Effect of stocking density on key growth traits of a fast‐growing and heat‐resistant strain of sea cucumber (Apostichopus japonicus)

We evaluated the effect of rearing density on the yield of a fast‐growing and heat‐resistant strain of Apostichopus japonicus using a full‐sib family. We analysed the relationship between density and key growth parameters during factory seedling of A. japonicus and developed a model to explain the variation in growth. From 130 to 220 days, the rearing density of A. japonicus had a significant effect on body weight, specific growth rate, coefficient of variation and survival rate (P < 0.05). We obtained predicted integral regression equations for yield and growth rate, density fluctuation, variable coefficient fluctuation and survival rate. Specific growth rate had a significant effect on the yield of A. japonicus and, therefore, can be used as a primary indicator of yield. We recommend that stocking density should be adjusted from age 130–166 days to avoid frequent seedling separation to different pools of different seedling sizes during the fast growth period of A. japonicus seedlings, a procedure that causes yield decline. The optimal initial stocking density was 24.4 g m^?2 (0.2 g L^?1).