoperiod, dissolved oxygen, unionized ammonia and food availability. In the model, food availability was estimated by a relative feeding level parameter, which was a function of potential net primary productivity based on limiting nutrients, and standing crop of Nile tilapia. The model was validated using growth data of Nile tilapia in 30 fertilized ponds, and successfully detected growth variations among ponds receiving the same nitrogen and phosphorus inputs. The model described 76% of the variance in growth in these ponds, and the relationship between predicted and observed growth rates had a slope of 0.93 and an intercept of 11.51, not significantly different from one and zero, respectively. The model indicated that the growth variations were caused by carbon limiting primary production during 55-99% of the culture period. Sensitivity analysis indicated that the paramters related to net energy from feeding were more sensitive than those related to fasting catabolism, and that the growth was most sensitive to photoperiod and then food availability when DO was above its critical limit (1.0 mg l-1), but was most sensitive to DO when it was below the critical limit. Tilapia growth was more sensitive to DO and UIA. Initial tilapia size was the least sensitive variable when UIA was above the critical limit in the model. Compared with previous models, this study provides a more reasonable and accurate way to estimate relative feeding level (f) based on fish standing crop and potential net primary productivity derived by a limiting nutrient.

A bioenergetics growth model for Nile tilapia (<i>Oreochromis niloticus</i>) based on limiting nutrients and fish standing crop in fertilized ponds
Journal Article
1998

1997

NOP 97-112 (English) (Spanish)

Forty-five soil samples were collected from aquaculture areas in 23 provinces of Thailand to include six soil orders and wide variation in physical and chemical properties. Soil-water microcosms were prepared containing 5 g of soil and 150 mL of distilled water. Microcosms were held on an oscillating table shaker (150 mm) for 1 wk at 25 C in the dark. Water DH . and concentrations of dissolved nutrients, total alkalinity, and total hardness were measured. Differences in properties within soil orders caused wide variation in composition of solutions and differences in concentrations of dissolved substances and pH were not related to soil order. Regression analyses revealed significant correlations between concentrations of soil nutrients extractable in dilute acid (0.05 N HCI plus 0.025 N H2SO4) or in neutral, 1 N ammonium acetate and aqueous concentrations. Regression coefficients usually were higher for dilute-acid extractable nutrients than for ammonium acetate extractable ones. Regression coefficients based an dilute-acid extractable nutrients follow: soluble reactive phosphorus (r = 0.816); calcium (r = 0.685); magnesium (r = 0.470); potassium (r = 0.959); sodium (r = 0.977); manganese (r = 0.462); boron (r = 0.399). The correlation between soil and solution iron was not significant and aqueous concentrations of copper and zinc were below detection limit. Hardness was correlated with soil carbon (r = 0.710) and soil pH was a good predictor of alkalinity (r = 0.877). Soil pH and aqueous pH were highly correlated (r = 0.939). Findings suggest that soil characteristics can he used to predict pH and concentrations of several dissolved substances in soil-water systems under aerobic conditions.

Water Quality in Laboratory Soil-Water Microcosms with Soils from Different Areas of Thailand
Journal Article
1997
Boyd, C. E., and J. R. Bowman. 1997. Pond bottom soils. Pp. 135 - 162 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A12 (English)

NOP 97-A12 (English)

The importance of soil characteristics in pond construction was discussed in Chapter 5. Characteristics and condition of bottom soil are also important in pond management. The exchange of substances between soil and water affects water quality, which in turn influences fish production. Although it is generally recognized that there are strong effects and interactions among soil characteristics, water quality, and fish production in ponds, much more attention has been given to water quality than soil condition as a factor limiting fish production in ponds. The PD/A CRSP has placed emphasis on measuring the effects of pond water quality variables on fish production and developing management procedures for improving water quality. However, some research has been conducted on pond soils, and future work on pond dynamics will no doubt have a greater focus on pond soil condition. The purpose of this brief chapter is to provide the reader with an overview of the role of bottom soil in pond aquaculture and to provide a summary of PD/A CRSP research on pond soils.

Pond bottom soils
Book Chapter
1997
Contreras-Sánchez, W. M., M. S. Fitzpatrick, R. H. Milston, and C. B. Schreck. 1997. Masculinization of Nile tilapia (Oreochromis niloticus) by single immersion in 17a-methyldihydrotestosterone and trenbolone acetate. Pp. 783 - 790 in Proceedings from the Fourth International Symposium on Tilapia in Aquaculture, Proceedings from the Fourth International Symposium on Tilapia in Aquaculture, edited by K. Fitzsimmons. Ithaca, New York: Northeast Regional Agricultural Engineering Service.
NOP 98-121 (English) (Spanish)

NOP 98-121 (English) (Spanish)

The production of single sex populations offers several advantages in tilapia aquaculture, including enhanced growth and prevention of unwanted reproduction. A number of androgens have been shown to masculinize various tilapia species, including 17a-methyltestosterone (MT; summarized by Pandian and Varadaraj 1990 for Oreochromis mossambicus); mibolerone (Torrans et al. 1988 with O. aureus); fluoxymesterone (Phelps et al. 1992 with O. niloticus); norethisterone acetate (Varadaraj 1990 with O. mossambicus); 17a-ethynyltestosterone (Shelton et al., 1981 with O. aureus); 17a-methylandrostendiol (Varadaraj and Pandian 1987 with O. mossambicus), and trenbolone acetate (Galvez et al. 1996 with O. niloticus). Aquaculturists usually administer hormones to fish through the diet, but this method is prone to inefficiencies such as uneven exposure to steroid due to the establishment of feeding hierarchies or the availability of supplemental feed from pond primary productivity. Immersion of tilapia fry in steroid solutions may be one way to achieve masculinization and avoid these inefficiencies. This technique is well-developed in salmonid aquaculture (Piferrer and Donaldson 1989; Feist et al. 1995); however, it remains largely experimental in tilapia culture. Most of the reported studies immersed tilapia fry in androgens for periods of over 1 week to 5 weeks (Varadaraj and Pandian 1987; Torrans et al. 1988). Recently, Gale et al. (1995) demonstrated that immersion for just three hours in 17a-methyldihydrotestosterone (MDHT) on two days resulted in masculinization of Nile tilapia. The study described below was undertaken to determine if these findings could be extended through examination of the effects of 1) rearing density on efficacy of MDHT immersion, 2) a single immersion in MDHT, and 3) immersion in another masculinizing androgen, trenbolone acetate (TBA).

Masculinization of Nile tilapia (<i>Oreochromis niloticus</i>) by single immersion in 17a-methyldihydrotestosterone and trenbolone acetate
Conference Paper
1997
Diana, J. S. 1997. Feeding Strategies. Pp. 245 - 262 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A14 (English)

NOP 97-A14 (English)

Aquaculture of tilapia originally developed as an extensive to semi-intensive system for local consumption (Pillay, 1990). While this sort of aquaculture continues today, high demand in the U.S. and elsewhere has made intensive production and export of tilapia more feasible (Anonymous, 1995). Such culture systems usually include provision of formulated or compete feed. Utilization of such feed may be made more efficient by certain feeding practices or techniques. It may also be more cost effective because it utilizes locally available items rather than relying entirely on imported complete feeds. The purpose of this chapter is to review CRSP experiments related to supplemental feeding of Nile Tilapia and to put these into context as they relate to water quality and to pond fertilization.

Feeding Strategies
Book Chapter
1997
Diana, J. S., J. P. Szyper, T. R. Batterson, C. E. Boyd, and R. H. Piedrahita. 1997. Water quality in ponds. Pp. 53 - 71 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A10 (English)

NOP 97-A10 (English)

The various chemicals dissolved in the water, as well as the temperature and other physical attributes of water, all combine to form what is called water quality. For aquaculture systems, changes in water characteristics that improve the production of an aquatic crop would be considered improvements in water quality, while those changes reducing production would be considered degradation of water quality. This definition is important in aquaculture, because the utilization of water to grow aquatic crops at high densities often results in chemical attributes which, by environmental standards, may be considered reductions in water quality. Unless these changes reduce the production, safety, or value of the target organism, they would not be considered degradations of water quality for aquaculture purposes. Good water quality characteristics will be considerably different for some species than for others. Characteristics that enhance production of tilapia might be detrimental to species such as rainbow trout. Species are often chosen for aquaculture because of their tolerance to poor water quality (Chapter 8). Thus, water quality must be viewed in the context of the species cultured. This chapter reviews the quality of water in relation to production of tilapia in semi-intensive to intensive ponds.

Water quality in ponds
Book Chapter
1997
Egna, H. S. 1997. History of the pond dynamics/aquaculture Collaborative Research Support Program. Pp. 19 - 52 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A02 (English) (Spanish)

NOP 97-A02 (English) (Spanish)

The research described in Dynamics of Pond Aquaculture resulted primarily from 14 years of work undertaken by the Pond Dynamics/Aquaculture Collaborative Research Support Program (CRSP). The long-term goal of the program has been to develop aquacultural technologies as a means of enhancing food security in developing countries and to strengthen the capacities of U.S. and international institutions to carry out aquacultural research. The Pond Dynamics/Aquaculture CRSP is one of a family of 11 CRSP's that were created to link the capabilities of U.S. agricultural universities with the needs of developing countries. Collaborative Research Support Programs are funded by the U.S. Agency for International Development (USAID) and by participating U.S. and host country institutions. They are among the longest lived international agricultural research efforts that exist within the U.S., and as such they have built vast networks through which research and development occur.

History of the pond dynamics/aquaculture Collaborative Research Support Program
Book Chapter
1997

NOP 04-203 (English)(Spanish)

The culmination of over a decade's worth of research by the Pond Dynamics / Aquaculture Collaborative Research Support Program (CRSP), Dynamics of Pond Aquaculture not only explains the physical, chemical, and biological processes that interact in pond culture systems, but also presents real-world research findings and considers the people who depend on these systems. This book uses data from CRSP field research sites in East Africa, Southeast Asia, Central America, and North America to present a complete picture of the pond system and the environment in which it exists. 

A thorough study of the principles and practices of aquaculture, the book reflects the state of the art in pond aquaculture and incorporates recent advances that have changed the science in the last decade or so. It provides a thorough review of the many methods, techniques, and ideas that comprise this complex and fascinating area of study. 

  • Includes chapters on fish diseases, fish reproduction, extension, social and economic considerations, and environmental effects
  • Describes improvements in pond management techniques including seed fish production, pond preparation, fertilization, feed composition and manufacturing, aerator design, and harvesting
  • Addresses the need for greater quantification and standardization in research
  • Provides a synopsis of the methods, techniques, and ideas explored by aquaculture practitioners and researchers Audience Researchers, students, field workers, technicians, and engineers involved in:
    • aquaculture research
    • agricultural engineering
    • bioresource engineering 
    • fisheries and wildlife programs
    • environmental studies
Dynamics of Pond Aquaculture
Book
1997
Egna, H. S., and C. E. Boyd, eds. 1997. Introduction, in Dynamics of Pond Aquaculture. Pp. 1 - 18 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture. CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A04 (English)(Spanish)

NOP 97-A04 (English)(Spanish)

Aquaculture is the cultivation of aquatic animals and plants. Its primary purpose is to produce aquatic food organisms for human consumption, but includes other purposes such as the cultivation of ornamental and aquarium fishes. Aquaculture may be done on many scales, ranging from small rainfed ponds to increase food production for rural families to large commercial farms to provide export products for international markets. Regardless of scale, aquaculture is an economic activity, and the value of aquacultural crops must exceed the cost of producing them. Knowledge of factors and interactions that determine success in aquaculture is not as well developed as in traditional agriculture; thus, aquaculture has tended to be risky and has suffered in some instances from unsustainability. But aquaculture technology is improving rapidly, and more reliable production systems are emerging. Most aquaculture involves cultivating a species of interest under conditions that can be monitored and controlled Sessile creatures such as mollusks can be cultivated by providing substrate for their attachment. However, fish, crustaceans, and other motile organisms are usually confined in order to cultivate them. The most common confinements used in aquaculture are ponds, raceways, cages, and pens. Ponds are by far the most widely used means of confining warm-water fish and crustaceans for cultivation. Therefore, it was quite appropriate for the U.S. Agency for International Development (USAID) to initiate a project on pond aquaculture as a Collaborative Research Support Program (CRSP). The purpose of this book is to summarize advances in pond aquaculture that have accrued from the CRSP effort. The intent of this introductory chapter is to summarize the role of aquaculture in world fisheries and to explain why research and development in the area of pond dynamics are critical to the sustainable development of aquaculture.

Introduction, in Dynamics of Pond Aquaculture
Book Chapter
1997

NOP 97-104 (English) (Spanish)

Although many small-scale fish farming projects around the world promote fish production as a source of low-cost protein, increasing evidence demonstrates fish to be an important cash crop, even for limited-resource farmers. A mathematical programming model was developed from survey data of Rwandan farmers to determine optimal resource allocation on subsistence farms in Rwanda. The specific objective of the study was to determine farm plans that maximize returns to a representative Rwandan farm family's resources, subject to constraints of the farm family's proteinic and caloric requirements. Soybeans, sweet potatoes, and maize were selected to meet household nutritional requirements. Fish production was selected as the principal cash crop, in most cases lending support to the evidence that fish is more important as a cash crop than as a primary protein source in Rwanda.

Optimal resource allocation by fish farmers in Rwanda
Journal Article
1997
Engle, C. R., R. Balakrishnan, T. R. Hanson, and J. J. Molnar. 1997. Economic Considerations. Pp. 377 - 396 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A09 (English) (Spanish)

NOP 97-A09 (English) (Spanish)

An important benefit of the PD/A CRSP is the positive economic and social impact that results from farmers adopting new technologies. CRSP researchers in collaboration with host-country institutions have generated knowledge that increases the understanding of the dynamics of fish ponds. This knowledge is then used to develop new technologies that can be applied by producers (Rogers, 1962). The technology or knowledge diffusion process varies across different countries and regions but often involves an extension component that serves to link research functions and output with the production sector. The principal focus of CRSP research since its inception has been the study of the biological And chemical dynamics of pond aquaculture systems. One end purpose of this effort is to contribute to economic development through aquaculture production. However, for this to happen, the recommendations must be consistent with the economic and social environment within which these technologies are to be adopted. In the early years of the PD/A CRSP, primarily pond dynamics studies were conducted. As the overall research effort developed, additional emphasis began to be placed on conducting some sociological and economic studies related to the technologies being developed. As has been the case in many other aquaculture development projects, social scientists in the PD/A CRSP had originally been called upon on a short-term basis to support the aquaculture research program. This type of approach led to a limited scope of economics and social science involvement in the PD/A CRSP prior to 1992. Involvement of social scientists in the PD/A CRSP has increased gradually over time. However, the limited nature of the economic and social science research that has been conducted to date precludes definitive answers to the following questions: (1) Should aquaculture be promoted to generate income or serve as a nutritional subsidy? (2) What are the key factors that determine economic feasibility of aquaculture that are common to all regions across the world? Yet the key findings from these studies still shed some light on these questions and provide some evidence that contributes to the attempt to provide answers. This chapter summarizes and compares what has been up to date. Assessment of the economic viability of aquaculture projects requires an interdisciplinary understanding of physical, social, and economic relationships. Quantitative or qualitative estimates of many relevant variables are not readily available because aquaculture is in early stages of development in most areas of the world. Incorporating economic analysis into aquacultural experiments ensures that unprofitable tech- Dialogs are not pursued. While a given technology may maximize yields, other technologies may yield higher profits. Market and social constraints vary from region to region and determine product acceptability. Production research that targets those products with greatest market and social acceptance will result in more rapid growth and development of aquaculture. This will increase the overall economic and social impact of the PD/A CRSP. Technology adoption occurs at many levels, from the researchers’ technical decisions on what to investigate down to the micro- or farm-level. However, once a technology is developed, a farmer’s decision to adopt a new technology will depend upon many factors that range from simple costs and returns to market factors to complex interactions between the new technology and the farming system practiced by the farmer. The focus of this chapter is to review the economic and sociological research that has been completed by the PD/A CRSP in Honduras, Rwandan, and Thailand sites. It is not the intent to review the entire literature on the economic and social considerations of aquaculture but rather to focus on the contributions of the social sciences to the PD/A CRSP effort.

Economic Considerations
Book Chapter
1997
Ernst, D. H., J. P. Bolte, D. Lowes, and S. S. Nath. 1997. PD/A CRSP Central Database: A standardized information resource for pond aquaculture. Pp. 683 - 700 in Proceedings from the Fourth International Symposium on Tilapia in Aquaculture, Proceedings from the Fourth International Symposium on Tilapia in Aquaculture, edited by K. Fitzsimmons. Ithaca, New York: Northeast Regional Agricultural Engineering Service.
NOP 98-119 (English) (Spanish)

NOP 98-119 (English) (Spanish)

The Pond Dynamics/Aquaculture Collaborative Research Support Program (PD/A CRSP) supports applied research and outreach programs for pond-based food-fish production, with funding under the U.S. Agency for International Development (USAID). Since its inception in 1982, the PD/A CRSP has accomplished a wealth of collaborative, multi-national, multi-institutional aquaculture projects, including facilities, investigators, and user-groups in Egypt, Honduras, Indonesia, Kenya, Panama, Peru, Philippines, Rwanda, Thailand, and the USA. The PD/A CRSP Central Database is a centralized data storage and retrieval system for PD/A CRSP research and for other aquaculture research programs with compatible objectives and standardized methodology. The Database currently contains over 80 aquaculture production studies and represents the world's largest inventory of standardized aquaculture data. The majority of studies currently in the Database are for production of Nile tilapia (Oreochromis niloticus) in sub-tropical and tropical, solar algae ponds, receiving inputs of plant materials, inorganic/organic fertilizers, and/or prepared feeds. Studies of other pond fishes and penaeid shrimp, under monoculture and polyculture management, are also available. The PD/A CRSP Database can be accessed free of cost by aquaculture researchers, educators, outreach and extension agents, and producers. Data may be searched and extracted according to geographical site, calendar year, fish species, and fish production methods. Weather, water quality, fish performance, and fish culture management regimes may be viewed in raw or summary forms and in graphical or tabular formats. All extracted datasets include references to research investigators, physical descriptions of research facilities, and related publications. This publication mechanism provides immediate and comprehensive access to the Database worldwide. The PD/A CRSP Database provides a model for standardized design and reporting of pond-based aquaculture research, and it provides a publication mechanism that leverages the usefulness of such research to the greater aquaculture community. Full reporting of weather, water quality, fish performance, and fish management regimes provides a sound empirical foundation for planning, design, management, and analysis of aquaculture enterprises.

PD/A CRSP Central Database: A standardized information resource for pond aquaculture
Conference Paper
1997
Green, B. W., K. L. Veverica, and M. S. Fitzpatrick. 1997. Fry and Fingerling Production. Pp. 215 - 243 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A08 (English) (Spanish)

NOP 97-A08 (English) (Spanish)

Tilapia production from aquaculture worldwide has grown rapidly, increasing from 241,681 metric tons (MT) in 1986 to 472,969 MT in 1992 (FAO, 1994). This growth has been facilitated in part through improvements in tilapia fry and fingerling production technology (e.g., mass production of monosex fingerlings through sex inversion) and dissemination of technology to fish farmers. Continued rapid expansion of tilapia aquaculture will require additional improvements in tilapia reproduction in order to ensure consistent, unlimited availability of high-quality fingerlings. Mass production of tilapia fingerlings requires the successful implementation of a number of activities. The first step is the procurement of adequate numbers of good quality broodfish of known lineage and of the proper age and size. Adequate numbers of broodfish may be defined as the number of broodfish necessary to produce the number of eggs needed to give the desired number of advanced fingerlings for stocking into grow-out units. Good management practices are required to maintain the broodfish population in good physical and genetic condition. These management practices usually involve maintenance of broodfish in fertile earthen ponds and provision of a formulated supplemental feed. Original and replacement broodfish should be offspring from a large, randomly breeding population in order to avoid problems associated with greater potential for expression of deleterious recessive alleles as a result of inbreeding. Spawning can be natural or artificial; artificial spawning involves the manual collection of eggs and milt from broodfish. As tilapia are sequential spawners, natural spawning predominates. Artificial spawning generally is limited to specific research projects. Spawning cycle duration will vary from days to months, depending on the management practice employed and on the size of fingerling produced. Segregation of broodfish by sex and intensive feeding of broodfish between spawning cycles (conditioning) mayor may not be practiced. Broodfish are spawned in a variety of containers, and the eggs and sac-fry mayor may not be removed for artificial incubation. A hatchery facility is necessary if eggs and sac-fry are removed from brooding females. Produced fry are mixed sex, or they can be treated with an androgen to produce monosex (all-male) populations. Finally, swim-up fry are nursed to advanced fingerling or stocker size for stocking into grow-out units. Tilapia are classified as substrate incubators or mouth-brooders, the latter being either maternal or paternal/biparental (Trewavas, 1982; Chapter 8 in this volume). Both groups of tilapia provide their eggs and young with a high degree of parental care, thereby increasing offspring survival (Jalabert and Zohar, 1982; Philippart and Ruwet, 1982; Macintosh and Little, 1995). The discussion in this chapter primarily concentrates on the commercially important species, which include Nile tilapia (Oreochromis niloticus), blue tilapia (0. aureus), Mozambique tilapia (0. mossambicus), and red tilapia (Oreochromis sp.). Oreochromis niloticus is cultured most commonly worldwide, followed by O. mossambicus and O. aureus (FAO, 1994). The Egyptian and Ivory Coast strains of O. niloticus are the predominant aquacultural strains worldwide.

Fry and Fingerling Production
Book Chapter
1997
Green, B. W., and D. R. Teichert-Coddington. 1997. A collaborative project to monitor the water quality of estuaries in the shrimp productive regions of Honduras. Pp. 22 - 27 in Proceedings IV Ecuadorian Aquaculture Conference, Proceedings IV Ecuadorian Aquaculture Conference.
NOP 97-118 (English) (Spanish)

NOP 97-118 (English) (Spanish)

A long-term water quality monitoring project in estuaries of the shrimp producing regions of Honduras was initiated in 1993 as part of the Honduras Pond Dynamics/Aquaculture Collaborative Research Support Program. This project is a collaborative effort of universities, the private sector and the public sector. A technical cooperation agreement that describes specific responsibilities of each participant was signed by all participants. The goal this agreement is to provide a scientific basis for estuarine management and sustainable development of shrimp culture in Honduras. Specific objectives, design and implementation of the project are described. Currently, water quality is monitored every one to two weeks at 19 sites on 12 estuaries. This project has generated the only known long-term data base on the impact of shrimp farming on estuarine water quality. Project results to date indicate no long-term trend in eutrophication in either riverine or embayment estuaries during the period 1993-1997. Nutrient concentrations in riverine estuaries follow a cyclical trend controlled by season; higher nutrient concentrations are observed during the dry season. Factors contributing to project success are discussed.

A collaborative project to monitor the water quality of estuaries in the shrimp productive regions of Honduras
Conference Paper
1997
Green, B. W. 1997. Inclusion of tilapia as a diversification strategy for penaeid shrimp culture. Pp. 85 - 93 in IV Symposium on Aquaculture in Central America: Focusing on Shrimp and Tilapia, IV Symposium on Aquaculture in Central America: Focusing on Shrimp and Tilapia, edited by D.E. Alston, Green, B.W., and Clifford, H.C.. Retrieved (http://crsps.net/resource/inclusion-of-tilapia-as-a-diversification-strategy-for-penaeid-shrimp-culture/).
NOP 97-107 (English) (Spanish)

NOP 97-107 (English) (Spanish)

The potential for tilapia culture in brackish water shrimp ponds is evaluated. Aquaculturally important tilapia are the Nile tilapia (Oreochromis niloticus), blue tilapia (O. aureus), red tilapia (Oreochromis spp.) and, to a lesser extent, Mozambique tilapia (O. mossambicus). Nile and blue tilapia can tolerate salinities as high as 36% to 40%, but best growth occurs at salinities below 20%. Red tilapia, either from Florida or Taiwan, survive and grow well in salinities of 3%. Mozambique tilapia is able to tolerate salinities as high as 120%, but good growth is reported through salinities of 36%. While these tilapia can spawn in waters of various salinities, greater fingerling production is achieved in freshwater or slightly saline (2% to 5%) waters. Maximum salinity tolerance in tilapia appears to be reached at a total length of 50 to 70 mm. Acclimation of tilapia from freshwater to saline water appears best accomplished by increasing salinity from 2.5-5% daily until the desired salinity is reached, although some producers acclimate more rapidly. Season, choice of culture species, source of tilapia fingerlings, market, and management/logistical considerations of tilapia-marine shrimp polyculture are discussed. Along the Pacific coast of Central America, polyculture of tilapia and marine shrimp may be limited to 6 to 7 months each year during and immediately following the rainy season depending on the tilapia species. Tilapia can be stocked directly into ponds or into cages placed in ponds, supply canals or drain canals. Both cage culture of tilapia in shrimp farm supply canals, and polyculture of tilapia and shrimp in production ponds are being implemented on shrimp farms in Latin America. Management systems have been developed for this polyculture where either tilapia or shrimp is the principal culture species.

Inclusion of tilapia as a diversification strategy for penaeid shrimp culture
Conference Paper
1997

NOP 98-122 (English) (Spanish)

Marine and many inland fishery resources are heavily exploited or overexploited, and although there is potential for increasing production from inland fisheries through intensification, development of aquaculture holds the most promise in the long term for improving food security through increasing the supply of fish. Currently, inland aquaculture production in Latin America is insignificant compared with the output from inland and marine fisheries. Lack of good planning at the national level has been identified as a serious impediment to the development of aquaculture. Estimates of potential are scarce that are both comprehensive and comparable over large geographic areas. Accordingly, the objective of this study was to estimate the potential for warm-water and temperate-water fish farming in the fresh waters of Latin America in order to stimulate improved planning for aquaculture development at national levels, and at the same time to provide a tool to plan comprehensively for technical assistance activities by FAO and other national and international organizations. The present study is patterned on an estimate of warm-water fish farming potential made for Africa. However, a number of refinements have been made, one of which is a fourfold increase in resolution (i.e., to 5 arc-minutes, equivalent to 9 km x 9 km grids at the equator), thereby making the results much more usable for assessing fish farming potential at the national level. Another refinement is that, for the first time, a bio-energetics model has been incorporated into a geographical information system (GIS) to predict fish yields over large geographic areas. A gridded water temperature data set was used as input to the bioenergetics model to predict numbers of crops per year for four species: Nile tilapia (Oreochromis niloticus), tambaqui (Colossoma macropomum), pacu (Piaractus mesopotamicus) and carp (Cyprinus carpio). By varying input levels and sizes at harvest, opportunities for two levels of commercial fish farming and for small-scale fish farming were identified. In addition to the suitability of each 9 x 9 km grid cell for the production of the above-mentioned species, each grid cell was evaluated for a number of other factors important for fish-farm development and operation. These included urban market potential based on travel time proximity and population size of urban centers, potential for farm-gate sales based on population density, engineering and terrain suitability for pond construction using a variety of soil attributes, water loss from ponds due to evaporation and seepage, and availability of agricultural by-products as feed inputs based on crop potential. Commercial and small-scale aquaculture models were developed by weighting these factors using a multiple criteria evaluation procedure. Areas unavailable for inland fish farming development were identified by incorporating protected areas and large inland water bodies as constraints. Finally, the yield potential of each grid cell for each of the four species was analyzed using the growth model together with the other factors in the commercial and small-scale models to show the coincidence of each class of suitability with each range of yield potential. Potential for inland fish farming is high in continental Latin America. From 8% to 60% of the continental area scores from suitable to very suitable for small-scale farming of Nile tilapia and carp, respectively. In the same areas, from 0.9 to 1.7 crops/y of Nile tilapia and from 0.9 to 1.8 crops/y of carp can be realized by harvesting at modest weights. The most important factor for commercial fish farming--urban market potential--scores high across more than one-half of the continent. For Nile tilapia and carp, from 19% to 44% of Latin America rates from suitable to very suitable for commercial farming. From 1.2 to 2.4 crops/y of Nile tilapia and from 1.2 to 2.3 crops/y of carp can be realized on the same areas by feeding at 75% satiation and harvesting at a moderate weight. Tambaqui and pacu occupy an intermediate position in terms of the surface area that is suitable or very suitable for commercial farming. From 0.7 to 1.4 crops/y for tambaqui and from 1.0 to 2.0 crops/y for pacu can be achieved from areas that are suitable or very suitable for commercial farming by feeding at 75% satiation and harvesting at a moderate weight. From a country viewpoint, at least 18 of the continental countries have some area with potential that rates suitable or very suitable for farming of Nile tilapia and pacu, while there are 19 in the same category for tambaqui. Finally, there are opportunities for carp farming in all 21 countries.

A strategic assessment of the potential for freshwater fish farming in Latin America
Report
1997
Kelly, A. M., and C. C. Kohler. 1997. Climate, Site, and Pond Design. Pp. 109 - 134 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A07 (English) (Spanish)

NOP 97-A07 (English) (Spanish)

The utilization of ponds for growing fish is not a novel concept, and in fact, it antedates recorded history. Early records indicate that the Chinese produced food fish in ponds some 2500 years ago, although the’ exact beginning of this practice is not known (Edminster, 1947; Landau, 1992).The Romans utilized fish ponds in the first century A.D., not only to raise food fish but also to raise fish for stocking in natural lakes and other ponds (Edminster, 1947). Bas-relief sculpture found in Egyptian tombs apparently depict pond culture ofti1apia around 2500 B.C. (Landau, 1992).

