The geographical distribution of the endangered bagrid catfish, Pseudobagrus
ichikawai, in Gifu Prefecture, was investigated utilizing literature records, questionnaires and field surveys. The results showed that populations of this species had originally been distributed widely in the middle reaches of rivers of the Kiso, Nagara, Ibi and Shonai River systems, flowing into Ise Bay (facing the Pacific Ocean), but have been decreasing and fragmenting in upper-middle river reaches and branches. The threatened situation of the populations, especially in middle to small scale branches, is noted. Limiting factors of the original distribu-tion range of this species in each river system are also discussed.
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