Method to improve efficiency for intermediate stage rearing of kuruma prawn (Penaeus japonicus) juveniles
2005
Ikewaki, Y.(Tokushima-ken. Fisheries Experiment Station, Hiwasa(Japan))
Rearing experiments were done to improve the intermediate rearing method of Kuruma prawn juveniles. The accommodation density of juveniles was changed to four levels in this experiment. The growth and survival rate were compared between the four rearing tanks. No difference of growth was observed between the rearing tanks. But the survival rates of prawn juveniles were remarkably different associated with rearing density. The higher the accommodation density of juveniles, the lower the survival rate. The decline of survival rate, which follows the mortality of juveniles, was considered to be caused by the accumulation of carcasses of prawn juveniles, leftovers and molts. The maximum permissible accommodation of prawn juveniles was estimated to be about 1 kg per m(2), and it was considered that it became easy for the mortality to happen when the rearing density of juveniles was exceeded this value. So the improvement method in which two times of thinning out are carried out was designed to maintain the accommodation of prawn juveniles under permissible value. This method was thought to be useful for increase in number of juveniles released and the risk diffusion as to the sea ranching of Kuruma prawn.
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