Impact of Thalamita crenata (Decapoda; Portunidae) predation on Holothuria scabra juvenile survival in farming sea pens

We evaluate the impact of predation by the crab Thalamita crenata on Holothuria scabra juvenile survival in a sea farming site in Madagascar where crab predation pressure is high. Three experiments were carried out: the first was conducted to estimate the survival of sea cucumber juveniles of different body masses when placed in open enclosures; the second compared the survival of juveniles placed in opened and closed enclosures; and the third evaluated the survival of juveniles when placed in the presence of crabs in closed enclosures. Holothuria scabra juveniles were of a body mass between 1 and 80 g. The results showed that predation by T. crenata is a key parameter to take into account when farming H. scabra. The seeding of juveniles at sea should be performed with large individuals weighing at least 30 g to avoid predation.