沖の島

The island of Okino-shima (130゜06'E, 34゜15'N) is located at the center of the East Tsushima Strait, about 77 km north of Fukuoka City, northern Kyushu, Japan. The whole island is in the precincts of a Shinto shrine of the Grand Shrine of Munakata, and the primeval forest was designated as a natural monument in 1925. A considerable number of faunal lists for terrestrial animals and plants including marine algae have been published. However, information about marine fauna of Okino-shima is quite scarce. From 1982 to 1985, we made underwater observations on marine organisms at the island. As a result, 86 fish species were collected with spears, gill nets, hand nets and fish-traps etc., and 39 species were identified by sight. Additionally, 6 species were observed in catches by local fishermen. In the present paper, 131 fish species belonging to 63 families are reported in a preliminary check list of the fishes of the island of Okino-shima. The following species, Kyphosus biggibus Lacepède, Pseudojuloides elongatus Ayling et Russell, Parioglossus dotui Tomiyama, Callogobius snelliusi Koumans, and Eviota epiphanus Jenkins which have been reported from the Pacific coasts of southern Japan and the Ryukyu Islands, are reported from Okino-shima as range extensions. The following four species were of the most representative rocky reef fishes at the island; the pomacentrid fish, Chromis notatus notatus (Temminck et Schlegel), the labrid fish, Pteragogus Plagllifera (Valenciennes), Pseudolabrus japonicus (Houttuyn), and Halichoeres tenuispinnls Gtinther. These four species from two families are also abundant at the northern coast of Fukuoka. However, several spcies of the same famlies, for instances, Chromis fumeus (Tanaka), Stegastes altus (Okada et Ikeda), Thalassoma cupido (Temminck et Schlegel), P. elongatus, which are established at Okino-shima, do not occur among the rocky reefs of the northern coast of Fukuoka. In addition, young fishes of some labrid species which are established at the island, appear along the northern coast of Fukuoka only from September to November, for instances, Stethojulis interrupta terina Jordan et Snyder and Cirrhilabrus temminckii Bleeker, do not survive in winter. The fish fauna of Okino-shima shows a degree of sub-tropical characteristics compared to that of the northern coast of Fukuoka, although the present check list has a partiality to the rocky reef fishes.