鄱阳湖湖口水域四大家鱼幼鱼出现的时间过程

TIME COURSE OF THE JUVENILE MAJOR CHINESE CARPS IN THE HUKOU WATERS OF POYANG LAKE

作为长江仅存的两个通江湖泊之一,鄱阳湖在长江四大家鱼幼鱼的肥育方面有着重要意义。迄今为止,关于长江四大家鱼幼鱼进入鄱阳湖的相关问题仍不清楚。以鄱阳湖湖口水域为研究对象,分析湖口水域四大家鱼幼鱼出现的时间过程。根据2007~2008年监测,湖口水域四大家鱼幼鱼出现的时间集中在7、8月份,其中7月中下旬~8月底为青鱼、草鱼和鲢幼鱼的高峰期;而鳙幼鱼的高峰期在7月份。青鱼、鳙的体长主要为5.00~9.99 cm,草鱼、鲢以5.00~14.99 cm的个体为主。此外,2007和2008年湖口水域四大家鱼幼鱼均以鲢为主,鳙所占比例较小,且它们每天出现的数量都与湖口的水位呈正相关。这为深入研究长江四大家鱼幼鱼进入鄱阳湖的时间过程提供了基础资料。

The black carp（Mylopharyngodon piceus）,grass carp（Ctenopharyngodon idellus）,silver carp（Hypophthalmichthys molitrix） and bighead carp（Aristichthys nobilis） are the four major Chinese carps,and the main species for freshwater fishery and aquaculture in China.They are migratory fishes between rivers and lakes.The Yangtze River is the largest river in China and the third longest river in the world.It is the main habitat for spawning of the four major Chinese carps.As one of the two large lakes maintaining a connection with the mainstream of the Yangtze River,Poyang Lake could be an invaluable feeding ground of the juvenile four major Chinese carps.So far,their migratory mechanism between the Yangtze River and Poyang Lake was still unclear.Time course of the juvenile four major Chinese carps in the Hukou waters of Poyang Lake was investigated from 2007 to 2008.Their peaks appeared in July and August respectively.The peak period of black carp,grass carp and silver carp ranged from middle of July to late August,and the peak of bighead carp appeared in July.The dominant standard length of black carp and bighead carp ranged from 5.00 to 9.00 cm respectively,and that of grass carp and silver carp were mostly ranged from 5.00 to 14.99 cm respectively.The dominant species of the juvenile four major Chinese carps collected in the Hukou waters of Poyang Lake was silver carp,and bighead carp was rare.Moreover,the relationships between water level of Poyang Lake（Hukou Station） and their respective daily number were significant positive.The result provided basic data for the research on the migration of the juvenile four major Chinese carps from the Yangtze River to Poyang Lake.Therefore,to protect their resources and increase the knowledge about their migration between the Yangtze River and Poyang Lake,a continued scrutiny seems well justified.