The coho, or “silver salmon”, has a metallic blue back and silver sides and belly. The adults turn muddy red as they begin their spawning run. Black spots are scattered along the back and upper tail. Their mouths are black except for a thin white line along their gums. Fishers have caught coho heavier than 30 lbs., but the average size is 8 lbs.
Coho adults return to the Columbia in the fall of their third year. The female may dig several redds and will deposit a total of 3,000 – 4,000 eggs.
After hatching, the young fish gather in schools in shallow areas near the stream bank. As they grow older, they disperse and become very aggressive, even towards each other. Coho typically rear for 18 months in freshwater and another 18 months in the ocean.
Coho salmon were declared extinct in Idaho in 1986, but through the efforts of the Nez Perce Tribe, they were successfully reintroduced and now return in numbers that support a fishery in a number of rivers and streams in the state.