Originally the concept of a fish pond was quite different than it is today. Early fish culturists simply attempted to make the pond resemble the natural waters in which the fish were found. Early fish culturists recognized the importance of maintaining cultural environments similar to each aquatic animal’s natural environment. As a result, aquatic organisms were not cultured in the densities they are today, but in some instances prepared feeds were provided (Landau, 1992).

Early pond construction methods were essentially the same as those utilized today with respect to the use of clay, proper sloping of sides, appropriate levee width, freeboard, and methods to dispose of flood waters (Edminster, 1947). These features were recorded in the early 1700s, but the importance of a controlled water supply was not mentioned until the 1800s by Boccius (Edminster, 1947). Boccius even cautioned against utilizing trees on levees.

The prominent pond design in the early days of aquaculture is equivalent to the modem raceway. Ponds were tiered, with each pond draining into the pond below it. A slightly different method of production was utilized in the Rhine Valley in France, where farmers combined aquaculture and agriculture. After raising crops for a couple of years, farmers flooded their fields with shallow water and stocked them with fish. Once the fish were harvested, the field was drained and utilized once again for crop production (Figure 1) (Edminster, 1947).

The methods of pond construction are based on techniques that are hundreds to thousands of years old; only the refinements are new. In this chapter the relevance of climatic factors and geographical features with respect to site selection and pond design are discussed. Once the pond is designed and built, then the principles of water budgets and pond management are important and are described as they relate to the various pond types. Climatic factors, geographical features, water budgets, and pond management are important basic elements that need to be understood in order to successfully produce an aquaculture crop.

Climate, Site, and Pond Design
Book Chapter
1997
Knud-Hansen, C. F. 1997. Experimental design and analysis in aquaculture. Pp. 325 - 375 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A17 (English)

NOP 97-A17 (English)

Although aquaculture as a farming practice dates back thousands of years, during the last three decades several simultaneous occurrences have simulated scientific research of shellfish and finfish cultivation. First, per capita consumption of fish, long appreciated as an excellent source of dietary protein, is increasing across the globe. Second, in countries with rapidly expanding human populations, natural waters no longer meet the growing demand for fish due to overfishing and water quality degradation from poor watershed and waste disposal management (Edwards, 1991). And systems, and pelleted feeds, have moved the production of commercial species (e.g., the tiger prawn and channel catfish) into large-scale operations. As aquaculture research rapidly expands in all directions, new species are constantly being considered for grow-out and market potential. Egg production and fry rearing strategies are improving with experimentation. Investigations into semi-intensive and integrated farming management often relate inputs (e.g. manures, cassava leaves, and urea) to water quality, primary production, and fish yield. Identification of nutritional requirements has helped develop more efficient formulated feeds for intensive fish culture systems. Progress has been made. But as the irony of science would have it, from each question answered springs forth more questions posed.

Experimental design and analysis in aquaculture
Book Chapter
1997
Lin, C. K., D. R. Teichert-Coddington, B. W. Green, and K. L. Veverica. 1997. Fertilization regimes. Pp. 73 - 107 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A11 (English)

NOP 97-A11 (English)

Pond Fertilization to increase fish yields has long been practiced throughout the world. It is a well-known tradition in China to utilize animal manures and human excreta as major sources of pond-inputs for polyculture of the major Chinese carps (Ling, 1967; Wohlfarth and Schroeder, 1979). The uses of inorganic fertilizer were introduced more recently in temperate regions (Mortimer, 1954; Gooch, 1967). There is voluminous literature on pond fertilization, documenting many conflicting and inconsistent results based on various types of fertilizer, rates of input, and methods and frequency of application (Coleman and Edwards, 1987). Those controversial viewpoints may actually reflect the differences in the physical and chemical environments of experimental ponds as well as variations in cultured fish species and chemical environments of experimental ponds as well as variations in cultured fish species and stocking densities. Some of the problems have also stemmed from the lack of proper statistical designs with sufficient replication and common protocols for pond fertilization experiments. A major thrust of the PD/A CRSP during the past 14 years has been to develop a data base for pond dynamics and fertilization management strategies for pond culture. The common global experiments were conducted primarily on pond fertilization and its impact on water quality and fish yield. The practical goal was to provide fish growers with sound strategies and guidelines for pond fertilization. Standardized fertilizer experiments were carried out during 2 to 3 years at sites in Honduras, Indonesia, Rwanda, Panama, Philippines, and Thailand. Work plans for global experiments consisted of simple inputs of phosphorus to calibrate sites, comparison of inorganic and organic fertilizers, and comparison of various loading rates of organic fertilizers. Some site-specific experiments were also conducted, depending on the needs of the individual site and the perspective of the researchers. Standardized experimental design and work plan protocols were followed at all sites (Egna et al. 1987). Results from the various sites are comparable because Nile tilapia (Oreochromis niloticus) was used as the cultured species with specified 5-month grow-out cycles, during which measurements of water quality, fish sampling, and methods of fertilizer application were standardized.

Fertilization regimes
Book Chapter
1997
Piedrahita, R. H. et al. 1997. Computer application in pond aquaculture - modeling and decision support systems. Pp. 289 - 323 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A16 (English)

NOP 97-A16 (English)

Modeling and the development of decision support systems for pond aquaculture have received considerable effort and support under the Pond Dynamics/ Aquaculture CRSP (PD/A CRSP). Models have been used as means for analyzing and organizing information and knowledge about aquaculture ponds. The models have served to test hypotheses of "how pond work", and to design field experiments to test those assumptions. As the information base has improved, decision support systems have been designed for management purposes. The current state of the art of pond modeling is very difficult from what it was at the initiation of the PD/A CRSP. At that time, Marjanovic and Orlob (1986) and Bernard (1986) conducted literature reviews of various aspects of pond modeling, especially as it referred to the types of ponds that were to be studied under the PD/A CRSP. In their reviews, they found that a great deal of related information existed but that there had been virtually no modeling of tropical aquaculture ponds. Related information found by Marjanovic and Orlob (1986) and by Bernard (1986) included models developed for lakes and reservoirs in temperate areas, as as information about processes that are important in determining water quality in ponds. General reviews of modeling of aquaculture systems have been conducted recently (Cuenco, 1989); (Piedrahita, 1991), and their work will not be repeated here. The objective of this chapter is to review and highlight the contributions of the PD/A CRSP to the status of aquaculture pond modeling and to the development of decision support systems for pond aquaculture. The review will include examples of different types of models and of decision support systems developed under the PD/A CRSP. The examples will be preceded by a brief description of the data base established under the PD/A CRSP and of its significance to the development of aquaculture science.

Computer application in pond aquaculture - modeling and decision support systems
Book Chapter
1997

NOP 97-A01 (English) (Spanish)

The duration of cytokinesis-1 (T), as measured in units of embryological age (intervals between consecutive and synchronous mitotic cell divisions), is termed to and is an important relationship in ploidy manipulations. T/to is constant and species specific in teleosts. Timing of shock initiation (ts) for intervention to retain extrusion of the 2nd polar body (2Pb), or for mitotic (late) intervention, is associated with cytokinesis-1 and can be referenced to to units. The present study compares effects of temperature determinants, which define T/to in nine fish species. The temperature dependence of embryological age to is expressed by the equation to = 10a x C-b. The equation corresponds with the Krogh’s curve, where the power coefficient b is equal to and replaced by T/to. A standard equation (St) was formulated to calulate T/to in fish species. The to equations were compared to the standard equation, using Q10-coefficients for oxygen demand of fish at four different temperatures: (alpha)- temperature limits of the fish’s distributional range, (beta)- the minimum temperature of reproduction as expressed by Krogh’s curve, (gamma)- the actual temperature of reproduction and (theta)- the temperture at which the T/to- curve intersects the standard curve.

Relationships Between Embryological Age, Cytokinesis-1 and the Timing of Ploidy Manipulations in Fish
Journal Article
1997
Seim, W. K., C. E. Boyd, and J. S. Diana. 1997. Environmental Considerations. Pp. 163 - 182 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A05 (English) (Spanish)

NOP 97-A05 (English) (Spanish)

Water, air, soil, and aquatic organisms can be viewed as overlapping compartments in the pond environment. Substances exchange between these compartments through their closely associated interfaces.Aquaculture, with its intimacy of contact with receiving waters, should include evaluation and mitigation of potential environmental risks. Such action will reduce constraints on development by this emerging industry and protect it from ineffective or unnecessary restrictions. Other water users, such as intensive agriculturists and wastewater managers, have been forced to consider the environmental concerns of society and the restrictions on both the characteristics and the amount of effluent released and the type of treatment required. The aquaculture industry may be in the process of following a similar pathway as it responds to environmental legislation while incorporating its own sense of environmental responsibility and awareness. Aquacultural scientists from industrialized nations, where environmental legislation may be well established, are helping to shape aquacultural practices in countries where legislation and environmental concern may be just emerging. Although regulation to limit the environmental impacts of aquaculture may be defensible, such restrictions have often been unnecessarily burdensome, complex, and purposeless. Surveys of U.S. aquaculturists indicate that aspects of the permitting process and operational regulations are often inappropriate extensions of regulations designed for other forms of agriculture. The aquaculture community may find it necessary to lobby and build influence within the political community, while conducting convincing environmental research, to effect changes in these regulations.

Aquaculture has expanded rapidly throughout the world, doubling production to about 14 million metric tons between 1984 and 1992 (FAO, 1994). As production has increased, aquacultural practices have begun to resemble traditional animal agriculture in terms of increased intensity. Aquaculturists have been able to operate aquatic systems near the water quality limitations of the species cultured. Careful monitoring of dissolved oxygen and ammonia, sometimes coupled with mechanical systems to prevent lethal conditions, have allowed production at high levels within the limits of real but allowable risk of crop failure. Traditional agriculture has increased production in much the same way, increasing inputs and stock density to maximize profits per unit area. However, just as traditional agriculture has encountered problems, such as point and non-point discharge of wastes, fertilizers, drugs, and other potentially toxic substances, aquaculture may now face such problems. Environmentalproblemsassociatedwithaquaculturemayleadtolegislativeconstraintsbeyond those encountered by traditional animal culture.Brackishwater shrimp culture, for instance, has attracted the attention of environmentalists and others concerned about the loss of wetlands, particularly valuable mangrove ecosystems, by improper culture practices. Such concerns, if ignored, may result in aquaculture facing confining legislation or public rejection of the product, as sometimes occurs in other areas of agriculture. Many examples already exist: consumers rejected apples from the Pacific Northwest because of concern over the use of the additive Alar; consumers have demanded “dolphin safe” tuna. Reduced red meat consumption may derive not only from health concerns but also from the perception that beef production is associated with poor rangeland practices and high resource commitments that impact other species. Recent appreciation for the value of preserving indigenous species must be addressed by aquaculturists. Cultured exotic species, such as tilapia, introduced into receiving waters have endangered native species through competition, disease, or predation. Even where cultured fish are indigenous, loss of genetic diversity in native fish has occurred from hybridization with cultured stocks. When choosing which species to culture, aquaculturists must now take potential impacts on indigenous species into account, along with performance and economical considerations. Aquaculture need not be environmentally damaging; instead, it can play a prominent role in conserving natural resources while contributing much needed social benefits. Attaining a more sustainable, productive, and environmentally sound food production base throughout the world may not be achievable, in fact, without the incorporation of an expanded aquaculture industry into the agricultural process. By avoiding negative impacts on the environment, aquaculture can solve rather than create environmental problems on a global scale.

Environmental Considerations
Book Chapter
1997
Soderburg, R. W. 1997. Factors affecting fish growth and production. Pp. 199 - 213 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A13 (English)

NOP 97-A13 (English)

Growth in Fishes in aquaculture is a complex process by which ingested energy is converted to biomass. The efficiency of this conversion is regulated by the growth potential of the organism, its trophic status, and various abiotic factors such as food supply, temperature, and adverse environmental factors brought about by the conditions in which the fish are cultured.

Factors affecting fish growth and production
Book Chapter
1997

NOP 97-111 (English) (Spanish)

Diammonium phosphate, monoammonium phosphate, triple superphosphate, and urea were dropped through a 1-m column of water which ranged from 0 to 40 ppt salinity. Mean solubility of nitrogen was 4.1% from diammonium phosphate, 11.8% from monoammonium phosphate, and 76.8% from urea. Mean solubility of phosphorus was 4.6% from diammonium phosphate, 10.4% from monoammonium phosphate and 4.4% from triple superphosphate. Salinity did not significantly affect the solubility of nitrogen and phosphorus from diammonium phosphate. Nitrogen solubility from monoammonium phosphate and phosphorus solubility from triple superphosphate significantly decreased with increasing salinity, but the correlations were low. Urea solubility and phosphorus solubility from monoammonium phosphate responded curvalinearly to increasing salinity. Solubility differences caused by salinity disappeared after 24 h of contact with water when all fertilizers dissolved completely regardless of salinity. No adjustment for salinity is necessary when fertilizer rates are calculated for brackish water or marine application.

Solubility of Selected Inorganic Fertilizers in Bracksih Water
Journal Article
1997
Teichert-Coddington, D. R., T. J. Popma, and L. L. Lovshin. 1997. Attributes of Tropical Pond-Cultured Fish. Pp. 183 - 198 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A08B (English) (Spanish); NOP 97-A03 (English)

NOP 97-A08B (English) (Spanish); NOP 97-A03 (English)

Food fish culture may be described as environmental management for growth of an edible product. The environment is managed contingent on a complex interaction of social, biological, and physical factors (Shell, 1993). The pond environment is demanding, and the marketing requirements for fish are even more restrictive, so only a few species of fish have been found suitable for culture. There are 20,000 to 40,000 species of fish (Lagler et al. 1977), but Hepher and Pruginin (1981) estimated that the number of documented species being cultured was only about 70. Fewer species are commercially cultivated. Fish must meet certain requirements for culture. The requirements may differ depending on the culture system and aquacultural experience of the fish culturist. Bardach et al. (1972) listed four areas of consideration when selecting a fish for culture: reproductive habits, requirements of the eggs and larvae, feeding habits, and adaptability to crowding. Huet (1972) listed seven requisite conditions for cultured fish. Fish must adapt to the climate where cultured, have fast growth rate (reach a large size), reproduce under culture conditions, accept feed, be satisfactory to the consumer, support high population densities, and resist disease. This chapter describes seven attributes that a fish should have for semi-intensive culture in tropical or subtropical ponds: handling tolerance, crowding tolerance, low susceptibility to disease, tolerance of poor water quality, efficient conversion of natural foods and feed, controllable reproduction, and marketability. This list does not include some of the requirements listed by Bardach et al. (1972) and Huet (1972), because CRSP experience and culture systems differ from theirs. For example, the requirements of eggs and larvae are important considerations for marine species that produce very small, delicate eggs and larvae that are difficult to propagate. Marine mollusks and invertebrates have various larval developmental stages as a further complication to seed production. However, larvae of most tropical freshwater fish species are comparatively large and uncomplicated to raise, so larval culture is not a chief concern. Huet (1972) emphasized climate adaptability. Indeed, adaptation to a particular temperature regime is an assumption underlying all other attributes. A tropical fish should be raised at tropical temperatures for the best expression of growth and other attributes. Failure to possess all attributes does not imply that the fish cannot be cultured, but success may be marginally dependent on local conditions, and not easily transferable to other sites. This chapter is organized to (1) discuss attributes of culture fish and suggest best management practices to enhance the attributes and (2) describe the attributes and biology of tilapia, a model culture fish.

Attributes of Tropical Pond-Cultured Fish
Book Chapter
1997
Teichert-Coddington, D. R. et al. 1997. Semi-Intensive Shrimp Pond Management and Quality of Effluents. Pp. 203 - 204 in IV Symposium on Aquaculture in Central America: Focusing on Shrimp and Tilapia, IV Symposium on Aquaculture in Central America: Focusing on Shrimp and Tilapia, edited by D.E. Alston, Green, B.W., and Clifford, H.C.
NOP 97-108 (English) (Spanish)

NOP 97-108 (English) (Spanish)

A collaborative research program was established in Choluteca, Honduras, in 1993 to establish a baseline of estuarine water quality in the shrimp producing regions and to study the impact of pond management on effluent water quality. Participants in the program included Auburn University AL, the Ministry of Natural Resources, Government of Honduras, the National Association of Honduran Aquaculturists (ANDAH), Pan-American Agricultural School at Zamorano, Honduras, and the Federation of Export Producers (FPX). This report summarizes studies on effluent quality from ponds and makes associations between pond management and effluent quality.

Semi-Intensive Shrimp Pond Management and Quality of Effluents
Conference Paper
1997
Teichert-Coddington, D. R., and B. W. Green. 1997. Experimental and commercial culture of tilapia in Honduras. Pp. 142 - 162 in Tilapia Aquacultue in the Americas, vol. 1, Tilapia Aquacultue in the Americas, edited by B.A. Costa-Pierce and Rakocy, J.E. Baton Rouge, Louisiana: World Aquaculture Society. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 98-123 (English) (Spanish)

NOP 98-123 (English) (Spanish)

In 1983 the USAID-funded Pond Dynamics/Aquaculture Collaborative Research Support Program (PD/A CRSP) was initiated in Central America, focusing on increasing natural productivity and fish yields of static water ponds by developing new input regimes without using mechanical aeration. Forty-one semi-intensive tilapia pond management systems were developed and evaluated in Honduras. Ponds were managed semi-intensively; Nile tilapia (Oreochromis niloticus) stocking rates did not exceed 3/m2. Nutrient inputs used were inorganic phosphorus, various levels of organic fertilization, combinations of organic and inorganic fertilization, and combinations of fertilizers and feeds. All tilapia production systems were evaluated in terms of income above variable costs and net returns to land and management from enterprise budgets for 150-day growing cycles. Incomes above variable costs were positive for all systems except where phosphorus was the sole input, and in one instance where chemical fertilizer was the sole input. Negative returns to land and management were demonstrated for systems based only on inorganic fertilization or on weekly chicken litter inputs less than 1000 kg/ha when fish were stocked at 1/m2. In general, profitability was higher when the stocking density was 2/m2, indicating available resources were not being used by fish at low stocking density. Positive returns to land and management in fed systems were obtained only at stocking rates of 2/m2. Fertilization was more profitable than feeding at low fish stocking rates. Greatest tilapia yields (5300 kg/ha for 150 days) were obtained with feeds, but a combination of chicken litter and nitrogen yielding 3700 kg/ha proved to be at least as profitable. Feed use was more profitable if feed requirements were reduced by substitution with chicken litter. If a large fish (> 300 gram) is required by the market, then feed will probably have to be used as a finisher. Production of 600-900 gram fish for the export market requires high quality feeds. Current practices in commercial intensive tilapia production practices in Honduras are described.

Experimental and commercial culture of tilapia in Honduras
Book Chapter
1997
Tonguthai, K., and S. Chinabut. 1997. Diseases of tilapia. Pp. 263 - 287 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A15 (English)

NOP 97-A15 (English)

Tilapias originated in Africa. They have a rapid growth rate and relatively few diseases, probably because of the nature of the environment within which they have evolved, with its regular droughts and other stresses. They have become one of the most economically important group of cultured species. Tilapia farms are widespread in the tropics and subtropics. The fish reared in ponds, cages, or pens, and they grow well in freshwater and brackish water environments. The high fecundity of the fish, its rapid growth rate, its few disease problems, and the ready availability of tilapia fry have resulted in intensification of production. Papers of diseases of tilapia were first published early this century. Under the original extensive or semi-intensive culture systems, tilapias were more resistant to disease than many other fish species (Roberts and Sommerville, 1982). However, the intensification of culture systems and resultant deterioration in the environment have been associated with an increase in parasitic and infectious disease problems. Formerly, parasitic diseases appeared to be more significant than other forms of infection, but the incidence of nonparasitic infections appears to be increasing. Consequently, although the literature on infectious diseases of tilapia is increasing rapidly, there has only been a slight increase in the reports of parasitic problems (Vega, 1988).

Diseases of tilapia
Book Chapter
1997
Veverica, K. L., ed. 1997. Proceedings of the Third Conference on the Culture of Tilapias at High Elevation in Africa. Pp. 1 - 26 in Proceeding of the Third Conference on the Culture of Tilapias at High Elevation in Africa, Proceeding of the Third Conference on the Culture of Tilapias at High Elevation in Africa. Pond Dynamics/Aquaculture Collaborative Research Support Program. Retrieved (http://pdacrsp.oregonstate.edu/pubs/featured_titles/Proceedings-Culture of Tilapia.pdf).
NOP 97-109 (English) (Spanish)

NOP 97-109 (English) (Spanish)

This was the third conference of its kind to be held for Rwanda, Burundi and Kivu province in the east part of Zaire. High elevation was understood to be greater than 1,000 meters. During the conference, country reports were presented describing the extension service and providing technical data following a list of points included in the conference invitation. Technical papers on rice-fish culture and extension strategy were presented from Burundi. Papers on rabbit-fish culture, composting regimes, elevation-related tilapia production and tilapia-clarias polyculture were presented from Rwanda. Kivu province presented a paper on the Zaire Peace Corps fish culture sustainable extension service. Attendees included ministry personnel, university professors, FAO personnel, university students, Peace Corps volunteers, station managers, model farmers, extension and training specialists, and some trainees. The organization and operation of the extension services in all three countries were compared. Fish culture extension has been assured mainly by Peace Corps volunteers in Zaire, with very few Zairian counterparts on hand. In Rwanda, although some Peace Corps volunteers have recently commenced activities in fish culture, Rwandese extension agents are responsible for all fish culture extension. Burundi is in the midst of re-vamping its fish culture extension service. It previously relied on Peace Corps volunteers but now has funding to train its own extension agents. However, Burundi presently has a freeze on hiring for government jobs and has opted to use extension agents already working in other domains such as forestry. A very lively discussion of the advantages and disadvantages of each country's extension service took place. All three countries have active farmer training programs. Fish culture techniques adapted to the climatic and social conditions of the high-elevation zones are: a longer growing cycle, use of larger fingerlings for stocking ponds, and smaller pond size. Oreochrornis niloticus remains the fish of choice, given the lack of access to station-produced fingerlings and the low quality inputs available. Burundi reports higher yields from ponds below 1,300 meters, compared to those over 1,300 meters, but net yields do not seem to steadily decrease with elevation above 1300 m in any of the countries. However, "best production" is much greater in the lower elevation zones. Size of fish at harvest is somewhat greater, and amount of reproduction is less as elevation increases. Pond management and input levels still seem to be the most important factors to increasing pond productivity. Recommendations made by the group of participants and a table of comparative data by country are presented. (The foregoing are the publication's executive summary.)

Proceedings of the Third Conference on the Culture of Tilapias at High Elevation in Africa
Conference Paper
1997
Veverica, K. L., and J. J. Molnar. 1997. Developing And Extending Aquaculture Technology For Producers. Pp. 397 - 414 in Dynamics of Pond Aquaculture, Dynamics of Pond Aquaculture, edited by H.S. Egna and Boyd, C.E. Boca Raton, Florida: CRC Press. Retrieved (https://www.crcpress.com/Dynamics-of-Pond-Aquaculture/Egna-Boyd/p/book/9781566702744).
NOP 97-A06 (English) (Spanish)

NOP 97-A06 (English) (Spanish)

Although most aspects of agricultural research have enjoyed a long history and the knowledge base is quite extensive, aquaculture is a relatively new science that still stands to gain considerably from research and development efforts (Shell, 1993). Even though the scientific information base dates back only about 25 years, there is much more information available than is being effectively diffused to prospective clients (Shell, 1993).

Collaborative Research Support Programs (CRSPs) focus on removing constraints to production through the development of technology and rely heavily on other agents and vehicles to disseminate the technologies. Clients of information emanating from the PD/A CRSP are farmers, educators, and other researchers, public policy makers, loan officers, and investors. Vehicles for transmitting the information vary with the client. As with most research programs, it is easiest to detect the products of research in the form of publications in scientific journals, theses, annual reports, and other research reports. Therefore, other researchers and, to a lesser extent, educators and policy makers are served.

The purpose of this chapter is to examine the connection between the Pond Dynamics/ Aquaculture CRSP and farm-level efforts to communicate research findings and production strategies and to elucidate the influence of farmers on the PD/A CRSP research program. We review PD/A CRSP efforts to participate in the development and extension of aquaculture technologies in the context of existing extension systems and the range of alternative approaches that are typically available to extension programs.

Developing And Extending Aquaculture Technology For Producers
Book Chapter
1997

1996

NOP 96-95 (English)(Spanish)

Total ammonia nitrogen pathways in fertilized fish ponds stocked with Nile tilapia Oreochromis niloticus were investigated. Three fertilizer treatments were used in a field experiment in Thailand: weekly application of 500 kg dry chicken manure/ha (1.2 g N/m2), 44 kg dry chicken manure plus 24 kg urea/ha (1.2 g N/m2), and 500 kg dry chicken manure plus 280 kg urea/ha (14.3 g N/m2). Substantial quantities of ammonia were reduced from pond water in each treatment during daylight hours. Ponds lost 36–75% of the average total ammonia that was present in early morning during daylight hours. Losses to the atmosphere (flux) were relatively small, varying from 1–5% of the total diurnal ammonia reductions. Uptake by algae was the most important mechanism for removal of ammonia from pond water. Net primary productivity varied between treatments and increased with the increased availability of inorganic nitrogen. Increasing the total ammonia present in the early morning increased net primary productivity. Fish mortalities were 71% in ponds with the highest weekly nitrogen input (14.3 g N/m2) and were between 22 and 26% in the two treatment ponds with low weekly nitrogen input (1.2 g N/m2). Average maximum concentrations of un-ionized ammonia (0.6 mg/L at 1600 hours), and low dissolved oxygen (2.8 mg/L at 0600 hours) may have combined to increase mortality in ponds with high nitrogen inputs. In the highest nitrogen treatment, neither the uptake of ammonia by algae nor its volatization to the atmosphere reduced un-ionized atmnonia concentration to a level safe for fish.

Ammonia Dynamics in Fertilized Fish Ponds Stocked with Nile Tilapia
Journal Article
1996

NOP 96-96 (English) (Spanish)

A series of 20 soil samples was collected from aquaculture areas in 14 provinces of Thailand. Samples represented 10 soil suborders and exhibited wide variation in physical and chemical properties. Soil samples were treated with 0, 25, 50, 100, and 200 ppm phosphorus and incubated under water-saturated conditions for 1 mo. Amounts of added phosphorus recoverable by water extraction decreased markedly as phosphorus adsorption capacity (PAC) of samples increased (r = 0.88 to 0.96, P < 0.01). This suggests that relative abilities of bottom soils to adsorb and release phosphorus added to ponds in fertilizers or feeds can be assessed from PAC data. Because of the importance of phosphorus adsorption by soil in regulating phosphorus availability to phytoplankton in ponds, the PAC appears to be a more useful technique than traditional phosphorus extraction methods as an index of the phosphorus status of aquaculture ponds. The PAC was highly correlated with clay content of soils (r = 0.957; P < 0.01), and a knowledge of clay content will permit a rough assessment of phosphorus status.

Phosphorus Adsorption Capacity and Availability of Added Phosphorus in Soils from Aquaculture Areas in Thailand
Journal Article
1996

NOP 96-A01 (English) (Spanish)

Accurate characterization of temperature and dissolved oxygen stratification in ponds used for aquaculture is of critical importance in understanding how these ponds may be constructed, oriented, or otherwise managed biophysically when one wishes to provide optimal environmental conditions for the organisms being cultured. While field studies can provide characterizations of water quality stratification at a single locale, to date there have been few attempts at developing reliable models which can be used at a variety of sites after initialization with appropriate local geographic and atmospheric data. In conjunction with the Pond Dynamics/Aquaculture Collaborative Research Support Program (PD/A CRSP), the authors have developed a water quality model (the Aquaculture Pond Ecosystem Model, A.P.E.M.) which predicts temperature and dissolved oxygen stratification at several sites, including Thailand, Rwanda, and Honduras. Advances in model structure and reduction of data requirements relative to previous models reflect the desire to provide for culturists the ability to predict stratification events with commonly available data, obtained either by hand or from a simple weather station located at or near the pond site. Strategies used for dealing with the reduced data sets, and the associated assumptions made, are also presented. Lastly, a series of simulation runs is performed to assess the quantitative effects on temperature and dissolved oxygen concentration generated by varying pond depth and phytoplankton density input values.

Aquaculture pond ecosystem model: temperature and dissolved oxygen prediction — mechanism and application
Journal Article
1996

NOP 97-103 (English) (Spanish)

The staged addition of feed to fertilized fish ponds was evaluated by adding fertilizers to 15 ponds stocked with Nile tilapia Oreochromis niloticus, then adding feed at half ad libitum rates once fish in the ponds reached a target weight. Each pond was stocked with 750 fish (3 fish/mz), and each treatment included three ponds with first feeding at (a) 50 g, (b) 100 g, (c) 150 g, (d) 200 g, and (e) 250 g. Ponds in Thailand (at the Ayutthaya Freshwater Fisheries Station, Royal Thai Department of Fisheries) were maintained for 236-328 d until the fish reached 500 g.

