Effects of diets on growth and survival of larval and juvenile sea cucumber Apostichopus japonicus in a marine net cage

The effects of different diets( alga Nannochloropsis sp.,yeast Rhodotorula benthica,sea lettuce Ulva pertusadetritus and sea weed Sargassum pallidium detritus) on survival and growth of larval and juvenile sea cucumber Apostichopus japonicus were studied in marine net cages for 30 d for the larvae and 21 d for the juveniles. The results showed that the later larvae fed the alga had significantly higher survival and growth than those fed the yeast(P 0. 05),both being significantly higher than the larvae in the control group(unfeeding)(P 0. 05). In 21 day rearing period,the maximal survival rate(20. 4% ± 0. 2%) was observed in the juveniles fed the sea weed, followed by the juveniles fed the sea lettuce(19. 9% ± 1. 7%),without significant difference( P 0. 05). There were no significant differences in the juveniles fed the yeast(13. 9% ± 0. 7%) and the alga(13. 6% ± 0. 9%), with the minimal survival in the control group(8. 9% ± 0. 8%). At the end of the experiment,the juveniles fed the sea weed(7. 79 ± 0. 47) mm,sea lettuce(7. 35 ± 0. 13) mm,and yeast(7. 08 ± 0. 63) mm showed higher growth in body length than those fed the alga(5. 08 ± 0. 40) mm and in the control group(4. 94 ± 0. 23)mm,without significant difference(P 0. 05). Compared with the unfeeding traditional culture methods in the marine net cage, the growth and survival of larval and juvenile sea cucumber were improved greatly by feeding at an optimal rate and types,including the larvae fed Nannochloropsis sp.,and the metamorphosed juveniles fed sea weed detritus.