人工养殖银鲳子代胚胎发育及仔稚幼鱼形态观察

采用人工培育的子代银鲳(Pampus argentus)为亲本,对银鲳的胚胎及胚后各发育阶段的形态特征进行观察测量,以期为今后苗种培育和繁殖生物学研究提供参考资料.银鲳成熟卵子为端黄卵,单个油球,卵径(1.417±0.063)mm,油球径(0.575±0.031)mm.在水温(20.0±0.5)℃、盐度24±1,pH8.0～8.5条件下,受精卵经36 h孵化出膜.初孵仔鱼在水温19.0～24.0℃、盐度 23±1,pH8.0～8.5、光照2 000～3 000 lx条件下,经60 d培育成幼鱼.银鲳早期发育分前期仔鱼、后期仔鱼、稚鱼和幼鱼,前期仔鱼以卵黄囊吸收消化为主要形态特征;后期仔鱼分化出侧囊、食道、胃、幽门育囊和肝脏等消化器官,外形特征是鱼体腹两侧星状黑色素及金黄色斑点明显,背鳍和臀鳍鳍条原基出现,13日龄仔鱼全长(5.586±0.479)mm,体高((1.068±0.087)mm;稚鱼期消化器官进一步完善,脊索末端向上曲屈,随后尾下骨出现并且尾下骨末端与体轴倾斜,至35日龄尾下骨与体轴垂直,45日龄体高明显增高,全长(25.560±3.870)mm,体高(11.157±1.266)mm.幼鱼期胸鳍前端呈尖形,尾鳍上下两侧生长加快形成深叉状,鳞片完全长成,60 d时全长为(引.000±3.300)mm,体高达(19.750±1.620)mm,此时体形与成鱼已无差别.此外,本研究还对仔稚幼鱼的划分、鲳属鱼类中主要品种胚胎与仔稚鱼发育的异同点以及育苗中容易出现死亡的关键时期进行了分析探讨.

Observation of embryonic,larval and juvenile development in Pampus argenteus offspring

The embryonic, larval and juvenile development of the offspring obtained from cultured silver pomfret () was observed, which contributed to the study of larvae rearing and breeding biology of pomfret. The eggs of silver pomfret were telolecithal, and had only one oil globule. The diameter of egg and oil globule were (1.417 ± 0.063) mm and (0.575 ± 0.031) mm, respectively. The hatching time was about 36 h after fertilization when the first larva was hatched at (20.0 ± 0.5) , salinity 24 ± 1 and pH 8.0−8.5. Juvenile stage occurred 60 d after hatching (DAH) at 19.0−24.0, salinity 23 ± 1, pH 8.0−8.5 and 2 000−3 000 lx. There were 4 consecutive periods: pre-larval, post-larval, juvenile and young stages, during the development of silver pomfret. The morphological feature of pre-larval was the utilization of yolk sac. The post-larval was known as the occurrence of some organs such as esophageal sac, esophagus, stomach, pyloric caeca and liver. And the external character of post-larval was as follows: there were visible star-shaped melanin and golden spots in the two sides of fish body. And the primordium of dorsal and ventral fins was also occurred in the post-larval stage. In the juvenile stage, the digestive organs had been further developed. At 13DAH, the body length and height were (5.586±0.479) mm and (1.068±0.087) mm; the tail end of dorsal chord curved upward slightly, and then the hypural occurred. In the beginning, the end of hypural and body axis inclined to one another. At 35 DAH, hypural was perpendicular to the body axis. At 45 DAH, the body height increased significantly, and total body length and body height were (25.560±3.870) mm and (11.157±1.266) mm, respectively. In the young stage, pectoral fin had a sharp-pointed front end; caudal fin grew fast and formed forked; all fish scales had been formed. At 60 DAH, the body length and height were (41.000±3. 300) mm and (19.750±1.620) mm, respectively. And there was no difference in the morphological feature between young fish and adult fish. In addition, the paper makes an analysis of the division of larvae and juvenile stages, difference in the embryo, larvae and juvenile developments between main species of pomfret, and key stages of death during artificial breeding of silver pomfret.