Growth was similar for all treatments under fertilizer alone (1.17 g/d) and was also similar when feed was applied (3.1 g/d). Feed application rates averaged 1.17% BW/d, indicating substantial use of natural food. Pond water quality did not deteriorate under supplemental feeding. Feed conversion rates averaged 1.03. Multiple regression indicated that 73.8% of the variance in growth was explained by design variables (feed input and days), while 86.2% of the variance in growth was explained by adding dissolved oxygen content and alkalinity into the equation.

The most efficient system was to grow fish to 100-150 g with fertilizers alone, then add feed. First adding feed (at 50% ad libitum) once fish reached 100 g produced the highest predicted annual revenues ($6,164 per hectare). Results of this experiment indicated that either critical standing crop occurred early (before the first fish sample) or did not occur at all in these ponds.

Timing of Supplemental Feeding for Tilapia Production
Journal Article
1996

NOP 97-100 (English) (Spanish)

Consistent low yields are a major problem of many small-scale fish farmers in developing economies. The problem plagues Rwandan fish farmers and is embedded in production factors that act, directly or indirectly, in combination with management practices to influence yields. Little is known, however about the causes and to what extent each factor contributes to the problem. Ordinary least squares (OLS) technique was applied to data collected through a survey of 267 small-scale Rwandan fish farmers, to determine which production and management factors affect yields in Rwanda. Selected variables such as pond ownership, elevation, pond size, stocking density, quantity of compost applied, length of production cycle, ability to pay labor, off-farm income, owner's age, educational level, and marital status were regressed on Oreochromis nilotica yields. At the 5% level, pond size, stocking density, and length of the production cycle had significant effects on yields. Increased pond sizes and long production cycles impeded fish production in Rwanda. Higher stocking densities resulted in increased fish yields. The model that best describes the O. nilotica production function in Rwanda is linear. Yield-maximizing composting rates are yet to be applied to fish ponds in Rwanda. The study indicates that farmers have gone beyond cost-minimizing pond sizes and production cycles, which are yet to be researched. Under the perfectly competitive fish and input markets and ceteris paribus assumptions, the optimal stocking density was found to be approximately 34,000 fingerlings/ha.

Estimating <i>Oreochromis nilotica</i> production function for small-scale fish culture in Rwanda
Journal Article
1996
Knud-Hansen, C. F., and C. K. Lin. 1996. Strategies for stocking Nile tilapia (Oreochromis niloticus) in fertilized ponds. Pp. 70 - 76 in The Third International Symposium on Tilapia in Aquaculture, The Third International Symposium on Tilapia in Aquaculture, edited by R.S.V. Pullin, Lazard, J., Legendre, M., Kothias, J.B. Amon, and Pauly, D. Manila, Philippines: International Center for Living Aquatic Resources Management (ICLARM). Retrieved (https://www.worldfishcenter.org/content/third-international-symposium-tilapia-aquaculture).
NOP 96-A03 (English)

NOP 96-A03 (English)

In a 149-day grow-out experiment, we tested the effects of stocking density, partial harvesting and intermediate stocking on net fish yield (NFY) and harvest size of Nile tilapia (Oreochromis niloticus). Sex reversed male tilapia were raised in 280-m2 earthen ponds, which received 8 kg dry weight chicken manure ha-1 day-1 with urea and triple superphosphate supplement to give a total fertilization rate of 4.0 kg N ha-1 day-1 and 1.0 kg P ha-1 day-1. The five treatments were three stocking densities of 0.8, 1.6, and 2.4 fish m-2, fish stocked at 0.8 fish m-2 with an additional 0.8 fish m-2 added after 2.5 months, and fish stocked at 1.6 fish m-2 with 50% of fish removed after 2.5 months. Stocking density significantly affected fish yield (r2-0.57, P<0.02); extrapolated mean NFY in ponds stocked at 0.8, 1.6 and 2.4 fish m-2 were 14.2, 19.2 and 25.7 kg ha-1 day-1, respectively; mean weights were 335, 230 and 214 g fish-1, respectively. Mean NFY for the first 2.5 months exceeded 39.0 kg ha-1 day-1 in ponds stocked at 2.4 fish m-2. Partial stocking gave slightly higher total NFYs than partial harvesting, or 21.7 kg ha-1 day-1 compared to 18.0 kg ha-1 day-1. Additional stocking did not significantly affect fish growth of the originally stocked fish. Mean harvest weights of fish stocked at 0.8 fish m-2 were similar to the first stocked fish in the treatment receiving an additional 0.8 fish m-2 after 2.5 months. Results suggest a partial intermediate stocking and partial harvesting strategy may produce annual tilapia yields of 30 kg ha-1 day-1, with mean weights over 300 g fish-1. Implications for managing ponds for higher yields at desired mean fish weights are discussed.

Strategies for stocking Nile tilapia (Oreochromis niloticus) in fertilized ponds
Conference Paper
1996

NOP 96-94 (English) (Spanish)

Experiments were conducted to assess the effects of polyculture on tilapia growth and to evaluate African catfish (Clarias gariepinus) as a predator control for unwanted tilapia offspring in a polyculture system. Three treatments were tested using nine 200 m2 earthen ponds. Ponds were stocked with male tilapia in treatment 1 (Tl), mixed sex tilapia in treatment 2 (T2), and mixed sex tilapia and catfish in treatment 3 (T3). Fish were fed a commercial diet ration of 1.5% of body weight per day twice a day at 0900 hr and 1500 hr. Feed inputs, adjusted biweekly, were based on Nile tilapia (Oreochromis niloticus) biomass. Gut contents of African catfish were analyzed two weeks prior to termination of the experiment. Water quality parameters were estimated biweekly. Diel analyses of dissolved oxygen (DO), temperature, and pH were performed at three depths and six time intervals, and net primary productivity (NPP) was estimated using DO concentrations. A t-test was used to compare final fry biomass, daily weight gain (DWG) of Nile tilapia, net fish yield (NFY), and the diel variability of gut content. DWG and NFY were significantly higher for treatment T1 in which male Nile tilapia were stocked. Mean fry biomass for each treatment showed large fluctuations. Statistical analyses of two of the three replicates of T1, T2, and all three replicates of T3 indicated that T2 production was significantly greater than T3 production. Forty-seven percent of the sampled African catfish contained one of the following in the stomach or intestines: whole fish, partially digested fish, fish flesh, fish scales, fins, or bones; twenty-six percent of the African catfish had freshly ingested fry in the stomach. Biweekly variation in mean values for water quality parameters were comparable for each treatment. Tilapia production in polyculture with African catfish was significantly lower than the culture systems with either all male tilapia or mixed sex tilapia. African catfish predation of tilapia fry was sufficiently effective to serve as a population control for tilapia; however, active predation occurred only in semi-intensive culture systems where fish were fed their natural diet.

Clarias and Tilapia Interaction in Polyculture
Journal Article
1996
Lovshin, L. L., J. J. Molnar, and T. R. Hanson. 1996. Social, Economic, and Institutional Impacts of Aquacultural Research on Tilapia. Auburn, Alabama: Dept. of Agricultural Economics and Rural Sociology, International Center for Aquaculture and Aquatic Environments, Alabama Agricultural Experiment Station, Auburn University. Retrieved (https://aurora.auburn.edu/handle/11200/1104?show=full).
NOP 96-A02 (English)

NOP 96-A02 (English)

The Pond Dynamics/Aquaculture Collaborative Research Support Program (PD/A CRSP) is a global research network organized to generate basic science that may be used to advance aquacultural development. One of a family of research programs funded by the United States Agency for International Development (USAID), this CRSP focuses on improving the efficiency of aquaculture systems.

The Pond Dynamics/Aquaculture CRSP began work in in 1982 in Thailand, and subsequently in the Philippines, Honduras, Rwanda, Indonesia, and Panama. Research continues today in Thailand, the Philippines, Honduras, the US, and until recently, Rwanda. At all the sites, the Goal is the same: to identify constraints to aquaculture production, and to design responses that are environmentally and culturally appropriate.

The PD/A CRSP has conducted a Global Experiment for over ten years. The Global Experiment has served as an organizing framework for guiding parallel studies in diverse locales in the tropics. Researchers have conducted a series of standardized research trials at each site, establishing baseline data on physical, chemical, and biological processes as they relate to fish growth. The research network has focused on tilapia (Oreochromis niloticus), although some sites have devoted attention to marine shrimp and other locally significant species. This report examines the impact of he network’s investigations with tilapia.

Social, Economic, and Institutional Impacts of Aquacultural Research on Tilapia
Book
1996
Moehl, J. F., and J. J. Molnar. 1996. Institutional Requirements for Aquacultural Development in Africa: Lessons from Rwanda. Pp. 233 - 248 in Aquacultural Development: Social Dimensions of an Emerging Industy, Aquacultural Development: Social Dimensions of an Emerging Industy, edited by C. Bailey, Jentoft, S., and Sinclair, P. Westview Press. Retrieved (http://www.journals.uchicago.edu/doi/pdfplus/10.1086/mre.13.1.42629221).
NOP 97-99 (English)(Spanish)

NOP 97-99 (English)(Spanish)

Institutional Requirements for Aquacultural Development in Africa: Lessons from Rwanda
Book Chapter
1996

NOP 97-116 (English) (Spanish)

Soil cores were taken from ponds at the Central Laboratory for Aquaculture Research, Abbassa, Sharkia, Egypt. Three ponds received little management since construction in the early 1980s. Three other ponds were fertilized heavily in 1993 and 1994 to stimulate tilapia (Oreochromis niloticus) production. Thicknesses of S, M, and T horizons in soil profiles averaged 5, 7.5, and 10 cm, respectively. The S horizon contained more silt than clay, but T and P horizons were 60% clay. Concentrations of total carbon, total nitrogen, total sulphur, phosphorus, calcium, and potassium were greatest in the S horizon and lowest in the P horizon. Intensively managed P-ponds had higher concentrations of phosphorus and lower concentrations of organic matter and sulphur in S and M horizons than B-ponds. Because of high moisture content, low dry bulk density, and greater concentrations of organic matter and nutrients in the S horizon, reactions in this layer probably have a greater influence on pond water quality than those in deeper horizons. For general purposes, soil sampling should be restricted to the S horizon or the upper 5-cm layer where depth of the S horizon is not known. Compared with pond soils from a humid climate in Auburn, Alabama (USA), pond soils at Abbassa had greater concentrations of sulphur, calcium, magnesium, potassium, and sodium, and lower concentrations of iron, manganese, zinc, and copper in S horizons.

Chemical and physical characteristics of bottom soil profiles in ponds on haplaquents in an arid climate at Abbassa, Egypt
Journal Article
1996

NOP 96-98 (English) (Spanish)

Analyses of bottom soils from three recently-established (newer) and three older ponds on each of two, semi-intensive shrimp farms near Choluteca, Honduras, revealed that the 0 to 2.5 cm layer had greater concentrations of most variables than deeper layers. Concentrations of total carbon, nitrogen, sulphur, phosphorus, calcium, iron, manganese, and zinc were greater in older than in newer ponds on one or the other of the farms. After 8-11 y of continuous production, total carbon concentrations varied over pond bottoms, and concentrations usually were greater (1.5 - 2.5%) in inlet sections. Nitrogen concentrations were about 20% those of carbon, and changes in nitrogen concentration closely followed those of carbon. Precipitation of iron pyrite (FeS2) in anaerobic soil layers was the apparent cause of sulphur accumulation in older ponds. Phosphorus accumulated in older ponds on the farm where heavy doses of fertilizer were applied. Soils of both older and newer ponds on both farms had large accumulations of major cations, a large portion of which were water-soluble salts. There was no evidence of development of adverse soil quality in older ponds.

Texture and chemical composition of soils from shrimp ponds near Choluteca, Honduras
Journal Article
1996

NOP 97-113 (English) (Spanish)

An experiment was conducted to determine the amount of P needed to saturate simulated fish pond sediments, formulated to contain six levels of clay (0, 30, 41, 64, 73 and 81% by weight). A series of cylindrical cement tanks were filled to 20 cm depth with the six sediment types and triple superphosphate (TSP) solution was added to reach P saturation in sediment. Results showed that all sediment types reached constant inorganic-p concentration in the upper 5 cm after 12 weeks of TSP application, and P adsorption capacity of sediment increased with increasing clay content. Sediment P adsorption was slower and not significant (P > 0.05) below 5 cm depth except in the sediment type containing 0% clay. Regression analysis showed that the rate and adsorption capacity of P in sediment are primarily governed by clay content and its dominant minerals. While organic-P and loosely bound- P are commonly deposited in sediment, most inorganic-p is adsorbed by cations to form cation-P complexes. The linear relationship between cation-P saturation level and the percentage of clay in sediment is highly significant (r2 = 0.84, P < 0.001), therefore, the maximum adsorption capacity of cation-P in pond sediment can be approximated by Y = 0.019X (where Y represents the 100% saturation level in mg P g -soil, and X is the percentage of clay in the sediment). In practice, the level of P saturation in sediment can be approximated by the initial cation-P and clay contents in the top 5 cm of pond mud using the equation: P saturation (%) = initial cation-P (mg g-1 soil) x 100/P adsorption capacity (mg g-1 soil).

Determination of Phosphorus Saturation Level in Relation to Clay Content in Formulated Pond Muds
Journal Article
1996

NOP 97-101 (English) (Spanish) ; NOP 97-114 (English)

Two experiments were conducted to determine effective P fertilization strategy in fish ponds in relation to sediment P saturation level. Experiment 1 was conducted in cement tanks with five levels of P saturation in the sediments (5, 24, 44, 60 and 79%) and with three P fertilization rates (0.2, 0.1 and 0.05 g m−3 day−1, N:P ratios of 2:1, 4:1 and 8:1, respectively). Nile tilapia (Oreochromis niloticus) were cultured in the tanks for 57 days. Results showed that the mean concentration of soluble reactive phosphorus (SRP) in the water column increased with increasing sediment P saturation and P fertilization rate. The maximum net fish yield (NFY), 4.2 ± 0.3 g m−3 day−1, was obtained at an SRP concentration of 0.3 mg 1−1; higher concentrations did not increase fish yield. These levels of SRP and NFY were attainable with P fertilization rates of 0.2 g m−3 day−1, 0.1 g m−3 day−1 and 0.05 g m−3 day−1 and N:P ratios of 2:1, 4:1 and 8:1 in ponds where the level of sediment P saturation was below 10%, above 45% and above 60%, respectively. Experiment 2 was conducted in earthen ponds to test and verify the P fertilization rate based on the cement tank results. Three new and three old ponds with 8 ± 1.7% and 88 ± 7.3% sediment P saturated in the top 5 cm of mud were fertilized at a rate of 0.2 g m−3 day−1 and 0.05 g m−3 day−1 and N:P ratio of 2:1 and 8:1, respectively. Nile tilapia were cultured at a density of two fish m−3 for 85 days. The mean NFY obtained in new and old ponds were 1.73 ± 0.08 g m−3 day−1 and 2.24 ± 0.32 g m−3 day−1, respectively, which were not significantly different (P > 0.05). We conclude that P fertilization rate should be based on P saturation level in mud to overcome the problem of under or over supply of P in fish ponds.

Phosphorus fertilization strategy in fish ponds based on sediment phosphorus saturation level
Journal Article
1996

NOP 97-105 (English) (Spanish)

Observations of daily gross primary production of oxygen per unit area in a eutrophic, brackish water shrimp culture pond over a 14-day period are compared with predictions from two models in order to assess the utility of the model approaches for ponds and to refine observational protocols and techniques for pond assessment.

The models predicted rates (3.2 to 37.7 g O2 m-2 d-1) which exceeded observations (4.7 to 15.7 g O2 m-2 d-1) at all but the lowest light levels. Observed rates were also lower than other observations at similar light levels. These shortfalls are attributed to (1) the inadequacy of the method for estimation of community respiration as a component of gross production, in the absence of direct observation; and (2) the possibility of nutrient limitation of rates in the pond ecosystem.

The models are sufficiently sensitive to chosen parameter values, and the day-to-day variation of the parameters in the ecosystem likely sufficiently variable, that daily determinations of parameters should be made when possible, with particular attention to timing and use of surface water. Field observations of daytime community respiration, and improved knowledge of its controlling factors and relationships, are important needs for the advancement of model treatment of photosynthesis in ponds.

Eutrophic pond ecosystems have characteristics (vertical temperature structure resembling natural water bodies, complete light extinction within the shallow water column) which make them amenable to study as microcosms of some general aspects of aquatic primary production, particularly problems involving the prediction of daily areal rates from small-scale volume-based rate data.

Observations and model predictions of daily areal primary production in a eutrophic brackish water culture pond
Journal Article
1996

NOP 97-106 (English) (Spanish)

Mechanical mixing of culture ponds with low-powered devices can conserve photosynthetically-produced dissolved oxygen, and so reduce the need for more expensive aeration. This work aimed to test inexpensive, easily obtained devices and to establish the utility of quantifying stratification and mixing processes in power units to facilitate comparisons and projection of requirements to new situations. Three mixing devices of power consumption less than 0.25 hp (63.5-173.6 W) were compared in tropical earthen ponds of surface areas ranging from 200 to 1400 m2. Mixers were operated during the time of maximum stratification in control ponds (13:00-16:00 h), to standardize test conditions. Performance was assessed as reduction in a pond's stratification energy (SE), contained in the uneven vertical distribution of mass.

Neighboring unmixed ponds showed very similar diel cycles of SE; unmixed ponds also showed similar patterns on successive days, but varied more than neighboring ponds assessed simultaneously. The mixing device of greatest power consumption, a fan-blade aerator-mixer (AM) operated below water surface, reduced stratification energy more quickly than a submersible impeller pump (SP) and an air-lift (AL). The AM and AL were more efficient than the SP, but all were of low efficiency (less than 0.1%). Efficiencies were related to pond size, with perimeter/area ratio being significant but surface/volume not so. Mixing effects propagated rapidly horizontally.

The AM applied sufficient power to exceed the observed daytime rate of increase in stratification energy, i.e. to prevent stratification, in ponds of all sizes except the largest. The AL and SP did not apply power at sufficient rates, and the AM would have been inadequate at other times. It is not necessary, however, to prevent stratification completely for all mixing applications.

Comparison of three mixing devices in earthen culture ponds of four different surface areas
Journal Article
1996
Szyper, J. P., and K. D. Hopkins. 1996. Effects of pond depth & mechanical mixing on production of Oreochromis niloticus in manured earthen ponds. Pp. 152 - 158 in The Third International Symposium on Tilapia in Aquaculture, The Third International Symposium on Tilapia in Aquaculture, edited by R.S.V. Pullin, Lazard, J., Legendre, M., Kothias, J.B. Amon, and Pauly, D. Manila, Philippines: International Center for Living Aquatic Resources Management (ICLARM). Retrieved (https://www.worldfishcenter.org/content/third-international-symposium-tilapia-aquaculture).
NOP 96-A04 (English)

NOP 96-A04 (English)

An experiment to assess the effects of water mixing on production of Nile tilapia (Oreochromis niloticus) in fertilized earthen ponds was performed at the Asian Institute of Technology in Thailand. Male fingerlings stocked at 3 fish m-3 grew to final weights of 106-233 g in 173 days in nine ponds of approximately 370- m-2 individual surface area. Yields were statistically indistinguishable among treatments, averaging 5.4 t ha-1 year-1 in three ponds of 1.5 m depth whose water was mixed for two hours each day; 6.7 t ha-1 year-1 in three similar but unmixed ponds: and 6.9 t ha-1 year-1 in three unmixed ponds of 0.9 m depth. Survival was significantly lower in the deep mixed ponds (72% compared with 91-93%). Fish grew more rapidly and had larger final weights in the shallow unmixed ponds, which had larger standing stocks of phytoplankton, as measured by chlorophyll a, and greater rates of gross dissolved oxygen (DO) production per unit volume during most of the growth period. Treatments did not differ in gross DO production per unit area. Daily mixing produced higher nighttime bottom oxygen concentrations up until 2300 hours, but did not change overnight DO minima. No treatment-related differences in ammonia concentrations or other water quality parameters were found. The oxygen-conserving effect of mixing was not effective in enhancing production of this species, which grows and survives well in unmixed ponds, tolerating or avoiding waters of low oxygen content. Mixing and aeration strategies must be examined carefully for both detrimental and beneficial effects.

Effects of pond depth & mechanical mixing on production of Oreochromis niloticus in manured earthen ponds
Conference Paper
1996

NOP 96-97 (English) (Spanish)

Tilapia and tambaquí (Colossoma macropomum) were co-stocked in earthen ponds at 0, 25, 75, and 100% of each species. Total density was three fish m-2. Fish were offered a 28% protein pellet. Mean treatment production ranged from 2537 to 5265 kg ha-1 after 182 days. Total production increased curvilinearly, and feed conversion ratios decreased curvilinearly as the rate of stocked tilapia increased. Feed conversion ratios ranged from 1.13 to 2.71. Total nitrogen and chlorophyll a decreased linearly as rate of stocked tilapia increased, because of grazing by tilapia on phytoplankton. Mean tilapia and tambaquí harvest weights ranged from 187 to 325 g, and 122-270 g, respectively. Tilapia mean weight decreased curvilinearly, and tambaquí mean weight increased linearly as the rate of stocked tilapia increased. Tambaquí growth appeared to be hindered by cool water temperature for part of the season. Thereafter, growth rate increased as stocking rate of tambaquí increased. The best species mixture for high production was 75% tilapia and 25% tambaquí, but the highest economic return would depend on prices for each species and size combination.

Effect of stocking ratio on semi-intensive polyculture of <i>Colossoma macropomum</i> and <i>Oreochromis niloticus</i> in Honduras, Central America
Journal Article
1996

NOP 97-115 (English) (Spanish)

An experiment was conducted for 90 days at the Asian Institute of Technology in Thailand to investigate the appropriate stocking density of large Nile tilapia placed in cages in earthen ponds where small Nile tilapia were stocked in open water to utilize the wastes derived from the cages. Large male tilapia (141 +/- 11.1 - 152 +/- 2.1 g) were stocked at 30, 40, 50, 60, and 70 fish m-3 in 4-m3 net cages. One cage was suspended in each of 15 earthen ponds, and three replicates were used for each density. Small male tilapia (54 +/- 2.3 - 57 +/- 1.2 g) were stocked at 2 fish m-3 in open water of all ponds. Caged tilapia were fed twice daily at 3%, 2.5%, and 2% body weight day-’ during the first, second, and third month, respectively, with commercial floating pellets containing 30% crude protein. Water quality was analyzed biweekly.

Stocking densities of caged tilapia had significant (P < 0.05) effects on the survival, growth, and food conversion ratio of caged tilapia, and on the growth of open-pond tilapia. The survival of caged tilapia decreased from 91.4% +/- 5.0 to 57.2% +/- 8.1 with increased stocking densities from 30 to 70 fish m-3, while survival of pond tilapia was higher than 90.0% in all treatments. The average treatment mean weights of tilapia harvested from cages ranged from 509 +/- 26.0 to 565 +/- 13.9 g. The growth of pond tilapia was quite slow, with daily weight gain increasing from 0.30 +/- 0.02 to 0.47 +/- 0.08 g per fish day-1, in response to increased feed inputs to caged tilapia. The combined net yield of both caged and open-pond tilapia was highest in the treatment with 50 fish m-3. Water quality analyses indicated that the wastes from caged tilapia were insufficient to generate abundant natural food for the growth of open-pond tilapia.

Influence of Nile tilapia (<i>Oreochromis niloticus</i>) stocking density in cages on their growth and yield in cages and in ponds containing the cages
Journal Article
1996

1995

NOP 95-86 (English) (French) (Spanish)

The pH-percent base saturation relationships of selected subsurface soil horizons were evaluated by fitting theoretical and empirical models to published soils data. The selected models were validated by fitting them to an independent set of data. The selected models did not fit the second set of data as well as the original data, but they provide initial approximations for use in cases when real values can't be measured. Possible reasons for the poorer fit to the second data set are discussed. One possibility for increasing the range of soils to which suitable pH-percent base saturation models can be fit is to refine the soil classification system being used. Valid pH-percent base saturation models can be combined with on-site soil pH measurements and typical cation exchange capacity values to estimate aquaculture pond lime requirements on a broad range of soil types in the field i.e., without reliance on laboratory analyses.

Evaluation of Soil pH-Percent Base Saturation Relationships for Use in Estimating the Lime Requirements of Earthen Aquaculture Ponds
Journal Article
1995

NOP 96-90 (English) (French) (Spanish)

Mass balance calculations for nutrient elements are useful in determining the efficiency of fertilizers and feeds in aquaculture ponds (Avnimelech and Lacher 1979; Tucker and Boyd 1985; Schroeder 1987), for studying the fate of nutrients within pond ecosystems (Boyd 1985; Krom et al. 1985; Daniels and Boyd 1989; Hopkins et al. 1993), and for estimating the pollution potential of pond effluents (Schwartz and Boyd 1994). In research, mass balance computations may be site specific and require complete data on all nutrient inputs and outputs for a particular pond (Boyd 1985). For general assessments of nutrient mass balance, fewer data are necessary. For example, the potential nitrogen and phosphorus loadings of intensive aquaculture ponds can be estimated from the stocking density, feeding rate, expected feed conversion ratio, and nitrogen and phosphorus concentrations in feed and aquaculture product (Boyd 1990). Most of the necessary information is easily obtained, but data on whole body, elemental composition of aquaculture species are scarce. 

The present study was conducted to assess the elemental composition of two species of shrimp (Penaeus vannamei and P. stylirostris) that are widely cultured in coastal regions of tropical and subtropical North and South America. Elements of primary concern for pond management and environmental impact considerations are carbon, nitrogen, and phosphorus, but analyses included several other nutrients. 

Dry Matter, Ash, and Elemental Composition of Pond-Cultured <i>Penaeus vannamei</i> and <i>P. stylirostris</i>
Journal Article
1995

NOP 95-85 (English)

A case study describing citizens' contentions that restarting Three Mile Island's nuclear reactor (TMI-1) would cause psychological distress provides historical and legislative impetus for federal agencies to consider psychosocial dimensions in their environmental impact statements (EISs). Although the Nuclear Regulatory Commission (NRC) rejected citizens" complaints on the grounds that dis- tress is not easily quantifiable, experts associated with the case noted that the NRC's contention was not entirely valid and that the National Environmental Protection Act missed a golden opportunity to promote the development of methodology and models for incorporating psychosocial factors into the EIS. This study describes some of the methods that have subsequently been used for measuring distress in the context of technological hazards.

Psychological Distress as a Factor in Environmental Impact Assessment: Some Methods and Ideas for Quantifying this Intangible Intangible
Journal Article
1995

NOP 95-A01 (English)

Application of the regulatory principle of ‘best available technology’ (BAT) to fish farm effluent control has, to some extent, been a driving force for the development of new culture and treatment technology. In Norway today, there are a number of farms for the production of Atlantic salmon, Salmon salar L., smolts and brown trout. Salmo trutta L., fingerlings that utilize microstrainers for the removal of particles from the effluent water. At least one commercial farm also utilizes a simplified recirculation system called BIOFISH as a demonstration of new and alternative technology for the production of brown trout restocking fish. In this paper, calculated effluent discharge and rates of waste production from the BIOFISH demonstration trials are compared to literature data and to measurements on un-treated as microstrained effluents from the production of Atlantic salmon smolts in a traditional flow through tank system. The results of these calculations show fish waste production rates that are low, but comparable to data found in the literature. Given the level of waste treatment that takes place in the BIOFISH tanks, the specific effluent discharge levels from those tanks, in terms of grams per kilogram biomass and grams per kilogram feed, are considerably lower than those found for salmon smolt production in traditional flow through tanks. There are also substantial differences in hydraulic self-cleaning properties of the two systems and a corresponding difference in the distribution for effluent discharge during normal tank operation and during the tank/effluent pipeline flushing. The results presented here give valuable information related to: (1) waste output characterization: (2) the long-term efficiency of commercially available particle separation systems; and (3) the capabilities of the simplified BIOFISH recirculation technology under field conditions.

Rates of fish waste production and effluent discharge from recirculating system (BIOFISH) under commercial conditions
Journal Article
1995

NOP 96-88 (English) (French) (Spanish)

Chemical budgets were determined for nitrogen, phosphorus, dissolved oxygen and chemical oxygen demand for three 0.1-ha earthen ponds stocked with Oreochrornis niloticus at the El Carao National Fish Culture Research Center, Comayagna, Honduras, for two 150-d culture periods, corresponding to the rainy and dry seasons. Layer chicken litter was added to ponds weekly at 500 kg dry matter/ha. Concentrations of nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) in pond water increased during each season. No significant seasonal differences in concentrations of water quality variables were observed. Chicken litter added to ponds represented 92–94% of N input, 93–95% of P input, and 43–52% of COD input. Photosynthesis by phytoplankton provided 47–56% of COD and 98% of dissolved oxygen (DO) added to ponds. Net inward diffusion of oxygen added 1.2–1.5% of total DO. Regulated inflow was a minor source of nutrients, and contributed 3–4% of input N, 3–4% of input P, 1% of COD input, and 1% of DO input. Nutrient inputs from rain were ≤1% of total for each nutrient. Fish harvest accounted for 18–21% of total N, 16–18% of total P and 2% of COD added to ponds. Community respiration accounted for 48–57% of COD and 99.5% of DO added to ponds. Nutrient losses in pond effluent at draining were: 7–9% of total N, 29–37% of total P and 2–3% of COD. While measured gains exceeded measured losses, significantly greater N, P and organic matter concentrations in pre-drain samples indicated pond mud was a major sink for added nutrients, accumulation in mud represented 70% of total N, 35–40% of total P, and 38–46% of COD.

