Abstract:

The black carp (〖WTBX〗Mylopharyngodon piceus〖WTBZ〗),grass carp (〖WTBX〗Ctenopharyngodon idellus〖WTBZ〗),silver carp (〖WTBX〗Hypophthalmichthys molitrix〖WTBZ〗) and bighead carp (〖WTBX〗Aristichthys nobilis〖WTBZ〗) 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