Abstract
Three specimens of the amago salmon, Oncorhynchus rhodurus, were caught off Chikubu Island in Lake Biwa, Shiga Prefecture, Japan. These specimens were females measuring 260-375 mm in standard length, with red spots on both sides of the body.The transverse scale counts above the lateral line were 27-32.Ridges of scales had disappeared in the apical margin of the scales.These characters resemble those of the amago salmon found in the Nagara River or Lake Suwa, and differ from those of the Biwa salmon found in Lake Biwa (Kato, 1973a, 1975a, b, 1978).Therefore the author identified the specimens as amago salmon.They are presumed to have descended in the smolt stage into Lake Biwa and to have grown there.
