Structure,composition and seasonal dynamics of the larval and juvenile fish community in the mangrove estuary of Tanshui River,Taiwan

The temporal and spatial patterns of species composition and abundance of fish larvae and juveniles in the Tanshui River mangrove estuary (Taiwan) were studied monthly using a drift bag-net in daylight. A total of 44591 individuals representing 55 families and 105 species were collected over 12 mo (August 1989 to July 1990). The community was dominated numerically by a few species. Sardinella melanura was most numerous, making up 70.15% of the total catch, followed by Stolephorus buccaneeri (19.59%), Thryssa kammalensis (2.96%), and Gerres abbreviatus (2.61%). These four species constituted ca. 95% of the total catch, the remaining 5% consisted of another 101 species. This estuary functions as a nursery and feeding area in the early life history of these fish. There was a separation in peak-immigration and seasonal utilization of the estuary by the dominant species. The abundance of fish larvae and juveniles decreased in an upstream direction.