Steelhead have the most complex life histories of any anadromous salmonid. Though many steelhead die after spawning, some are able to return to the ocean and spawn multiple times during their lifetimes. Juvenile steelhead spend between 1-4 years in freshwater before migrating to the ocean, and then spend 1-4 years at sea. Returning adults average 4-8 pounds. Run timing of steelhead varies considerably, and some regions support both summer and winter stocks.
There are six distinct population segments (DPSs) for steelhead in Oregon: the lower and middle Columbia River (which also include regions of Washington), the Snake River Basin (which also includes regions of Idaho and Washington), the upper Willamette River, the Oregon Coast, and the Klamath Mountains Province (which also includes regions of California).
Data for Lower Columbia, Upper Willamette, Middle Columbia, and Snake River Basin steelhead are currently available on the website.