Induced spawning, larval rearing and juvenile growout of sea cucumber

Abstract

Severe overfishing and stock depletion of worldwide sea cucumber has encouraged the development of sea cucumber aquaculture. Five species of local microalgae were cultured prior to larval and juvenile rearing as the main food source. Results for mass culture showed that they can be cultured outdoor which yielded a higher volume production than indoor culture. Culture in polythene bag showed a significant difference in growth compared to carboy culture and subsequently resulted in shorter harvest period. Adult H. scabra were collected from wild and subjected to two spawning induction method namely the thermal stimulation and dry-algae stimulation. Thermal stimulation was proven to be the best method by producing about 1.7 million eggs. Early auricularia larvae were observed 48 h after fertilization and were fed on mix microalgal culture. Auriculariae larvae transformed into dolilaria larvae after 11th day fertilization and the non feeding doliolaria metamorphosed into creeping pentactulae after 17th day. The survival rate of 4.2 % was achieved. Juveniles were fed with mixture of microalgae, sea weed and spirulina according to their growth stages. Average growth rate was 0.8 mm per day. Survival rate in the juvenile rearing tank was 32%. After 60 days of tank cultivation, juveniles reached 20 mm and were transferred either to hapanet or outgrow pond at 200 animals/m2. Total loss was observed in the hapanet while good growth was observed in the outgrow pond with survival rate of 36%. Juveniles reached average weight of 270 g after 3 months of outgrow pond cultivation. Growth was generally inversely proportional to the stocking density. Higher survival rate and better growth was observed in pond with lesser stocking density.