Chemical Budgets for Organically Fertilized Fish Ponds in the Dry Tropics
Journal Article
1995

Experiments were conducted at the Central Laboratory for Aquacultural Research to 1.) evaluate and compare the performance of established PD/A CRSP pond management systems to Egyptian pond management systems and 2.) to assess the economic potential of different tilapia pond culture systems. Five management practices --Traditional Egyptian, Enhanced Egyptian, Feed Only, Fertilization then Feed,and Chemical Fertilization-- were tested in twenty 0.1-ha earthen ponds. Young-of-year Nile tilapia (Oreochromis niloticus) were stocked 20,000 fish/ha and fingerling African catfish were subsequently stocked 60 fish/ha to prey on tilapia offspring. Water quality variables were analyzed weekly for 17 weeks. The Free-Water Diel curve method was used to determine primary productivity on six occasions. Dissolved oxygen was measured with a polarographic dissolved oxygen meter at depths of 5 cm, 25 cm, 50 cm, and 75 cm. Economic potential and profitability were also evaluated using Enterprise Budget Analysis. Fertilization then Feed, Traditional Egyptian, and Enhanced Egyptian treatments, in decreasing order, were more economically viable and produced the greatest gross fish yields, net returns, and average rates of' return on capital. These treatments had the highest values of production per man-hour per kilogram of feed and per Egyptian pound. In addition, the treatments achieved the highest margins between average prices and break even prices to cover total variable costs of total costs. Production trial results and economic analyses demonstrated sufficient incentive for the expansion of intensified pond culture in Egypt.

Evaluation of Nile Tilapia Production Systems in Egypt
Report
1995

NOP 96-87 (English) (French) (Spanish)

Water budgets were calculated for embankment fish ponds located in the dry tropics. Two 5-month studies were conducted at Comayagua, Honduras. Daily pond evaporation averaged 0.55 ± 0.22 and 0.64 ± 0.17 cm during studies 1 and 2, respectively. Pond evaporation was 14·5% greater during study 2. Significantly greater pond evaporation was measured during the 3 driest months compared to the 3 rainiest months. Mean daily seepage ranged from 0.11 to 0.43 cm and from 0.06 to 0.60 cm during studies 1 and 2, respectively. Total rainfall during study 1 exceeded that during study 2 by 43%. Regulated inflow water was required every month to replace water losses to pond evaporation and seepage. Pond evaporation accounted for 70% of total water loss during both studies, while seepage accounted for the remaining water loss. Rain accounted for 45.5 and 21.8% of gains during studies 1 and 2, respectively. Regulated inflow water accounted for 52.8 and 77.9% of the respective gains.

Water Budgets For Fish Ponds in the Dry Tropics
Journal Article
1995
Green, B. W. 1995. Polyculture of Tilapia with Marine Shrimp. Pp. 117 - 125 in Primer Simposio Centoamericano sobre Cultico De Tilapia, Primer Simposio Centoamericano sobre Cultico De Tilapia, edited by N. Galvez, Gunther, J., Porras, A., Athanasiadis, H.P., and Zurburg, W. Panama. Retrieved (http://www.sidalc.net/cgi-bin/wxis.exe/?IsisScript=CENIDA.xis&method=post&formato=2&cantidad=1&expresion=mfn=054400).
NOP 97-102 (English) (Spanish)

NOP 97-102 (English) (Spanish)

The potential for tilapia-marine shrimp polyculture is evaluated. Aquaculturally important tilapia are the Nile tilapia (Oreochromis niloticus), blue tilapia (O. aureus), red tilapia (Oreochromis spp.) and, to a lesser extent, Mozambique tilapia (O. mossambicus). Nile and blue tilapia can tolerate salinities as high as 36 ppt to 40 ppt, but best growth occurs at salinities below 20 ppt. Red tilapia, either from Florida or Taiwan, survive and grow well in salinities of 36 ppt. Mozambique tilapia is able to tolerate salinities as high as 120 ppt, but good growth is reported through salinities of 36 ppt. While these tilapia can spawn in waters of various salinities, greater fingerling production is achieved in freshwater or slightly saline (2 ppt to 5 ppt) waters. Maximum salinity tolerance in tilapia appears to be reached at a total length of 50 to 70 mm. Acclimation of tilapia from freshwater to saline water is best accomplished by increasing salinity from 2.5 ppt to 5 ppt daily until the desired salinity is reached. Season, choice of culture species, market, and management/logistical considerations of tilapia-marine shrimp polyculture are discussed. Polyculture of tilapia and marine shrimp may be limited to 6 to 7 months each year during and immediately following the rainy season along the Pacific Coast of Central America depending on the tilapia species selected for culture. Tilapia can be stocked directly into ponds or into cages placed in ponds, supply canals or drain canals. It remains necessary to determine the optimum stocking rates of tilapia for polyculture with marine shrimp and to validate these production systems on commercial farms.

Polyculture of Tilapia with Marine Shrimp
Conference Paper
1995

NOP 96-93 (English) (Spanish)

The experiment was conducted for 122 days in central Thailand to test rearing of hybrid catfish in cages in earthen ponds, where tilapia (Oreochromis niloticus) was stocked to utilize the waste products derived from intensively reared catfish. Catfish fingerlings (13-17 g size) was stocked in plastic net cages at a density of 275 fish/m3. Six earthen ponds (250 m2 - 110 m3 each) were used to suspend the cages in two loading densities as experimental treatments: 880 and 1760 catfish / pond. Each loading density was replicated in 3 ponds. Each pond was stocked with 440 sex-reversed male tilapia of 6-7 g size in open water, giving the catfish and tilapia stocking ratios of 2:1 and 4:1, respectively. Catfish was fed twice daily at 3-10% body weight per day with commercial floating pellets containing 25-30% crude protein. Water quality was analyzed bi-weekly for concentration of dissolved oxygen, ammonia and chlorophyll a.

Results showed that there was no significant difference (p < 0.05) in catfish growth rate and survival between the two loading densities. The mean weight gain of harvested catfish was 259.5 +/- 34.5 g and 255.2 +/- 8.4 g/fish, giving the total net yield of 218.0 +/- 26.8 kg and 391.5 +/- 88.0 kg per pond in low and high loading density, respectively. Tilapia was harvested with mean weight of 172.3 +/- 37.8 g and 297.5 +/- 32.0 g/fish, and the net yield of 68.1 +/- 13.6 and 86.0 +/- 27.2 kg/pond for low and high loading catfish density treatment, respectively. Chlorophyll a and total ammonia concentrations differed greatly between the two treatments. Early morning dissolved oxygen (DO) declined steadily both treatments over the culture period

Co-culture of catfish (<i>Clarias macrocqbhalus</i> x <i>C . gariepinus</i>) and tilapia (<i>Oreochromis niloticus</i>) in ponds
Journal Article
1995

NOP 94-A05 (English) ; NOP 95-A03 (English)

A procedure for the calculation of pH in fresh and salt waters has been developed. The method is based on a fourth-order polynomial relationship between hydrogen ion concentration and other (conservative) water quality parameters.

The method avoids trial and error estimations and results in a direct calculation procedure that can be implemented in models developed in various modeling environments, such as spreadsheets, conventional programming languages (BASIC, C, FORTRAN, PASCAL, etc.) or specialized modeling languages (Extend™, Stella™). The method developed is based on the solution of the full alkalinity-pH equation. Because of the need for simplification of the equations to yield explicitly solvable polynomial equations, the accuracy of the solutions depends on the simplification made and varies with water properties. Three simplifications are tested based on a second-, a third-and a fourth-order polynomial equation for hydrogen ion concentrations. the equations have been tested for salinities ranging from 0 to 35ppt (fresh to sea water), for temperatures ranging from 0 to 35 degrees C, for total carbonate carbon concentrations of 0.1 and 5.0 mmol/liter, and for total ammonia nitrogen concentrations of 0 and 10 mg/liter. Approximations are most accurate in waters of high total carbonate carbon and low ammonia concentrations, where the fourth-order approximation yields results that are within 0.05 pH units for the full range of pH values tested (5-10).

Calculation of pH in fresh and sea water aquaculture systems
Journal Article
1995

NOP 95-A04 (English)

Black carp, Mylopharyngodon piceus, has powerful pharyngeal teeth which are adapted for crushing mollusks. Several species of gastropods are nuisance organisms or intermediate hosts in parasite transmission. The black carp may serve as an agent for biological control of some of these pests. Laboratory experiments were conducted to test various aspects of their feeding biology. Mouth gape was determined to be a good estimator of the largest size snail that a particular fish could ingest, crush and swallow. The relationship, gape/total length, can be used to evaluate the scope of predator/prey potential in water bodies with snail pests. Fish between 100 and 500 mm had gapes from 7 to 25 mm, respectively. Based on the size of fish tested in predator/prey studies (120-320 mm; gape 7-17 mm) and gastropod species used, snails of 7 to 17 mm were eaten. Fish between 100 and 200 g (210-270 mm TL) were satiated at 1.5 to 13% of the body weight, while fish around 300 g ( similar to 320 mm) were satiated at 1-6% of the body weight. Based on the limited and small size range of fish examined, about 10 g of snail biomass could be eaten per day by these relatively small black carp. These preliminary data might permit some estimate of fish numbers to stock for snail control.

Experimental observations on feeding biology of Black Carp (<i>Mylopharyngodon piceus</i>)
Journal Article
1995
Szyper, J. P. et al. 1995. Techniques for Efficient and Sustainable Mass Production of Tilapia in Thailand. Pp. 349 - 356 in Proceedings of the PACON International Sustainable Aquaculture 95 Symposium, Proceedings of the PACON International Sustainable Aquaculture 95 Symposium. Retrieved (https://catalog.hathitrust.org/Record/008341214).
NOP 95-84 (English) (French) (Spanish)

NOP 95-84 (English) (French) (Spanish)

Tilapia culture in Southeast Asia is presently both spreading and intensifying. Researchers at the Asian Institute of Technology (AIT) have learned from and contributed to the sustainability of current techniques. Several hatcheries produce fry at rates exceeding two million fish per month using low-technology apparatus and methods developed at AIT. Fish survival and production rates in growout culture are enhanced by nursing fry to reasonable stocking sizes in hapa nets deployed in fertilized ponds, which may be fed relatively low quantities of inexpensive feeds, but produce reasonable yields with none at all. Inputs to growout ponds of on-farm organic materials (manures) and inorganic fertilizers can stimulate the ecosystems to be capable of supporting fish growth to more than 200 grams/fish without other feed inputs, with little disadvantage in growth rate compared to fed ponds, but with considerable economic and efficiency advantages. Beyond 200-300 grams/fish, growth is slower on plankton feeding alone because larger fish lack the capacity to acquire sufficient ration even in ponds with high plankton stocks. Feeding is begun as a supplement to plankton forage, and soon becomes the dominant nutritional source; rapid, near optimal growth is attained on a ration of approximately 50% of satiation amounts.

Economic analyses of these practices under current conditions in Thailand show reasonable viability despite some of Asia's lowest farm-gate tilapia prices and the incipient state of export enterprise in tilapia. The stability of the pond ecosystems during the growout periods without water addition to ponds indicates sustainable and efficient use of water resources in a region of seasonal drought. These practices offer hope of alleviating the predicted shortfalls in animal protein availability in rural areas of southeast Asia, and potentially workable scenarios for periurban enterprises serving, and using processing wastes and other inputs from, large urban Asian markets.

Techniques for Efficient and Sustainable Mass Production of Tilapia in Thailand
Conference Paper
1995

NOP 95-A02 (English) ; NOP 96-89 (English) (French) (Spanish)

Shrimp were grown under ideal management conditions during two distinct seasons of the year at stocking densities used most often in Honduras with the objective of evaluating the usefulness of high protein diets. A randomized design in 2 x 2 factorial arrangement was used to test a diet composed of either 20 or 40% crude protein in earthen ponds that were stocked with juvenile Penaeus vannamei at 5 to 11/m2 . The study was repeated during wet and dry seasons. Dietary protein level had no significant effect (P > 0.05) on survival, yield, or average weight of shrimp production during both seasons. Mean shrimp weight in high density ponds were significantly lower than mean shrimp weight in low density ponds during the wet season, but there was no significant weight difference because of stocking density during the dry season. Net income was negative during the dry season, particularly at the high stocking density during the dry season. Net income was negative during the dry season, particularly at the high stocking density. Mean production was 240% greater in the wet season than in the dry season. Diets offered P. vannamei stocked at 5 to 11/m2 should contain no more than 20% protein, regardless of season. Higher dietary protein levels increase costs and waste nitrogen without resulting in greater shrimp yields. The high stocking density might increase profitability in the wet season, but long term sustainable production may be more feasible at lower stocking rates because of reduced nutrient wastes.

Semi-Intensive Commercial Grow-Out of <i>Penaeus vannamei</i> Fed Diets Containing Differing Levels of Crude Protein During Wet and Dry Seasons in Honduras
Journal Article
1995
Ward, G. H. 1995. A Strategic Approach to Carrying-Capactiy Analysis for Aquaculture in Estuaries. Pp. 71 - 84 in Water Effluent and Quality, with Special Emphasis on Finfish and Shrimp Aquaculture: Proceedings of the Twenty-fourth U.S.-Japan Aquaculture Panel Symposium, Water Effluent and Quality, with Special Emphasis on Finfish and Shrimp Aquaculture: Proceedings of the Twenty-fourth U.S.-Japan Aquaculture Panel Symposium, edited by B.J. Keller, Park, P.K., McVey, J.P., Takayanagi, K., and Hosoya, K.
NOP 97-117 (English) (Spanish)

NOP 97-117 (English) (Spanish)

Estuaries are coastal watercourses that are subject to both marine and riverine influences. Their principal hydrographic controls are morphology, tides, freshwater inflows, meteorology, and density currents. The propagation of tides and the distribution of salinity are important indicators of circulation in an estuary. Circulation in particular imposes a limit on the ability of an estuary to assimilate wastes without degrading its water quality. This is an important constraint on concentrated aquaculture operations that circulate water, since these produce a large volume of wastewater and also require a supply of uncontaminated water. A general procedure is outlined for determining the "carrying capacity" of the estuary. This requires (1) specification of the water quality parameter(s) that form the basis of water quality evaluation, (2) determining the parameter value(s) of acceptable water quality, (3) development of a water quality model appropriate for the estuary, and (4) establishing the conditions that are critical for water quality. The water quality model is central to the procedure: it is a combined hydrodynamic and mass balance calculation, designed to reflect the space-time scales controlling the water management problem. Its development requires an extensive base of field data. The model is applied to predicting the water quality regime that would result under a hypothetical distribution and volume of wasteloads. The largest volume of wasteloads that results in water quality equal to the level judged acceptable under critical conditions is the assimilative capacity. It is important to note that assimilative capacity is a function of position in the estuary, and depends upon both local and larger scale hydrography. Single values of "carrying capacity" or "flushing time" applied to an entire estuary are of little use. A case study is presented of shrimp aquaculture in Golfo de Fonseca, Central America. A preliminary analysis of the operations around Estero Pedregal is performed using a one-dimensional model, to illustrate the kinds of analyses that can be carried out and the types of results that can be obtained. These results indicate that shrimp aquaculture in this area is already approaching a level of being self-limited.

A Strategic Approach to Carrying-Capactiy Analysis for Aquaculture in Estuaries
Conference Paper
1995
Yohe, J. M. et al. 1995. The CRSPs: International Collaborative Research Support Programs. Pp. 321 - 338 in Disease Analysis through Genetics and Biotechnology: Interdisciplinary Bridges to Improved Sorghum and Millet Corps, Disease Analysis through Genetics and Biotechnology: Interdisciplinary Bridges to Improved Sorghum and Millet Corps, edited by J.F. Leslie and Frederiksen, R.A. Iowa State University Press.
NOP 97-110 (English) (Spanish)

NOP 97-110 (English) (Spanish)

The Collaborative Research Support Programs (CRSPs) are communities of U.S. Universities, U.S. Agency for International Development (USAID) and USAID missions, and developing countries national agriculture research systems (NARS), other U.S. federal agencies, international agricultural research centers (IARCs), private agencies, industry, private voluntary organizations (PVOs), and other developing country institutions. Their scientists, in close collaboration with one another and for the mutual benefits of their programs, carry out agricultural research and training around identified constraints to food production, storage, marketing, and consumption. More specifically, they include components which address food and agricultural policy/planning, natural resource management, plant and animal improvement (including basic genetics, biodiversity, applied genetics and biotechnology), plant and animal physiology and improved production practices, plant and animal protection, socio-economic and socio-cultural factors influencing production and consumption patterns; cultural constraints to technology adoption and development; and improved food processing, household food security and human nutrition. Through shared resources, peer review and institutional support, these communities of scientists and institutions give emphasis to the needs of small scale producers and the rural and urban poor.

The CRSPs: International Collaborative Research Support Programs
Book Chapter
1995

1994

NOP 94-70 (English) (French) (Spanish)

Benthic respiration in two fish culture ponds at Comayagua, Honduras, was below 1 g CO2/m2 per day during culture periods. When ponds were drained for fish harvest, bottom soils were exposed to the air, and soil respiration rates as high as 10 g CO2/m2 per day were recorded. High rates of soil respiration following removal of saturated conditions declined as labile organic matter was consumed and soil moisture content declined. Laboratory studies showed that the moisture content for greatest soil respiration was near saturation, and either drying soils or completely saturating them drastically reduced respiration. Although soil respiration rates were much greater during the fallow period than during the culture period, more organic matter was decomposed during the culture period because it was much longer (5 months) than the fallow periods (2 weeks).

Pond Bottom Soil Respiration during Fallow and Culture Periods in Heavily-Fertilized Tropical Fish Ponds
Journal Article
1994

NOP 94-A03 (English); NOP 94-A08 (English)

Two experiments were conducted to study the effects of feeding frequency on growth, and of handling stress on growth and mortality, in intensive tank culture of the walking catfish Clarias fuscus. In the first experiment, fish were grown from an initial weight of 37 g for 34 d. A fixed ration of 3.0% body weight per day was divided into either 1, 2, or 3 feedings per day, and fish were either handled weekly or left unhandled for the entire experiment. Fish given 3 feedings per day experienced 19% faster growth (P < 0.05) than fish given the same ration in a single feeding per day. These differences in growth reflect differences in assimilation efficiency, assuming all other metabolic costs were constant among treatments. Handling of individuals caused decreased growth; however, there was no effect on mortality.

In the second experiment, fish were grown from an initial weight of 78 g for 29d. Fish were fed either 1 or 2 satiation feedings per day and were either handled weekly or left unhandled for the entire experiment. Fish fed 2 satiation feedings per day experienced 47% faster growth (P < 0.05) than fish fed 1 satiation feeding per day, which was assumed to reflect a higher level of food consumption. No effect of handling on either growth or mortality was observed for fish in experiment 2. Multiple meals per day also reduced depensatory growth among individuals in both experiments.

Effects of Feeding Frequency and Handling on Growth and Mortality of Cultured Walking Catfish <i>Clarias fuscus</i>
Journal Article
1994

NOP 94-73 (English) (French) (Spanish)

The addition of feed to fertilized fish ponds was evaluated by adding feed alone, feed plus fertilizer, or fertilizer alone to nine ponds stocked with Nile tilapia Oreochromis niloticus. Two experiments were conducted. The first had 500 fish per 250 m2 pond in 3 treatments: ad-libitum feeding; fertilizer only; or fertilizer and ad-libitum feeding. The second experiment had 5 treatments with 750 fish per pond ad-libitum feed only; fertilizer only; or 0.25, 0.50, and 0.75 satiation ration plus fertilizer. Ponds in Thailand were maintained for 155–162 d, during which chemical and physical properties were monitored. In experiment 1 tilapia growth was highest in feed only ponds, and lowest in fertilizer only ponds. Net yield did not differ significantly among treatments, due to variation in survival. In experiment 2, tilapia growth was lowest in fertilizer only ponds, intermediate in 0.25 ration ponds, and highest in 0.50, 0.75, and ad-libitum ponds. The latter treatments were not significantly different. Multiple regressions for each experiment indicated only 47–87% of the variance in growth was explained by feed and fertilizer input, while 52–89% of the variance in yield was explained by those factors. For both experiments combined, 90.3% of the variance in growth was explained by feed input, fertilizer input, alkalinity, and total inorganic nitrogen concentration. For yield, R2 was 0.888 and the regression included feed input, pH, and number of low dissolved oxygen events. Experiment 1 appeared to approach carrying capacity near the end, while no reduction in growth occurred in experiment 2 at higher fish density and biomass. Reductions in growth in experiment 1 were not correlated with declining water quality late in the grow out. Combinations of feed and fertilizer were most efficient in growing tilapia to large size (500 g) compared to complete feeding or fertilizing alone.

Supplemental Feeding of Tilapia in Fertilized Ponds
Journal Article
1994

NOP 94-A01 (English)

Ten cooperating farmers in Northeast Thailand obtained a mean net yield of 1.8 tonnes/ha/yr of Nile tilapia (Oreochromis niloticus) in 200-m2 ponds manured at a rate of 200 kg dry matter (DM)/ha/day. Farmers were enthusiastic about the trial but fish production was most inefficient. A mean of 4.0 tonnes of fresh manure was collected and loaded into the 200-m2 pond over a 7-month period to yield only 20.7 kg of fish. Mean manure to fish conversion ratios were 195 and 34:1 on fresh and dry matter bases, respectively, with a dry matter conversion efficiency of manure to fish of <1%. Buffalo manure should not be recommended to farmers as a major pond fertilizer.

An assessment of the role of buffalo manure of pond culture of tilapia. II. Field trial
Journal Article
1994

NOP 94-A04 (English) ; NOP 96-92 (English) (French) (Spanish)

Water quality in tropical fish ponds is generally evaluated without the assistance of remote sensing because of cost, cloud cover, and other constraints, but certain parameters such as suspended solid concentrations, color, clorophyll and temperature can effectively be monitored by aerial photography and satellite imagery. This paper reviews applications of remote sensing to tropical inland fisheries and aquaculture and includes applications from related disciplines. A brief assessment of new platforms and sensors is also presented. Remote sensing images may help to inform researchers and planners about water quality trends that are occurring over a broad area in which fisheries and aquaculture activities occur. However, the operational use of remote sensing in aquaculture remains largely experimental.

Monitoring water quality for tropical freshwater fisheries and aquaculture: a review of aircraft and satellite imagery applications
Journal Article
1994

NOP 95-79 (English

In an aquaculture pond, the primary production system serves both as the basis for the natural food chain, and as a primary source of dissolved oxygen (DO). As the productivity of the pond system and the standing crop of phytoplankton increases, so does the degree of fluctuation in diel DO concentrations, water quality, and the degree of vertical stratifications of the water column. In highly turbid pond systems the rapid extinction of incident light in the surface layers results in benthic zones serving only as a net oxygen sinks, even while the surface is exposed to full sunlight and is a net oxygen source. As the standing phytoplankton crop is reduced, self shading decreases, as does total food availability and gross production of oxygen, but the stability of the system, in terms of DO fluctuations and water quality, increases. Therefore, in this respect, the trade-off in balancing the pond system is in terms of gross productive potential versus water-quality stability.

Modeling Photosynthetic Production Optimization for Aquaculture Ponds
Journal Article
1994
Grace, G. R., and R. H. Piedrahita. 1994. Chapter 7: Carbon Dioxide Control in Aquaculture Water Reuse Systems: Engineering Design and Management. Pp. 209 - 234 in Developments in Aquaculture and Fisheries Science, vol. 27, Developments in Aquaculture and Fisheries Science, edited by M.B. Timmons and Losordo, T.M. Elsevier.
NOP 94-A07 (English)

NOP 94-A07 (English)

Carbon dioxide management should be one of many important considerations in intensive aquaculture systems. Unchecked, carbon dioxide may lower the pH to stressful levels, suffocate animals even in the presence of oxygen, and reduce the efficiency of biological filters. Carbon dioxide concentrations in culture waters may be controlled by pH management or through gas exchange. Carbon dioxide control by pH management is reviewed in general terms based on principles of carbonate chemistry. Carbon dioxide removal by gas transfer is easily attained, but its quantitative description requires a multi-step approach due to the influences of the relative ratios of gas and liquid flow rates, gas flow characteristics, and chemical reactions among the carbonate species. Carbon dioxide removal by gas transfer is often limited by the build up of carbon dioxide in the gas phase, requiring gas to liquid flow ratios that are substantially higher than those needed for other important gases such as oxygen and nitrogen. Carbon dioxide removal is described here in detail for a packed column aerator where the gas to liquid ratio can be controlled. Principles of carbon dioxide removal may be applied to other aeration devices, however, quantification of gas to liquid ratios and flow characteristics are not currently available.

Chapter 7: Carbon Dioxide Control in Aquaculture Water Reuse Systems: Engineering Design and Management
Book Chapter
1994

NOP 94-75 (English) (French) (Spanish) ; NOP 94-A02 (English)

Masculinization of sexually undifferentiated tilapia fry is achieved by oral administration of the androgen 17-α methyltestosterone (MT). An anabolic response to androgen treatment of tilapia has been reported. Growth of control and MT-treated tilapia was evaluated during consecutive treatment, nursery, and grow-out phases under conditions approximating commercial, semi-intensive tilapia farms in Central America. Oreochromis niloticus (L.) fry were fed a 0 or 60 mg/kg MT diet for 28 days. Growth curves for control and MT-treated fish did not have significantly different slopes. Mean harvest fry weights were similar, averaging 0·1 g/fry for both treatments. Fry were subsequently stocked into 0·2-ha nursery ponds for 94 days growth. Slopes of control and MT-treated fish growth curves were not significantly different. Mean final individual weights did not differ significantly between treatments. Control fish did not deviate significantly from the 1:1 male: female ratio, but MT-treated fish were 97% males. Control male and MT-treated male fingerlings were stocked for grow-out into 0·1-ha organically fertilized earthen ponds. No significant difference in growth was observed between control and MT-treated fish. Mean gross yields after 150 days and mean final individual weights were similar for both treatments.

Growth of control and androgen-treated Nile tilapia, <i>Oreochromis niloticus</i> (L.), during treatment, nursery and grow-out phases in tropical fish ponds
Journal Article
1994

NOP 94-72 (English) (French) (Spanish)

A ten-step methodology for research on integrated agriculture-aquaculture farming systems is described. Particular attention is given to the interactions between the agriculture and aquaculture components. References to appropriate "standard" agriculture and aquaculture research methods are made.

A Research Methodology for Integrated Agriculture-Aquaculture Farming Systems
Conference Paper
1994

NOP 94-65 (English) (French) (Spanish

An experiment was conducted to determine the most efficient frequency of urea and triple superphosphate (TSP) fertilization of earthen ponds stocked with Nile tilapia (Oreochromis niloticus). There were five treatments consisting of the following fertilization frequencies: daily, twice per week, weekly, twice every 3 weeks, or once every 2 weeks. All ponds received the same total fertilization inputs for the entire growout period. Net fish yield (NFY) was not correlated to fertilization frequency, but strongly linearly related to net primary productivity (NP) (r2 = 0.90, P < 0.001). NP was related to low inorganic carbon availability and/or inversely related to light availability. The latter was reduced by inorganic suspended solids. Urea and TSP input rates resulted in soluble nitrogen (N) and phosphorus (P) accumulation in all ponds, with greater accumulations in more turbid ponds. As NP was not limited by either N or P, varying the frequency of urea or TSP inputs had no effect on either NP or NFY. The frequency of urea and TSP fertilization may become a management concern only when the availability of either N or P limits phytoplankton productivity.

