Reproductive characteristics and conditions of anadromous Coilia ectenes(Engraulidae) in Yangtze Estuary

To survey the reproductive characteristics and conditions of the stock of spawning migration Coilia ectenes in Yangtze Estuary,C.ectenes samples were collected during the spawning migration periods from 2006 to 2008.To understand the reproduction status of the C.ectenes,some biological parameters were analyzed,such as body-length,body-weight,hepatosomatic-weight,gonad-weight,fat-weight and condition factor.The results revealed:(1) The body-length and body-weight changed in different years,and the relationship between body-length and body-weight showed variations in three years.(2) The reproductive characteristics of spawning migration C.ectenes varied in different years,and positive correlation between gonad-weight and both body-length and body-weight were found.(3) The condition factor of spawning migration C.ectenes changed in different years,and positive correlation between the liver-weight or lipid-weight and the body-length or body-weight were detected;the condition factor in 2007 was higher than that of other years,and the condition factor of spawning migration C.ectenes increased with the fish age,which showed the biggest changes between 1 and 2-year-old-ones(P0.01).In summary,the reproductive characteristics and condition variations of spawning migration C.ectenes indicated the processes of how the climate impacted the reproductive status of anadromous fish.