Summer Distribution of and Habitat Use by Chinook Salmon and Steelhead within a Major Basin of the South Umpqua River, Oregon

Abstract

Abstract Snorkeling and established stream habitat assessment methods were used to determine basinwide summer habitat use by juvenile Chinook salmon Oncorhynchus tshawytscha and juvenile steelhead O. mykiss in 1989 in eight reaches along 39 km of Jackson Creek, a fifth-order tributary to the South Umpqua River, Oregon. Juvenile steelhead (ages 0–3) were widely distributed throughout the entire stream but age-1 and older fish were found in higher densities in the middle reaches whereas age-0 fish were found in higher densities in the upper reaches. Juvenile Chinook salmon were found in the highest densities in the middle reaches. Juvenile steelhead used mostly riffles in the downstream reaches but mostly pools in the upstream reaches. Age-0 Chinook salmon were strongly associated with pools in all reaches. Several factors are suggested that may have influenced distribution and abundance of both species; these include high stream temperatures in the lower reaches, habitat preferences of each species, and th...