再次分级、驯食对小规格鳡生长、残食的影响

研究了再次分级、驯食对初次分级产生的鳡(Elopichthys bambusa)幼鱼弱小群体(S群)生长、存活的影响。试验设5组,A组试验鱼取自初次分级并驯食后的大规格群(B群),为对照组;B、C、D、E组取自S群,B组再次分级不再驯食,所分两级为B1、B2亚组;C组再次分级再次驯食,两级为C1、C2亚组;D组不再分级再次驯食;E组不再分级不再驯食。饲养85 d。结果显示:A组全长(TL)、体重(BW)始终最高,终末BW以E组最低;E组体重特定生长率(SGRBW)(55～139 DAH)最低;总存活率(SR)(55～139 DAH)A组最高,C组其次,E组最低;总残食率(CR)(55～139 DAH)E组最高,D组其次;初始体重变异系数(CVBW)对总CR影响显著(P=0.001),可用线性模型y=0.514 9x-7.761 7(r2=0.667)阐释两者关系。结果表明,再次分级和再次驯食有利于S群存活,但不能使S群规格在85 d内追及B群。

Effects of re-grading and re-weaning on growth,cannibalism of smaller-size juvenile yellowcheek carp(Elopichthys bambusa)

Effects of re-grading and re-weaning on growth,size heterogeneity,cannibalism and survival of smaller-size juvenile yellowcheek carp,Elopichthys bambusa,were investigated in the 85 days feeding experiment.There were 5 groups which were fed with different feeding regimes.Fish in group A(the control group) was bigger,which were produced by first grading and weaning.Fish in group B,C,D and E produced by first grading and weaning were smaller,and rearing with the regime of re-grading(B),re-grading and re-weaning(C),re-weaning(D),and neither re-grading nor re-weaning(E).According to the size categories,juveniles in both group B and C were re-graded two subgroups,B1 and B2,C1 and C2.The results of present experiment were as follows:total length and body weight of juveniles in group A were higher than those in other groups during the experiment.Body weight was the lowest in group E at the end of the experiment.SGR of body weight(55~139 DAH) was the lowest in group E.Total survival rate(55~139 DAH) was the highest in group A,the second in group B,and the lowest in group E.Total cannibalism rate(55~139 DAH) was the highest(63.98%) in group E,the next highest in group D.Initial coefficient of variation of body weight of juveniles exhibited a significant effect on total cannibalism rate(P=0.001),and the relationship between the two parameters could be explained by the line model y=0.5149x-7.7617(r2=0.667).These results suggested that:re-grading and re-weaning were good for the survival of the smaller juveniles produced by first grading.However,the size of smaller juveniles produced by first grading,feeding with any regime in the present experiment,was still lower than the size of bigger juveniles.