2021 Volume 26 Issue 2 Article ID: 2027
Due to a postwar forestry expansion policy in Japan, upstream catchment areas are currently forested, and flow conditions are being homogenized by dam construction and river improvement. To document any adverse effects of this policy as well as hydraulic and water-utilization policies, it is important to monitor systems over the long term, such as the most recent 30 years of the postwar period. This report focuses on the Minami River, Fukui Prefecture, Japan. I estimate how changes in the river environment have affected the number of fish in the long term and propose crucial river development plans. Using the results of a national census along rivers, temporal changes in the fish communities of rivers with abundant fish fauna and populations were statistically analyzed. The biomass of Rhinogobius flumineus has increased, while those of Tribolodon hakonensis and Liobagrus reinii have significantly decreased in the Minami River. I hypothesize that an increase in the abundance of river runs led to the increase in Rhinogobius flumineus, whereas the reduced abundance of rapids and pools caused the decreases in Tribolodon hakonensis and Liobagrus reinii. A future river development plan is proposed to create additional rapids and pools in the Minami River.
