早繁鮸鱼仔鱼饥饿试验及不可逆点的确定

在盐度29、水温23~25℃的条件下,进行了早繁鮸鱼仔鱼饥饿实验和不可逆点(PNR)的确定;观察了饥饿条件下早繁鮸鱼初孵仔鱼0、6、9、12、15和18日龄的存活、生长、卵黄囊与油球利用和游泳行为的变化。结果表明:早繁鮸鱼仔鱼从初次摄食到PNR期为4.5~5 d,这个耐受饥饿的时间临界点发生在孵化后的第7天。在饥饿的条件下初孵仔鱼、6、9、12、15和18日龄仔鱼的全部死亡时间分别为10.5 d、5 d、2.5 d、3 d、4 d和5 d;半数死亡时间分别为8.5 d、3 d、1 d、1.5 d、2 d和3.5 d。说明9~15日龄是早繁鮸鱼早期发育中最为敏感的阶段。饥饿会延缓初孵仔鱼对油球的利用。随着饥饿时间的延长,仔鱼的生长与正常条件下仔鱼差异显著(P<0.05)。饥饿仔鱼体长较短,头大且体瘦,长期饥饿后脑后部下陷。饥饿仔鱼行为变化表现为表层集群游动觅食,缓慢游动反应迟钝和外部形态变化并开始下沉水底。

Experiment on the starvation and determination of the point of no return for the ahead of schedule breeding larvae of Miichthys miiuy Basilewsky

At the water temperature of 23-25 ℃ and salinity of 29,the starvation trial and the determination of the point of no return(PNR) for the ahead of schedule breeding larvae of Miichthys miiuy were conducted.The change of starvation on survival,using oil globules and yolk-sac,growth and swimming behavior of Miichthys miiuy larvae with 0 d,6 d,9 d,12 d,15 d and 18 d age were observed.The results showed that from the initial feeding to the PNR stage of the larvae lasted 4.5-5 d,the PNR of larvae appeared on the day after hatched 7 days.The survival rate of larvae varied with the developmental stages,0 d,6 d,9 d,12 d,15 d and 18 d after hatched larvae were whole death experienced sustainedly 10.5 d、5 d、2.5 d、3 d、4 d and 5 d starvation respectively,and the half-death time of the larvae were 8.5 d、3 d、1 d、1.5 d、2 d and 3.5 d respectively,which indicated that the 9-15 day after hatched larvae might be the most sensitive stage to starvation in the early life stage.Starvation delayed the using of oil globules,and the length of larvae was significantly smaller than that of normal larvae in control group(P<0.05).After long-time starvation larvae had shorter body length,bigger head and thin body,hind-brain caved in.The behavioral responses to starvation of Miichthys miiuy larvae might be divided into three stages:(1)congregated to search food in the surface layer of the water;(2)swam slowly and reacted obtusely;(3)morphological features of the larvae transformed and most of them sunk on the water bottom.