河川域から水田域までの分断されたエコロジカルネットワークの魚道による再生

抄録

  We set up two types of fishways in the ecological network consisting of river, drainage channel and paddy fields and investigated the fish population in the drainage channel before and after their introduction, as well as the species that used the fishways. Nine species using the fishway were found. Additionally, two of these species bred in the ascended paddy fields. Consequently, the number of species inhabiting the survey sections in the drainage channel increased from four to six, and the populations of four species increased significantly. Furthermore, the fish population increased when the water and the sediment deposition depths were large and the flow velocity was low. We believed that this diversification of fish communities resulted from the establishment of the fishways, which allowed fishes to move between water bodies and breed in paddy fields. Therefore, we revealed that the introduction of fishways can effectively improve fish habitats, and that it is necessary to consider improving the environmental conditions of drainage channels, such as the installation of wand pools and water depth works as well.