Young Snake River steelhead migrated to the ocean at the second highest rate on record last year, according to new research.
About 21 percent more steelhead passed safely through dams on the Columbia and Snake rivers in 2010 than the average number since the late 1990s, according to the National Oceanic and Atmospheric Administration's Northwest Fisheries Science Center.
Young chinook and sockeye salmon also made it through the dams at rates higher than average, according to the center.
The eight federal dams spill water for fish migration through the end of the juvenile migration in August and the Army Corps of Engineers has installed surface passage systems at all eight dams in the last decade. Electric ratepayers paid for most of the improvements through the Bonneville Power Administration.
NOAA research also showed that the surface passage systems, including a new fish slide at Little Goose Dam, helped speed young fish downstream by moving surface water more quickly through spillways.
Faster travel reduces exposure of young fish to predators and higher water temperatures.
About 35 percent of fish were taken downstream by barge in 2010, fewer than in almost all years since 1995.
NOAA's report also showed that new aerial wires hung below John Day Dam to discourage bird predation and completion of a spill wall to guide fish away from predators at The Dalles Dam contributed to fish survival.