Effects of Shelter on the Hatching, Immune Performance, and Profitability of the Ovigerous Red Swamp Crayfish Procambarus clarkii under High Stocking Density

To develop the intensive breeding technology of the seed of the red swamp crayfish Procambarus clarkii, the survival rates, hatching effects (hatching rate, incubation level, and number of juveniles), and immune performance of ovigerous P. clarkia as well as economic benefits are evaluated under different shelter conditions under a high stocking density in this study. The experimental design includes three different forms of shelter treatments (D1: experiment without any shelters; D2: experiment with closed shelters; D3: experiment with open shelters), each with three replicates. The results show that the concentration of the total antioxidant capacity (T-AOC) and activities of phenoloxidase (PO), catalase (CAT), and acid phosphatase (ACP) in the D3 treatment are higher than those in the D1 treatment (all p < 0.05), with the highest concentrations of total antioxidant capacity (T-AOC) and malondialdehyde (MDA) and the highest activities of phenoloxidase (PO), superoxide dismutase (SOD), catalase (CAT), acid phosphatase (ACP), and alkaline phosphatase (AKP) among the treatments being present in the ovigerous P. clarkii in the D3 treatment. The hatching rates of the three treatments vary from 69.51% to 94.28%, with the highest rate found in the D3 treatment and the lowest in the D1 treatment, but there is no significant difference among them (p > 0.05). The highest incubation level (ind.center dot m(-2)) and the highest number of juveniles (ind.center dot m(-2)) among treatments are found in the D3 treatment, with the incubation level (ind.center dot m(-2)) in the D3 treatment being significantly higher than that in the D1 treatment (p < 0.05). The benefit-cost ratios (BCRs) of the D2 and D3 treatments remain significantly higher than that of the D1 treatment when P. clarkii prices change (all p < 0.05). Our results indicate that a high stocking density habitat with open shelters could effectively improve the hatching and immune performance of ovigerous P. clarkii. Our findings are relevant for the indoor aquaculture management of ovigerous P. clarkii.