Despite its potential use for population control, the winter ecology of nonnative fishes is still poorly understood due to the difficulty of conducting field surveys. In this study, we investigated the winter habitat use of invasive rainbow trout Oncorhynchus mykiss at the cannel unit scale (i.e., pool, riffle). Twenty-four reaches were surveyed in late December 2013 along the Obicha River, a tributary of the Otofuke River, Tokachi River basin, Hokkaido, Japan. A total of 532 fish were captured, of which 96% were rainbow trout, whereas native salmonid was only a single southern Asian Dolly Varden Salvelinus curilus. Smaller rainbow trout (< 250 mm) used reaches with low velocity, whereas larger trout (250–520 mm) aggregated in specific reaches with deep pools with abundant cover and coarse substrate. A previous tributary-scale study in the same river system showed the importance of velocity and temperature, but not depth and substrate. Therefore, habitat selection would be scale-, as well as size-, dependent. This study provides useful information on capturing large mature adults in winter for effective control of nonnative salmonids.

尽管它有可能用于种群控制，但由于难以进行实地调查，对非本地鱼类的冬季生态仍然知之甚少。在这项研究中，我们调查了入侵虹鳟鱼Oncorhynchus mykiss在渠道单位规模（即水池、浅滩）的冬季栖息地使用情况。2013 年 12 月下旬，沿着日本北海道十胜川流域音更川的支流 Obicha 河对 24 个河段进行了调查。一共捕获了 532 条鱼，其中 96% 是虹鳟鱼，而原生鲑鱼只有一条南亚 Dolly Varden Salvelinus curilus. 较小的虹鳟鱼 (< 250 毫米) 使用低速河段，而较大的鳟鱼 (250-520 毫米) 聚集在特定河段，具有丰富的覆盖和粗糙的底物的深水池。之前在同一河流系统中进行的一项支流规模研究显示了速度和温度的重要性，而不是深度和底质。因此，栖息地的选择将取决于规模和大小。这项研究提供了有关在冬季捕获大型成熟成鱼以有效控制非本地鲑鱼的有用信息。