在多年对日本鳗鲡人工育苗技术研究的基础上,通过采用对胚胎和早期仔鱼的活体观察、计算机图文分析以及组织切片等方法,系统研究了鳗鲡胚胎及孵化后19 d前仔鱼的生物学特性。研究结果表明,在水温(23?0.5) ℃条件下,日本鳗鲡从受精卵到仔鱼出膜需约38 h 30 min,总积温为885.50 ℃?h。其特征与一般硬骨鱼类胚胎发育基本相同,鳗鲡胚胎发育可分为14期,为典型的盘状卵裂,原肠作用通过细胞的下包和内卷完成。但日本鳗鲡早期仔鱼与一般硬骨鱼类的仔鱼存在较大差异,表现为无色透明的血细胞和S形心管;开放型的口腔,发达且不能闭合的上下颌和3对颌齿;孵化后3~9 d在身体两侧出现由神经细胞和支持细胞构成发达的感觉丘,其数目为6~9对不等;以及形态不断变化的尾垂体等生物学特性。分析认为这些生物学特性决定了日本鳗鲡仔鱼的孵化环境可能相对较稳定,以及仔鱼摄食方式可能为触碰后咬食的方式。

The purpose of this study is to accumulate the research data about artificial reproduction of Japanese eel and provide guidance on breaking through the key technology of successful larva survival.On the foundation of the studying on artificial reproduction in Japanese eel for many years,this experiment systematically studied the biological characteristics of embryo and the larva before 19 days incubation used by the methods of observing living body,computer-aided analysis,as well as tissue slice.The results indicated that the time needed 38 h 30 min from fertilized egg to the larva just leaving egg,and the total accumulated temperature was 885.50 ℃?h for this time.The development characteristic of embryo,similar to those of most other teleosts,is a classical meroblastic.The gastrulation is completed by cells wrapped downward and curled inward through yolk.The embryo development of Japanese eel can be divided into 14 stages.However,the development characteristic of larva was different from those of most other teleosts,such as transparent blood cell and Stransformer tubular heart,open oral cavity,3 pairs of genasauria that are developed and cannot close,about 6-9 pairs of neuromast which are located at both sides of body from the 3-day to 9-day of leaving egg,as well as the urohypophysis whose morphology continually changed during the development stages.Analyses for these results indicated that the environment of incubation for the larva of Japanese eel in nature may be very stable,and ingestion feed of larva may depend on the method of bite-after-touch.

国家“十一五”科技支撑计划项目(2006BAD03B08-04)