Variation in short-term survival of cultured sandfish (Holothuria scabra) released in mangrove–seagrass and coral reef flat habitats in Solomon Islands

Juvenile cultured sandfish (Holothuria scabra) with a mean size of 35.6 mm±11.4 S.D. were released on soft substrata near mangrove–seagrass and lagoonal coral reef flat habitats in the Western Province of Solomon Islands. Mean survival of H. scabra at the mangrove–seagrass sites was 95–100% 1 h after release and approximated 70% 3 days later. At the coral reef flat sites, however, mean survival was as low as 37.5% 1 h after release and total mortality occurred in two of the three releases within 48 h. Mortality of the juvenile H. scabra was due mainly to predation by fish in the families Balistidae, Labridae, Lethrinidae and Nemipteridae. Survival of juvenile H. scabra was improved significantly by releasing them within a cage of 8-mm mesh. This procedure resulted in 100% survival of juveniles in the coral reef flat habitat during the course of the experiment. Our data indicate that mangrove–seagrass areas should be suitable habitats for release of cultured juvenile sandfish in restocking and stock enhancement programs. Release of sandfish at night, to coincide with the time they emerge during their inherent diel burrowing cycle, and the short-term use of protective cages, should be investigated to improve survival of individuals released in mangrove–seagrass habitats.