长江、珠江水系鲢、镛的性成熟速度及其遗传分析

在上海与广东两地的池塘中,对4种不同繁育群体鲢、鳙,即长江天然繁殖鲢、鳙,长江流域人工繁殖鲢、鳙,珠江天然繁殖鲢、鳙,以及珠江流域人工繁殖鲢、鳙,从二龄(1~+)起至四龄,逐年观察不同群体在各龄期的性腺发育状况及催产结果,发现在广东培育的比在上海培育的早一年成熟,这与天然环境里珠江鲢、鳙比长江鲢、鳙早成熟一年一致;而在同一饲养环境里,长江天然繁殖鲢、鳙与珠江天然繁殖鲢、鳙同时成熟,长江人工繁殖鲢、鳙与珠江人工繁殖鲢、鳙同时成熟,表明环境因子在不同繁育群体的性腺发育速度上起决定作用。人工繁殖鲢、鳙同天然繁殖鲢、鳙同时成熟则表明在无近交情况下,人工繁殖不会导致早熟。据推算,鲢发育成熟约需20000度日的总热量,鳙发育成熟约需26000度日的总热量。

MATURITY SPEED AND GENETIC ANALYSIS OF SILVER CARP AND BIGHEAD FROM CHANGJIANG AND ZHUJIANG RIVER SYSTEMS

The experimentss were carried out in ponds of Shanghai and Gu-angdong province. The gonad development and inducing results of silver carp andbighead were observed annually from age 1+ to 4 on 4 populations, of whichtwo of them were the natural populations from Changjiang and ZLujiang Rivers,the other two populations were from hatcherjes of Cliangjiang and Zhujiang riversystems. The fish raised in Guangdong matured one year earlier than thoseraised in shanghai, it is coincident with the fish from the original rivers. In thesame coltivated environment the two natural populations and two hatchery popula-tions all matured in the same month and were successful in induced spawning.The results indicate that the environmental factors play an essential role in gona-dal maturation of silver carp and bighead, while the artificial reproduotion does notcause the earlier maturity under non-inbreeding condition. It is estimated that thedemand of total heat for maturtity of silver carp is about 20,000 degree--days andfor bighead is about 26,000 degree--days.