Spawning, larval development and juvenile growth of the sea cucumber Stichopus horrens

Tropical commercial sea cucumber Stichopus horrens is extensively distributed throughout the tropical Indo-Pacific region, and wild stocks are severely depleted over the past decade. This study firstly presented preliminary results on the spawning, the development of larvae and the growth of the juvenile of S. horrens in Xisha Islands. It was proved that S. horrens followed a predictable lunar spawning periodicity and might reproduce throughout the year in Xisha Islands. Dry stimulation was a simple and efficient way to induce S. horrens to spawn. The mean quantity of spawned eggs was 1.37 × 106 (s.e. = 2.09 × 106, n = 8), and the mean egg diameter was 114 μm (s.e. = 2.8 μm, n = 8). S. horrens developed from fertilized eggs to pentactula larval after 19-27 days at 25-27 °C. From oosperm to settled juvenile, the survival rate of S. horrens was 1.0%-6.83% when enough live microalgae were supplied. The mean growth rate of juveniles was 0.4 mm per day and the survival rate was about 23.3%-50.5% during 80 days culture after settlement. Then some juveniles of S. horrens were further cultivated in tanks and majority were released in the wild. Ongoing observations showed good survival and growth of juvenile in the wild. The study indicates S. horrens are amenable to culture using standard techniques which may also be applied on the culture of other tropical species. They exhibit a relatively quick growth both in indoor and wild culture. Furthermore, the test results support possible aquaculture and stock restoration using hatchery produced stocks.