Preferences of Juvenile Coho Salmon (Oncorhynchus kisutch) and Cutthroat Trout (Salmo clarki) Relative to Simulated Alteration of Winter Habitat

Abstract

Winter habitat preferences of juvenile coho salmon (Oncorhynchus kisutch) and cutthroat trout (Salmo clarki) were tested by simulating conditions before and after stream disturbance such as might result from logging: (1) sidepools with or without an overhanging bank and roots, and (2) sidepools with clean or silted rubble substrate. Both coho and cutthroat demonstrated a strong preference for sidepools offering overhanging bank cover as opposed to those without bank cover. Similarly they preferred sidepools with clean rubble substrate as opposed to silted rubble. In both the bank and rubble tests, when given the option of either remaining in the sidepools or of moving into the stream, a greater percentage of the total number of coho and cutthroat originally in the sidepools remained in the pools with cover as opposed to those without cover. Coho utilized bank cover more readily than rubble cover whereas cutthroat used both bank and rubble cover.