We surveyed fish fauna at 3 boulder sites in Uchiumi Bay, Shikoku Isla
nd, Japan. Numbers of fish species and individuals of each species wer
e recorded along 2 lines (50 and 100 m) at each site, using SCUBA in S
eptember 1992. A total of 126 species were recorded; about 66% of them
were tropical or subtropical fishes. Number of temperate species was
similar among the 3 sites (26-28 spp.). Numbers of tropical or subtrop
ical species (30-60 spp.) was greater at the sites where the coral cov
erage was higher (4-37%). The location in the bay and the strength of
water current in each site are also suggested to affect recruitment an
d density of tropical fishes transported by the Kuroshio Current. The
fish fauna of Uchiumi Bay was compared with those of 16 localities of
southern Japan. The number of species common to Uchiumi Bay was relati
vely high in Kushimoto, Kagoshima Bay and Shirahama; all the 4 localit
ies are situated near the border between the warm temperate region and
the subtropical region.