Produção de juvenis do camarão Litopenaeus vannamei com diferentes densidades de estocagem em baixa salinidade e meio heterotrófico

Abstract

Zero-water exchange systems and low salinity culture are used by shrimp farmers as alternatives to alleviate the restrictions imposed by environmental regulations regarding the use of coastal areas, and allow better control of diseases and their spread. Thus, the effects at six densities (2000, 4000, 6000, 8000, 10000, and 12000 shrimp/m²) in Litopenaeus vannamei reared under zero water exchange and low salinity were evaluated in a complete randomized design with three replications. Eighteen fiberglass tanks (1000 L) were stocked with postlarvae (PL18) at densities corresponding to each treatment and fed commercial diets. Daily, molasses was added to water for provide C/N ratio between 20 and 30:1, to encourage the development of heterotrophic bacterial community. The study showed that density increase influenced significantly (P<0.05) the feed conversion ratio and final biomass. The highest values where observed at 12000 shrimp/m² (1.47 ± 0.06 and 390.00 ± 16.97 g, respectively). The final weight of shrimp ranged from 85.55 ± 63.60 to 105.37 ± 89.64 mg, but there was nodifference (P 0.05) between the densities evaluated. Survival was inversely proportional to the increase in densities (P<0.05), with an average rate of 98.57 ± 11.70% between 2000 and 4000 shrimp/m² and 37.69 ± 19.96% in density of 12000 shrimp/m². It was concluded that intensive production of L. vannamei can be done in low salinity (0.5 g/L) and heterotrophic environment with excellent rates of survival and FCR in 45 days of culture.