Stocking density and growth of Pacific white shrimp <i>Litopenaeus vannamei</i> in intensive recirculating (indoor biofloc and outdoor mixotrophic) systems

Abstract Objective This purpose of this study was to evaluate the response of Pacific white shrimp Litopenaeus vannamei when cultured at different stocking densities in recirculating indoor biofloc and outdoor mixotrophic systems. Methods Two independent growth trials were conducted. The first was conducted in an indoor biofloc-based recirculating aquaculture system with twenty-four 150-L tanks. The shrimp were stocked at varying densities (67, 133, 200, 267, 333, 400, 467, and 533 shrimp/m3) with three replicates and cultured for 30 d. The second trial was conducted in an outdoor recirculating mixotrophic system with twenty 800-L tanks. Four replicate tanks were stocked with 50, 100, 200, 300, and 400 shrimp/m3 and reared for 56 d. The shrimp were fed a commercial shrimp diet (Zeigler Shrimp Grower HI-35, protein content 35%) four times daily via hand feeding. Water quality parameters (temperature, dissolved oxygen, salinity, pH, ammonia, and nitrite) were monitored throughout the trial. Growth parameters, including final biomass, final mean weight, weight gain, feed conversion ratio (FCR), and survival, were measured at the end of the trial. Results Significant differences in growth (biomass, mean weight, weight gain) and FCR were observed between different stocking densities in both systems. In the mixotrophic system, the highest mean weight of 16.8 g and a weight gain of 4,040% were achieved at a density of 50 shrimp/m3. In the biofloc system, the highest mean weight of 6.0 g and a weight gain of 546% were observed at a density of 67 shrimp/m3. Higher densities resulted in lower mean weights and weight gains, whereas FCR and final biomass increased with density. Conclusions Higher biomass (potentially from higher stocking densities) is desirable for producers, but elevated stocking densities can lead to reduced survival, increased FCR, and poorer water quality. Effective management is crucial to maintaining water quality to ensure good growth and survival at higher densities.