Low salinity reduces survival rate of a commercially important sea cucumber (Sandfish: Holothuria scabra)

Abstract Sandfish culture had been implemented for more than 20 years but has frequently failed to yield the expected results due to low survival rates. A decrease in salinity during the rainy season was suspected as a cause of sandfish mortality. This study aimed to assess the influence of salinity on sandfish survival rates. Treatments included sudden shock and gradual acclimation trial methods. Even though the results of this study indicate a mean survival rate of 50% at 14.6 ppt, the survival rate fell drastically as water salinity was reduced below the salinity of saltwater bony fish body fluids (around 18 ppt). Sandfish cannot live in water with salinity lower than the osmotic body fluid of freshwater bony fish (around 14 ppt). Therefore, for the cultivation of sandfish in coastal ponds, salinity should not be allowed to fall below a minimum of 18 ppt.