Pacific Southwest

Title: Characteristics of pools used by adult summer steelhead oversummering in the New River, California

Author: Nakamoto, Rodney J.

Date: 1994

Source: Transactions of the American Fisheries Society 123(5): 757-765.

Description: Abstract - I assessed characteristics of pools used by oversummering adults of summer steelhead Oncorhynchus mykiss between July and October 1991 in the New River, northwestern California. Most fish occupied channel confluence pools and other pools of moderate size (200-1,200 m 2); these pools had less than 35% substrate embeddedness and mean water depths of about 1.0-1.4 m. Microhabitat occupied during daylight hours included cover provided by bedrock ledges and boulders where water velocity averaged 9.3 cm/s (range, 1-34 cm/s; steelhead densities under this cover were highest at the higher velocities. Fish also occupied areas with riparian shading and waters deeper than 1 m. I observed localized areas of cool water in some of the study pools. The availability of coolwater areas in pools did not increase adult fish use of those pools. The results of this study indicate that the distribution of summer steelhead in the New River during July–October is more strongly controlled by physical habitat characteristics than by the availability of thermal refugia.

Keywords: PSW4351, steelhead, fish, Oncorhynchus mykiss, pools, New River, California

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Citation

Nakamoto, Rodney J.  1994.  Characteristics of pools used by adult summer steelhead oversummering in the New River, California.   Transactions of the American Fisheries Society 123(5): 757-765..