The Effect of Food Quality and Rearing Density on the Growth and Survival of Epibenthic Juveniles of the Sea Cucumber Holothuria scabra

Abstract

Abstract—Seven combinations of aquatic plant extracts were tested to feed juveniles of H. scabra: Thalassia hemprichii, T. hemprichii with 3 % Spirulina, Sargassum latifolium, S. latifolium with 3 % Spirulina, Thalassodendron ciliatum, Syringodium isoetifolium and organic biofilm. A control test consisted in rearing epibenthic juveniles in tank without any food supply. The results showed that extracts of S. latifolium with or without Spirulina gave the best growth and high survival rates: the mean epibenthic volumes were 112 +/- 55 mm³ and 81 +/- 21 mm3 and the survival rates were 60 and 68 % respectively at the end of the experiment (8 weeks). Rearing densities of 150, 300, 450 and 600 individuals mm-2 were tested. The best survival rates (greater than 60 %) were observed in the batches with an initial density of 450 individuals mm-2 or less. The best growth rate was observed with an initial rearing density of 150 individuals m-². The study of biomass showed that the optimum level for the rearing density is 450 +/- 150 juveniles mm-2. When the parameters of survival, growth rate and biomass (expressed in volume) are all taken into consideration, the optimum rearing density suggested for epibenthic juveniles of H. scabra is between 300 and 450 individuals m-2.

Keywords: Holothuria scabra, epibenthic juveniles, rearing, survival, growth