Preliminary study on broodstock rearing, induced breeding and grow-out culture of the sea cucumber Holothuria scabra in Sri Lanka

摘要

Experiments were conducted to identify suitable methods for broodstock rearing, induced breeding and grow-out culture of Holothuria scabra in Sri Lanka. Two hundred and seventy-two brooders (500-600g) collected from off Mannar were individually packed in oxygen-filled polythene bags with and without sea water and transported to a sea cucumber hatchery at Kalpitiya. Lagoon pens, sand-filled fibreglass tanks and bare tanks were used in triplicates to maintain brooders. Spawning was initiated using air dry, water jet and thermal-stimulation methods. Hatchery produced juveniles with an average weight of 11 +/- 5g were reared (2 individuals m(-2)) in lagoon pens, mud ponds and fibreglass tanks in triplicates. The significantly high evisceration rate was observed when brooders were transported without sea water (t-test, P<0.05). Brooders maintained in bare tanks showed a significant weight reduction than the brooders in sand-filled tanks and lagoon pens (anova, P<0.05, d.f.=2). Thermal stimulation (ambient temperature +/- 3-5 degrees C) was found to be the most successful method of spawning initiation of H.scabra. The mean (+/- SD) percentage males and females participated for spawning per trial was 9.2 (+/- 10) and 4.6 (+/- 5.6) respectively. On an average, 1.16 millions of eggs (+/- 1.03 SD, n=5) were obtained per spawning trial. H.scabra juveniles reared in tanks showed significantly lower growth rate than the juveniles in pens and ponds (anova, P<0.05). Lagoon pens and sand-filled tanks are suitable to maintain brooders and lagoon pens can be successfully used for mass rearing of juveniles.