Predators effects on mortality of sandfish Holothuria scabra cultured in multitrophic system

Abstract

Sandfish Holothuria scabra is a species of high economic value that causes sandfish to be the most captured sea cucumber species, and is an important source of income for fishermen in coastal villages. Sandfish capture causes already over fishing. If the wild population of sandfish is not managed properly, over fishing could cause sandfish extinction. This reason, an alternative efforts are needed to increase sandfish production, such as cultivation and restocking. Sandfish was a species that can live in the estuary region, so that it has the potential to be maintained in brackish water ponds. One of the problems of Sandfish cultivation in the brackish water ponds was the predators attack. This study aims to analyze the predator attack on sandfish. The study was carried out on a microcosm scale by using the tanks. The organism used was Sandfish H. scabra, Nile Tilapia Oreochromis niloticus, and seaweed Gracilaria sp. Mangrove Snail attack can cause death if the sandfish has already eviscerated. The healing process takes one to several weeks, depending on the size of the wound. Nile Tilapia attacks were generally not deadly. Death only occurs if the wound is too deep and causes internal organs to come out, but this was very rare. During the study, only one case occurred in which the sandfish died due to the attack of Nile Tilapia. The sandfish that not injured in the ventral side, and does not suffer from evisceration, the mortality was zero. Sandfish wounds heal within one to three weeks, depending on the surface area of the tegument eaten by Nile Tilapia. Healed wounds appear darker in color.