Multiscale habitat electivity and movement patterns by adult spring chinook salmon in seven river basins of northeast Oregon

Graduation date: 1999I examined habitat electivity and movement patterns of adult spring chinook\ud salmon at microhabitat and channel unit spatial scales, and seasonal to annual temporal\ud scales in seven streams in the Grande Ronde, John Day, and Imnaha basins. The\ud objective was to compare habitat use and availability among streams, channel units, and\ud microhabitats, and to assess chinook salmon fidelity to those habitats using radio-telemetry.\ud The analyses showed that habitat quality and availability in the seven study streams\ud varied. Each stream posed different physical constraints on adult chinook salmon habitat;\ud this was reflected by the differential use of habitat by salmon among streams. Salmon\ud elected pools almost exclusively in the John Day Basin, whereas pools and riffles were\ud elected in near equal proportion in the Grande Ronde and Inmaha basins. Within streams,\ud use was similar between years. Almost all salmon were observed in association with cover,\ud but the type of cover largely reflected availablity. Chinook salmon elected the deepest\ud depths within channel units (microhabitat scale), but not necessarily the deepest channel\ud units among streams (channel unit scale). Chinook salmon did not elect cooler stream temperatures within channel units in any study stream, except the Middle Fork John Day\ud River. Radio-tagged chinook showed a high fidelity to habitats, except when stream\ud temperatures approached lethal limits. Due to stream specific differences in habitat\ud availability and use, multiscale habitat assessments for individual streams are\ud recommended to increase the success of watershed restoration activities