Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Pacific Northwest). Coho salmon. [Oncorhynchus kisutch]

The coho is anadromous, swimming upstream from the ocean in fall to spawn. The fry hatch in the spring and outmigrate 1 to 2 years later. They usually spend two growing seasons at sea. They require clear, cold, well-oxygenated (<4 mg/l) stream water (1 m/sec) for spawning and rearing, with a gravel substrate, adequate cover, and a food supply of insects, crustaceans, and fishes for the young. All populations of coho salmon are limited by the amount of suitable rearing area available. They are sought after in both sport and commercial fisheries, and are very sensitive, especially the early life stages in streams, to such human-made impacts as siltation, pollution, removal of cover, and barriers to migration. Current management objectives of the State of Washington are toward MSH (maximum susstained harvest), with the treaty Indian tribes under the Boldt Decision (United States vs State of Washington) having a legal right to 50% of the catchable allocation.