Iwana-charr, Salvelinus leucomaenis is not indigenous to Kyushu Island western Japan. In 1971, this species was transplanted to a commercial hatchery by the Haki River (32°32'N, 130°57'E), a tributary of the upper reaches of the Kuma River System. Some of the charr individuals escaped from the hatchery's holding pond and came into the stream. Fifty-one were collected in the lower reaches near the hatchery but none in the upper reaches during 1994-1996. The collected sample consisted of individuals belonging to plural age classes. In addition, we observed some spawning activities of the charr in November every year during 1994-1997 and found some eggs in the redd. Our findings suggest that reproduction of the charr occurs in some tributaries of the upper reaches of the Kuma River and their distribution is expanding downstream. They also suggest that dams without fishways prevent the charr from migrating upstream.
