Bottom culture of the sea cucumber Apostichopus japonicus Selenka (Echinodermata: Holothuroidea) in a fish farm, southern China

The bottom culture of southward-transplanted sea cucumber Apostichopus japonicus in a subtropical fish farm was investigated in a field study at Dapeng Cove, Daya Bay, from January 5-August 5 2011, with the aim of finding the ideal period for culturing A. japonicus in fish farms, and developing an integrated multi-trophic aquaculture (IMTA) in southern China. Results showed that the bottom-cultured sea cucumbers survived well (100%) before summer, survival rates decreased to 65.00 +/- 21.21% in July, and all animals had died at the end of the study. Specific growth rates of the sea cucumbers were high during winter (1.05 +/- 0.03% d(-1)), decreased in early spring (0.44 +/- 0.11% d(-1)) and became negative in the following months. Growth rate was mainly influenced by water temperature, dissolved oxygen and sulphide content; the anoxia caused by water column stratification at the sea-floor in the summer were the main causes of mass mortality. Our results indicate that bottom culture in the temperate season (winter and spring, optimally from late November to early April) is a viable way to rear the deposit feeder A. japonicus underneath a subtropical fish farm.