Abstract
Shrimp farming in floating cages has advantages over conventional cultivation systems and is a potential production alternative for low-income communities. We present advances in intensifying the cultivation of L. vannamei in floating cages by testing high stocking densities and a large cage-size not previously used, and introducing partial harvesting for the management of the high shrimp biomass. A 38-day nursery trial made during 2006, using 9-m2cages showed that the final weight of shrimp and specific growth rate (SGR) were significantly (P < 0.05) greater when postlarvae was stocked at 950 and 1300 PL/m2, rather than at 1600 PL/m2. However, the highest number of juveniles per cage was obtained when the later stocking density was used. A 62-day grow-out trial in 2006, using 9-m2 cages, resulted in a significantly lower growth rate (0.17 g/day) when juveniles were stocked at 300/m2, as compared to 0.18 and 0.18 g/day obtained at 200 and 250/m2. The final shrimp biomass varied significantly among densities and ranged from 1.9 to 2.6 kg/m2. There were no significant differences in final weight (11.3–12.0 g), survival (77% to 81%), and feed conversion ratio (FCR) (0.84–0.93). A 58-day grow-out trial in 2006 using 200-m2 cages showed that the final weight and growth rate were significantly greater (17.7 g and 0.27 g/day) when juveniles were stocked at 45/m2, as compared to 13.3 g and 0.20 g/day obtained at 180/m2. This density did produce the highest biomass yield (1.9 kg/m2). A nursery trial was made during 2008, stocking at 1500 PL/m2 and obtaining results that were consistent with those from the trial of 2006. A 93-day grow-out trial was made during 2008 stocked with 420 and 560 juveniles/m2 in 9-m2cages. A partial harvest was made after 62 days when shrimp weighed 8.9 to 9.5 g. A significantly higher biomass yield (1.5 kg/m2) was obtained at the higher density when compared to 1.2 g/m2 harvested from the lower density. After the final harvest, the weight of shrimp differed significantly between the lower (14.4 g) and higher (13.2 g) densities, and the corresponding total biomass yields were 4.4 and 5.0 kg/m2. The values of the zootechnical variables were acceptable when compared to those reported for shrimp cultivation in floating cages, intensive ponds, or raceways, thus indicating the feasibility of further intensifying the cultivation of L. vannamei in cages.