Effect of fertilization frequency on the production of Nila tilapia (<i>Oreochromis niloticus</i>)
Journal Article
1994

NOP 94-A09 (English)

Beginning in 1983, the Rwanda National Fish Culture Project helped farmers improve their ponds and pond management. It also identified and provided a species of tilapia better-suited to the high-elevation, cool-water environment. The report focuses on the experiences of three specific categories of farmers, about which little systematic information exists. Interviews were conducted with 115 active farmers including 56 women who were pond group members or individual operators. Interviews were conducted with 21 dropouts about their reasons for quitting fish culture. Similarly, 16 emulators were interviewed about their lack of contact with extension personnel. The results suggest that aquaculture has become an integral part of the diversification strategy of Rwandan farmers. Despite a lessening in the intensity of extension assistance, farmers continue to grow repeated crops of fish. They express positive sentiments about the activity, its benefits, and the technical support they receive. The segment of farmers that has stopped growing fish seems to have done so for reasons other than dissatisfaction with the enterprise per se. Dropouts were slightly more involved in other farm enterprises, but the problems they identified were more related to circumstances in their household or in the milieu of neighboring landowners than with fish culture itself. A narrow segment quit because the water was too cold or otherwise was not conducive to growing fish. Dropout farmers perceived more time and effort conflicts with other farm enterprises and household work. They were more interested in the cash proceeds of fish culture than the other sample segments and less likely to feel that the pond was the best use of the land it occupied. Women in groups seemed the most satisfied and productive segment of the study respondents. They had larger harvests, they experienced fewer marketing problems, and they were more attentive to the general practice of fish culture. They also seemed to get better prices. Women in groups seemed better able to exploit pond bank sales as a marketing channel for tilapia. Friends, relatives, and neighbors are an immediate network of fish consumers that are readily alerted and mobilized to purchase fish at harvest. Women in pond groups were characterized by an overlay of multiple social networks, and seem better positioned to distribute fish among rural households. Women in pond groups seem to have most effectively realized the promise of fish culture to yield benefits for families, particularly children. The access to land, sociability, and perhaps gender solidarity in a male-oriented society, are major advantages of fish culture for women.

Socioeconomic Factors Affecting the Transfer and Sustainability of Aqucultural Technology in Rwanda
Report
1994

NOP 94-60 (English) (French) (Spanish)

Feeding of attached microorganisms and detrital biomass (AMDB) by Nile tilapia (Oreochromis niloticus) was examined in two 8-week experiments conducted in outdoor concrete tanks. Although the addition of vertically placed plastic baffles and bamboo poles did not significantly increase net fish yield, differences in AMDB in tanks with and without fish clearly demonstrated AMDB was ingested by tilapia. Tilapia feeding behavior and gut analyses supported this conclusion. Because of similarities between fish and algal productivities in tanks with and without additional substrates, however, the added financial and labor costs do not warrent (sic) the use of plastic baffles or bamboo poles in static water tilapia culture systems.

Increasing attached microorganism biomass as a management strategy for Nile tilapia (<i>Oreochromis niloticus</i>) production
Journal Article
1994

NOP 94-67 (English) (French) (Spanish)

In aquaculture experiments of only a few months' duration, fish can approach their asymptotic size and growth rates may change greatly. One objective of aquaculture is to obtain a maximum economic return, and a growth model is needed to relate rate of growth to food consumption and other costs to find the optimum duration of growth cycles. Von Bertalanffy's equation is an asymptotic growth model which can be used for this purpose. A variable growth rate model was developed to describe fish growth oscillations observed in aquaculture experiments. This growth model provides improved estimates of von Bertalanffy's equation in aquaculture and can be used for an efficient evaluation of fish production during production cycles.

A variable growth rate modification of von Bertalanffy's equation for aquaculture
Journal Article
1994

NOP 94-66 (English) (French) (Spanish

Relationships among stocking, harvest, and environmental variables for two commercial shrimp farms in southern Honduras were evaluated using stocking date as the time of reference. Data were analyzed from consecutive production cycles during 1986 to 1991 in Farm A and 1988 to 1991 in Farm B. Stocking ponds during March to June and November to February resulted in good and poor shrimp yields, respectively. Step-wise regression analyses revealed that survival, stocking density, salinity, and temperature accounted for up to 80% of the total variation in shrimp yield. The environmental variables alone could account for only a third of total variation. A similar analysis of a monthly means, which emphasized time related variation by minimizing inter-pond variability, revealed that temperature (75 to 85%) and percentage of stocked P. vannamei accounted for up to 88% of total monthly variation. Effects of salinity were minor. The majority of variation in shrimp yields within a farm was related to non-environmental factors whereas cyclical variation over a calendar year was primarily related to temperature and proportion of stocked P. vannamei. Climate cannot be controlled, but farm management can take its predictability into account.

Cause of Cyclic Variation in Honduran Shrimp Production
Journal Article
1994

1993

NOP 94-69 (English) (French) (Spanish)

Aerated ponds did not accumulate as much carbon in bottom soils as control ponds. Application of urea to manured ponds did not accelerate carbon loss from bottom soils. When ponds were drained for fish harvest, appreciable carbon was eroded from the surface layers of bottom soil. Further decomposition of soil carbon occurred during the 5-week drying period between crops. Within-pond variation in soil carbon concentration was high; a technique for selecting replication and sample size requirements for experiments on changes in bottom soil carbon concentration is provided.

Effects of Urea Application, Aeration, and Drying on Total Carbon Concentrations in Pond Bottom Soils
Journal Article
1993
Culberson, S. D., and R. H. Piedrahita. 1993. Model for Predicting Dissolved Oxygen Levels in Stratified Ponds Using Reduced Data Inputs. Pp. 543 - 552 in Techniques for Modern Aquaculture: Proceedings of an Aquaculture Engineering Conference, Techniques for Modern Aquaculture: Proceedings of an Aquaculture Engineering Conference, edited by J. Wang. St. Joseph, Michigan: American Society of Agricultural Engineers. Retrieved (https://catalog.hathitrust.org/Record/009175608).
NOP 95-80 (English) (French) (Spanish)

NOP 95-80 (English) (French) (Spanish)

Previous attempts at the prediction of dissolved oxygen (D.O.) levels in ponds used for aquaculture have often relied on the assumption of homogeneous pond water quality over the water column depth. Using a previously-reported stratified temperature model as a basis for structure, the authors have modified a mass-balance model for the prediction of dissolved oxygen levels in shallow aquaculture ponds. The model has been updated with recent information concerning the behavior of pond phytoplankton throughout the diurnal cycle, rendering accurate predictions of D.O. levels in both stratified and fully-mixed ponds. In addition, the overall data inputs required by the model have been significantly reduced from those required by previous models. Simulations for sites in Northern California are presented, as well as for several sites located in various places around the globe, using the Pond Dynamics/Aquaculture Collaborative Research Support Program Database for input data. The strategies used for dealing with reduced data sets, and the associated assumptions made, are also presented.

Model for Predicting Dissolved Oxygen Levels in Stratified Ponds Using Reduced Data Inputs
Conference Paper
1993

NOP 94-64 (English) (French) (Spanish)

A survey of 55 fish farmers in Rwanda provided data to analyze the economics of fish production in a subsistence agricultural economy. Survey results demonstrated that fish are primarily a cash crop and secondarily a source of food for the family. Net cash returns to labor por 100cm2 varied from FRW 510 at high altitudes to FRW 1308 at low altitudes and represented approximately 7% and 29%, respectively, of average annual income on high- and low-altitude farms. Labor was the primary resource utilized in fish farming and yielded cash returns that were competitive with daily wage rates even though realistic employment opportunities were scarce. Income from fish farming represented a significant proportion of total cash income in addition to its food value for the household.

An Economic Analysis of Fish Production in a Subsistence Agricultural Economy: The Case of Rwanda
Journal Article
1993

NOP 94-63 (English) (French) (Spanish)

Recently hatched tilapia fry 9 to 11 mm total length (TL) are preferred for hormonal sex reversal because they are most likely to be sexually undifferentiated. Thirty-three trials were conducted in Honduras between September 1988 and March 1990 to quantify the effect of water temperature on Oreochromis niloticus fry production in earthen ponds for hormonal sex reversal. Two 0.05-ha ponds were simultaneously stocked with brood fish in each trial; generally, one pond was harvested after 17 days, the other after 20 days (range 16 to 21 days). Fry production was evaluated in relation to degree-days from the threshold temperature of 15°C. Harvests averaged 86,000 fry/0.05 ha. A total of 4,897,000 fry were produced, of which 4,363,000 fry were of appropriate size for hormone treatment. No fry production occurred at less than 140 degree-days; fry production increased significantly with increased degree-days above this level. Above 195 degree-days percent of the population retained by a 3.2-mm vexar-mesh grader (too large for androgen treatment) increased significantly with increased degree-days. Fry retained by the grader averaged 14.2 mm TL, while fry not retained averaged 9.5 mm TL. No significant linear relationship between degree-days and number of fry not retained b the grader was observed between 140 to 280 degree-days. However, production appeared to peak at about 210 degree-days.

Production of <i>Oreochromis niloticus</i> fry for hormonal sex reversal in relation to water temperature
Journal Article
1993
Hopkins, K. D., and D. Pauly. 1993. Instantaneous Mortalities and Multivariate Models: Applications to TIlapia Culture in Saline Water. Pp. 105 - 111 in Multivariate Methods in Aquaculture Research: Case Studies of Tilapias in Experimental and Commercial Systems, Multivariate Methods in Aquaculture Research: Case Studies of Tilapias in Experimental and Commercial Systems, edited by M. Prien, Hulata, G., and Pauly, D. Manila, Philippines: International Center for Living Aquatic Resources Management (ICLARM). Retrieved (http://agris.fao.org/agris-search/search.do?recordID=PH19940104563).
NOP 93-A02 (English); NOP 94-62 (English) (French) (Spanish)

NOP 93-A02 (English); NOP 94-62 (English) (French) (Spanish)

The “percent mortalities"· commonly used by aquaculturists do not allow separation of the different components of fish mortality between stocking and harvesting in aquaculture experiments. It is shown that “instantaneous” or exponential mortalities, as used in fish population dynamics, have the properties required for such separation. especially when used in conjunction with a multiple regression model. Examples drawn from tilapia experiments conducted in seawater tanks in Kuwait and brackish water ponds in the Philippines are presented.

Instantaneous Mortalities and Multivariate Models: Applications to TIlapia Culture in Saline Water
Book Chapter
1993

NOP 93-59 (English) (French) (Spanish)

Two experiments were conducted to better understand the role of urea in pond fertilization. In Experiment 1, urea dissolved in pond water and incubated in aquaria at approximately 30°C disappeared at a rate of 303 μg urea-N l−1 day−1 under natural sunlight conditions, and 102 μg urea-N l−1 day−1 under dark conditions. Total alkalinity decreased in dark aquaria and increased in sun-exposed aquaria, consistent with stoichiometric expectations. Urea hydrolysis was negligible in distilled water exposed to light. Experiment 2 was a toxicity test. Median lethal concentrations (LC50'S) of urea at 24 and 96 h exposure were 19,700 mg l−1 and 16,800 mg l−1 for sex-reversed male Nile tilapia (Oreochromis niloticus) fingerlings, and 17,000 mg l−1 and 16,000 mg l−1 for silver barb (Puntius gonionotus) fingerlings, respectively. All test fish survived 96-h exposure to 14,000 mg urea l−1, whereas no fish survived 48-h exposure to 22,000 mg urea l−1.

On the role of urea in pond fertilization
Journal Article
1993

NOP 93-56 (English) (French) (Spanish)

Two grow-out experiments were conducted to evaluate the functional role of chicken manure for Nile tilapia, Oreochromis niloticus (L.). production in central Thailand. Experiment 1 examined the relationship between chicken manure input and net fish yield (NFY). Experiment 2 determined the value of chicken manure in providing tilapia particulate organic carbon, and/or dissolved inorganic carbon (DIC) for stimulating algal productivity. In both experiments supplemental urea and triple superphosphate (TSP) gave all treatments total nitrogen (N) and phosphorus (P) inputs of 28·0kg/ha/week and 7·0kg/ha/week, respectively. Addition of chicken manure to inorganic fertilization did not enhance production of Nile tilapia. NFY in experiment 1 increased with decreasing manure loading, which corresponded to increasing TSP input. Regression analysis suggested that chicken manure-P was about 10% effective as TSP-P at increasing NFY. NFY was linearly correlated to net primary productivity (r2= 0·62, P < 0·001), which was linearly correlated to total alkalinity (r2= 0·77. P < 0·001).Treatment differences in alkalinity, community respiration or dissolved oxygen concentrations at dawn were not related to manure input. Simple economic comparisons discourage the purchase of chicken manure as a source of soluble N and P for increasing algal productivity in Thailand.

The role of chicken manure in the production of Nile tilapia, <i>Oreochromis niloticus</i> (L.)
Journal Article
1993

An experiment on integrated walking catfish-tilapia culture was conducted for 5 months. The walking catfish were stocked at 400 and 800 fish/cage in two 4-m3 nylon cages, which were suspended in each of two 250-m2 earthen ponds. Sex-reversed male tilapia (Oreochromis niloticus) were reared at 1 fish/m2 in the open pond. Whereas the catfish were reared with supplemental feed, tilapia were solely dependent on the natural diet derived from the recycled catfish waste. Weekly analysis of temperature, dissolved oxygen, ammonia, total phosphorus, total Kjeldahl organic nitrogen and chlorophyll a in the pond water showed that water quality was suitable for both tilapia and catfish growth. Total catfish and tilapia production was approximately 100 and 140 kg/pond, respectively. The experiment demonstrated that tilapia can efficiently use catfish waste and maintain desirable water quality.

Integration of Intensive and Semi-Intensive Aquaculture : Concept and Example
Report
1993
Lu, Z., and R. H. Piedrahita. 1993. Nitrifying Characteristics of a High Rate Packed Column. Pp. 345 - 351 in Techniques for Modern Aquaculture: Proceedings of an Aquaculture Engineering Conference, Techniques for Modern Aquaculture: Proceedings of an Aquaculture Engineering Conference, edited by J.K. Wang. St. Joseph, Michigan: American Society of Agricultural Engineers. Retrieved (https://catalog.hathitrust.org/Record/009175608).
NOP 93-A04 (English)

NOP 93-A04 (English)

A system of high rate bio lter packed columns was operated using “synthetic” sh waste in order to characterize the operating parameters and nitri cation rate for aquacultural water. Two sets of experiments were conducted: the rst was designed to determine the range of hy- draulic loading rates that could be achieved with the nitri cation columns. The second served to determine the effect of oxygen concentration on nitri cation rate within the columns. Three columns (0.15m diameter and 3 m tall) were lled with 1.6 cm PallTM rings. The columns were set on a 3 m3 reservoir (test tank). In the rst experiment, the columns were operated at three different ow rates (2 L min-I, 20 L min- L, 40 L min-l) and dissolved oxygen concentra- tion was maintained at 100% saturation. In the second experiment, the three columns were operated at the same ow rate (24 L min-l) with 150% dissolved oxygen concentration. The “synthetic” sh waste was prepared daily and maintained refrigerated at 4 ̊C to reduce bacte- rial contamination and activity prior to introduction to the test tank. The synthetic sh waste was introduced into the test tank by means of a metering pump. The rst experiment veri ed that the lowest hydraulic ow rate did not allow effective nitri ca- tion in the column. Conversely, the highest ow rate resulted in high nitri cation rate but the column had a tendency to ood or restrict air ow as the lter matured. The second experiment resulted in nitri cation rites that average 0.08 g m-2 d-1 with maximum of 0.15 g m-2 d-1. The second experiment will be continued by operating the columns at alternate dissolved oxygen concentrations (100%, 200%). The higher concentrations of dissolved oxygen are expected to result in higher nitri cation rates.

Nitrifying Characteristics of a High Rate Packed Column
Conference Paper
1993

NOP 93-55 (English) (French) (Spanish)

A 14 d period of dense but stable phytoplankton stock in a brackish water earthen pond (0.2 ha area, 0.7 m depth) was characterized to provide d baseline for study of instability. Results illustrate the potential of ponds to serve as microcosms of natural systems. Primary production and community respiration were assessed by diel curve analysis of oxygen and inorganic carbon sampled every 30 min at 3 depths. Neither stocks nor diel oxygen regimes were destabilized by 2 isolated days of low light, the first accompanied by heavy rainfall. Among nutrient elements, only inorganic nitrogen exhibited marginally limiting values. Daytime net production (dNPP) of oxygen ranged from 0 to 0.26 mol m-2 d-1, carbon uptake from 0.01 to 0.22 Mol M-2 d-1. Nighttime respiration (nR) approximately matched dNPP, resulting in low mean diel net production (NPP). Minimal estimates of daytime respiration (dR) were substantially greater than nR and dNPP; minimal gross production (GPP = dR + dNPP) averaged 2.5 times dNPP. Estimated dR varied with dNPP in a stabilizing negative feedback, possibly mediated by photosynthetic products. Both dNPP and NPP varied with diel irradiance, but nR did not. Both dNPP and nR decreased with depth; positive NPP was concentrated in the upper layer. Stocks and oxygen cycles were more resistant to disturbance by low light than predicted by models assuming 1.0 m pond depth. We suggest for further examination that stability was related to the shallow depth of this pond, which permitted sufficient light penetration to the bottom layer for positive dNPP on most dates.

Photosynthesis and community respiration at three depths during a period of stable phytoplankton stock in a eutrophic brackish water culture pond
Journal Article
1993
Teichert-Coddington, D. R. 1993. Development of Production Technologies for Semi-Intensive Fishfarming During the Past Decade in Central America. Pp. 71 - 88 in Actas del Simposio: Investigacion Acuicola en Centroamerica, Actas del Simposio: Investigacion Acuicola en Centroamerica, edited by J. Gunther and Kleijin, K. Heredia, Costa Rica: Universidad Nacional de Heredia. Retrieved (http://agris.fao.org/agris-search/search.do?recordID=XF2015005005).
NOP 95-82 (English) (French) (Spanish)

NOP 95-82 (English) (French) (Spanish)

This paper reports on techniques that have been developed by the Pond Dynamics/Aquaculture Collaborative Research Program in Central America to increase Tilapia production by optimizing resource use in systems based predominantly on natural pond productivity. Tilapia yields in ponds fertilized only with phosphorus averaged 409 kg/ha are were unprofitable. Additions of 24 kg/ha nitrogen and enough phosphorus to maintain N:P ratios of 4:1 increased yields to 2079 kg/ha. Tilapia yield responded curvilinearly to chicken litter fertilization at weekly rates ranging from 125 to 1000 kg dry matter/ha; tilapia yields ranged from 1095 to 2593 kg/ha. Profitability was greatest at the highest litter application rate. Culture systems based solely on organic fertilization were nitrogen limited because of the low N;P ratio in chicken litter. Yields could be increased to 3600 kg/ha when weekly chicken litter applications at 750 kg/ha were supplemented with inorganic nitrogen to raise total available nitrogen to 25 hg/ha. Higher additions of nitrogen resulted in heavy blue-green algal blooms and decreased fish yields. Blue-green algae are thought to have out-competed other algae in the high pH and low CO2 conditions that predominated during high nitrogen fertilization.

Development of Production Technologies for Semi-Intensive Fishfarming During the Past Decade in Central America
Conference Paper
1993

NOP 93-58 (English) (French) (Spanish)

Water column respiration (WCR) was measured in dark BOD bottles for 2, 4 and 8 h intervals during 22 h periods in two 1000 m2 ponds stocked with Oreochromis niloticus at 1 m−2, and fertilized weekly with chicken litter at 750 kg total solids ha−1. Mean WCR ranged from a low of 0.39 mg l−1 for 8 h nocturnal intervals to a high of 0.62 mg l−1 for 2-h diurnal intervals. WCR was significantly influenced by daylight and time into the diurnal or nocturnal period when it was determined. Mean WCR was significantly greater during the day than during the night (P < 0.01). During the day, 2 h incubation intervals resulted in significantly higher WCR than 4 h or 8 h intervals (P < 0.01); length of incubation interval did not significantly influence nocturnal WCR (P > 0.05). Higher WCR during the day and during short diurnal incubation intervals was attributed to greater availability of photosynthetic respiration substrate. Diurnal, diel, or nocturnal WCR could be best estimated by a single 2, 4 or 8 h incubation interval, respectively, beginning at 0800 h.

Influence of daylight and incubation interval on water column respiration in tropical fish ponds
Journal Article
1993

NOP 94-76 (English) (French) (Spanish)

Two techniques for determining community respiration in organically fertilized tilapia grow-out ponds were compared: (1) whole pond respiration (WPR) from changes in nocturnal dissolved oxygen concentrations corrected for diffusion, and (2) the sum of water column (WCR), benthic (BR), and fish respiration (FR), components of community respiration. Mean WPR (0.568 g O2 m-2 h-1) was significantly higher (P < 0.01) than mean sum of community respiration components (0.401 g O2 m-1 h-1). Mean WCR, BR, and FR were 0.319, 0.068, and 0.015 g O2 m-2 h-1, respectively. Indirect determinations of community components by difference of WPR and the sum of the other two components will be significantly higher than in situ determinations.

Comparison of two techniques for determining community respiration in tropical fish ponds
Journal Article
1993

NOP 93-A01 (English) ; NOP 94-77 (English) (French) (Spanish)

Tilapia yields and water quality were compared in 1000-m2 grow-out ponds that were unaerated, or aerated beginning at 10 or 30% of oxygen saturation. Tilapia yield and individual final size were significantly greater in aerated ponds than in unaerated ponds, but there were no significant differences between levels of aeration. Treatment means of organic-N, total P. chlorophyll a, net primary productivity, and total volatile solids were not significantly different. However, aeration caused higher clay turbidity as indicated by significantly higher total fixed solids and lower Secchi disk visibility in aerated treatments. Maintenance of oxygen above minimal levels augmented tilapia yields, but additional research is needed to make aerator use in tilapia culture more efficient and profitable.

Tilapia yield improvement through maintenance of minimal oxygen concentrations in experimental grow-out ponds in Honduras
Journal Article
1993

1992

NOP 93-57 (English) (French) (Spanish)

Two 1000 m2 ponds at the El Carao National Aquaculture Center at Comayagua, Honduras were deoxygenated by treatment with sodium sulfite and cobalt chloride, and biological activity was suppressed by formalin and copper sulfate application. Wind speed and the change in dissolved oxygen concentration were monitored with a data logger system during reaeration period. Standard oxygen transfer coefficients were related to wind speed measured at 3-m height by the equation: KLa20=0·017x − 0·014; r2=0·882 where KLa20 = standard oxygen transfer coefficient at 20°C (h−1) and X = wind speed (m s−1). A method for computing pond reaeration rate from the standard oxygen transfer coefficient is presented.

Relationship Between Wind Speed and Reaeration in Small Aquaculture Ponds
Journal Article
1992
Culberson, S. D., and R. H. Piedrahita. 1992. Modification of Stratified Temperature Model to Accomodate Reduced Data Inputs: Identifying Critical Requirements. Pp. 1 - 37 in Aquaculture '92 International Conference, Aquaculture '92 International Conference. Orlando, Flordia: American Society of Agricultural Engineers.
NOP 95-81 (English) (French) (Spanish)

NOP 95-81 (English) (French) (Spanish)

Accurate characterization of temperature stratification in ponds used for aquaculture is of critical importance in understanding how these ponds may be constructed, oriented, or otherwise managed biophysically when one wishes to provide optimal environmental conditions for the organisms cultured therein. While field studies can provide characterizations of water quality stratification at a single locale, to date there have been few attempts at developing reliable models which can be used at a variety of sites after initialization with appropriate local geographic and atmospheric data. In conjunction with Pond Dynamics/Aquaculture Collaborative Research Support Program (PD/A CRSP), the authors have modified a previously developed water quality model which closely predicts temperature stratification at several different sites in northern California. Changes in model structure and reduction of data requirements reflect the desire to provide for culturists the opportunity to predict stratification events with commonly available data, obtained either by hand or from a simple weather station located at or near the pond site. Validation of the model has been conducted with data sets generated through PD/A CRSP experiments, and the importance of wind vector and relative humidity inputs is considered here.

Modification of Stratified Temperature Model to Accomodate Reduced Data Inputs: Identifying Critical Requirements
Conference Paper
1992

The Pond Dynamics/Aquaculture CRSP has conducted basic research since 1983 on the biological and chemical factors that influence fish production. The goal of these studies is the improved well-being of farmers that adopt new aquaculture technologies. The ultimate test of the value of the research results generated is if farmers themselves demonstrate the economic benefit by incorporating new technologies into their farming systems. Therefore, economic analysis of the costs and benefits to the farmer of the various technologies developed will provide insight into the value of these technologies to farmers.

The Economic Benefit of Chicken Manure Utilization in Fish Production in Thailand
Report
1992

NOP 92-46 (English) (French) (Spanish)

The partial substitution of organic manure for pelleted feed in monosex Oreochromis niloticus (20,000/ha) production ponds was studied in Honduras. Treatments were: (1) pelleted feed only (23% protein; 3% fish biomass/day), (2) organic manure (1,000 kg total solids (TS)/ha per week chicken litter) only during the first 60 days, followed by pelleted feed only, and (3) organic manure (500 kg TS/ha per week chicken litter) and pelleted feed (1.5% fish biomass/day) offered simultaneously. Mean gross yields after 151 days were 5,305, 4,794, and 4,351 kg/ha for treatments 1 through 3, respectively. At harvest, fish averaged 262, 284, and 251 g/fish, respectively. No significant differences were detected among treatments for gross yield or average individual weight. Feed conversion ratio for treatment 1 (1.83) was significantly greater than for treatment 3 (0.95). Layer chicken litter can replace 27 to 58% of pelleted supplemental feed without significantly affecting tilapia yield. Total production costs from enterprise budgets were $5,336/ha (feed only), $4,645/ha (manure followed by feed), and $3,471/ha (manure and feed simultaneously). Net returns to land, labor, and management were $2,469/ha, $2,956/ha, and $3,330/ha, respectively.

Substitution of organic manure for pelleted feed in tilapia production
Journal Article
1992

NOP 94-71 (English) (French) (Spanish)

Aquaculturists typically report growth using absolute (g/d), relative (% increase in body weight), and specific growth rates (%d). Less frequently, von Bertalanffy Growth Functions (VBGF) are used. Each of these rates is a numerical representation of growth which assumes a specific relationship between size and time (linear, exponential, or asymptotic). Aquaculturists typically determine size at time throughout their experiments. Unfortunately, the intermediate data points are usually ignored when computing growth rates (except for VBGF) and the appropriateness of the method for calculating growth for a particular data set is not tested. This paper reviews the basis and computation of each of the growth rates in an effort to encourage aquaculturists to use the appropriate growth rates.

Reporting Fish Growth: A Review of the Basics
Journal Article
1992

NOP 94-74 (English) (French) (Spanish)

Nine successive 5-month experiments, which examined relationships between fertilization strategies (with chicken manure, triple superphosphate and urea), water quality and yields of Nile tilapia (Oreochromis niloticus), took place from February 1985 through March 1990 in 16 earthen ponds at the Ayutthaya Freshwater Fisheries Center, Bang Sai, Thailand. Over the course of these experiments, randomization of treatments resulted in all ponds having different fertilization histories. Analysis of covariance was used to quantify the carry-over effects of nutrient inputs from earlier experiments on experimental errors in Experiment 9. Analyses of variance indicated that the residual (experimental error) accounted for approximately 39% of the total variation of net fish yield (NFY) observed in Experiment 9. Covariate analysis revealed that residuals were most significantly correlated to accumulated chicken manure input from Experiments 5 through 8. Previous pond fertilizations accounted for approximately 49% of total experimental variation in NFY observed in Experiment 9. Multiple linear regression analysis, using treatment inputs and the pond history covariate as the two independent variables to explain NFY, gave an 2 = 0.75 (P < 0.001). Pond sediment chemistry data proved to be ineffective as covariates for reducing experimental error and/or predicting NFY. Reasons for the positive effect of earlier experiments on NFY most likely involved the inverse relationship between the ability of pond sediments to remove soluble phosphorus from overlying water, and the accumulation of organic matter and phosphorus on pond bottoms. Pond management considerations and recommendations for fish culture experiments are given to better account for between-pond variability due to different fertilization histories.

Pond history as a source of error in fish culture experiments: a quantitative assessment using covariate analysis
Journal Article
1992

NOP 93-51 (English) (French) (Spanish)

The fundamental principle in colorimetric analyses of water chemistry is the relationship between concentration of a particular chemical and color intensity. Color intensity is determined by measuring the absorbance of light of a particular wavelength. The relationship should follow a standard curve made with a series of standard concentrations selected to cover the expected range of unknown samples/ The absorbance of a solution is directly proportional to the concentration of absorbing constituents at a fixed light pathlength, and directly proportional to the pathlength at a fixed concentration. Within a certain range of concentrations, the relationship is linear (y = a+bx, where y = absorbance, a = the y-intercept, x = concentration and b = slope of line). Linear regression can be utilized to determine the slope (b) of the line and the regression coefficient (r), which describes how well the straight line fits the plotted points from standards. Some spectrophotometers measure only transmittance, in which case the logarithm of transmittance should give a linear relationship with concentration. As reliable standard curves are essential, the purpose of this article is to help aquaculture researchers identify, troubleshoot, and hopefully correct common problems associated with colorimetric analysis of water.

Analyzing Standard Curves in the Chemistry of Waters Used for Aquaculture
Magazine Article
1992

NOP 92-A04 (English)

Currently there are 2 sources of freshwater prawn Macrobrachium rosenbergii production in Vietnam - natural production from the rivers and canals and aquaculture production from ponds and ricefields. An account is given of the production of this prawn in the Mekong Delta. The prawns are harvested primarily by a common small scale method using shelter traps. The total annual freshwater prawn production in Vietnam during 1985-90 was reported to vary from 5,000 to 8,000 tons, most of it from natural fisheries; although there are no official statistics on the production of farmed prawns, the amount is believed to be very small. The grow-out system includes intensive monospecies pond culture, and semi-intensive or extensive integrated rice-prawn or vegetable-prawn culture.

