扁吻鱼胚胎发育及仔稚鱼形态与生长观察研究

文章采用干法受精获取受精卵的方法,对扁吻鱼(Aspiorhynchus laticeps)胚胎发育和仔稚鱼的形态变化进行观察。研究结果表明,扁吻鱼卵为沉性卵,卵细胞呈青灰色、微黏性。该次孵化共获取成熟卵21.45×104粒,受精率88.95%,孵化率93.27%。扁吻鱼成熟卵卵径(2.46±0.13)mm,受精卵吸水后膨胀,卵径(3.42±0.15)mm。根据胚胎发育的外部形态和典型特征将其分为受精卵、胚盘形成、卵裂、囊胚、原肠、神经胚、器官分化和孵化共8个阶段,整个胚胎发育耗时115.72 h,所需积温3765.42℃·h。初孵仔鱼全长(7.58±0.31)mm,从初孵到卵黄吸收完全历时9 d,全长特定生长率为(3.63±0.68)%。仔鱼后期历时36 d,全长特定生长率为(3.51±2.10)%。稚鱼期历时63 d,全长特定生长率为(1.32±0.17)%,与仔鱼前期和仔鱼后期差异显著(P<0.05)。1年后幼鱼全长(15.71±0.89)cm,体质量(28.29±6.15)g,体色和体型接近成鱼。

Observation on embryonic development,morphology and growth of larvae and juveniles of Aspiorhynchus laticeps

In this study,the embryonic development and morphological changes of larvae and juveniles of Aspiorhynchus laticeps were observed by dry fertilization.The results show that the eggs were sinking eggs,and the color of egg cells was bluish gray and slightly sticky.A total of 21.45×104 mature eggs were obtained and the average of fertilization rate and hatching rate were 88.95%and 93.27%,respectively.The diameter of mature eggs was(2.46±0.13)mm,and that of fertilized eggs was(3.42±0.15)mm.According to the external morphology and typical characteristics of embryo development,it can be divided into eight stages:fertilization,cleavage,blastocyst,gastrula,neuroembryo,organ differentiation and hatching.It took 115.5 h for the whole embryo to develop,and the total accumulative temperature was 3765.42℃·h.The total length of newly hatched larvae was(7.58±0.31)mm.The development of prelarva from hatching to yolk absorption took approximately 9 d,and the specific growth rate(SGR)of total length was(3.63±0.68)%and that of total length was(3.51±2.10)%.The juvenile period lasted 63 d and the SGR of total length was(1.32±0.17)%,significantly different from those of early and late larval stages(P<0.05).The total length and body mass of A.laticeps young fish was(15.71±0.89)cm and(28.29±6.15)g,respectively,and the body color and body shape were similar to adult fish.