Nursery of Litopenaeus vannamei reared in a biofloc system: The effect of stocking densities and compensatory growth

The purpose of this study was to evaluate the effect of stocking density and the occurrence of compensatory growth in the white shrimp Litopenaeus vannamei in the nursery phase reared in a biofloc culture system. Two experiments were performed in a recirculating water system with 12 experimental tanks (microcosm), each with a bottom area of 0.5 m². The tanks were supplied by a matrix 70-m² biofloc technology water tank (macrocosm), where a shrimp biofloc technology systems culture was maintained concurrently. The water was returned to the system by gravity, providing a daily renewal rate of approximately 4,800%. During the first experiment, L. vannamei postlarvae with an initial weight of 0.003 g were cultured for 30 days at densities of 1,500, 3,000, 4,500, and 6,000 shrimp/m². The cultures reached significantly different final weights (P < 0.05) of 0.45 g, 0.33 g, 0.30 g, and 0.23 g, respectively. Mean survival rates were greater than 87.6% in all treatments. To evaluate the occurrence of compensatory growth in L. vannamei after a period of enclosure stress, the second experiment was organized in 2 phases. During the first, shrimp postlarvae were reared at densities of 1,500, 3,000, 4,500, and 6,000 shrimp/m² for 35 days. The shrimp were then restocked at a density of 300 shrimp/m² and were maintained until compensatory growth was observed. In 20 days, the shrimp showed full compensatory growth. The mean final weight and survival rate did not differ significantly (P > 0.05) between the treatments. The results confirm that the strategy of enclosure rearing can be applied to the culture of L. vannamei.