Coho salmon hatch in cold, clear streams, head to the Pacific Ocean to grow, and return to the stream where they were born to spawn and die. Young coho spend about a year in fresh water, then roughly a year and a half feeding at sea before coming home in fall or early winter, usually at three or four years old. In the ocean they are bright silver; by spawning time they have turned dark with reddish maroon sides, and males grow a hooked snout and large teeth.
Coho favor small, gently sloping tributary streams with gravel about the size of peas to oranges, plenty of fallen wood and tree-lined banks. The female digs a nest in the gravel, called a redd, and the eggs hatch after six or seven weeks. Every adult dies after spawning, and the carcasses feed the stream, adding nutrients that help newly hatched salmon grow and survive.
About 70 percent of the Sandy River basin lies within Mt. Hood National Forest, and the forest and its partners have spent decades restoring salmon habitat there, including miles of the Salmon River and Still Creek. Since Marmot Dam was removed and large-scale restoration began in 2007, yearly returns of coho, Chinook and winter steelhead to the upper basin have nearly doubled. The coho in Mt. Hood’s rivers belong to a population protected under the Endangered Species Act.
How to identify it
Ocean-bright coho are silvery on the sides with a dark blue to greenish back, small black spots on the back, spots on only the upper half of the tail, and a white gum line along the lower jaw. Spawning adults turn dark with reddish maroon sides and greenish backs and heads, and males develop a hooked jaw. Adults usually run 24 to 30 inches and 8 to 12 pounds.
Look-alikes
Chinook salmon look similar in the ocean, but they have dark gums along the lower jaw and spots on both lobes of the tail. Coho have a white gum line and spots only on the upper tail lobe.
Habitat
Grows up in small, low-gradient tributary streams with gravel beds, fallen wood and shaded banks, and sometimes in lakes, then spends its adult life in the ocean. On Mt. Hood National Forest the Sandy River basin, where the Salmon River and Still Creek have been restored for salmon, is key habitat.
Sightings in the forest
163 research-grade sightings in Mt. Hood National Forest on iNaturalist, most recently on October 31, 2026. See them on iNaturalist →