A total of 23, 404 larval and juvenile fishes, representing over 65 species from 28 families, were collected by monthly seine-net (surf-net) and beam trawl sampling along the littoral zone of a tidal flat in north-eastern Ariake Bay, from March 1998 to May 1999. Dominant species were Konosirus puctatus (63% of total fish number) in spring, Leiognathus nuchalis (12%) in summer, Plecoglossus altivelis altivelis (5%) in autumn and winter (surf net), Favonigobius gymnauchen (31%) and Acentrogobius pflaumii (16%) year-round and Acanthogobius flavimanus (9%) in spring (beam trawl). Characteristically, juveniles of gobiid and some important commercial species, also common in other enclosed bays around Japan, were frequently collected, whereas larvae and juveniles of species endemic to Ariake Bay were rarely collected. Salinity at the study site was almost constant through the tidal changes, being relatively high (ca. 30). The bottom type was a mixture of sand and mud. The results suggested that tidal flat littoral zones not di-rectly influenced by rivers are used as long-term and/or juvenile-stage nurseries for various common non-commercial and commercial species, although it rarely used by early stage larvae of endemic species.
