Effect of nurseries and size of released Holothuria scabra juveniles on their survival and growth
Lavitra, T.; Tsiresy, G.; Rasolofonirina, R.; Eeckhaut, I. (2015). Effect of nurseries and size of released Holothuria scabra juveniles on their survival and growth. SPC Beche-de-mer Information Bulletin 35: 37-41
In: SPC Beche-de-mer Information Bulletin. Secretariat of the Pacific Community: Noumea. ISSN 1095-4943, meer
When 15-g juveniles of Holothuria scabra are transferred into sea pens for farming in Madagascar, there is high mortality during the two first months of rearing, which is principally due to predation by the crab Tha¬lamita crenata. The use of nurseries (covered pens) is thought to be the best way of protecting those juveniles against predation. An experiment was carried out in Tampolove, a sea cucumber farming site where there is a very low density of predators. The purpose of the experiment was to see how the use of nurseries and the size at which juveniles are released into them affected their survival and growth. For this experiment, eight nurseries and eight sea pens, all 16 m², were constructed and four size groups of juveniles were tested: 0–5 g, 5–10 g, 10–15 g and 15–20 g. The rearing density was 3 ind. m-2. After three months, the average survival rates were between 78.00 and 83.75%, which suggests that the size of released juveniles did not affect the survival rate. Also, the use of a nursery did not significantly increase the survival rates; they were 87.50% and 78.88% respectively for juveniles reared in nurseries and in sea pens. This experiment showed that the use of nurseries is not necessary in farming sites with a low density of predators, and that juveniles less than 5 g can be released in these sites.
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