Effects of stocking density and water temperature on survival and growth of the juvenile Chinese mitten crab, Eriocheir sinensis, reared under laboratory conditions

Abstract

The interaction effects of stocking density and water temperature on survival, molting, growth and feeding of juvenile crabs (0.91 ± 0.09 g) were studied in the laboratory. Stocking densities per m2 were as follows: 14 (group D1), 42 (D3), 85 (D6), 128 (D9), 170 (D12) and 215 (D15), and water temperatures were 22 °C and 28 °C. The experiment was conducted in temperature-controlled recirculating rearing systems and lasted for 60 days. The results indicated that water temperature and stocking density have significant interaction effects on survival rate and molting frequency (P < .05), but no significant interaction effects on body weight, specific growth rate (SGR), deformity rate, daily feed intake and feed conversion efficiency (FCE) (P > .05). At 22 °C, the survival rate of group D1 was significantly higher than in other densities, while there was no significant difference in molting frequency between each density. At 28 °C, the survival rate of group D1 was similar to D3 and both were significantly higher than the other densities (P < .05), molting frequency increased firstly and then decreased significantly with increasing stocking density (P < .05). Water temperature had a significant influence on molting frequency at lower stocking densities (D1, D3 and D6), but not at higher densities, and only significantly influenced survival in group D12 (P < .05). The deformity rate in group D12 at both temperatures was significantly higher than in other groups (P < .05). Growth, body weight and SGR were significantly lower at high stocking densities (D12 and D15) than at lower densities (P < .05). Moreover, water temperature had a significant positive effect on daily feed intake and the daily feed intake of group D1 was significantly higher than in other groups (P < .05). In conclusion, a high stocking density limited molting increment (MI) of Eriocheir sinensis, and the results suggest an optimal stocking density of 42–85 crabs per m2. Our findings are relevant both for juvenile and adults E. sinensis aquaculture management in both ponds and lake stocking.