ABSTRACT
Pacific salmon Oncorhynchus spp. exist in fluvial systems that are physically and biologically dynamic. Salmonid life history characteristics and associated habitat requirements vary widely by species. Some species use the freshwater environment almost solely for incubation, while others use it for both incubation and extended rearing. Salmon species have evolved into several life history patterns that maximize their potential for survival and minimize their spatial and temporal overlap. To rehabilitate salmon habitat and thereby strengthen wild runs requires a knowledge of fish life histories and the aquatic system’s potential range of conditions. Using large woody debris to rehabilitate stream channels is a popular management activity in the Pacific Northwest. Prior knowledge of factors such as spawning distribution and timing, incubation environment quality, seasonal rearing habitat needs (i.e., summer/winter), limiting factors in freshwater production, and the relative habitat quality and availability is imperative for successful projects. We review woody debris ecology in streams and provide planning information for woody debris placement projects. In addressing limiting aspects of properly functioning aquatic and riparian ecosystems, instream and riparian habitats can be created that provide the interim structural framework for streams until riparian and upland forests recover from past disturbances. The discussion is based on a decision flow diagram that guides the need assessment process and suggests appropriate rehabilitation technique. Visits to several stream rehabilitation projects, combined with information from the literature and our own experience, led us to a number of conclusions supporting stream restoration for future sustainability of Pacific salmonids.
