黑龙江乌苏里白鲑(Coregonus ussuriensis Berg)胚胎发育观察研究

OBSERVATION ON EMBRYO DEVELOPMENT OF USSURI WHITEFISH COREGONUS USSURIENSIS BERG IN HEILONGJIANG RIVER

乌苏里白鲑(Coregonus ussuriensis Berg)是中国黑龙江流域唯一的白鲑属鱼类。由于栖息地破坏、水体污染等原因,野生种群数量逐年减少,属于濒危物种。为了解乌苏里白鲑胚胎及仔稚鱼发育特点,在人工繁育条件下获得受精卵,并观察乌苏里白鲑胚胎发育及仔稚鱼的形态变化与生长特征。通过观察发现,受精卵为沉性卵,呈现浅黄色,具有微黏性。乌苏里白鲑胚胎发育时序分为8个阶段,即受精卵、卵裂期、囊胚期、原肠胚期、神经胚期、早期器官形成及孵出阶段,进一步分为16个分期。整个胚胎发育期间的平均温度为4.30°C,有效积温达到7753.80(°C·h)。初孵仔鱼游泳能力较差,全身透明,卵黄囊呈圆形,占身体比例约1/2,并且成为仔鱼营养来源。出膜后10d的仔鱼,眼囊内晶体颜色变黑,卵黄囊变成椭圆形,口裂和胸鳍逐渐形成,少数仔鱼游泳能力增强,进入平游状态但仍无法开口摄食;出膜后18d,仔鱼开始上浮,卵黄囊基本吸收,血管分布较明显,腹部有黑色素沉积;上浮37d后仔鱼继续发育成稚鱼,胸鳍、腹鳍、尾鳍分化完成。本研究初步了解了乌苏里白鲑胚胎发育的特征与规律,为乌苏里白鲑种群资源恢复及人工苗种繁育工作提供科学依据。

Ussuri whitefish Coregonus ussuriensis Berg is the only fish of the genus in Heilong River basin in China.Due to habitat destruction,water pollution,and other reasons,the number of wild population decreased year after year,thus it became an endangered species.To understand the developmental characteristics of embryo and larval and juvenile of C.ussuriensis,fertilized eggs were obtained under artificial breeding conditions,and morphological changes and growth characteristics of embryo development and larval fish were observed.By observation,it was found that the zygote was a settled egg,pale yellow,and slightly viscous.The embryonic development time sequence of C.ussuriensis conforms to the general law of embryonic development of other salmon,and could be divided into eight stages,i.e.,zygote,cleavage stage,blastocyst stage,Gaelic embryo stage,neural embryo stage,early organ formation,and hatching stage,and further divided into 16 substages.The average temperature of the whole embryonic development period was 4.30°C,and the effective accumulated temperature reached 7753.80(°C·h).Poor in swimming ability of the newly hatched,transparent body,round yolk sac about half of the body size as the nutrition source of the larvae.After hatching for 10 days,the crystal inside the eye sac turned black,the yolk sac elongated,the fissure of the mouth and pectoral fin gradually formed,and the swimming ability of a few larvae enhanced,and they entered the state of flat swimming but mouths remain closed.After hatching for 18 days,the larvae began to float up,the yolk sac had been largely absorbed,the blood vessel distribution was obvious,and the abdomen had melanin deposition.After floating up for 37 days,larvae continued to develop into juveniles,and the differentiation of pectoral,pelvic,and caudal fins were completed.This study which preliminary explored the characteristics and rules of C.ussuriensis embryo development.provided a scientific basis for resource protection and artificial breeding of C.ussuriensis.