最上川, 日向川水系 (山形県) の特殊斑紋のイワナ

抄録

Specimens of char with atypical color patterns were collected in the Shiratama River, tributary to the Nikko River, and in the Aizawa River, tributary to the Mogami River, both located in Yamagata Prefecture, northern Honshu, Japan.These specimens exhibited marked color variations, ranging from individuals with no light spots nor parr marks to those having vermicular, arabesque or zigzag patterns.According to the shape and distri-bution of the body markings, these specimens were classified into four types.Comparison of electrophoresis of cyanmetho Hb, as well as that of morphometric characters, of these atypical-pattern specimens with Salvelinus leucomaenis possessing ordinary color patterns showed no difference between them.These atypical-pattern specimens are therefore con-sidered to be color variants of S.leucomaenis, rather than hybrids between S.leucomaenis and other salmonid species.