Stocking density affects culture performance and economic profit of adult all-female Chinese mitten crabs (Eriocheir sinensis) reared in earthen ponds

Abstract

As female Chinese mitten crab (Eriocheir sinensis) generally offer the higher edible yield, greater nutritional value, and consequently, higher market price compared to males, therefore all-female monosex culture has been popularized for the farming E. sinensis. However, the optimal stocking density remains unknown for all-female culture of E. sinensis. The present study was conducted to evaluate the effect of different stocking densities (D1.3: 1.3 inds/m2, D1.9: 1.9 inds./m2, D2.5: 2.5 inds./m2 and D3.8: 3.8 inds./m2) on growth performance, gonadal development, and economic profits of all-female E. sinensis during nine months culture period. The results showed that all growth parameters including mean body weight, body weight gain (BWG) and specific growth rate (SGR), exhibited an inverse relationship with stocking density. However, stocking density did not have a significant effect on the percentage of puberty molting, gonadosomatic index (GSI) and hepatosomatic index (HSI). At the end of the experiment, the survival rate significantly decreased with the increasing stocking density, while both final production yield and economic feed conversion ratio (eFCR) significantly increased with stocking density (P < 0.05). Profitability analysis showed that total cost and total return increased significantly with the stocking density, but the highest net profit (129.68 × 103 CNY/ha) and return-on-investment (ROI, 87.65%) were achieved at the D2.5 group. Overall, these results suggested that the optimal stocking density might range from 1.9 to 2.5 individuals/m2 in grow-out ponds for all-female mono-culture of E. sinensis.