军曹鱼仔鱼期的摄食与生长

以人工孵化的军曹鱼(Rachycentron canadum)卵黄囊期仔鱼为材料,对仔鱼早期阶段的摄食及生长情况进行研究。结果表明:在水温28~32℃条件下,军曹鱼仔鱼3日龄开始摄食,6日龄时卵黄完全耗尽,6~7日龄饥饿仔鱼进入不可逆点(PNR)期;混合营养期3~4 d。饥饿仔鱼的初次摄食率开始较低,此后上升,到卵黄囊快要耗尽时达高峰(50%),以后又下降。内营养期,仔鱼日平均生长率为0.86 mm/d;PNR前的摄食期,饥饿仔鱼的日平均增长率为0.068 mm/d,而摄食仔鱼的日平均生长率为0.64 mm/d;PNR后至死亡前,饥饿仔鱼体长呈负增长,而摄食仔鱼的日平均生长率达1.04 mm/d。摄食仔鱼在孵化后8 d内的全长和日龄呈指数关系;前10 d的口径与全长呈正比关系。

Feeding and Growth of Rachycentron canadum During Early Development

This paper deals with the feeding and growth of larval Rachycentron canadum. The results show that the larvae begins to feed at the age of 3 days at 28~32 ℃. The yolk is absorbed completely at the age of 6 days. At the age of 6~7 days, the larvae, which does not feed from the outside, enters the period of PNR. The initial feeding rate is low, then slowly reaches the peak when the yolk is exhausted and follows with decreasing. The highest initial feeding rate is 50%. The growth rate of larvae before feeding is 0.86 mm/d. When they enter feeding period the unfed larvae almost stop growing. At the same time the growth rate of feeding larvae decreases to 0.64mm/d. The relationship between the feeding larvae total length(L) and days of age of the feeding larvae within 8 days after hatching may be presented with L= 3.432 7e~(0.120 3d) (mm), R~2=0.976 3. The relationship between mouth gape(y) and total length(x) of the feeding larvae within 10 days after hatching may be presented with y=0.127 7x-0.227 5,R~2=0.963 6.