Effects of Stocking Density on Growth and Survival of Sea Cucumber (Apostichopus japonicus) in a Net Cage Positioned in an Earthern Pond

Juvenile sea cucumber(Apostichopus japonicus) weighing from 0.003 g to 0.0169 g were stocked into 9 net cages of each 3.0 m × 2.0 m × 2.0 m positioned with plastic net attachments in a of each 40 m×20 m×(1.6～2.0) mearthern pond at a rate of 500 g(Group A,small initial size;Group B,large initial size),1000 g(Group C),1500 g(Group D)or 160 g(Group E,with initial body weight 0.0385 g) and fed for 115 days from May to Octoker in 2009.The final body weight and special growth rates were found to be decreased with increase in the stocking density.There were 6.48% and 30.82 % higher final body weight in the same stocking density Groups A(1.1535 g) and B(1.3014 g) and the minimal density Group E(1.508 g) than those in Groups C(1.1527 g) and D(0.8601 g),and 42.71%,and 75.33% higher special growth rates in the same density Groups A and B and the minimal density Group E than those in Groups C and D.A total of 55.1 kg overwintered juveniles were harvested in the experimental pond in May of 2010.It is suggested that the sea cucumber juveniles be stocked into a net cage with attachments in an earthen pond from later June to early July at a rate of 80～90 g/m2 for high survival and yield.