Habitat segregation of Gerres japonicas and G.limbatus in early stages in the Tien Yen estuary, northern Vietnam

Abstract

Silver-biddy (Gerreidae: Gerres) are commercially important euryhaline fishes in coastal waters; however, information about their distribution during early stages in estuarine environments is poorly known. The present study aims to elucidate the habitat utilization of two species of the family, Gerres japonicus and G. limbatus as larvae and juveniles based on monthly collections from 2013 to 2015 in the Tien Yen estuary, northern Vietnam. They occurred from April to June for G. japonicas and in April and May for G. limbatus with a peak in May for both the species. Both G. japonicas and G. limbatus used the Tien Yen estuary as a nursery ground; however, the former species that colonized the shallows along the banks of the estuary extended to near freshwater habitat, whereas the latter was found at the end of the upper reach and the middle reach. The different habitat uses between the two species in the early life history may be related to their specific salinity preference as G. japonicas prefer lower salinities than G. limbatus.