匙吻鲟胚胎与胚后发育的观察

Embryonic and postembryonic development of Polyodon spathula

在福建地区，利用池养匙吻鲟亲鱼进行人工催产和干法人工授精后，对其胚胎和胚后发育进行了观察。结果表明：成熟卵为椭圆形、多黄卵，平均卵径（2．41士0．04）mm×（2．30±0．03）mm。卵裂为特殊的辐射卵裂。水温17．0～19．8℃时，胚胎发育历时115．75～147．00h，孵化时间为134．75h。胚后发育分为卵黄囊期仔鱼、晚期仔鱼和稚鱼期。水温（20±0．5）℃条件下，8日龄卵黄囊完全耗尽，仔鱼才开始摄食进入晚期仔鱼；水温（22±0．5）℃时，10日龄进入稚鱼期；水温21～23℃时，35日龄的平均全长（74．91±6．12）mm，平均体重（2．32±0．55）g，吻长接近全长的30％，外部形态与成鱼相似。

Polyodon spathula parents cultivated in a pond in Fujian were stimulated to spawn followed by artificial fertilization using the dry method. The embryonic and postembryonic development observed indicated that （a） the mature eggs were rich in yolk and oval in shape with an average size of （2.41±0.04） mm× （2.30±0. 03） mm （b） the cleavage pattern was special radial holoblastic; （c） at water temperature of 17.0 ℃to19.8 ℃, the embryonic development lasted from 115.75 h to 147.0 h, with a hatching time of 134.75 h; （d） the postembryonic development consisted of three stages, i. e. , yolk-sac larva, late-stage larva and juvenile; （e） at the water temperature of （20±0.5） ℃, the 8-day-old larvae had their yolks exhausted, and the larvae began to feed and entered the late- stage larva; （f） the larvae entered into juvenile stage at water temperature of （22±0. 5） ℃ on the 10th day; and （g） when the water temperature reached 21 ℃ to 23 ℃, the 35-day-old fingerlings had an average length of （74.9±16.12） mm, body weight of （2.32±0.55） g and length of snout almost 30% of its eventual length, and the body proportion was similar to the adult paddlefish.