四指马鲅仔稚鱼发育及生长特征的初步研究

Characteristics of morphological development and growth of four-finger threadfin Eleutheronema tetradactylum( Shaw) larvae and juveniles

在人工育苗条件下,对四指马鲅Eleutheronema tetradactylum（Shaw）早期发育的形态及生长特性进行了观察和初步研究。形态发育观察结果表明：四指马鲅初孵仔鱼全长为（1.957±0.055）mm,在培育水温为26℃、盐度为30的条件下,第2天开口,第3天卵黄囊完全被吸收,可开始摄食;初孵仔鱼～13 d为仔鱼期,14～36 d为稚鱼期,之后转为幼鱼期。生长特性分析结果表明：四指马鲅仔鱼期全长、肛前长和体高的生长速度明显快于稚鱼期,全长、肛前长和体高与日龄均呈多项式函数关系（P〈0.01）;仔鱼培育过程中,个体生长速度存在明显差异,20日龄仔鱼全长和肛前长的差异较大,其最大值和最小值的比分别是2.437倍和2.004倍。因此,在仔鱼培育生产实践中要注意分池,足量投喂适口饵料,以减少个体间的相互残杀。

Morphological development and growth characteristics of four-finger threadfin Eleutheronema tetradactylum（ Shaw） larvae and juveniles were investigated under artificial hatchery condition. It was found that the newly hatched four-finger threadfin larvae had total length of（ 1. 957 ± 0. 055） mm,began initial feeding on 2nd day,and showed complete exhausted yolk sac on 3rd day at a salinity of 30 at 26 ℃,when the larvae were fed. The larval stage lasted for 13 days after hatching,and the juvenile stage was kept from 14 th day to 36 th day when the juveniles developed into young stage. Growth characteristics analysis revealed that there were significantly higher total length,pre-anal length and body height in larval stage than in the juveniles,with very significant polynomial function correlation between day-age and total length,pre-anal length and body height（ P〈0. 01）. Significant differences in individual size were observed during the larva rearing with the differences between the minimum and maximum of 2. 437 times in total length,and 2. 004 times in pre-anal length. Thus it is suggested that enough suitable food be fed during larvae rearing.