合浦绒螯蟹大眼幼体在长江流域蟹种培育中的效果

Culture Performance of Hepu Mitten Crab Eriocheir hepuensis Megalopae in the Changjiang River Basin at Juvenile Culture Stage

为探明合浦绒螯蟹大眼幼体在长江流域培育蟹种的可行性,进行室外网箱群体养殖和室内循环水系统单体养殖试验,比较野生亲本合浦绒螯蟹和中华绒螯蟹繁育的大眼幼体的生长性能和养殖效果。将1500只大眼幼体放入6个内种伊乐藻、2 m×2 m×1 m的40目网箱中,6月中旬各网箱中幼蟹数量调整为400只(雌、雄各半),伊乐藻换成水花生,每日17:00投喂1%~5%的配合饲料。7月初,从网箱中取体质量1.4~1.6 g扣蟹30只(雌、雄各半)放入循环水槽中水深12 cm的30 cm×24 cm×15 cm塑料盒中单体养殖,投喂同网箱养殖。网箱养殖试验结果显示,合浦绒螯蟹在扣蟹养殖阶段的平均体质量及最终1龄性早熟率均高于中华绒螯蟹,但成活率及产量均显著低于中华绒螯蟹(P<0.05)。室内单体养殖试验结果显示,两组绒螯蟹在第1次及第2次蜕壳后的平均体质量均无明显差异(P>0.05),但合浦绒螯蟹第2次蜕壳的蜕壳周期显著长于中华绒螯蟹(P<0.05),合浦绒螯蟹第2次蜕壳后的特定生长率明显低于中华绒螯蟹。室内单体养殖试验中,合浦绒螯蟹的成活率亦低于中华绒螯蟹,但差异不显著(P>0.05)。综上,合浦绒螯蟹大眼幼体在长江流域扣蟹养殖过程中成活率低、蜕壳周期长、1龄早熟率高,如何通过养殖环境优化及营养调控来改善其在蟹种培育阶段的养殖性能有待进一步研究。

In order to explore the feasibility of Hepu mitten crab Eriocheir hepuensis megalopae in juvenile culture in the Changjiang River basin,the growth performance and breeding effect of megalopae bred by wild broodstocks Hepu mitten crab and Chinese mitten crab E.sinensis were compared in outdoor cage group culture and indoor circulating water system individual culture trials.Some 1500 megalopae were reared in 40 mesh cages with length of 2 m × width of 2 m × height of 1 m and aquatic plant elodea Elodea nuttallii,and the number of juvenile crabs was adjusted to 400(half female and half male) in each cage in mid-June,and aquatic plant elodea was replaced by alligator weed Alternanthera philoxeroides.The Hepu mitten crab and Chinese mitten crab were fed at feeding rate of 1%—5% compound feed at 17:00 every day.At the beginning of July,30 crabs with body weight of 1.4—1.6 g(half female and half male) were taken from the cages and reared in a circulating water tank with a water depth of 12 cm in a plastic box of 30 cm× 24 cm × 15 cm for individual culture,with the same feeding regime.There were higher average body weight and the rate of one-year precocius in Hepu mitten crab than those in Chinese mitten crab,with significantly lower survival rate and yield in Hepu mitten crab than those in Chinese mitten crab(P<0.05).No significant difference in the average body weight was observed between the two groups after the first and second moltings(P>0.05),with significantly longer second molting interval and lower specific growth rate(SGR) in Hepu mitten crab than those in Chinese mitten crab due to the longer second molting(P<0.05).Furthermore,there was lower survival rate in Hepu mitten crab than that in Chinese mitten crab in indoor individual culture trial,without significant difference(P>0.05).In conclusion,the Hepu mitten crab had lower survival rate during juvenile culture stage in the Changjiang River Basin,with longer molting interval and higher rate of one-year precocious.It is required to further investigation to improve the culture performance of Hepu mitten crab through the optimization of culture environment and nutritional regulation.