Log weirs placed in a small coastal Washington stream to create pools and habitat for coho salmon

Project Title

Evaluation of instream restoration techniques for juvenile salmonids

Description

Millions of dollars are spent annually on habitat enhancement and restoration in an effort to recover salmon populations listed as threatened or endangered under the Endangered Species Act. The placement of large woody debris (LWD) and boulders are some of the most common techniques used to increase habitat complexity and improve fish habitat. Hundreds of projects occur annually in the Pacific Northwest; however, comprehensive evaluation of these projects has not occurred and most instream techniques remain controversial. We initiated the Instream Restoration Project to evaluate the response of fishes and other aquatic biota to LWD, boulder placement, and other instream structures in Pacific Northwest streams and help guide restoration activities.

Initially, we examined the response of fish and salamanders to LWD placement in 30 streams in western Oregon and Washington. Results indicated that salmonids and larval lamprey responded positively to wood placement and that the largest increases were seen in those streams that had the largest increase in pool area and wood loading suggesting that large changes in physical habitat are needed to detect a significant fish response. The details of this study have recently been published in several papers (see relevant publications below).

Heavy equipment placing logs in a stream to create pools and increase habitat complexity Boulder weirs in an Oregon coast river creating pools and salmon spawning and rearing habitat

The placement of boulder and boulder weirs is another technique that is also common, controversial, and in need of adequate physical and biological evaluation. This technique has become particularly common in areas such as the south Oregon coast, where stream channels have been scoured to bedrock and greatly simplified following decades of intense forestry activities (e.g., splash damming, stream cleaning). We are in the process of completing a cooperative study with the Bureau of Land Management, Oregon Department of Fish and Wildlife, and Environmental Protection Agency evaluating the effectiveness of boulder weir projects in southwest Oregon. Fifteen study streams with treatment and control reaches were sampled in the Coos and Coquille basins to examine the fish and macroinvertebrate response to boulder placement. Preliminary results indicate significantly higher numbers of juvenile coho in stream reaches treated with boulder weirs than those without. Thus boulder weir placement appears to be a first step in recovering these highly incised and simplified stream channels. We are also examining the use of boulder weirs by spawning adult salmon. Initial results suggest higher numbers of spawning salmon in reaches with boulder weirs.

Investigators

Phil Roni, Todd Bennett, Sarah Morley, and George Pess

Collaborators

Karrie Hanson (NWFSC), NOAA Fisheries, U.S. Bureau of Land Management, U.S. Forest Service, U.S. Fish and Wildlife Service, and Oregon Department of Fish and Wildlife

Support

NOAA Fisheries and U.S. Bureau of Land Management

Relevant Publications

Roni, P., T. Bennett, S. Morley, G. Pess, K. Hanson, D. Van Slyke, and P. Olmsted. 2006 Rehabilitation of bedrock stream channels: the effects of Boulder weir placement on aquatic habitat and biota. River Research and Applications 22(9): 967-980

Roni, P. 2003. Responses of benthic fishes and giant salamanders to placement of large woody debris in small Pacific Northwest streams. North American Journal of Fisheries Management 23:1087-1097.

Roni, P., M. Liermann, and A. Steel. 2003. Monitoring and evaluating responses of salmonids and other fishes to in-stream restoration. In D.R. Montgomery, S. Bolton, and D.B. Booth, (editors), Restoration of Puget Sound Rivers, University of Washington Press.

Roni, P., T.J. Beechie, R.E. Bilby, F.E. Leonetti, M.M. Pollock, and G.P. Pess. 2002. A review of stream restoration techniques and a hierarchical strategy for prioritizing restoration in Pacific Northwest watersheds. North American Journal of Fisheries Management 22:1-20.

Roni, P. and T.P. Quinn. 2001. Effects of artificial wood placement on movements of trout and juvenile coho in natural and artificial channels. Transactions of American Fisheries Society 130:675-685.

Kahler, T., T.P Quinn, and P. Roni. 2001. Summer movement and growth of juvenile anadromous salmonids in small western Washington streams. Canadian Journal of Fisheries and Aquatic Sciences 58:1947-1956.

Roni, P. and T.P. Quinn. 2001. Density and size of juvenile salmonids in response to placement of large woody debris in western Oregon and Washington streams. Canadian Journal of Fisheries and Aquatic Sciences 58:282-292.

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