Evaluation of a stream channel-type system for southeast Alaska.

Abstract

Nine channel types within a hierarchical channel-type classification system (CTCS) were surveyed to determine relations between salmonid densities and species distribution, and channel type. Two other habitat classification systems and the amount of large woody debris also were compared to species distribution and salmonid densities, and to stream channel types. Although trends appeared in salmonid densities and channel types, population estimates were too variable to show a relation between density and channel types. Depth-velocity criteria that separated habitat into shallow-slow, deep-slow, shallow-fast, and deep-fast were poorly related to fish populations and channel types. Within the Bisson classification system, coho salmon (Oncorhynchus kisutch (Walbaum)) parr were positively correlated to off-channel habitat types. Large wood was more abundant in depositional channel types, and coho salmon densities were positively related to debris accumulations of 10 or more pieces and to rootwads. Although salmonid densities were not statistically related to channel types within the CTCS, the system seems to be a useful tool to classify stream habitat and to identify its use by salmonids.

Citation

Bryant, M.D.; Porter, P.E.; Paustian, S.J. 1991. Evaluation of a stream channel-type system for southeast Alaska. Gen. Tech. Rep. PNW-GTR-267. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 25 p