Replacement of white-spotted charr Salvelinus leucomaenis by brown trout Salmo trutta in a branch of the Chitose River, Hokkaido [Japan]
2002
Takami, T. (Hokkaido. Fish Hatchery, Eniwa (Japan)) | Yoshihara, T. | Miyakoshi, Y. | Kuwabara, R.
In the Monbetsu River, a small branch of the Ishikari River basin, west Hokkaido, a brown trout population that was probably introduced 15 years ago is dominant. The population of brown trout was estimated to be 1.8 times greater than that of the native white-spotted charr. The brown trout occurred markedly in the mid- and downstream reaches. On the contrary, the white-spotted charr was predominant only in the upstream reaches above weirs in the river. The water temperature ranged from 5 to 16degC during the summer-autumn period at the lower reaches of the stream. In the mid- and downstream reaches of this stream, the non-native brown trout have likely replaced the native white-spotted charr over the last 15 years.
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