豊平川のサケ産卵環境改善区間における掘削路閉塞後の環境変化計測

抄録

In alcove where chum salmon have spawned every year, the number of spawning beds decreased due to the accumulation of fine sediment. We made channel to make inflow and reduce the fine sediment. The flow path made salmon redds increased. In the following year, the artificial channel was closed due to the sedimentation caused by the flood. In order to understand effects of without inflow to the alcove on the number of redds, we measured spawning environmental variables. Half number of redds before channel closed were recognized, whereas almost variables (e.g. substrate, water depth, hyporheic temperature) were suitable for spawning, except for current velocity. Faster flow may be a necessary element to guide salmon to the alcove, and running water from the channel it is important for maintaining salmon spawning environment.