Growth and Behavioral Patterns Associated with Increased Occupancy of River Habitat Restored with Instream Structures

Juvenile Chinook salmon (Oncorhynchus tschawytscha) and steelhead trout (Oncorhynchus mykiss) show increased occupancy of stream habitat enhanced with in-stream restoration structures, such as engineered log jams in the Entiat River, Washington, USA. Although occupancy is one indicator of the effectiveness of restoration projects, increased performance in terms of life history traits such as growth and behavior is a more robust correlate of successful transition into the next life stage. We measured growth and habitat affinity in these two species in three different years and show that both short-term and long-term recapture rates were higher for both species. Chinook salmon recaptures were especially low in unrestored habitat, making comparisons of growth over time, difficult. Steelhead growth was significantly greater in restored pools than in unrestored pools in 2009 and 2010, but was equivocal in 2012. For both species, we were able to examine correlates of growth in restored habitat only. We found that growth was correlated with depth and current velocity, consistent with correlates of occupancy found in previous research.