Nursery rearing of Indian white shrimp, Penaeus indicus: Optimization of dietary protein levels and stocking densities under different management regimes

Abstract

Two sets of experimental trials (45 days each) were carried out to optimize protein requirement and stocking densities of Indian white shrimp, Penaeus indicus post-larvae in nursery rearing. In experiment 1, the effect of varying dietary protein levels (30, 40, 50, and 60%) on the growth performance of nursery reared P. indicus (PL12) was evaluated. The experiment 2 had 3 × 3 factorial design with three levels of stocking density (1650, 3350, 8350 PL m−3) and three management systems; zero water exchange (ZWE), ZWE with soil base (ZWE + SN), and ZWE with soil base and substrate integration (ZWE + SN + SUB) resulting in nine treatments. Experiment 2 was followed by a 21-day growth trial in low volume floating cages to estimate the compensatory growth performance. In Exp I, shrimp fed with 30% dietary protein recorded on par (p > 0.05) growth (0.39 ± 0.02 g) and survival (89.13 ± 5.04%) compared to higher protein fed shrimps (ABW: 0.39–0.44 g and 86–93% survival). In experiment 2, both the stocking density and management system had a significant effect (p < 0.05) on growth performance parameters. The final body weight and survival in low (1650 PL m−3) and medium-density (3350 PL m−3) groups were not significantly different (p > 0.05). However, a density-dependent growth reduction (p < 0.05) was observed in high-density (ZWE and ZWE + SN) groups. Integration of substrate (ZWE + SN + SUB) in nursery rearing has resulted in better growth characteristics even at high-density groups (8350 PL m−3) through alleviating the adverse effects of crowding stress. Water quality parameters such as total ammonia nitrogen (TAN), nitrite-N, dissolved oxygen level, and total suspended solids (TSS) varied significantly (p < 0.05) among the treatments. Significantly lower TSS (p < 0.01) and TAN (p < 0.05) were recorded in zero water exchange (ZWE) and zero water with substrate integrated nurseries (ZWE + SN + SUB), respectively. The compensatory growth of the nursery reared shrimp in cages exhibited stocking size-dependent (p < 0.05) growth gain. The study explores the growth potential of Indian white shrimp under different nursery rearing techniques in tropical conditions.