Production of Freshwater Prawns in the Mekong Delta
Magazine Article
1992

NOP 92-48 (English) (French) (Spanish) ; NOP 92-A03 (English) ; NOP 93-53 (English)

A bioenergetic growth model was developed to examine the integrated effects of fertilization, stocking density, and spawning on the growth of tiiapia, Oreochromis niloticus (L.), in pond aquaculture. The analyses showed that growth rates increase with higher levels of organic fertilization up to 5(HJ kg/ha/week. Growth rates increased with added food rations in ponds, reaching a maximum growth of 2.07 g/day at about 44-48 days after stocking. Fish growth rates decreased with increased levels of stocking density. The stocking density for optimal growth is 1 fish/m2; the optimal density for total harvesting weight and fish size is 2 fish/m2. Model sensitivity analysis indicated that tiliapia growth is most sensitive to catabolism (metabolism) and anabolism (synthesis) coefficients, both of which are geometrically related to the fish body weight. Food assimilation efficiency (b) and the food consumption coefficient (h) have a modest effect on fish growth. Spawning in grow-out ponds can have a major effect on fish growth.

Bioenergetic modelling of effects of fertilization, stocking density, and spawning on growth of the Nile tilapia, <i>Oreochromis niloticus</i> (L.)
Journal Article
1992

NOP 94-61 (English) (French) (Spanish)

A simple method is presented for determining the optimum time to harvest fish and the effect of fertilization type on optimum harvest time for aquaculture. Optimum harvest time was similar for either maximizing fish yield or maximizing profit of fish harvested, because the daily change in fish production cost was low for the low-input Nile tilapia, Oreochromis niloticus (L.), production system in Thailand. At a harvest time of 150 days for an organic fertilization treatment compared to an inorganic fertilization treatment fish yield increased from 1.505 t/ha to 2.295 t/ha, and profit of fish harvested increased from 15,657.1 baht/ha (US$590.8/ha) to 25,127.5 baht/ha (US$948.2/ha). For the organic treatment, optimum harvest time occurred at 191 days, with a fish yield of 2.328 t/ha and a profit of 25,520.5 baht/ha (US$963.0/ha), compared to the inorganic treatment where optimum harvest time occurred at 105 days with a fish yield of 1.536 t/ha and a profit of 16,035.4 baht/ha (US$605.1/ha). 

Optimum harvest time in Aquaculture: an application of economic principles to a Nile tilapia, <i>Oreochromis niloticus</i> (L.), growth model
Journal Article
1992

NOP 92-A02 (English)

Red tilapia with an average size of 75 g were reared for 70 days in concrete circular tanks at densities of 50, 100 and 200 fish/m3 in a recirculated water system. At a loading rate of 1 kg/liter/min and a feeding rate of 1.5% body weight/day with 22% protein commercial pellets, the daily weight gains were in the order of 0.77, 0.65 and 0.64 g/fish in the low, medium and high stocking densities, respectively, with corresponding net yields of 27.01, 40.98 and 57.37 g/m3 day. The FCR values were 2.25, 2.57 and 2.61 in the low, medium and high stocking densities, respectively. Although the individual fish growth rate and feed utilization efficiency were inversely related to increasing stocking density, there were no significant differences between these parameters at the medium and high densities. The net yield increased with increasing density levels, but appeared to level off at the higher densities. Behavioral studies indicated that the growth-inhibiting agonistic behavioral patterns were generally unabated even at the highest stocking density. Use of constant loading rates maintained almost similar and safe water quality levels in all treatments. Stocking levels did not influence the digestibility of the feed and carcass composition of the fish. Nitrogen budget constructed for the experimental period suggested that in all treatments about 80% of the nitrogen consumed by the fish was wasted in the form of solids and solubles. The apparent rates of oxygen consumption and ammonia produced by the fish in the different treatments were not significantly different. The treatment system was found to be effective in removing various waste metabolites, but the efficiency varied among the parameters. Ammonia and solids were removed more efficiently than others. Nitrite, COD and TP were removed less efficiently and wre found to accumulate in the system over time.

Effect of Stocking Density on Water Quality and Prodction of Red Tilapia in a Recirculated Water System
Journal Article
1992

NOP 93-50 (English) (French) (Spanish)

This review attempts to evaluate the potential of tilapia culture in saline waters and in the process employs biological, economic and environmental considerations in the analytical framework. Biological potential of many commercially important tilapine species is promising. They tolerate, grow and even reproduce in saline waters, although this capacity is somewhat offset under high salinity conditions. Particularly, they are sensitive to handling and succumb to secondary infections in seawater salinities. However, it is technically feasible to produce seed by clutch-removal management technique in salinities less than 18 ppt and to grow the fish in 35 ppt. A range of 10-20 ppt is optimal for growth. Optimal dietary protein content is 20-25% and feeding rates close to satiation levels lead to the highest growth. Various production systems ranging from earthen ponds to intensively stocked tanks, raceways and cages have been tested for grow-out; choice of a particular system would largely depend on the economics of water use. Production technology needs to be verified in several locations and, in light of the fact that tilapia get easily established as feral populations in natural ecosystems, extreme caution should be exercised in the introduction of fish into those culture systems connected to estuaries and mangroves.

Tilapia culture in saline waters: a review
Journal Article
1992

NOP 93-52 (English) (French) (Spanish

Planktonic community respiration rates were assessed every 30 min through two 48-h periods in near-surface water taken automatically from a fertilized earthen pond and incubated in a plastic chamber for 21 min of each sampling cycle. Parallel records of water temperature, air temperature, windspeed, and solar irradiance permitted calculation of gross and net primary production and photosynthesis-irradiance relationships. Nighttime respiration rates generally matched oxygen depletion rates in pond water, indicating that incubation-based rates were representative of a quickly darkened pond community throughout the day. Daytime rates averaged nearly 2 times the mean night rate and 58% higher than the mean day rate determined by a typical interpolation used in free-water production calculations. Daily gross production ranged from 0.7 to 1.2 mmol O2 liter−1 d−1; respiration constituted 65–75% of gross rates. Gross oxygen production per unit Chl a during sampling intervals was light saturated at irradiance values > 600 µEinst m−2 s−1, with an asymptotic value of 1.58 µmol O2 (µg Chl a)−1 h−1. This system and method were capable of resolving respiration and gross and net production when chlorophyll concentrations were near 40 µg liter−1.

Diel cycles of planktonic respiration rates in briefly incubated water samples from a fertile earthen pond
Journal Article
1992

NOP 92-A05 (English)

The US Agency for International Development (US AID) funds a number of Collaborative Research Support Programs (CRSPs), which conduct research on a variety of food production issues, always with international collaboration among researchers from the host countries and the United States. One research group os called the Pond Dynamics/ Aquaculture (PD/A) CRSP. It aims to improve yields and reliability of animal protein production through increased understanding of pond ecosystems. Researchers from universities and government research stations in four tropical countries (Honduras, the Phillippines, Rwanda, and Thailand) work with colleagues from six US universities, usually at more than one site in each country. My home institution, the University of Hawaii, participates in projects in Thailand and the Phillippines.  

A Standard Format for Design and Evaluation of Pond Experiments
Magazine Article
1992

NOP 93-49 (English) (French) (Spanish

Data from 2 years of standardized experimental protocols in Panama and Honduras were analyzed to ascertain the influence of site and season on production of Oreochromis niloticus in earthen ponds. In Experiment 1, ponds were fertilized every 2 weeks with trip le superphosphate at 4 kg P2O2/ha, and were monitored to establish baseline of edaphic, climatic and fish production data. In Experiment 2, ponds were fertilized weekly with chicken litter at 125, 250, 500, or 1000 kg total solids/ha. Both experiments were repeated during wet and dry seasons at each site. Honduras ponds were more alkaline and higher in phosphorus than Panama ponds that were excavated in acidic soils. However, Honduras ponds were turbid with clay. The net result of acidic, nutrient-poor soils in Panama and clay turbidity in Honduras was low biological productivity at both sites for inorganically fertilized ponds. Primary productivity and net daily fish yield significantly increased with increasing chicken litter application (P < 0.05). Primary productivity, chlorophyll a, and net daily fish yield were similar at both sites in ponds fertilized weekly with chicken sitter at 125–500 kg/ha; however, at the highest fertilization rate, primary productivity, chlorophyll a, and net daily fish yield were 57, 29, and 37% greater in Panama than in Honduras. Higher fish yield was significantly correlated with higher chlorophyll a and primary productivity. Lower primary production and net daily fish yield in Honduras were attributed to light limitation by clay turbidity.

Influence of site and season on water quality and tilapia production in Panama and Honduras
Journal Article
1992

1991

NOP 91-A02 (English)

17α-Methyltestosterone (MT) is of potential use in commercial production of all male cohorts of food fish. Sexually undifferentiated Oreochromis niloticus received control ration or 30 mg MT/kg ration for 30 days. On day 31 control and MT pretreated fish received a single dietary dose of 3H-MT and were killed 1, 3, 7, and 10 days later. At 1 day after dosing only 2.5 - 3% of whole body  3H-MT residues were identified as parent compound. The concentration of residues remaining 1–10 days after 3H-MT dosing were similar in control and MT pretreated fish. 3H-MT whole body residues decreased logarithmically during this period and had a 1-day half-life. At day 3 after dosing, 95% of 3H-MT had been convened to polar metabolites, which decreased to 70% by 7 days, and to only trace concentrations by day 10. Five months after MT pretreatment control and pretreated fish received a single oral dose of 3H-MT and were killed 1, 3, 7, and 10 days thereafter. In both groups, concentrations of 3H-MT residues were biliary ≫ liver > kidney > muscle at all times points. Bile contained 97–99% polar metabolites of 3H-MT in all cases and appeared a major route of excretion. These data indicated MT was readily eliminated by Oreochromis niloticus and that the pretreatment regimen proposed for commercial use did not substantially alter disposition of subsequent doses.

Disposition and elimination of 17a-methyltestosterone in Nile tilapia (<i>Oreochromis niloticus</i>)
Journal Article
1991

NOP 91-A03 (English)

Experiments were run to assess the physical, chemical, and biological processes leading to increased production of fertilized fish ponds in Thailand for approximately 5 months during wet season 1984 and wet and dry seasons 1985. Eight or 12 ponds (250 m2) were stocked with male Nile tilapia at 1 fish/m3. Ponds received fertilizer according to three different schemes: (1) low input inorganic (0.27 kg triple superphosphate, equalling 0.12 kg P ha−1 d−1); (2) high input organic (71.4 dry kg chicken manure ha−1 d−1); and (3) high input inorganic (14.3 kg triple superphosphate ha−1 d−1 and 4.3 kg urea ha−1 d−1). Treatments 2 and 3 yielded identical loadings of 2 kg N ha−1 d−1 and 3.2 kg P ha−1 d-1. Ponds receiving high fertilizer inputs had higher nutrient concentrations in water, higher primary production, and higher fish production than ponds treated with low fertilizer inputs. At high fertilizer inputs, chlorophyll a content and primary production were similar for all ponds, but fish growth and adult yield were significantly greater in organically rather than inorganically fertilized ponds. This was attributed to increased heterotrophy by fish in ponds treated with organic fertilizer. Regression analysis indicated only marginally predictive relationships between total inorganic nitrogen or total phosphorus concentration in the water and primary production. Secchi disk depth was a reasonable predictor of both primary production and chlorophyll a (r2=0.67). Diel temperature stratification was low, but correlated with air temperature, solar radiation, rainfall, and wind velocity. Diel oxygen stratification was more pronounced with inorganic fertilization, probably due to greater water clarity and more even distribution of primary production in organically fertilized ponds. Yield of stocked fish was correlated with rainfall and primary production.

Relationships among nutrient inputs, water nutrient concentrations, primary production, and yield of <i>Oreochromis niloticus</i> in ponds
Journal Article
1991

NOP 94-68 (English) (French) (Spanish)

The trophic cascade hypothesis holds that an increase in fish biomass causes a decline in food organisms of the fish, which cascades down to regulate lower trophic levels by altered consumptive demands. This hypothesis was evaluated by stocking Nile tilapia (Oreochromis niloticus) at densities of 0, 1, 2, or 3 fish/m3 in triplicated 220-m3 ponds near Bangkok, Thailand. All ponds were fertilized with 500 kg chicken manure∙ha−1∙wk−1. We measured phosphorus, nitrogen, chlorophyll a, primary productivity, zooplankton abundance, and fish yield in all ponds. Increased stocking density resulted in decreased adult fish growth but similar yields among the three density treatments. Regressions relating the abundance of each trophic level to the next higher trophic level were either positive or nonsignificant, which is contrary to trophic cascade predictions. Zooplankton became significantly more dense over time in fishless ponds than the other three treatments, but no other trophic level differed among treatments. These results indicate that presence of fish had a significant effect on zooplankton in ponds, but biomass of fish or abundance of zooplankton did not significantly affect other trophic levels.

Effect of nile Tilapia (<i>Oreochromis niloticus</i>) on the Ecosystem of Aquaculture Ponds, and Its Significance to the Trophic Cascade Hypothesis
Journal Article
1991
NOP 92-44 (English) (French) (Spanish)

NOP 92-44 (English) (French) (Spanish)

Seine sampling is widely recognized by aquaculturists to produce upwardly-biased estimates of size. This bias is sometimes given as a reason for not including sampling data collected by seining when analyzing growth (i.e., only stocking and harvest data are used). Fisheries biologists recognize that many fish sampling methods produce biased size estimates, and considerable effort is expended to correct for bias, e.g., mesh selection curves (Gulland 1983). Aquaculturists, on the other hand, tend to either ignore the bias or, worse, ignore the supposedly biased data. This note quantifies the degree of bias in size estimates of Nile tilapia (Oreochromis niloticus) that were obtained from seine samples. Additionally, the effects of fish size and sample size on precision of size estimates from seine samples are quantified. These quantifications are based on comparisons of seine sample data collected the day before harvest and the fish size at harvest.

Bias in Seine Sampling of Tilapia
Journal Article
1991
Knud-Hansen, C. F., C. D. McNabb, and T. R. Batterson. 1991. Application of limnology for efficient nutrient utilization in tropical pond aquaculture. Proceedings of the International Association of Theoretical and Applied Limnology 24:2541 - 2543. Retrieved (https://www.schweizerbart.de/series/proceedings_sil).
NOP 92-43 (English) (French) (Spanish)

NOP 92-43 (English) (French) (Spanish)

In most waste-fed systems, water quality degradation ultimately limits net fish yields (FY). Often as fertilization rates increase, inefficient nitrogen utilization together with daytime pHs exceeding 9.0 results in high unionized ammonia concentrations which reduce fish growth and survival. FY generally increases until high unionized ammonia concentrations and/or low morning dissolved oxygen concentrations become growth limiting. For optimal fish yields, maximum food availability must be balanced with favorable pond water quality. This paper examines the role of nitrogen limitation in managing pond eutrophication in order to produce greater and more predictable fish yields.

Application of limnology for efficient nutrient utilization in tropical pond aquaculture
Journal Article
1991

NOP 91-32 (English) (French) (Spanish)

Twelve 0.2-ha ponds in West Java were fertilized weekly with four levels of chicken manure (12.5, 25, 50, and 100 g dry weight/m2 week−1) during a 149-day growout experiment for Nile tilapia (Oreochromis niloticus) production. Laboratory leaching experiments for measuring dissolved inorganic nitrogen (DIN) release from chicken manure showed that nitrogen was released as ammonia-N, which was rapidly lost from the manure and leveled off at about 6 mg NH4-N/g dry weight chicken manure after 4–5 days. Allochthonous DIN input from both chicken manure fertilization and almost daily source-water additions ranged from 0.055 to 0.142 g N/m2 day−1. Source water contributed more nitrogen than manure in all but the highest fertilization treatment. Pond averages of net primary productivity (NP) ranged from 0.54 to 2.00 g C/m2 day−1, while gross fish yield at harvest ranged from 4.9 to 15.7 kg fresh weight/ha day−1. Net fish yield (NFY) was linearly correlated to both the dry weight sum of NP and chicken manure fertilization (r2=0.97) and allochthonous DIN input (r2=0.96). Results suggest that Nile tilapia obtained organic carbon from both primary productivity and manure-derived detritus. DIN availability limited algal productivity at a chicken manure fertilization rate of 100 g dry weight/m2 week−1 when microbial decomposition of manure supplied sufficient CO2. Incorporation of allochthonous DIN input into NFY increased significantly from 15.0% at the three lower fertilization rates to 25.4% at the highest loading rate. Using organic fertilizers proportionally rich in phosphorus and carbon relative to nitrogen may maintain this element's limitation of algal productivity. Efficient utilization of DIN input also may minimize total and un-ionized ammonia concentrations. In the absence of deleterious ammonia effects on survival and growth, fish yields can be readily predicted from measurements of nitrogen inputs.

Nitrogen input, primary productivity and fish yield in fertilized freshwater ponds in Indonesia
Journal Article
1991

NOP 92-A01 (English)

A mathematical model to stimulate thermal stratification in shallow aquaculture ponds is described. The dynamic, mechanistic model was developed to simulate the water column of ponds in discrete, completely mixed, horizontal volume elements. Energy exchanges between the pond's surface and atmosphere were calculated with theoretical and empirical relationships commonly applied to heat balance calculations in lakes, reservoirs and waste treatment ponds. Energy transfer between the volume elements caused by turbulent mixing were simulated as functions of the temperature gradient in the water column and a diffusion coefficient. The value of the diffusion coefficient was calculated in each time step as a function of wind speed, depth, and the water column density gradient. The model was implemented using a dynamics simulation language (STELLA™) using an Apple Macintosh™ microcomputer. Also described are the model calibration and verification procedure and results.

Modelling temperature variation and thermal stratification in shallow aquaculture ponds
Journal Article
1991

NOP 91-A04 (English)

Red drum (Sciaenops ocellatus) is an estuarine-dependent sciaenid that inhabits estuaries, bays, and coastal regions from New York to Mexico. In Texas, the red drum population began a dramatic decline in the 1970s, prompting the Texas Parks and Wildlife Department (TPWD) to set up a three-pronged recovery plan. Management approaches were: 1) Initiate an independent monitoring program to assess relative abundance; 2) Implement restrictive regulations to reduce fishing pressure, including license restrictions, size, bag, and possession limits, a commercial quota, restrictions on netting, and a ban on commercial sale of red drum; and 3) Develop and start a marine enhancement program based on the release of hatchery-reared fingerlings and assessment of subsequent survival. Recently, the red drum population in Texas coastal water rebounded because of several factors that had a positive effect on the recovery. TPWDs long-term management plan utilizing hatcheries and stocking to supplement natural spawning played a role in reversing the decline of the red drum population. The strategy used by the TPWD can serve as a blueprint for other marine enhancement programs.

Systematic Approach to Maximizing Nutrient Efficiency and Growth of Nile Tilapia (<i>Oreochromis niloticus</i>) Under Semi-Intensive Pond Culture
Journal Article
1991
Piedrahita, R. H., and P. Giovannini. 1991. Fertilized Non-Fed Pond Systems. Pp. 1 - 14 in Proceedings of the World Aquaculture Society and the American Society of Agricultural Engineers, Proceedings of the World Aquaculture Society and the American Society of Agricultural Engineers, edited by P. Giovannini. San Juan, Puerto Rico: American Society of Agricultural Engineers. Retrieved (http://agris.fao.org/agris-search/search.do?recordID=US19930000713).
NOP 91-36 (English) (French) (Spanish)

NOP 91-36 (English) (French) (Spanish)

Non-fed ponds are aquaculture production systems that do not depend on the addition of fish food, but derive their productivity from organic and inorganic fertilizers. Design and management goals for non-fed ponds are directed to the manipulation of the pond ecosystem to achieve predictable fish yields. This paper discusses new developments in the engineering of non-fed pond production systems. Included are quantitative techniques for determining optimum pond characteristics based on insolation at the production site; use of efficiency models to evaluate pond characteristics and management inputs over time; topics related to fertilization and other water quality management strategies; and a discussion of the significance of pond stratification on pond management.

Fertilized Non-Fed Pond Systems
Conference Paper
1991
Piedrahita, R. H. 1991. Engineering Aspects of Warmwater Hatchery Design. Pp. 85 - 100 in Proceedings of the World Aquaculture Society and the American Society of Agricultural Engineers, Proceedings of the World Aquaculture Society and the American Society of Agricultural Engineers, edited by P. Giovannini. San Juan, Puerto Rico: American Society of Agricultural Engineers. Retrieved (http://agris.fao.org/agris-search/search.do?recordID=US19930000713).
NOP 91-35 (English) (French) (Spanish)

NOP 91-35 (English) (French) (Spanish)

Engineering considerations for the design of hatchery systems for warmwater fishes are presented in this paper. The material is presented as it relates to specific unit operations or activities in a hatchery. Topics covered include aspects of water quality, water delivery systems, impoundment types, and water conditioning. The material is generally applicable and is not specific to a particular level of technological sophistication, or investment, or to a particular species. Application of the general principles mentioned to specific situations is dependent on the requirements for a particular installation.

Engineering Aspects of Warmwater Hatchery Design
Conference Paper
1991

NOP 91-A05 (English) ; NOP 92-41 (English) (French) (Spanish)

This study examined possible changes in dissolved oxygen concentration resulting from various short-term management actions that can be undertaken in response to cloudy conditions. The management actions were examined with a computer model of water quality in a pond, and include nutrient enrichment (fertilization, pH adjustment), water level control, and water exchange. Results of these simulations indicated that general management strategies directed at increasing nutrient availability were the least effective in counteracting the effect of the increased cloud cover. Flushing and reducing the water level in the pond were considerably more effective short-term management actions. Areas for field research were suggested to confirm the effectiveness of the various strategies.

Simulation of Short-Term Management Actions to Prevent Oxygen Depletion in Ponds
Journal Article
1991
Piedrahita, R. H. 1991. Modeling water quality in aquaculture ecosystems. Pp. 322 - 362 in Aquaculture and Water Quality, vol. 3, Aquaculture and Water Quality, edited by D.E. Brune and Tomasso, J.R. Clemson, South Carolina: The World Aquaculture Society. Retrieved (https://books.google.com/books/about/Aquaculture_and_water_quality.html?id=dQ0XAQAAIAAJ).
NOP 91-34 (English) (French) (Spanish)

NOP 91-34 (English) (French) (Spanish)

The techniques and uses of computer models, future developments and applications of computer modeling in aquaculture are reviewed. The general characteristics of aquaculture ecosystems are summarized from a computer modeling point of view. Various types of models of aquaculture systems are presented, including models that simulate dissolved oxygen concentration, water temperature, and other water quality variables. The models presented are reviewed from perspectives of modeling technique, model uses, data requirements, and predictive ability. Future applications of computer models in aquaculture research and commercial practice are proposed. These applications include the development of models integrated with automated data acquisition and control systems, models that simulate water temperature and water quality parameters simultaneously, and models for use in stratified ponds.

Modeling water quality in aquaculture ecosystems
Book Chapter
1991

NOP 92-40 (English) (French) (Spanish)

During three 5-month experiments in Thailand, earthen ponds of approximately 370 m2 surface area were stocked with male Nile tilapia, Oreochromis niloticus (L.), fingerlings of 4–12g weight at densities of 0.5 to l.6 fish/m2. Stocking and fertilization (with chicken manure, urea and TSP) in triplicated depth treatments of 0.6,1.0 and 1.5m were proportional to pond volume in two experiments (wet and dry seasons) and to pond area in the other (dry season). Depth showed no direct effect on fish yields of 0.9–6.3t/ha/year, on survival rates of 66 to 98%, nor on final individual weights of 96 – 313 g/fish. Greater yields were obtained from deeper ponds when they received proportionally greater stocking and fertilizer inputs. Inputs per unit area were the most important factor accounting for yield variation. Temperature, dissolved N and P, and suspended solids showed little or no relation to depth treatments. Time-averaged chlorophyll concentrations and photosynthetic production of dissolved oxygen were greater in treatments receiving greater inputs of nitrogen per unit pond volume. Deeper ponds produced the greatest areal yields of fish, when fertilized in proportion to their volumes. Shallow ponds produced fish and dissolved oxygen at least as efficiently per unit input as did deep ponds, which is consistent with models of photosynthesis-depth relations.

Production of <i>Oreochromis niloticus</i> (L.) and ecosystem dynamics in manured ponds of three depths
Journal Article
1991

NOP 91-A01 (English) ; NOP 92-47 (English) (French) (Spanish)

Automated data-logging equipment permits frequent in situ measurements of water quality variables and allows for better estimates of primary production and community metabolism in aquaculture ponds. A system to sample four contiguous 0.1-hectare earthen ponds is described. Two samplers for obtaining water samples for analysis were designed and compared. The first sampled at discrete depths throughout the water column, whereas the second obtained a composite water column sample. Samplers were constructed from readily available stocks of iron accessories or polyvinyl chloride fittings. Mean dissolved oxygen concentration, pH, and temperature did not differ significantly between water samples taken by the two samplers.

Comparison of Two Samplers Used with an Automated Data Acquisition System in Whole-Pond, Community Metabolism Studies
Journal Article
1991

NOP 92-42 (English) (French) (Spanish)

Two experiments were conducted in Choluteca, Honduras, to ascertain effects on yield and profitability of partial substitution of chicken litter for feed during initial growth of semiintensively cultured penaeid shrimp. In the first experiment, four management strategies based on various combinations of chicken litter (60 kg/hectare per week, total solids) and prepared feed were tested. After 99 d of growth, shrimp yield was not increased significantly by manuring in addition to feeding, and chicken litter was not profitability substituted for feed during the first 4–8 weeks. Mean total yields for the nonsubstitution treatments were 7–41% greater than those for treatments in which chicken litter was partially substituted for feed, and net income for the nonsubstitution treatments was 27–58% greater than that for substitution treatments. Differences were not significant (P > 0.05) because of large yield variation resulting from variable survival. In the second experiment, two combinations of chicken litter at higher rates and prepared feed were tested. Low-cost chicken litter applied weekly at 220 kg/hectare was profitably substituted for high-cost feeds during the first 8–9 weeks of grow-out. However, chicken litter applied at low rates is an ineffective substitute for feed and would not improve yields if applied with feeds.

Substitution of Chicken Litter for Feed in Production of Penaeid Shrimp in Honduras
Journal Article
1991

1990

NOP 90-27 (English) (French) (Spanish)

The demand for young male fish of Tilapia nilotica for seeding in reproduction ponds has significantly increased in the last five years. New production technologies are necessary in order to have adequate supply for existent and future demands of the young fish. One of those is the hormonal sexual inversion of the young fish of Tilapia nilotica via the oral ingestion of a synthetic male hormone (17 a-methyl-testosterone) during a period of 28 days which starts shortly after hatching and before differentiation of genital tissue. The objective of this work which was conducted during the months of January through November, 1988 was to determine the feasibility of implementing the massive production of young males of Tilapia nilotica using the hormonal sexual inversion process at the experimental station "Acuicola El Carao" in Comayagua, Honduras. The process requires obtaining young fish less than 13 mm long from reproduction ponds (0.05-0.1 ha) that have been seeded with Tilapia nilotica (2 females: 1 male). The ponds are then drained within 18 to 20 days after having been seeded, the reproducers are transferred to concrete separating tanks and the young fish are harvested by hand using a net 1.6mm long. The complete cycle for young fish production lasts approximately 23 days. The average number of harvested fish varies between 66,500 to 99,500. The fish are seeded at a population of 4,400/m2 in "japas" (wire nets of 1.6 mm, with dimensions 2 m x 2.5 m x 1 m x 1 m x 2 m x 1 m, with an average water depth of 60 cm) after having been passed through a 3.2mm separator net. The hormone is incorporated into the ground feed (23% protein) at a rate of 60 mg kg1. The ground feed is applied four times per day, seven days a week. The duration of the treatment described is 28 days. The average life span of the hormonal treatment was 87.6%. Treated fish were seeded in pre-fattening ponds (0.2 ha) for additional growth (102,500 ha-1). A total of 1,935,000 fish were harvested from the reproduction ponds of which 350,000 were discarded due to excess size. Of the 1,585,000 fish, 1,313,500 were treated with the hormone. Of that 1,189,600 fish were found to complete the treatment cycle. Of the seeded pre-fattening ponds with a total of 661,700 fish an average survival rate of 81.6% was obtained. Up till November, 1988, 399,000 18 g fish were produced, 97% being males. The cost of production of treating the fish (0.15 g each) was L 9.12/1000. This technology has resulted in being feasible not only for the experiment station in Comyagua but should also be feasible for qualified fisheries.

