Feed the Future Innovation Lab for Collaborative Research on Aquaculture & Fisheries

In a 149-day grow-out experiment, we tested the effects of stocking density, partial harvesting and intermediate stocking on net fish yield (NFY) and harvest size of Nile tilapia (Oreochromis niloticus). Sex reversed male tilapia were raised in 280-m² earthen ponds, which received 8 kg dry weight chicken manure ha^-1 day^-1 with urea and triple superphosphate supplement to give a total fertilization rate of 4.0 kg N ha^-1 day^-1 and 1.0 kg P ha^-1 day^-1. The five treatments were three stocking densities of 0.8, 1.6, and 2.4 fish m^-2, fish stocked at 0.8 fish m^-2 with an additional 0.8 fish m^-2 added after 2.5 months, and fish stocked at 1.6 fish m^-2 with 50% of fish removed after 2.5 months. Stocking density significantly affected fish yield (r²-0.57, P<0.02); extrapolated mean NFY in ponds stocked at 0.8, 1.6 and 2.4 fish m^-2 were 14.2, 19.2 and 25.7 kg ha^-1 day^-1, respectively; mean weights were 335, 230 and 214 g fish^-1, respectively. Mean NFY for the first 2.5 months exceeded 39.0 kg ha^-1 day^-1 in ponds stocked at 2.4 fish m^-2. Partial stocking gave slightly higher total NFYs than partial harvesting, or 21.7 kg ha^-1 day^-1 compared to 18.0 kg ha^-1 day^-1. Additional stocking did not significantly affect fish growth of the originally stocked fish. Mean harvest weights of fish stocked at 0.8 fish m^-2 were similar to the first stocked fish in the treatment receiving an additional 0.8 fish m^-2 after 2.5 months. Results suggest a partial intermediate stocking and partial harvesting strategy may produce annual tilapia yields of 30 kg ha^-1 day^-1, with mean weights over 300 g fish^-1. Implications for managing ponds for higher yields at desired mean fish weights are discussed.

NOP 96-A03 (English)