Adult fall chinook salmon passage through fishways at lower Columbia River dams in 1998, 2000, and 2001

As part of an ongoing study to examine fish behavior at hydropower dams, we gastrically implanted radiotelemetry tags in a total of 3,142 adult fall-run Chinook salmon (Oncorhynchus tshawytsclici) and monitored their movements as they migrated upstream through the Columbia River Basin in 1998, 2000, and 2001. Radio receivers were placed along the Columbia River, at the mouths of most tributaries, and throughout the various fishways at four lower Columbia River dams (Bonneville, The Dalles, John Day, and McNary Dams). Passage efficiency at these dams ranged from 86.5 to 97.4% during the 3 years and varied little through time at three of the four dams (The Dalles Dam being the exception).