Implementing the Large-scale Production of Young Males in <i>Tilapia nilotica</i> Using Hormonal Sex Inversion in Honduras
Journal Article
1990

NOP 91-30 (English) (French) (Spanish)

The response of Nile tilapia (Oreochromis niloticus) yield to weekly applications of chicken litter at 125, 250, 500 or 1000 kg total solids (T.S.)/ha was determined in Honduras and Panama using a completely randomized design. Tilapia were stocked at 10,000/ha into 0.1-ha (Honduras) and 0.087-ha (Panama) earthen ponds. Each experiment, which lasted approximately 150 days, was performed during the rainy and dry season. Enterprise budgets were developed for each fertilization rate in each country. Gross yield of tilapia (y) increased significantly with chicken litter applications (x) in both countries, and was described by the model y = 797.3 + 2.945x−0.001 x 2 (r= 0.775; n = 48). Gross yields ranged from 827 –2,729 kg/ha in 147 days during the rainy season, and from 1145–2984 kg/ha in 150 days during the dry season. Maximum tilapia gross yields were achieved at 1000 kg T.S./ha week−1 chicken litter in both countries. In Honduras, rainy (1761 kg/ha in 152 days) and dry (1705 kg/ha in 150 days) season mean tilapia gross yields were similar (P = 0.05). Dry season (2071 kg/ha in 149 days) mean tilapia gross yield in Panama was significantly greater (P < 0.05) than rainy season mean gross yield (1683 kg/ha in 141 days). Rainy season climatic conditions in Panama probably contributed to the lower fish yields. Mean fish gross yield at the cooler, drier Honduras site (1733 kg/ha in 151 days), an upland valley located 580 m above sea level, and at the Panama site (1855 kg/ha in 145 days), a coastal plateau 100 m above sea level, was similar (P = 0.05). Mean gross yields were similar in both countries for all but the highest fertilization rate, where the Panama mean yield was significantly greater. This difference was caused by site-specific factors other than nutrient input. The use of chicken litter as an organic fertilizer was profitable in both Honduras and Panama. Net returns to land, labor and management during the 5.5-month production cycle ranged from $ 642 to $ 1724/ha (Honduras) or from −$237 to $313/ha (Panama) for the low to high fertilization rates, respectively. Application of 1000 kg T.S./ha week−1 chicken litter yielded the greatest estimated profit in both countries.

Response of tilapia yield and economics to varying rates of organic fertilization and season in two Central American countries
Journal Article
1990
Green, B. W., and D. R. Teichert-Coddington. 1990. Comparison of two sampler designs for use with automated data aquisition systems in whole-pond commuity metabolism studies. Pp. 392 - 403 in Proceedings of the Food and Agriculture Organization-European Inland Fisheries Advisory Commision Symposium on Production Enhancement in Still-Water Pond Culture, Proceedings of the Food and Agriculture Organization-European Inland Fisheries Advisory Commision Symposium on Production Enhancement in Still-Water Pond Culture, edited by B.W. Green and Teichert-Coddington, D.R. Prague: Research Institute of Fish Culture and Hydrobiology. Retrieved (http://ezfind.technion.ac.il/vufind/Record/002127459).
NOP 90-A03 (English)

NOP 90-A03 (English)

Automated data-logging equipment permits frequent in-situ measurements of water quality variables in aquaculture ponds. A simple system to sample 4 contiguous 0.1 ha earthen ponds is described, and consists of an automated data-logger and memory storage module, a polaro­graphic dissolved oxygen meter, a pH meter, temperature sensors, a quantum solar sensor, an anemometer, DC-voltage relays, 12 V-DC pumps, and a power source. Two sampling devices were designed for obtaining water samples for analysis. The first design allows samples to be collected at discrete depths throughout the water column. A composite water column sample is obtained using the second design. Both samplers are easily constructed from readily available stocks of iron accessories or PVC fittings. Diurnal dissolved oxygen (DO), pH and temperature data collected using eachtype of sampler were compared. Mean DO, pH and temperature, as determined by averaging data from 3 different depths in the water column, was not significantly different from means as determined by the composite water column sampler.

Comparison of two sampler designs for use with automated data aquisition systems in whole-pond commuity metabolism studies
Conference Paper
1990

Tilapia culture in Rwanda is practical in ponds at altitudes from 1,300 m to 2,500 m. Air and water temperature are lower than those in other tropical countries where tilapia culture is typically practiced. These conditions require careful pond water management practices for tilapia culture to be successful. Results from experiments and rural harvests indicate that Oreochromis niloticus is superior to Tilapia rendalli and O. macrohir in Rwandan conditions. Reproductive tendencies of O. niloticus are different from those seen elsewhere; age at first reproduction is higher, time before resumption of reproduction after restocking is longer, and number of fingerlings produced per surface area from 40 to 210 kg/ha/year. However, in well managed ponds, O. niloticus can show average growth of over 1.0 g/day and net productivity of 3,000 kg/ha/year.

Pond Culture of Tilapia in Rwanda, a High Alititude Equatorial Afican Country
Report
1990

NOP 90-29 (English) (French) (Spanish)

Egg hatching, and fry growth and survival of the walking catfish, Clarias batrachus (Linnaeus), were investigated under hatchery conditions in West Java, Indonesia. Spawning was environmentally induced in a specialized breeding pond. Gravid females utilized nests containing kakaban, a fibrous matting from local palm trees (Arenga sp.), which facilitated egg collection. Newly hatched fry fed with Artemia nauplii though day 8 (after hatching), an Artemia/cladoceran mix from days 9 to 16, and cladocerans only from days 17 to 23 resulted in over 90% survival of young from hatched eggs. Other diets examined (rotifers, cladocerans, ground fish meal, and ground Nile tilapia flesh) proved inadequate for fry through day 16. Fry reared in hatchery aquaria for 16 days versus 23 days before introduction into nursery ponds showed no significant differences in mean length, mean weight, or percent survival when harvested at day 58. Suggested guidelines are given for hatchery production of C. batrachus fry and fingerlings.

Hatchery techniques for egg and fry production of <i>Clarias batrachus</i> (Linnaeus)
Journal Article
1990

NOP 90-A01 (English)

This issue of Food Reviews International is devoted to aquaculture,the farming and ranching of aquatic species. The editors of Food Reviews International elected to prepare this special issue in response to growing interest among the global community of food producers,processors, and food-related interests about seafood production in general, and specifically about aquacultural production. This issue is intended to provide a broad perspective on the nature and extent of contemporary aquacultural production as well as a glimpse of what the future may hold. This collection of articles begins with a global overview of aquaculture production. This is followed by in-depth perspectives on several aspects of aquacultural research and technology, and an article describing the role of international development agencies in aquaculture. Finally, three successful aquacultural producers, each working in a different region of the world, present their insights into the business of aquaculture. Each article is authored by a recognized leader within the global aquacultural community. As sometimes happens when sampling a global community, the technical contributors tend to be representative of a particular region, in this case North America. The regional bias is unfortunate but should not obscure the global implications of the several articles. The generalizations may be directly extended to other regions and species of reader interest. Collectively, the global of the contributing authors of this issue is to provide information about aquaculture to the food-related industries and sciences. There is a consensus among the global aquacultural community that increasing communications with other food-related disciplines would be mutually beneficial. In fact, many aquaculturists regard themselves as food producers. Further, although aquaculture employs specialized methods and has evolved its own jargon, it also shares many commonalities with other food-producing systems. Hopefully, this volume will enable readers to uncover some of these common denominators and discover familiar concepts and constraints. Principal among the recurring themes explicit or implied in the included articles is that aquaculture is a form of agriculture and is based on familiar agricultural concepts. Therefore, aquaculture systems can be evaluated in exactly the same way that one would evaluate agricultural production systems. Additionally, the agricultural concepts of efficiency and intensity are directly applicable to aquaculture.

Farming and Ranching in Aquatic Systems
Journal Article
1990

The purpose of this work was to develop a strategy for fertilizer application that improved predictions of yields. Pond productivity was analyzed relative to supplies of dissolved inorganic carbon (DIC), dissolved inorganic nitrogen, and dissolved reactive phosphorus. Phosphorus did not limit pond production in any of the treatments used. Algal productivity and yield of male Nile tilapia (Oreochromis niloticus Trewavas) were limited by DIC when low alkalinity ponds were fertilized with chicken manure or triple superphosphate and urea. In high alkalinity ponds with adequate DIC, nitrogen limited production when chicken manure was added. Nitrogen limitation with adequate DIC was demonstrated in a two treatment experiment. In the first, chicken manure was added at 500 kg/ha/wk. In the second, chicken manure and urea were added at 44 kg/ha/wk and 25 kg/ha/wk respectively. The experimental design provided the same amount of nitrogen in both treatments. Also, the ratio of phosphorus to nitrogen in the second treatment was made 1:7 by weight in order to avoid phosphorus limitation. Our prediction that mean net algal productivities and fish yields would be the same for these treatments was verified by the data. Fertilizer costs per kg of yield were $0.07 for the chicken manure treatment, and $0.06 for the chicken manure + urea treatment. Guidelines for developing fertilizer applications that result in predictable yields of fish can be taken from this work.

Managing Fertilizers for Fish Yield in Tropical Ponds in Asia
Report
1990

NOP 91-33 (English) (French) (Spanish)

A computer model of water quality in aquaculture ponds (The Aquaculture Pond model, TAP) has been run for data obtained from five research sites around the world. The procedures followed for data manipulation, and the assumptions made to complete the data requirements are described. Agreement between simulated and measured dissolved oxygen values was used as an indicator of the quality of the simulations. The quality of the simulations varied between sites and in some cases between pond treatments at a given site. Possible reasons for the variations in quality of fit are discussed.

Calibration and Validation of TAP, an Aquaculture Pond Water Quality Model
Journal Article
1990
NOP 90-A02 (English)

NOP 90-A02 (English)

The general characteristics of detritus-based aquaculture systems are reviewed, where detritus is defined as particulate and dissolved organic matter. Basic criteria of water quality, nutrient cycles, fish stocking, and pond management practices are described. Public health considerations are important questions in the use of detritus in aquaculture, and some relevant management and risk estimation issues are discussed here.

Detritus-Based Aquaculture Systems
Journal Article
1990

NOP 91-31 (English) (French) (Spanish)

Density stratification isolates near-surface from bottom pond waters and prevents exchange of dissolved oxygen (DO) and nutrient elements, potentially restricting photosynthesis and production. Destratification strategies have become important for cost-effective intensification of pond aquaculture. Evaluation of methods and devices has emphasized effects on production, with little detailed description of effects on physicochemical components of pond ecosystems. This paper describes short-term effects of mechanical mixing on temporal and spatial distribution of temperature and DO in tropical freshwater fish ponds. Intensely stratified ponds of 1.5 m depth were monitored at eight depths for temperature and two depths for DO every 30 min with a modest-cost automated system of commercially available hardware. Results are presented as time-series plots, isotherm diagrams of temperature distribution with time and depth, and a stability index of energy required to mix a pond to uniform temperature. Required mixing energy is minuscule compared with electrical energy consumption of the lowest-powered mixing devices discussed in literature. Strategy for application of mechanical energy to water is critical for efficiency. A relatively subtle difference between two mixing regimes (daytime mixing for one 2-h period or two 1-h periods) produced potentially important differences in temperature and DO distribution.

Techniques for Assessment of Stratification and Effects of Mechanical Mixing in Tropical Fish Ponds
Journal Article
1990

NOP 90-26 (English) (French) (Spanish)

The objective of this research was to determine the effects of substituting chicken manure for the common feed stuffs used in the first four to eight weeks of the growing period of shrimp. Economical evaluations of shrimp production was also considered. Twelve man made pond (2.2-3.0 ha) located at Granjas Marinas, San Bernardo, S.A., San Bernardo, Choluteca, Honduras were assigned to four treatments at random and seeded with young shrimp (average weight 0.8 g) at a rate of 5m-2 on September 7, 1988. The treatments tested were: 1) (STANDARD) the normal treatment used at Granjas Marinas San Bernardo which consisted in the application of chicken manure during the first eight weeks plus added feed, 2) (FEED) feed only, 3) (4WEEKS) chicken manure only during the first four weeks followed by feeding, 4) (8WEEKS) chicken manure only during the first eight weeks followed by feeding. After ninety nine days of shrimp cultivation, there was no increase in production using low rates of chicken manure (60 kg total solids/ha/week) during the first eight weeks of feeding. It was also found not to be economical to substitute feeding for low rates of fertilization with chicken manure, especially after the first two or three weeks of cultivation. The average weight of shrimp for treatments FEED 14.4, and STANDARD 14.1, was significantly greater than that observed for 4 WEEKS 12.2, and 8 WEEKS 12.1. The average shrimp production was 7 - 41% greater in STANDARD and FEED treatments (%) and 518 kg/ha respectively) compared to 4 WEEKS (476 kg/ha) and 8 WEEKS (368 kg/ha). However, there were no significant differences between treatments due to the high amount of variability caused by survival rate (P < 0.01). The total costs for FEED and STANDARD were significantly greater compared to 4 and 8 WEEKS. This was due to a greater feed utilization in the previous treatments. Estimated gains in FEED (L.3085/ha) and STANDARD (L.3026/ha) were 27-58% greater than 4 and 8 WEEKS (L.2389/ha, and 1947/ha respectively). This was due to the increased reproduction obtained with greater prices received for the larger shrimp obtained in FEED and STANDARD treatments. There was potential to significantly increase the estimated gains by substituting feed for fertilization with chicken manure at a higher rate of application (250 kg/ha/week) during the first four to eight weeks of cultivation.

The substitution of chicken litter for feed in the commercial production of peneid shrimp in Honduras
Journal Article
1990

1989

NOP 89-A01 (English) ; NOP 91-39 (English) (French) (Spanish)

The production of male tilapia (Oreochromis niloticus) (10,000 fish/ha) in 0.1 ha earthen ponds fertilized with layer chicken litter was studied during the rainy and dry seasons at the "El Carao" Aquaculture Experiment Station, Comayagua, Honduras. Four rates of chicken litter application were tested using a completely randomized design; weekly applications of chicken litter, on a dry matter basis, were: 125, 250, 500, and 1000 kg/ha. After a culture period of 150 days, yields during the rainy season were, respectively, 1159, 1589, 1856, and 2229 kg/ha, while during the dry season the respective yields were 1116, 1399, 1884, and 2295 kg/ha. No seasonal differences in production (P > 0.05) were detected at any fertilizer level. Fish production increased significantly (P < 0.05) with an increase in manure input, and was described by the equation Y = 832.693 + 2.813x - 0.0014x2, r2 = 0.893. Income from the sale of fish produced ranged from L. 3674/ha (2 Lempiras = $1 USD) to L. 7256/ha and total production costs ranged from L. 2364/ha to L. 3856/ha for the low and high fertilization rates, respectively. The cost per kilogram of fish produced was L. 2.13 at the 125 kg/ha/wk rate of chicken litter application and L. 1.75 where chicken litter was applied at 1000 kg/ha/wk. The lowest production cost (L. 1.68/kg) was obtained at the 500 kg/ha/wk fertilization rate.

Production and economic aspects of tilapia cultivation in ponds fertilized with chicken litter
Journal Article
1989

NOP 89-17 (English) (French) (Spanish)

Shallow tropical integrated culture ponds in the Pearl River Delta, China, have been found to stratify almost daily, with high organic loadings and dense algal growth. The dissolved oxygen (DO) concentration is super-saturated in the epilimnion and is under 2 mg/l in the hypolimnion (>1 m). The compensation depth corresponds to twice the Secchi disk depth ranging from 50 to 80 cm. As a result, little or no net oxygen is produced in the hypolimnion (>1m). The low DO concentration in the hypolimnion causes organic materials, such as unused organic wastes an senescent algae cells, to be incompletely oxidized, since the rate of oxygen consumption by oxidable matter in water is dependent on the dissolved oxygen concentration in water. This material becomes the source of hypolimniotic oxygen deficits (HOD) which can drive whole pond DO to a dangerously low level, should sudden destratification occur. An improved estimate of hypolimnetic oxygen deficits is introduced in this article, and the advantages of this method are discussed.

Estimates of hypolimnetic oxygen deficits in ponds
Journal Article
1989

NOP 90-22 (English) (French) (Spanish)

Large shallow lakes in the Pacific Drainage Basin of China are unique aquatic natural resources intensively exploited in recent years for integrated lake farming. This paper presents a general description and major components of this culture method and discusses potential concerns and effects of increased fishery production on aquatic environments.

Integrated lake farming for fish and environmental management in large shallow Chinese lakes: a review
Journal Article
1989

NOP 89-18 (English) (French) (Spanish)

High stocking densities (600 fish/ m3) of walking catfish resulted in slightly higher mortality rate, no difference in growth rate, and a much higher yield than low density stocking (300 fish/ m3). Water flow rate (10, 5, or 2.5 turnovers/day--turnover is defined as one diluted replacement volume) had no effect on survival, growth, or yield. Fish were cultured from an initial weight of 5.4 g for 90 days, and most mortality occurred early in the cycle when the fish weighed <26 g. Growth also was high initially and declined with time. Dissolved oxygen did not differ between tanks of different density, but was altered by flow rate. Water supply parameters, such as short-term BOD, strongly affected dissolved oxygen content at all flow rates. Ammonia concentrations increased with density and decreased with increased flow rate. Mortality rate of all fish was strongly dependent on size, and mortality of small fish was correlated with short-term BOD.

The effects of water exchange rate and density on yield of the walking catfish, <i>Clarias fuscus</i>
Journal Article
1989

NOP 89-15 (English) (French) (Spanish)

The effect of weekly applications of similar quantities of nitrogen and phosphorus from three different sources on the production of Oreochromis niloticus (10 000/ ha) was studied in 0.1-ha earthen ponds. Layer chicken litter (500 kg total solids (TS)/ ha), dairy cow manure (1020 kg TS/ ha) and chemical fertilizer (46-0-0 at 30.6 kg/ ha and 0-46-0 at 62.6 kg/ha) were applied weekly. Mean total net production after 150 days was greater with chicken litter (1759 kg/ha). Differences in fish production were explained in terms of net and gross primary productivity and community respiration.

The effect of manures and chemical fertilizers on the production of <i>Oreochromis niloticus</i> in earthen ponds
Journal Article
1989

NOP 91-38 (English) (French) (Spanish)

Production of male tilapia (Oreochromis niloticus) (1 fish/m2) in 0.1 ha earthen ponds fertilized with different rates of chicken litter was studied using a completely randomized design at the "El Carao" Aquaculture Experiment Station, Comayagua, Honduras. The purpose of this study was to quantify tilapia production at different rates of chicken litter application. Chicken litter was applied at the following rates: 125, 250, 500, and 1000 kg TS/ha/wk. After 150 days the net total production was 895, 1321, 1612, and 1950 kg/ha where 125, 250, 500, and 1000 kg TS/ha/wk, respectively, were applied. Net total production was regressed against rate of chicken litter application yielding the equation: [[Ydieresis]] = 933.5 + 1.09X, r = 0.87. There was a positive relationship (P < 0.05) between rate of chicken litter application and net total fish production.

The effect of different application rates of chicken litter on tilapia production.
Journal Article
1989

NOP 89-A03 (English)

The aquatic ecosystems of the world, including inland, coastal, and marine waters, host a remarkable diversity of species. The number of fish species alone exceeds 20,000, or approximately one-half of all vertebrate species (Nelson 1984). This diverse ichthyofauna is in addition to thousands of aquatic species representing other phyla. The diversity of form and life-history pattern clearly represents a wealth of genetic resources. This report is intended to provide an overview of fish genetic resource management. However, the management of fish genetic resources has direct parallels to other aquatic organisms, and many of the concepts of generalizations that follow are equally applicable to other aquatic species. The global ichtyofauna is of significant intrinsic value. The genetic resources represent the capacity for the adaptive evolution of extant species to changing environments and for the evolution of new species. In a more practical sense, the genetic resources represent present and future opportunities for the development and harvest of new sources of human foods, and germ plasm for present and future development of improved varieties for aquaculture. Furthermore, because many fish species manifest a high degree of adaptive specialization, they serve as sensitive indicators of environmental quality. Although it can be argued that the intrinsic value of genetic resources justifies their conservation, it is the economic value of the resources rather than the intrinsic value that has historically exerted the greater influence on resource management policies. Contemporary fisheries resource management is strongly biased towards preservation of economic resources, and conservation of genetic resources is a secondary consideration, if it is considered at all. Economic values of fisheries resources are related to both commercial and noncommercial resource utilization. Commercial resource utilization includes harvesting or farming fish for food, ornamental use, and various specialized uses such as bait. Noncommercial resource utilization includes recreational fishing and aesthetic value. All aquatic species are at risk of losing genetic resources as a consequence of human activities that alter their habitat and (or) population structure. Agriculture, fisheries, forest exploitation, and hydroelectric, residential, and industrial development are examples of human activities that may threaten aquatic species and impose risks of losing genetic resources. The nature of these human interventions is so diverse that it is difficult to generalize about their management. Therefore, this report will focus on the genetic aspects of management, harvesting, and production of fish for human use.

Genetic resource management of fish
Journal Article
1989

NOP 90-25 (English) (French) (Spanish)

The production of Colossoma macropomum (tambaqui), a relatively little studied fish from the Amazon and Orinoco basins, was compared with that of Tilapia nilotica, a fish well known for its good production characteristics. The experimental design was randomized and arranged in 2 x 2 factorial with each species being tested at 2,500 and 10,000 fish/ha. Treatments were replicated three times. Fingerlings (22-31 g) were stocked into 870 m2 earthen ponds, fed a commercial diet (25% protein), and harvested after 129 days. Mean yield (kg/ha) for tilapia at high and low density was 3,361 and 917, respectively, and for Colossoma was 3,682 and 977, respectively. The yield difference between species was not significant (P < 0.01). Although yield was not different for the species, tambaqui weight gain was significantly greater than that of adult tilapia because of reproduction in the tilapia ponds. Mean tilapia and tambaqui weight gains (g) for low density were 379 and 471, respectivley, and 321 and 395, respectively, for high density. Increasing the stocking density fourfold resulted in an almost fourfold increase in net yield for both species, although individual weight gains were not significantly affected. There was no interaction between species and density for the production characteristics studied.

Comparative production of <i>Colossoma macropomum</i> and <i>Tilapia nilotica</i> in Panama
Journal Article
1989

NOP 88-10 (English) (French) (Spanish)

1. Plasma sex steroid concentrations, onset of gonadal maturation, and hepatic microsomal UDP-glucuronyltransferase (UDPGT) activities were followed under natural temperature and photoperiod in outdoor tanks, and under controlled laboratory temperature and photoperiod regimens in common carp (Cyprinus carpio). 2. Decreased activity of UDPGT was out of phase with elevations in plasma testosterone and 17 beta-estradiol during gonadal maturation. 3. Injection of pituitary extract induced final gonadal maturation and transient elevations (within 24 hr) of both plasma sex steroid concentrations and UDPGT activities. 4. There were no simple relationships between plasma sex steroid concentrations and activity of hepatic microsomal UDPGT in common carp.

Elevation of sex steroids and inhibition of UDP-Glucoronyltransferase are out of phase during gonadal maturation in the common carp
Journal Article
1989

NOP 89-21 (English) (French) (Spanish)

Twelve earthen ponds (870 m2 by 0.9 m) located on permeable, acidic soils in Gualaca, Panama, were limed and stocked with Oreochromis niloticus at a rate of 1/m2. Ponds were fertilized every two weeks with triple superphosphate (42% P2O5) at a rate of 4 kg/ha P2O5). Seasonal means of primary production, chlorophyll a, filterable orthophosphates, total phosphorus, total alkalinity, total hardness, and fish production were correlated with the mean seepage for each pond. The same experiment was accomplished during both the dry and wet seasons of 1985. Mean seepage for all ponds ranged from 19 to 58 mm/day. Of the chemical variables, only total alkalinity and total hardness consistently decreased with increasing seepage rates. Primary production and chlorophyll a were not correlated with seepage. Fish production was unrelated to seepage during the dry season when total alkalinities were high, ranging from 37 to 60 mg/l CaCO3, but significantly decreased with high seepage during the wet season when total alkalinity became lower than 10 mg/l CaCO3. The study indicates that ponds located on acidic soils with high seepage rates will require significantly greater additions of lime to maintain alkalinity and hardness levels suitable for fish production.

Effects of Seepage on Water Quality and Productivity of Inorganically Fertilized Tropical Ponds
Journal Article
1989

NOP 94-78 (English) (French) (Spanish)

The effect on seepage of adding chicken litter at the rate of 125, 250, 500 and 1000 kg ha−1 wk−1 total solids (TS) for 5 months to earthen fish ponds in Panama was measured. Each treatment was replicated 3 times. Application of litter at all rates reduced seepage. Before litter application, mean seepage for all ponds ranged from 27 to 37 mm day−1; after application, mean seepage ranged from 8 to 17 mm day−1. This represented a seepage reduction of 54–76%. Linear regression of mean seepage reduction on rate of chicken litter was significantly positive (P < 0·01). Reduction of seepage was most rapid for ponds receiving the highest rate of chicken litter. Near maximum reduction occurred during the first month within the three highest application rates. The lowest rate resulted in a linear reduction of seepage with time. A limit was reached at all application rates where additional litter application did not result in greater seepage reduction. Litter applications of at least 250 kg ha−1 wk−1 TS for a month are recommended for rapid seepage reduction in ponds. Draining and drying the ponds following 5 months of litter application did not appreciably increase seepage.

Seepage Reduction in Tropical Fish Ponds Using Chicken Litter
Journal Article
1989

NOP 89-A02 (English)

Chinese catfish (Clarias fuscus) were successfully spawned in Hawaii using human chorionic gonadotropin (HCG) at dosage rates of two and four international units (IU) per gram body weight. Fish not injected with HCG did not produce viable eggs. Successful spawns with HCG occurred between May and October. Hatch rates of up to 80% were obtained during June, July, and August for those fish given either a 2 or 4 IU per gram body weight injection of HCG. Fish spawned in either May or October yielded significantly higher hatch rates when injected with 4 rather than 2 IU per gram body weight. Fish held at elevated temperatures (28 to 30 C) prior to the normal spawning season developed significantly larger oocyte diameters, 60 days earlier than fish held under ambient temperature conditions (21.5 to 24 C). Photoperiod manipulation at ambient temperature conditions was associated with earlier oocyte maturation, but photoperiod effects were much less important than temperature.

Induced Maturation and Spawning of the Chinese Catfish <i>Clarias fuscus</i>
Journal Article
1989

NOP 88-A03 (English)

Four fish species, Aristichthys nobilis (Richardson), Ctenopharyngodon idella Val., Cyprinus carpio L. and Puntius gonionotus (Bleeker) were grown for 352 days in three treatments a reference treatment, triple super phosphate (TSP) treatment and triple super phosphate plus urea (TSP-urea) treatment. Reference ponds received no fertilizer, while TSP ponds received 28.3 kg P2O/ha/mon, and TSP-urea ponds received 7.1 kg P2O5/ha/wk plus 35.5 kg urea/ha/wk. Net fish productions were 437 kg/ha, 1,034 kg/ha and 1,713 kg/ha in reference, TSP and TSP-urea treatments respectively. Bioassay tests using the alga (Selenastrum capricornotum) Printz, supported the above contention by showing higher growth in response to phosphorus enrichment of reference pond water relative to control cultures, response to nitrogen addition in TSP treatment water and response to phosphorus addition in TSP-urea treatment water. Input of phosphorus and nitrogen fertilizers to provide well balanced concentrations for algae uptake was important to increase and maintain high primary productivity and thus fish yield in these fish ponds.

Effects of nutrient availability on primary productivity and fish production in fertilized tropical ponds
Journal Article
1989

1988

Results of experiment in Cycle III of the Pond Dynamics/Aquaculture CRSP are reported here. Two experiments were conducted: one lasted 156 days and the other lasted 149 days. During both experiments four levels of dried chicken manure (12.5, 25, 50 and 100 g/m2/wk) were added to 0.02 ha ponds. There were three ponds in each treatment. Results of the two experiments were similar. Yield of Nile tilapia (Oreochromis niloticus) at final harvest increased linearly with increasing fertilizer application from about 900 kg/ha in the lowest treatment to approximately 2300 kg/ha in the highest. Increased algal productivity and an apparent increase in detritus accompanied increasing fish yield. Analyses of nitrogen and phosphorus suggested that higher algal productivity and fish yields could be obtained by improving the fertilizer regime so that N and P are available in these ponds in proportions required by pond mircroflora.

Effect of Chicken Manure Additions on Fish Production in Ponds in West Java, Indonesia
Report
1988

NOP 89-14 (English) (French) (Spanish)

Dissolved oxygen dynamics and vertical water circulation in high density integrated fish culture ponds were monitored monthly at 2-h intervals for 26h from March through September at the Pearl River Delta, China. Stable thermal stratification was found almost daily in May through September. Vertical circulation began daily between 8 and 10 p.m. The average depth for this turnover in summer can be as great as 0.7-1 m. Complete vertical circulation occurs only during major storms. A convection turbulence model was used to examine the vertical mixing process and showed that light wind (<100 cm/s) and surface cooling (<2°C) after sunset can substantially influence the depth of mixing. Photosynthesis by algae is the most important natural mechanism contributing oxygen to ponds; compared to photosynthesis, net oxygen gain and loss due to diffusion during daylight is small. The compensation depth corresponded to twice the Secchi disk depth, ranging from 50 to 80 cm. The dissolved oxygen concentration in the hypolimnion was usually less than 2 mg/l, but increased at night during the period of vertical circulation. Hypolimnion oxygen deficit (HOD) was explored with the in situ dissolved oxygen concentration. HOD was found to increase during the daylight period and decrease at night after destratification.

