Species composition and seasonal occurrence of fish larvae and juveniles in the Shimanto Estuary, Japan

Abstract

To clarify the characteristics of the larval and juvenile fish community in a Japanese estuary, monthly collections were conducted in the shallow waters of the Shimanto Estuary, Japan from July 1985 to June 1987. A total of 49 101 fishes of more than 100 species from 44 families were sampled over the 2-year period. Numerically, Gerres equulus was most common, accounting for 20.02% of the total abundance. Rhyncopelates oxyrhynchus was ranked second, followed by Acanthopagrus latus, Acanthogobius flavimanus, Mugil cephalus cephalus, Parioglossus dotui, and Acanthopagrus schlegeli. Thus, fishes observed in the estuary were mostly marine species that spawn in the sea. The majority of these fish first appeared within the estuary at late postlarval and/or early juvenile stages. Based on their utilization of the shallow waters in the estuary, the majority of species could be categorized as residents. In the Shimanto Estuary, shallow waters are studded with shelters, especially eelgrass beds, which serve as important nursery grounds for coastal and euryhaline fishes.