Southern Steelhead, Hard Woody Debris, and Temperature in a California Central Coast Watershed

We surveyed large wood volumes in relation to the distribution and density of rainbow trout Oncorhynchus mykiss and steelhead (anadromous rainbow trout) in 15 stream reaches in the upper Salinas River watershed, California, which represents the southern end of the species’ range. The main tree species contributing to large wood were hardwoods: coast live oak Quercus agrifolia , California sycamore Platanus racemosa , red willow Salix laevigata , and valley oak Q. lobata . Large wood jams were important in pool formation and typically had red willow as their key pieces. Temperatures were exceptionally warm during the study period. No steelhead were observed at sites where the mean water temperature exceeded 21.5°C or the maximum water temperature exceeded 26°C. The combined importance of high temperatures and large wood on the distribution and abundance of southern steelhead indicates that suitable habitat may be reduced if climate change continues on its present course of warming and the frequency of fires increases. Received February 9, 2011; accepted July 18, 2011