Upstream Migration in the Columbia River Basin: Lessons Learned from Two Decades of Adult Salmon and Steelhead Radiotelemetry Projects

Dramatic declines of Pacific salmon and steelhead (Oncorhynchus spp.) in the Columbia and Snake rivers and their subsequent protection under the U.S. Endangered Species Act in the 1990s prompted one of the largest fish conservation programs in the world.  Our research group has spent nearly two decades evaluating the upstream migrations of these populations.  We have used radiotelemetry data from more than 20,000 adult migrants to address a diverse series of research objectives.  These have included: 1) fine-scale behavioral evaluations of fish passage through dam fishways; 2) migration-scale studies of survival to spawning grounds; 3) downstream movement (i.e., ‘fallback’) past dams by both pre-spawn migrants and post-spawn steelhead (O. mykiss) kelts; 4) use of archival data transmitters to record fish temperature and swim depths in a variety of habitats; 5) assessments of fisheries; 6) impact of pinniped predation; and 7) inter-population and inter-species comparisons.  At dams, the telemetry results have been used to improve fishways via operational changes, structural retrofits, and new design features.  More broadly, the collected data have greatly advanced our understanding of long-distance migration in a highly-regulated, yet environmentally dynamic river system.  Lessons learned in the Columbia basin can inform fishway and fish migration studies worldwide.