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The Willamette River has both spring and fall runs of chinook salmon. Spring chinook move through the Willamette Falls ladder between March and July, spawning in September and October. Fall chinook pass through the ladder between August and October, spawning in those months. Daily counts of spring and fall chinook passing Willamette Falls are available online from the Oregon Department of Fish and Wildlife.
Prior to fish ladder construction, only spring chinook and winter steelhead traveled above the falls, aided by higher water in late winter and spring. Historically, spring chinook spawned in the Middle Fork Willamette, McKenzie, South Santiam and North Santiam Rivers. By the 1950s, dams on all the major tributaries above Willamette Falls blocked more than 400 stream miles that were originally important spawning and rearing grounds.
Currently, four large hatcheries above Willamette Falls produce about 8.8 million smolts each year, plus additional fingerlings to seed reservoir and stream areas. About three-quarters of this hatchery production is funded by the Army Corps of Engineers as mitigation for lost production areas. The percentage of wild fish in the present run is unknown, but is estimated at 5 percent to 15 percent of the total.
Fall chinook salmon
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Fall chinook salmon were introduced above Willamette Falls in 1964, after upstream fish passage was improved. Releases of the early spawning (tule) stock ranged from 5 to 12 million smolts annually. The state discontinued releasing hatchery fall chinook in 1996. Tule fall chinook pass Willamette Falls from mid-August through late September on their way upstream. Fall chinook spawn in the main stem Willamette River and lower reaches of eastside tributaries. Natural production comprises about 28 percent of recent runs.
The construction and successful operation of fish ladders in the Willamette made it possible for coho salmon to migrate above the falls. Migrating over the falls from August to November, they spawn in October and November. Efforts to establish coho above Willamette Falls began in 1952. The run never reached expectations, and due to concerns regarding competition between coho and native game fish, coho have been de-emphasized. Releases were terminated in 1988, except in the Tualatin River.
Daily counts of coho passing Willamette Falls are available online from the Oregon Department of Fish and Wildlife.
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The Willamette Falls fish ladder allows both summer and winter steelhead to pass over the falls. Summer steelhead were introduced in the late 1960s to provide sport fishing opportunities. They move upriver from March to October and spawn in January and February. Hatchery spawning occurs January through March, and one-year-old juveniles are released mid-April through early May.
The native Willamette winter steelhead stock is a late run, passing Willamette Falls from February through May. In an effort to expand angling opportunities, Big Creek Hatchery stock were introduced in the 1960s. These fish return in December and January and have established naturally reproducing populations.
Daily counts of winter and summer steelhead passing Willamette Falls are available online from the Oregon Department of Fish and Wildlife.
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