Profile of Iwana
|OshorokomaSalvelinus malma malma
AmemasuS. leucomaenis f. leucomaenis
Nikko IwanaS. l. f. pluvius
Yamato IwanaS. l. f. japonicus
GogiS. l. imbrius
|Japanese chars are two species that are Oshorokoma (S. malma) 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. They live in middle of Hokkaido, Sakhalin, Kamchatka, Alaska, and the northern California. Their lake form is called Miyabe Iwana, Lake Shikaribetsu and rivers that flow into its lake are their homes. They are regarded as Oshorokoma's subspecies but Miyabe Iwana and Oshorokoma are not different externally. Miyabe Iwana have many gill than Oshorokoma. It is regarded as adaptation to get animal plankton while circular tour 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. And their color of body are from dark brown to dark gray or silver white. They live in 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 running type and river type. Sea-running types 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 live in 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. As Nikko Iwana grew up, their color of spots become more and more pale. But Yamato Iwana's spot color is not pale even if they have grown up. They live in 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 live 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, Kinji. Iwana and Yamame. Tokyo, Heibonsha, 1989. Kawanabe, Hiroya; Mizuno, Nobuhiko (ed.). Nihon no Tansuigyo. Tokyo, Yama-kei publishers, 1993. Shiraishi, Katsuhiko; Wda, Satoru. Iwana no Kao. Tokyo, Yama-kei publishers, 1993. Matsubara, Hiroshi. "Sakeka Keiryugyo no Bunrui to Seitai". Besatsu Fishiing Iwana Yamame. Tokyo, Sanpou Publishing, 1981.|
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