稀有鮈鲫产卵频次和卵子发育的研究

SPAWNING PERFORMANCE AND DEVELOPMENT OF OOCYTES IN GOBIOCYPRIS RARUS

对室养条件下20尾雌性稀有 鲫的产卵频次、成熟卵巢卵径分布及卵子补充过程进行了研究。产卵间隔中卵径分布呈现不同的峰值，卵母细胞成熟是分批的，Ⅴ期卵巢中MA、RE卵母细胞的数量代表了即将进行的一次产卵的产卵量；卵子补充速度快，成熟卵巢每隔数天可发育成熟一批卵，一级贮备库在12─33d即更新一次，不同发育时期卵母细胞的补充是连续的。对273批 产卵进行了统计，每尾雌鱼平均4．5d产卵一次，平均批产卵量265．6粒。稀有 鲫的产卵类型为连续产卵类型。

Twenty pairs of laboratory-reared F1 and F3 of Gobiocypris rarus were used to study spawning performance and development of oocytes. Analyses of spawning performance and ovum diameter histograms demonstrated that females produced clutches of eggs. In Stage V ovaries, the number of eggs in final clutch that contains mature and ripe eggs represents the present batch fecundity. Every a few days, such a final clutCh could be produced and spawned by mature females.Recruitment of oocytes is so fast that primary recruitment pool can be renewed in 13 to 33 days. Based on spawning frequency and ovum development it was confirmed that the process of eggs' recruitment is continuous. A total of 273 spawnings were observed in 20 pairs kept at 21.61±3.0℃ in the laboratory. The interspawning intervals ranged from 2 to 9 days, with a mean of 4.5 days and a mode of 4 days.The batCh size ranged from 96 to 655 eggs with a mean of 265.6 eggs for females of 47.6 to 56.0 mm total length. This paper proved that Gobiocypris rarus is a continuous batch spawner.