Abstract
The distribution and present status of fishes was investigated in Lake Takkobu and adjacent rivers of the Kushiro Mire from July to October, 2003. Gymnogobius castaneus, Hypomesus olidus and Phoxinus percnurus sachalinensis were dominant species found. G. castaneus which prefers sand and mud beds was especially abundant in the coastal area, and its distribution pattern was considered to be related to those features of the lake bottom. H. olidus which is potamodromy type was widely distributed in the area offshore, while P. percnurus sachalinensis was most abundant near the water plant community of Trapa japonica. Salvelinus leucomaenis and Cottus nozawae were abundant in the Takkobu River. Moreover, the fact that the number of fish species was most abundant in the mouth of river area where rivers joined the lake, suggested that it was an important site for the conservation of species diversity. Fishes of 24 species divided into 9 families found in Lake Takkobu and adjacent rivers were applied to fish species assigned to the Ministry of the Environment and Hokkaido Government categories of the Red Data Book. As a result, the most of fishes listed in the Red Data Book were from areas where large number of individuals occurred. Therefore, it is confirmed that the present status of fish species in this catchment area is a healthy one.
