Comparison of Habitats Near Spur Dikes, Continuous Revetments, and Natural Banks for Larval, Juvenile, and Adult Fishes of the Willamette River

摘要

Natural banks, because they are diverse in structure, afford the best habitat for resident fishes of the mid-Willamette River. Spur dikes contain a diversity of habitats, in terms of velocities, depths, and cover, that is unavailable at continuous revetments. The numbers of species of fishes and the densities of larval and juvenile fishes at spur dikes are intermediate between those at natural banks and at continuous revetments. The number of species of adult fishes found were similar at spur dikes and continuous revetments. Juvenile chinook salmon were found to use the slack water between spur dikes during early spring but were not captured near continuous revetments. Wood debris was observed to accumulate between spur dikes. As more debris accumulates and as riparian vegetation develops, habitat for adult fishes should improve, especially during the winter.