延迟投饵对浅色黄姑鱼仔鱼摄食、生长和存活的影响

Effect of delayed initial feeding on foraging,growth and survival of Chu's drum Nibea chui larvae

对延迟投饵0～7 d的浅色黄姑鱼Nibea chui仔鱼的摄食、生长与存活进行了研究,结果表明:1)当盐度为24.0～24.8、温度20.5～23.0℃时,仔鱼2日龄开口,于开口当天投饵及延迟投饵1、2、3、4 d,投饵后2 h内仔鱼的摄食率分别为30%、50%、30%、20%、10%,平均每尾鱼的摄食量分别为0.8、1.4、0.5、0.2、0.1个轮虫,延迟投饵5、6 d,摄食率均为0;2)延迟投饵0、1 d的8日龄仔鱼全长无显著差异(P>0.05),而与其它组仔鱼的全长则有极显著差异(P<0.01);3)延迟投饵0、1、2 d 仔鱼的存活率相差不大,但延迟3 d以上仔鱼的存活率急剧下降;4)浅色黄姑鱼仔鱼的不可逆点(PNR)出现在仔鱼开口后第3天,开始投喂的最佳时间在仔鱼开口后的2 d之内.

Effects of delayed initial feeding on foraging, growth and survival of larval Chu＇ s drum （Nibea chui） was investigated in May 2004. The results showed that 1 ） at a temperature of 20.5 - 23.0℃ and salinity of 24.0 - 24.8, the larval mouth opened 2 days post hatching, and the initial feeding rate was 30% at a rate of 0.8 prey per larva in two hours. With delayed initial feeding of 1 day,2 days,3 days and 4 days, the feeding rate was 50%, 30%, 20% and 10% ,1.4,0.5,0.2 and 0.1 prey per larva in two hours, respectively. While the feeding rates of larvae delayed initial feeding of 5 days and 6 days was 0. 2） there was no significant difference in the growth of the larvae delayed initial feeding of 0 day and 1 day, while there were significant differences in the other groups. 3） The larvae delayed initial feeding of 0 day, 1 day and 2 days had no significandy different survival; but the larvae delayed feeding of 3 days had significantly low survival. 4） The larvae occurred the point of no return （PNR） at 3 days after the mouth opened, indicating that the optimum initial feeding time for the larvae is within 2 days after mouth opened.