青海湖裸鲤繁殖生物学研究

Study on reproductive biology of Gymnocypris przewalskii przewalskii

通过常规生物学测定、组织切片等手段,较详细的研究了青海湖裸鲤的繁殖生物学.卵母细胞从第3时相发育到第4时相基本同步,产后卵巢和精巢的组织学结构恢复到Ⅱ期.青海湖裸鲤为重复产卵类型,以Ⅳ期卵巢越冬,其卵巢1年只成熟1次,已达性成熟的个体并不是每年都进行繁殖活动.青海湖裸鲤性成熟迟、繁殖力低.每年5～7月,裸鲤洄游到沿湖各河流中繁殖,沙柳河、布哈河和黑马河3条河流为其主要产卵场.调查的繁殖群体总的性比(():♀)为1.66:1.总繁殖群体中,雄性个体最小体长130.0 mm,体重28.0 g,年龄4龄;雌性个体最小体长170.0 mm,体重51.0 g,年龄5龄.青海湖裸鲤性成熟群体的性体指标1年只有1个峰值,出现在繁殖盛期的6～7月.其平均成熟卵径为2.33 mm,平均绝对繁殖力为4337.81粒,平均相对繁殖力为27.09粒/g.

This paper deals with the reproductive biology of Gymnocypris przewalskii przewalskii by means of biological survey and tissue section. The development of the oocyte from phase 3 to phase 4 is basically synchronous. The tissue structures of the ovary and testis after spawning return to stage Ⅱ. G. przewalskii przewalskii is of the replicate spawning type, and it servives the winter with the ovaries at stage 4. Its ovary matures once a year. The individuals that have reached sexual maturity do not conduct reproductive activities every year. The sex organ of G. przewalskii przewalskii matures late, and has low fecundity. They ascend the rivers along the Lake for reproduction from May to July. The Shaliu River, the Buha River and the Heima River are their main spawning migration grounds. The survey showed that the sex ratio of males to females in the brood stock was 1.416 to 1. In all the brood stocks, the body length and body weight of the smallest male individual at the age of 4 are 130.0 mm and 28.0 g, respectively, while the body length and body weight of the smallest female individual at the age of 5 are 170.0 mm and 51.0 g, respectively. The sexual mature stocks of G. przewalskii przewalskii have only one peak value in their gonadosomatic index (GSI). It occurs in the period from June to July when reproduction is in a period of great spawning. The mean diameter of the mature eggs is 2.33 mm, the mean absolute fecundity 4 337.81 eggs and the relative fecundity 27.09 eggs/g.