2019 Volume 66 Issue 2 Pages 187-194
Distribution of the anadromous red-spotted masu salmon, Oncorhynchus masou ishikawae in Japan was evaluated from data published in “River Fishery, vol. 1–6” between 1930 and 1934 and in 1937 by the Fisheries Agency, Ministry of Agriculture and Forestry, Japan. Catches of salmon were recorded in 26 rivers from Shizuoka to Yamaguchi Prefecture on Honshu Island and 5 rivers in Tokushima and Kochi Prefectures on Shikoku Island, but no distribution was indicated in rivers in Fukuoka and Oita Prefectures on Kyushu Island between 1927 and 1931. The best-fitted model of Generalized Liner Model indicated that both of latitude and river length had significant positive effects on the presence of salmon. Salmon is possibly distributed only in large rivers, particularly in the southern region. Probability of distribution of salmon as correct classification in 64 rivers and misclassification in 15 rivers including the Shimanto River in southwestern Shikoku Island were calculated from the best-fitted model. Catch of salmon was not recorded in data published by the Fisheries Agency, but that published in 1912 by the local government in Hata, Kochi Prefecture, and our analysis indicated salmon presence in the Shimanto River. Although the Nahari River (the river mouth, 33˚25'21″N, 134˚0'42″E) in southeastern Shikoku Island had been shown to be the southern limit in data published by the Fisheries Agency, we suggested the Shimanto River (32˚55'58″N, 132˚59'39″E) the southernmost limit. In this study, we reveal previous distribution of the anadromous red-spotted masu salmon in 26 rivers in Honshu Island and 6 rivers including the Shimanto River, in Shikoku Island in Japan.
