Seasonal occurrences of fish larvae and juveniles in the surf zone of the Yangtze River estuary

A total of 6 892 fish larvae and juveniles,representing over 50 species from 23 families,were collected by monthly seine net in the surf zone of the Yangtze River estuary from March 2004 to March 2005.The most dominant species,Coilia nasus,was accounted for 55.19%,and then Pseudolaubuca sinensis (16.99%),Liza haematocheila(10.94%),Tridentiger trigonocephalus(3.92%),Acanthogobius ommaturus(2.67%),Siniperca chuatsi(1.68%),Sillago japonica(1.68%),Acentrogobius pflaumii(0.99%),Periophthalmus modestus((0.99%)),Acanthogobius flavimanus((0.89%)). These 10 species were accounted for 96% in the total abundance.In the surf zone of the Yangtze River estuary,there were not only the fish larvae and juveniles of migrating fishes and estuary fishes,but also the fish larvae and juveniles of coastal marine fishes and freshwater fishes.And the number of species and mean density showed seasonal tendencies.According to the regulation of seasonal occurrences of fish larvae and juveniles in the surf zone of the Yangtze River estuary,some protective measure for fish larvae and juveniles resources were offered.