尖吻细鳞鲑胚胎及仔、稚、幼鱼发育的研究

通过活体观察和Bouin＇s液固定对乌苏里江尖吻细鳞鲑Brachymystax lenok的胚胎及仔、稚、幼鱼的发育进行观察,确定尖吻细鳞鲑的发育过程,详细描述了胚胎各发育时期的时序、形态特征以及仔、稚、幼鱼的发育特点,并将尖吻细鳞鲑与其它几种鱼类进行比较,探讨破膜所需时间与卵子性质和孵化水温的关系。结果表明：尖吻细鳞鲑成熟卵呈淡黄色,圆球形,卵径为（4.32±0.21）mm,含有大量卵黄,卵的比重大于水,属端黄卵,卵膜厚,无黏性,有弹性;受精卵在水温6.0~10.7℃条件下,历时597 h孵出,有效积温为190.79℃.d;尖吻细鳞鲑胚胎发育过程包括受精卵、卵裂、囊胚、原肠胚、神经胚、器官形成等6个阶段、26个发育时期。初孵仔鱼全长为（10.67±0.02）mm,破膜第13天仔鱼出现鳔并开始上浮,第14天仔鱼卵黄囊吸收完全,仔鱼期结束,进入稚鱼期;破膜后第25天稚鱼体侧出现幼鲑斑,第35天各鳍发育完全,进入幼鱼期,此时鱼体外观与成鱼无异。

Development of embryos,larvae,fry and juveniles in lenok Brachymystax lenok

The development of embryos,larvae,fry and juveniles in lenok Brachymystax lenok was observed on live and histological sections in order to provide theoretical information with artificial propagation and culture of the lenok.The morphologic characteristics and duration of embryonic,and larval,fry and juvenile development were described in detail,with special comparison with other fishes in characterization of eggs,development and incubation period.The lenok fertilized eggs with average diameter of（4.32±0.21）mm and greater specific gravity than water were of telolecithal,amber,globular,nondahesive,with the thick flexible egg envelope and a great deal of yolk.Under the water temperature of 6.0-10.7 ℃,it took 597 hours from fertilization to hatching,the effective accumulative day temperature of 190.79 ℃·d.The embryonic development process can be divided into 6 stages,including fertilized egg stage,cell division stage,blastula stage,gastrula stage,neurula stage and organogenesis stage,26 subdevelopmental phases.Newly hatched larvae were（10.67±0.02） mm in total length,and started to flow upward 13 days after hatching.Yolk sac was exhausted completely 1 day after flowing upward,fry beginning.The parr mark appeared 24 days after hatching,and all fins developed completely more 13 days later.There was no difference in appearance between juveniles and adults.