Kyoto Institute of Oceanic and Fishery Science, Kyoto 626-0052, Japan
A tag-release and recapture experiment of wild Japanese flounder Paralichthys olivaceus was conducted in western Wakasa Bay in order to evaluate their distribution and migration. A total of 599 immature and 278 adult fish were tagged and released in spring and early summer during the period from 1993 to 1998. Most of the immature fish were recaptured within 40km from the release site until August. The number of recaptured immature fish near the release site (<40km) decreased after August, although some immature fish were recaptured. Some of the immature fish migrated westward more than 100km from the release site. No eastward migration was observed. On the other hand, most of the adult fish were recaptured within 40km from the release site with a few exceptions in which fish migrated westward in winter or northeastward in summer from the release site. The recapture of adult fish occurred all year around in western Wakasa Bay. Those results suggest that immature flounder spend spring and summer inside western Wakasa Bay, then some of them migrate westward in autumn and winter, whereas most of the adult flounder stay in the Bay for the whole year around.