河川構造物が設置された非放流河川におけるサケ産卵床の分布

抄録

To understand effects of artificial barriers on the natural recruitment of chum salmon, spatial distribution of spawning redds was investigated for five years in a non-stocked river with a small dam. Spawning redds were observed from October to December every year, but not in January. Redd density in the section just below the dam was more than five times higher than that in downstream sections. Some redds in the high-density section were superimposed by later spawners. These results suggest that spawning ground expansion by artificial structure modification (e.g., installation of fish ways) is important for enhancing chum salmon reproductive success.