Trout and Seasons of The Mountain Village

Profile of Iwana

OshorokomaSalvelinus curilus AmemasuS. leucomaenis leucomaenis Nikko-iwanaS. l. pluvius Yamato-iwanaS. l. japonicus GogiS. l. imbrius		Japanese chars are two species that are Oshorokoma (S. curilus) of Hokkaido, Iwana (S. leucomaenis) of Hokkaido and Honshu. Until now, Iwana (S. leucomaenis) were classified in detail to Amemasu, Nikko-iwana, Yamato-iwana, Kirikuchi and Gogi because of spot's size, color, etc., but Dr. Kinji Imanishi (1967) regarded those Iwana as local variety in the same species on the basis of the theory "clin" (HUXLEY, J. S. 1938; 1940), and Iwana's color represent variety that range from light color to deep color. Oshorokoma have 5 or 10 parr marks and red spots on the body side. Their stomach turn into red or orange color in the spawning season. There are sea-running type and river type, but in Hokkaido almost all of they are river type because Hokkaido is most southern life area in the world. They are about 30cm (12in.) long. As a species, they are distributed in the Arctic Ocean and along the coast of the North Pacific Ocean, and in Japan inhabit in north of the middle part of Hokkaido. Oshorokoma in Japan was considered to be a subspecies of Dolly Varden in North America, but it was classified as a distinct species in 2023. The lake form is called Miyabe-iwana, a subspecies that inhabits Lake Shikaribetsu and its inflowing rivers. They looks the same as Oshorokoma, but have more gillraker counts than Oshorokoma. It is regarded as adaptation for eating zooplankton while migrating in the lake. Amemasu have body just like a log. They have white spots that are the same size of their pupil or bigger on the body side. Their color of body are from dark brown to dark gray or silver white. They inhabits Mogamigawa River (Yamagata), the Pacific Ocean side of North of Tonegawa River, Hokkaido, Northeast of Korean Peninsula, Saghalien, the Far Eastern Russia and Kamchatka Peninsula. There are sea-run form and river form. Sea-run forms are about 70cm (27.5in.) long or longer.
Nikko-iwana have yellowish orange spots or pink spots that are the same size of their pupil on the body side, and spots of small size are scattered on the back. They inhabits Sea of Japan side of North of Hinogawa River (Tottori), the Pacific Ocean side of North of Fujigawa River (Yamanashi) or Sagamigawa River (Kanagawa). Yamato-iwana have vermilion spots up and down on lateral line. The spot color of Nikko-iwana becomes more and more pale as they grew up, but the spot color of Yamato-iwana are not pale even if they have grown up. They inhabits mountainous region of middle Honshu, rivers of east of Lake Biwa. They are 25cm (10in.) long. Distribution's boundary of Nikko-iwana and Amemasu is not clear. Iwana that live in Kii Peninsula is called Kirikuchi. They have spots of vermilion that are outline indistinct on the body side and white spots are also not clear. Now, they live slightly in only two places that are upper area of Kawarabigawa River and Tenkawa River in Nara. Those are the most southern life spot of Iwana (Salvelinus) in the world. Gogi is like Nikko-iwana, but they have clear white spots on the head. They inhabits from Hiigawa River to Takatsugawa River (Shimane), from Yoshiigawa River (Okayama) to Otagawa River (Hiroshima) and Nishikigawa River (Yamaguchi). Kabatanigawa of Takatsugawa River and Agetani of Nishikigawa River are the most western life spot of Iwana (Salvelinus) in Sea of Japan side and the Pacific Ocean side respectively in Japan. They are about 20cm (8in.) long. There is a view by Dr. Kinji Imanishi (1967) Gogi is subspecies of Iwana (S. leucomaenis). Gogi was derived from Kogi of Korean that means fish.
		References: Imanishi, K. (1989). Iwana and Yamame. Tokyo: Heibonsha. Kawanabe, H., & Mizuno, N. (ed.). (1993). Nihon no Tansuigyo [Japanese freshwater fish]. Tokyo: Yama-kei publishers. Matsubara, H. (1981). Sakeka Keiryugyo no Bunrui to Seitai [Classification and Ecology of Salmonid]. Besatsu Fishiing Iwana Yamame. Tokyo: Sanpou Publishing. Shiraishi, K., & Wda, S. (1993). Iwana no Kao [Iwana's Face]. Tokyo: Yama-kei publishers. Ministry of the Environment Ikimono Log. Red List and Red Data Book, Retrieved January 12, 2022.

My drawings of trout were used in the scientific documentary film "A TROUT IN THE MILK" that reexamines the relationship between Japanese people and char and explores the vision for the future to better conserve the natural environment.

Click on the images.