Results from this study indicated that juvenile yearling Chinook were consistently observed in fall and winter throughout the lower mainstem Snoqualmie River, used a variety of mainstem edge habitat types, and displayed seasonal shifts in habitat use. While relatively little is known about the Snoqualmie River yearling life history, they can contribute a considerable proportion of returning adults and generally return as older-larger adults. Results from this study highlight the importance of mainstem edge habitats for juvenile yearling Chinook and emphasize that a diversity of habitat types is needed to support all juvenile Chinook life histories.

Since yearling Chinook spend an extended period among freshwater habitats, targeted conservation strategies focused on freshwater habitat conditions, particularly from summer throughout winter, may be integral in supporting yearling Chinook and life-history diversity. Integrating juvenile yearling Chinook into salmon conservation strategies and restoration projects may include: designing mainstem projects with consideration of summer throughout winter habitat use and conditions, ensuring that improved and restored habitat areas are connected and engaged across summer/winter low-flow periods, increasing mainstem large wood, focused restoration of tributaries and confluences, restoring spring/summer temperature conditions and preserving fall/winter thermal diversity, and adopting multi-season approaches to monitoring habitat and juvenile salmonids. Supporting life-history diversity will help Chinook populations withstand environmental-population variability and will ensure that restoration and conservation efforts are strategic and comprehensive.