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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:
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.
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.
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).
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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].
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.]
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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]
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.
NOP 16-357 (English)
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.
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.
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
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.
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).
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.
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%.
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.
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.
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.
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.
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.
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.
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.
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]
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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).
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.
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.
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.
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]
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%.
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.
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 (R2 = 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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]
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.]
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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”.
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.
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.
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.
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.
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.
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.
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.
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)
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.
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.
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].
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
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).
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.
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.
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.
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
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.
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.
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.
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.
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.
NOP 10-269 (English)
Aquaculture ponds sequester about 16.6MTyr(-1) of organic carbon worldwide representing around 0.21% of annual, global carbon emissions.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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%.
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.
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.]
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.
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.
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.
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.
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.
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.
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.
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.
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