Abstract
Larvae and juveniles of Lateolabrax japonicus and L. latus occurred from January to May 1986 in the shallow waters of the Shimanto estuary. L. japonicus markedly outnumbered L. latus. Distinct ecological differences were recognized in habitats and food habits between the two species: L. japonicus mainly inhabited eelgrass beds composed of Zostera nana, while L. latusappeared evenly in both eelgrass beds and non-eelgrass habitats; the former fed on copepods and cladocerans, while the latter fed on copepods and fish larvae. From these habitat and food habit analyses, estuaries were considered to be important as a main habitat for L. japonicus, but not for L. latus. The fact that ecological differences have occurred during the early life stages was inferred to be one of the possible keys to speculate on the speciation of the two species.
