草鱼、鲢、鳙秋繁及其对次年春繁的影响

AUTUMN PROPAGATION OF FARM FISHES AND ITS EFFECT ON NEXT SPRING PROPAGATION

1991年秋催产草鱼、鲂、鲢、鳙亲鱼256组,共获鱼苗5040万尾。平均催产率78.2%,受精率71.9%,孵化率75.4%。秋繁鱼苗当年可育成10cm以上鲢、鳙鱼种和8cm以上草鱼、鲂鱼种。鱼苗到鱼种成活率为37.2%。秋繁亲鱼次年春繁催产率、受精率和孵化率基本不受影响,产卵量比往年未秋繁者低6.8%～9.6%,卵径、卵粒重和鱼苗体长等无显著差异。草鱼、鲢、鳙卵母细胞发育不同步,春繁后经60天左右强化培育,卵巢中未成熟的卵母细胞可发育成熟。

256 sets of brood fish of grass carp, silver carp, bighead and bluntsnout bream were induced to spawn in the autumn of 1991, and up to 50.4 million frywere obtained. The mean spawning rate, fertilizing rate and hatching rate were 78.2%,71.9% and 75.4% respectively. The fry from autumn propagation could breed intolarger fingerling in the same year (over 10 cm for bighead and silver carp, over 8 cm for grass carp and blunt snout bream). The viability of the fingerling was 37.2%.Compared with the results for once a year spring propagation, the spawning, fertilizing,and hatching rate were generally not affected. Only the egg number decreased 6.8%-9.6%. There are no significant differences in size and weight of eggs and length offry. In grass carp, silver carp and bighead the oocytes develop asynchronously. Theimmature oocytes in the ovary of the brood fish after the spring propagation coulddevelop to full mature under strengthened culture for about 60 days.