Comparison of survival, growth and burying behavior of cultured and wild sandfish (Holothuria scabra) juveniles: implications for ocean mariculture

The success of mariculture activities involving the release of cultured marine invertebrates into the ocean is contingent on high survival and appropriate growth rates. Physical, physiological or behavioral characteristics that differ from those of wild conspecifics may be acquired through hatchery rearing, or as a result of stress induced by the release process. Such differences may compromise the 'fitness' of cultured animals. We investigated the influence of hatchery rearing and transport/handling stress on a commercial sea cucumber, sandfish (Holothuria scabra), by comparing survival, growth and behavior of release-size (5-15 g) cultured juveniles to those of like-size wild conspecifics. At the conclusion of an 85-day growth experiment in natural habitat, there was no significant difference in weight between cultured and wild sandfish juveniles. Burying behavior of cultured and wild sandfish juveniles was observed over a 48-h period in natural habitat with or without seagrass. A generalized additive model showed that cultured juveniles were slower to bury in the substrate after release, less likely to be buried at most times, and more likely to be buried in substrate where seagrass was present. However, they became better synchronized with their wild counterparts after 30 h. Survival of cultured and wild sandfish was high in both experiments (> 85%), but reduced burying by cultured individuals may increase the potential for predation because diel burying is the main predator avoidance strategy of sandfish juveniles