Dynamics of Dissolved Oxygen and Vertical Circulation in Fish Ponds
Journal Article
1988
Diana, J. S., P. J. Schneeberger, and C. K. Lin. 1988. Relationships Between Primary Production and Yield of Tilapia in Ponds. Pp. 1 - 6 in The Second International Symposium on Tilapia in Aquaculture, The Second International Symposium on Tilapia in Aquaculture. Retrieved (http://agris.fao.org/agris-search/search.do?recordID=PH8912312).
NOP 89-19 (English) (French) (Spanish)

NOP 89-19 (English) (French) (Spanish)

The purpose of this study was to determine relations between physicochemical variables and primary productivity of fish yield using multiple regression analysis. In Thailand, 8-12 pond (250 m2) were stocked with male Oreochromis niloticus (25-35 g) at a density of 1 fish/m3. Experiments were run for approximately 5 months during the wet season of 1984 and the wet and dry seasons of 1985. Ponds received nutrient inputs according to three different management schemes: (1) low input inorganic fertilizer (8 kg/ ha/month P2O5); (2) high input organic fertilizer (500 kg/ha/week chicken manure); and (3) high input inorganic fertilizer (100 kg/ha/week P2O5 and 30 kg/ha/week urea). Air and water temperature, solar radiation, rainfall, dissolved oxygen (DO), total phosphorus, nitrate-nitrite, ammonia, turbidity, chlorophyll alpha (a), primary productivity, fish weight, and fish survival were measured regularly throughout each experiment. Data were examined by regression analyses. Ponds receiving high fertilizer inputs exhibited higher nutrient levels in water, higher primary productivity, and higher fish production than ponds treated with low inputs of fertilizer. Nitrogen and phosphorus appeared to be limiting factors for primary productivity, although multiple regression between these two factors and primary production indicated no significant relationship. The availability of nutrients may have been related more closely to regeneration rate than absolute concentration. Fish yield was strongly correlated to rainfall, fish biomass, DO, water temperature and solar radiation. The correlation between net yield and fish biomass was a positive one, indicating that carrying capacity was not reached in the ponds.

Relationships Between Primary Production and Yield of Tilapia in Ponds
Conference Paper
1988

NOP 88-A04 (English)

A yield model for Clarias culture was produced using a combination of laboratory data for Clarias lazera and field data on Clarias batrachus culture in Thailand. The model was used for simulations to fulfill three distinct objectives: (1) to consolidate knowledge of fish physiology and aquaculture practices for Clarias into a model which can be validated; (2) to determine sensitivity of predictions to variation in model parameters; and (3) to predict yield of Clarias ponds under different stocking density, size at stocking, and type of containment. The accuracy of this model was tested with an independent data set of 32 grow-out periods. The model was relatively poor at predicting yield when the measured feeding rate was input (r2=0.022), but reasonably good at predicting yield if maximum feeding rate was input (r2=0.52). This may reflect poor data collection of feeding rate in the ponds. Sensitivity analyses indicated that changes in parameters related to maximum consumption showed high importance in predicting yield, while changes in metabolic parameters had low importance. A doubling of feeding rate increased yield 548% in earthen ponds and 465% in concrete tanks. Density stocked was of secondary importance in increasing simulated yield, while size at stocking was relatively unimportant. The maximum consumption rate of different food types (pellets, trash fish) was also extremely important in determining simulated yield.

A Yield Model for Walking Catfish Production in Aquaculture Systems
Journal Article
1988

NOP 89-13 (English) (French) (Spanish

The effects of pond water depth (0.5, 1.0 and 1.5 m) and artificial circulation on certain pond dynamic processes were evaluated in a factorial design. Deep ponds had more uniform temperatures, with less rapid temperature changes, greater whole pond respiration, and greater temperature and oxygen stratification. Artificial circulation reduced thermal and oxygen stratification. Sediment respiration, which was estimated using a new technique, was more than three times greater than plankton and shrimp respiration combined, regardless of treatment combination. Shrimp yields were not significantly different for any of the six treatment combinations.

Effects of Water Depth and Artificial Mixing on Dynamics of Philippines Brackishwater Shrimp Ponds
Journal Article
1988

NOP 90-24 (English

The frustrations encountered when trying to compare technical reports in which fishpond yield figures are reported in a variety of units (e.g., kg/ha, kg/pond, lb/acre, etc.) are familiar to most aquaculturists. However, severe problems may develop when trying to communicate research results to other audiences if data are transformed to a hectare basis. The authors gives his own experience in conveying research data to the farmers and the problem encountered.

Reporting Fishpond Yields to Farmers
Journal Article
1988
Hopkins, K. D., D. Pauly, and M. L. Hopkins. 1988. A Multivariate Model of Tilapia Growth, Applied to Seawater Tilapia Culture in Kuwait. Pp. 29 - 39 in The Second International Symposium on Tilapia in Aquaculture, vol. 15, The Second International Symposium on Tilapia in Aquaculture. Retrieved (https://www.worldfishcenter.org/content/multivariate-model-tilapia-growth-applied-seawater-tilapia-culture-kuwait).
NOP 90-23 (English) (French) (Spanish)

NOP 90-23 (English) (French) (Spanish)

Traditional analyses of aquaculture growth experiments usually consider only the yield at the end of the experiments and ignore the growth data collected during intermediate samplings. A multivariate model based on an expansion of the “Gulland and Holt Plot” used in fisheries biology provides a methodology to extract growth information from the data from intermediate samplings. This model is applied to data from three tilapia yield experiments conducted in seawater in Kuwait. The effects of temperature, sex ratio, and fish length on growth rate are quantified.

A Multivariate Model of Tilapia Growth, Applied to Seawater Tilapia Culture in Kuwait
Conference Paper
1988

NOP 88-A01 (English)

Twelve 0.2 ha aquaculture ponds for Nile Tilapia production in West Java were fertilized weekly with 4 levels of chicken manure: 12.5, 25, 50, and 100g m-2. During a 150 day grow out period, weekly ammonia-N and nitrate-N concentrations often exceeded 0.05 mg L-1 in ponds fertilized with 12.5 and 25 g m-2 wk-1, but were usually less than 0.05 mg L-1 in ponds fertilized with 50 and 100 g m-2 wk-1. These differences between treatments in dissolved inorganic nitrogen (DIN), and apparent nitrogen limitation of algal productivity at higher loading rates, were examined through daily and diurnal measurements of ammonia-N and nitrate-N. Data suggest that algal production was limited by a shortage of DIN at higher fertilization rates. At higher fertilization rates, CO2 at lower fertilization rates and by a shortage of DIN at higher fertilization rates. At higher fertilization rates, CO2 for algae was additionally supplied through microbial respiration of organic carbon in chicken manure. Laboratory experiments measuring the release of ammonia-N and nitrate-N for chicken manure and urea were conducted to evaluate nitrogen transfer rates from these materials. An economic analysis is presented which relates appropriate application rates to fish yields and the cost of fertilizers in West Java.

Nitrate and Ammonia Depletion in Indonesian Aquaculture Ponds Fertilize with Chicken Manure
Journal Article
1988

NOP 88-A05 (English) ; NOP 89-16 (English) (French) (Spanish)

Data on production and marketing of giant freshwater prawn were collected over a 7-month grow-out period through collaboration with a medium-sized commercial prawn farm in central Thailand. Juvenile prawns with an average weight of 4.2 g were stocked at a density of 6 prawns/m2 in three 0.5-ha earthen ponds. Average growth rate determined during the first 3 months of the grow-out period was 0.4 g/prawn per day; prawns of marketable size were harvested selectively during the remaining 4 months of the rearing period, resulting in a total accumulated yield of 1.3 tonnes/ha with an average prawn weight of 32 g and 60% survival. As different sexes and sizes of prawns were sold at different prices, the harvests were customarily sorted into several categories: large, medium, and small males, long-clawed males, soft shells, females with eggs, females without eggs, and terminal males. The total weight and number of prawns recorded for each of these categories showed that the female to male ratios were 1.6:1 and 4:1 by weight and number, respectively while the ratio of short to long-clawed males was 3:1 by weight and 4:1 by number. Four percent of the marketable population was termed "soft shells" and 64% of the females bore eggs. The ratio of head weight to tail weight of marketable prawns varied substantially among the different categories: 1.0:1 for females, 2.5:1 for long-clawed males, and 1.6:1 for short-clawed males. Females predominated in the first and second 1.5-month harvest periods while males predominated in the final 1.5 months of the harvest. The economic yield of prawn culture was not only determined by the biomass, but also by the population structure of the various biological categories and the harvest season. 

An Analysis of Biological Characteristics of <i>Macrobrachium rosenbergii</i> (de Man) in Relation to Pond Production and Marketing in Thailand
Journal Article
1988
Lin, C. K., C. Apinhapath, and V. Tansakul. 1988. Biological Nitrogen Fixation as a Source of Nitrogen Input in Fishponds. Pp. 53 - 58 in The Second International Symposium on Tilapia in Aquaculture, vol. 15, The Second International Symposium on Tilapia in Aquaculture. Retrieved (http://www.nrcresearchpress.com/doi/abs/10.1139/g89-141#.WRNKP5MrJrI).
NOP 89-20 (English) (French) (Spanish)

NOP 89-20 (English) (French) (Spanish)

The potential input of nitrogen derived from natural biological fixation in water of fertilized tilapia grow-out ponds in Thailand was determined by the acetylene reduction technique for 12 ponds over a 15-month period. On average, nitrogen fixation ranged from undetectable levels of N to 105 µg/L/day in the water column, compared with 200µg/L/day input of N from chicken manure loading at a rate of 500 kg/ha/week. Estimated total nitrogen fixation in fishponds during a 5-month grow-out cycle ranged from 8.8 to 85.7 kg N/ha. Nitrogen fixation primarily occurred in daylight; it was inhibited in the dark and suppressed by elevated ammonium concentrations present in pond water. Nitrogen-fixing blue-green algae commonly present in the pond water were Anabaena, Cylindrospermum, and Nodularia.

Biological Nitrogen Fixation as a Source of Nitrogen Input in Fishponds
Conference Paper
1988

NOP 88-A02 (English)

The backbone of Java consists of chain at some 25 major volcanic peaks. Among the peaks are ridges of uplifted limestone reefs. Groundwater and runoff from volcanic regions were mineral poor carbonate-bicarbonate alkalinity was on the order of 20 mg L-1. By contrast, waster emerging from limestone regions had alkalinity near 160 mg L-1. When phosphorus and nitrogen fertilizers were added to low alkalinity water in ponds in a volcanic region, the growth of algae and subsequent yield of Nile Tilapia were low: 1.1 g C m-1 day-1 and 1080 kg fish ha-1 per 150 day grow-out period respectively. With low alkalinity, carbon dioxide limited pond production, and phosphorus and nitrogen remained in pond water unused by the algae. When alkalinity was increased to 50-60 mg L-1 and fertilizer was applied at the same rate, algae productivity and sh yield increased to 1.5 g C m-2 day-1 and 1475 kg fish ha-1 per 150 day grow-out period. With increased abundance of CO2 and increased growth of algae, phosphorus and nitrogen uptake from pond water increased, thus improving fertilizer effciency. CO2 continued to be in short supply at the highest levels of pond production obtained in the experiment. Fertilizer applied at the same rate to ponds in limestone drainage systems of Java with greater alkalinity would likely support pond productivity in excess of that obtained h ere. This work shows that CO2 availability needs to be assessed during design of fertilizer application schemes in order to use fertilizers economically and to obtain consistent fertilizer-based yields from site to site in Java.

Carbon Limitation in Fertilized Fish Ponds in Java.
Journal Article
1988
Moehl, J. F., K. L. Veverica, B. J. Hanson, and N. Hishamunda. 1988. Development of Appropriate Pond Management Techniques for Use by Rural Rwandan Farmers. Pp. 561 - 568 in The Second International Symposium on Tilapia in Aquaculture, The Second International Symposium on Tilapia in Aquaculture. Retrieved (http://agris.fao.org/agris-search/search.do?recordID=PH8912443).
NOP 88-A06 (English)

NOP 88-A06 (English)

With fishponds at elevations of 1,300 - 2,500 m, Rwanda has a unique environment for tropical fish culture. Average pond temperatures are 21°C in the morning and 26°C in the afternoon. Introductory efforts at promoting aquaculture met with farmers support but their approach failed to compensate for cooler temperature. Results were minimal with production of only 200-500 kg/ha/year. Thousands of small hand-dug ponds were built. With an ever-increasing population, competition developed for land and agricultural inputs. Pressure to increase farm outputs, especially those with high nutritional and cash value, focused attention upon increasing yields from existing fishponds.

Development of Appropriate Pond Management Techniques for Use by Rural Rwandan Farmers
Conference Paper
1988

NOP 87-03 (English) (French) (Spanish)

Large-scale production of sand goby fry was conducted at the Nong-Sua Hatchery Station, Thailand, for one year. Approximately 1,000 egg nests containing 25 million eggs were collected from January through October under semi-natural breeding conditions. The hatching rate of fertilized eggs reached 80%. Fry were reared in two stages. In stage 1, the newly-developed fry, with average total body length of 4 mm and mouth clutch opening of about 0.1 mm, were first fed with a combination of chicken-egg slurry and live rotifers. The survival rate at this stage ranged from 7 to 55%, with an average of 20% among batches of egg nests collected during the year. Stage 2 involved raising older fry that were fed with live Moina sp., chironomid larvae, and ground trash fish from days 30 to 60, during which the survival rate ranged from 60 to 90% and length increased from 2.4 to 3.8 cm. Growth rate was inversely related to stocking density at this stage. A total of 147,300 juvenile fish was produced in the one-year effort.

Breeding and Rearing of Sand Goby (<i>Oxyeleotris marmoratus,</i> Blk). Fry
Journal Article
1988

NOP 87-A01 (English) ; NOP 95-83 (English) (French) (Spanish)

A 2 * 2 factoral analysis was made to investigate the effect of protein diets on the growth of Penaeus vannamei sown at different densities in land tanks. The juvenile shrimp sown at densities of 4 x 8 shrimp/m2 were fed 25% to 35% protein diets. The treatments were replicated from 3 to 4 times. At 99 days of growth there were no significant differences in terms of production, survival and average weight (P>0.05), between the two protein levels. The average production (kg/ha) for the 25% and 35% protein treated groups was 564 and 586, respectively, and the average weight (g) was 12.7 and 11.8, respectively. The shrimp production was significantly greater (P<0.05) when sown at a high density, while the average weight and survival in that case were significantly low. The average production at high and at low density was 624 and 533, respectively, and the average weight was 9.7 and 14.5 grams. The high density production, however, resulted in a reduced income because of the low unit price paid for small shrimp.

Effects of protein diet and sowing density on the production of <i>Penaeus vannamei</i> in land tanks
Journal Article
1988

NOP 88-09 (English) (French) (Spanish)

During 1985, rainfall, evaporation and seepage were measured in 12 experimental fish culture ponds at the Gualaca Freshwater Aquaculture Research Station, Gualaca, Panama, to provide baseline pond hydrology data for the area and a water budget for the station. Mean monthly rainfall ranged from 0 to 27 mm/day, while pond evaporation ranged from 1.4 to 8.4 mm/day. An equation was developed to predict pond evaporation from solar radiation measured by photometry. Among the 12 ponds, mean seepage ranged from 19 to 58 mm/day and averaged 31 mm/day. Seepage accounted for 87% of water lost from the ponds. A regression equation was developed to prediect the quantity of water gained by runoff into ponds during rainfall. Monthly water balances (mm/day) for the station ranged from -39 to 14 and averaged -13. Water deficits occurred during 9 of 12 months. The annual water defcit could be reduced to zero should seepage be reduced by 66%. Particular attention needs to be given to pond construction on kaolinitic soils, which although high in clay, may be very porous.

Hydrology of Fish Culture Ponds in Gualaca, Panama
Journal Article
1988

1987

NOP 87-01 (English(French) (Spanish)

This paper describes a data base management system used in the analysis and synthesis of data from a global experiment investigating dynamics of tropical farm ponds. Data synthesis is directed toward developing comprehensive farm pond management models. The experimental plan includes standardized data collection on physical, chemical and biological variables on 12 or more ponds at each of seven locations in Africa, Central America, and Southeast Asia. Field data from each location are compiled on microcomputers at the project sites. Project staff at each site perform routine statistical analyses and presentations of these data sets using statistical and graphics software packages of their choice. Field data are forwarded to a central office for filing on a mainframe computer. More sophisticated data analysis and syntheses (modeling) are done on mainframe computers. The standardized experimental design and centralized data base management system facilitates analyses of observations within ponds, between ponds within locations, and between locations. This design allows identification and analysis of both general and site-specific considerations over a broad range of environmental conditions. We propose that aquaculture scientists standardize data collection and management to permit direct comparisons of observations among and between research projects. The resulting comprehensive data base will improve understanding of the dynamic processes that regulate productivity in tropical farm ponds.

A Data Base Management System Design Philosophy
Report
1987

NOP 87-02 (English) (French) (Spanish)

A mass mortality of up to 60% per tank occurred in 28-day-old Macrobrachium reosenbergii postlarvae cultured under intensive conditions in a hatchery in Thailand. Grossly affected prawns displayed a diffuse 'milky' white body opacity; histologically and ultrastructurally, segmental myofibre (myofibrillar and sarcoplasmic) necrosis unassociated with any infectious agents was observed and diagnosed as idiopathic muscle necrosis. Avoidance of overstocking and increased dissolved oxygen in tank water have proved effective in preventing subsequent recurrence of the condition.

Idiopathic Muscle Necrosis in the Freshwater Prawn, <i>Macrobrachium rosenbergit</i> de Man, cultured in Thailand
Journal Article
1987

1986

NOP 86-A01 (English)

Growth and production of all male Tilapia nilotica and male hybrid, T. nilotica x T. hornorum, stocked at 1 Fish/m2, were compared in 0.1 ha earthen ponds. Fish were fed a 23% protein pellet 5 days a week. After 90 days the average net production for T. nilotica was 1.197 kg/ha, not different (P > 0.05) From the 1,143 kg/ha of the hybrid. The average final weight of the T. nilotica was 133.7 g similar (P > 0.05) to the 131.1g of the hybrid.

Production and growth of male Nile tilapia and the hybrid of <i>Oreochromis niloticus</i> x <i>Tilapia hornorum</i> in ponds
Journal Article
1986

Successful high intensive shrimp grow-out schemes typically use deep ponds (1-2 m) together with aeration/circulation. Little is known, however, why deep ponds are more productive than shallow ponds. It is important to understand the water quality and production dynamics of ponds of different depths to develop appropriate shrimp culture methods. The effects of water depth and circulation on the production of the giant tiger shrimp, Penaeus monodon, in 0.1-ha earthen ponds were tested in a 3 x 2 factorial experiment, with three depth treatments (0.5, 1.0, and 1.5 m) and two circulation regimes (daytime circulation and uncirculated). Stocking density was 4 postlarvae/m2. Production and survival were determined after five- and four-month culture periods during the dry and wet seasons, respectively, in 1985. Water circulation positively influenced primary productivity, decreased the surface temperature, and reduced stratification of temperature and dissolved oxygen. Water depth significantly affected almost all water quality parameters, the deeper ponds producing shrimp of significantly larger size. However, there were no treatment effects on shrimp production due to an inverse relation of survival and average size. It can be said that water depth and circulation profoundly affect the water quality of brackishwater shrimp ponds, but that the effects on shrimp production are not apparent at the stocking density used in this experiment. Further tests at higher stocking densities are necessary to establish the causal relationships of water depth, survival and average size of shrimp.

The Effects of Water Depth and Circulation on the Water Quality and Production of <i>Penaeus monodon</i> in Earthen Ponds
Report
1986

NOP 88-12 (English) (French) (Spanish)

An experiment was conducted to test the effect of chicken manure, 16-20-0, feeds with 20% crude protein (CP) and their combinations on pond productivity and water quality and on the growth and production of Nile tilapia (Oreochromis niloticus) in brackishwater ponds. Results showed low average daily weight increments of Nile tilapia of 0.52 to 1.25 g/day and 0.56 to 1.04 g/day for the first and second runs, respectively. Fish from treatments that received feed (either alone or in combination with chicken manure and/or 16-20-0) were significantly bigger (P < 0.01) than fish from treatments without feed. The combination of chicken manure and 16-20-0 did not contribute significantly to the production of tilapia. Higher temperatures were obtained in the treatments with inputs. Dissolved oxygen content was lowest in the feed-chicken manure-16-20-0 combination. Nitrate and nitrite levels were significantly higher in the treatments that received chicken manure (P < 0.05); available phosphorus was significantly highest (P < 0.05); available phosphorus was significantly highest (P < 0.01) in the chicken manure-feed combination. There are indications that the phosphorus content of chicken manure increased that in the soil although total phosphorus in the soil contributed only about 0.8% of that in water. The organic matter content of the pond soil was influenced by the various inputs resulting in significantly higher (P < 0.01) organic matter content of the sediments in the treatments that received chicken manure, feeds and their combination. There were no significant differences (P > 0.05) among the treatments in terms of primary productivity, zoo- and phytoplankton populations and algal biomass. A highly significant difference (P < 0.01) among the treatments was observed in terms of chlorophyll-alpha (a) concentration.

Effects of Fertilizers and Feeds as Nutrient Sources on <i>Oreochromis niloticus</i> Production in Philippine Brackishwater Ponds
Journal Article
1986

An experiment was conducted to examine the chemical characteristics of and the effects of fertilization on water quality and biological productivity in fishponds built in the acid sulfate soil region of Thailand. The acid soil acidified the overlying pond water rapidly to pH less than 4, but its acidification effect was reduced remarkably by repeated changing of the pond water with alkaline source water. Further improvement of the pond water was done by liming and enriching the ponds with inorganic and organic fertilizers. The pH in ponds receiving inorganic fertilizers (N16P20K0 fluctuated widely necessitating repeated liming. Production of food organisms (phyto-and zooplankton) was relatively poor. Fish yield (Oreochromis niloticus and Puntius gonionotus stocked at a density of 3 fish/m2) in five months was only 426 kg/ha. In comparison, the pH in ponds fertilized with chicken manure stabilized in the alkaline range and fluctuated little after initial liming. Relatively high plankton productions were achieved and fish yield was 1,528 kg/ha. Methods for reclaiming the acid soils for productive fishponds are recommended.

Acidification and Reclamation of Acid Sulphate Soil Fishponds in Thailand
Journal Article
1986

Teaseed cake contains 5.2-7.2% saponin, a glucoside that causes hemolysis in organisms. The higher sensitivity of finfish than crustaceans to the glucoside has made it an effective pesticide in shrimp ponds. To develop management techniques for the use of teaseed cake, the effect of dissolved oxygen (DO) and temperature at levels normally found in shrimp ponds on the potency of the toxicant and its rate of degradation when mixed with water were investigated. The experiments were conducted in 20-1 plastic tanks, using two species of finfish, Oreochromis mossambicus and Glossogobius giurus, and two species of crustaceans, Metapenaeus ensis and Penaeus monodon. The experiments were run on a completely randomized design with three replicate tanks for each treatment. In experiment 1, 15 ppm of teaseed cake was needed to eliminate both species of finfishes within six hours of application. Significant differences in the response of the two species of finfishes were observed. Both species of crustaceans survived concentrations of up to 20 ppm. Results of experiment 2 showed that the decrease of DO levels due to lack of aeration and the increase in water temperature resulting from exposure to sunlight significantly increased the sensitivity of finfish to teaseed cake. Exposure to sunlight for about 12 hours significantly decreased the potency of the glucoside on O. mossambicus in another experiment. The change was small and was not observed with G.giurus. It is recommended that the water level in shrimp ponds be reduced to one third before application, that teaseed cake be applied in shrimp ponds in minimum dosages towards noon when water temperature is higher and that the water depth be restored after about six hours of application.

Effects of Teaseed Cake on Selective Elimination of Finfish in Shrimp Ponds
Journal Article
1986

NOP 88-07 (English) (French) (Spanish)

Water aeration and circulation using paddlewheel aerator and motor-driven propeller blades, respectively, were maintained under four different diurnal regimes to test their effects on water quality and production of Penaeus monodon. Shrimp with an average weight of 0.03 gm were stocked at density of 33 individuals/m2 in four 0.05-ha earthen ponds. The four treatments were: (1) continuous aeration, (2) nighttime aeration, (3) nighttime aeration and daytime circulation, and (4) no aeration or circulation. Ammonia nitrogen (NH3-N), dissolved oxygen, temperature and shrimp growth were monitored during a culture period of 10 weeks. Ammonia nitrogen concentration did not differ significantly under the various aeration and circulation treatments. Dissolved oxygen and temperature stratification was least evident in treatments 1 and 3. Nighttime dissolved oxygen levels were significantly lower in treatments 1 and 4. The average size of shrimp at harvest was significantly higher in treatments 1 and 3. These findings taken together indicated that there was no clear benefit from continuous aeration. Rather, a combination of nighttime aeration, when needed, and daytime circulation could result in the greatest water quality benefits with the least energy consumption.

Water Quality Dynamics in Brackishwater Shrimp Ponds with Artificial Aeration and Circulation
Journal Article
1986

NOP 88-05 (English) (French) (Spanish)

In intensive pond fish culture, good water quality is critical for fish growth and survival. Various water management techniques have been developed to maintain adequate levels of dissolved oxygen and to prevent the accumulation of ammonia and carbon dioxide to toxic levels. This study investigated the effect of paddlewheel aerators on the removal of ammonia and carbon dioxide and to ascertain its well-established effect of maintaining optimum dissolved oxygen levels in ponds sustaining a high biomass. A 500-m2 earthen pond was stocked with Oreochromis niloticus averaging 170 g each to attain a total biomass of 3,000 kg/ha. Un-ionized ammonia and carbon dioxide levels were monitored every four hours for both aerated and unaerated conditions in the same pond. Each treatment was monitored over 24-hours cycles. Results indicate a significant effect of aeration on the diel pattern for carbon dioxide but none on ammonia. Carbon dioxide levels accumulated through the night and peaked between 4 and 8 a.m. at which time aeration significantly reduced it. Ammonia concentration was highest at 4 p.m. regardless of treatment.

The Effect of Paddlewheel Aerators on Ammonia and Carbon Dioxide Removal in Intensive Pond Culture
Journal Article
1986

1983

Diana, J. S., and D. R. Ottey. 1983. Biological Principles of Pond Culture: Fish. Pp. 39 - 52 in Principles and Practices of Pond Aquaculture: A State of the Art Review, Principles and Practices of Pond Aquaculture: A State of the Art Review, edited by J.E. Lannan, Smitherman, R.O., and Tchobanoglous, G. Oregon State Univeristy Press. Retrieved (http://crsps.net/resource/biological-principles-of-pond-culture-fish/).
NOP 83-A01 (English)

NOP 83-A01 (English)

Production of fish biomass in pond culture systems is regulated by three parameters: stock density, mortality, and growth in individual weight (Backiel and LeCren 1967, 1978; Chapman 1971). These parameters are related through mechanisms of biotic interactions and their physico-chemical environments (Fry 1947, 1971; Kerr 1980; Werner 1980), as previously shown in this document. For many cultured fish species, pond mangement for maximization of biomass production and standing stocks remains limited by knowledge of the ecological principles of the systems. The mechanisms relating stocking density, mortality, and growth are therefore key considerations of this study.

Biological Principles of Pond Culture: Fish
Book Chapter
1983
Lin, C. K. 1983. Biological Principles Of Pond Culture: Phytoplankton And Macrophytes. Pp. 21 - 26 in Principles and Practices of Pond Aquaculture: A State of the Art Review, Principles and Practices of Pond Aquaculture: A State of the Art Review, edited by J.E. Lannan, Smitherman, R.O., and Tchobanoglous, G. Oregon State Univeristy Press. Retrieved (http://crsps.net/resource/biological-principles-of-pond-culture-phytoplankton-and-macrophytes/).
NOP 83-A02 (English)

NOP 83-A02 (English)

Freshwater fish culture has a long history, but an enormous expansion has taken place during the last few decades. The fishes most commonly used in pond culture in warm climates are various herbivorous species, such as carp (grass carp – Ctenopharyngodon idellus, silver carp- Hypothalmichthys molitrix, bighead carp – Aristichthys nobilis, and mud carp – Cirrhina molitorella), species of Tilapia and grey mullet (Mugil cephalus). The important species in tropical fish ponds are herbivores, plankton feeders, or omnivores that can thrive on detritus material. Generally, a mixture of two or more species having different feeding habits and stocked in the same pond result in greater gross yields. Although some freshwater fish farming is carried out in cold temperate climates in Europe and North America, those high-yield intensive cultures (catfish, trout, etc.) require expensive fishmeal. The acute need for animal protein in many underdeveloped tropical countries has turned them to supplies from pond cultured fish. In the tropics, the potential growth rates of fishes under the warmer conditions and extended active ,growing season provide the most productive fish culture systems (Hickling 1968; Horn and Pillay 1962; Chen 1976). Fish farming in ponds has a long history of empirical development and “green-thumb” expertise, but the scientific investigation and documentation fall relatively short.

Biological Principles Of Pond Culture: Phytoplankton And Macrophytes
Book Chapter
1983