Coho Salmon

Oncorhynchus kisutch

Coho salmon are also known as silver salmon.

Description: Coho average between 6 and 12 pounds (although they may weigh up to 30 pounds and be more than 38 inches long). In the ocean, coho have silver-grey flanks and silver-blue backs earning them a common name “silver”. When in full spawning colors, the backs of the coho salmon turn dark and their bodies turn a deep red color, especially for males. Spawning males have prominent hooked jaws, less so in females. Like Chinook, coho salmon have black spots covering their backs, but black spots only occur on the dorsal lobe of their caudal (tail) fin unlike Chinook’s black spots on both lobes. Another character to distinguish coho from Chinook is, although both have black tongues, a coho’s teeth are in a white gum whereas a Chinook’s teeth are in a black gum (see local common name “blackmouth” in the species section for Chinook).

In Whatcom County:  Coho salmon are the most widely distributed salmon in Whatcom County. They occur throughout the anadromous zone (to where salmon can migrate unimpeded) of the Nooksack River watershed; spawning in the three forks and their tributaries and in the mainstem and its tributaries.  Coho also occur in independent coastal drainages including Dakota, California, Terrell, Squalicum, Whatcom, Padden and Chuckanut Creeks. Hatchey production occurs at Lummi Nation’s hatchery at the South Fork’s Skookum Creek.

Range: Central California to Point Hope, Alaska; patchy in Asia and abundant only in the Sea of Okhotsk and Kamchatka Peninsula; successfully introduced to southern Chile and the Great Lakes. Coho may not have extensive northern Pacific Ocean distribution and may remain mainly along the continental shelf waters.

Abundance: Although coho are widespread, they are often more abundant than Chinook but less abundant than sockeye, pink, and chum salmon. 

Life History: Juvenile coho in this region usually spend 1 year in freshwater before migrating to the ocean in the spring. Coho typically spend 2 years (2 winters) at sea and return to spawn at three years of age.  Some male coho, called jacks, mature early and return to freshwater in the fall after five to seven months in the ocean.

Spawning Season: November to January. 

Habitat Requirements: Coho require cool, clean well oxygenated water the same as other salmon species. Coho often use small tributaries for spawning and because the juveniles rear for a year in freshwater, they require a consistent nutrient source of macro-invertebrates especially aquatic stages of insects and compete with resident trout and juvenile steelhead. 

 Did You Know?  Because males reaching sexual maturity have hooked jaws, coho caught in this area in the fall are often called “hooknose silvers”. The genus name Oncorhynchus is derived from the Greek onkos (“hook”) and rynchos (“nose”). Jacks, rarely is there a Jill, are reproductively mature and are called “sneaker males” because they attempt to and do spawn with normal size females and avoid the larger, aggressive “hooknose” males. Coho may spawn in intermittent streams (lack flow in the summer) and they seek larger streams to survive unless the intermittent stream has deep pools fed by cool water flowing through the gravel and then perks up into a pool.

Photo credit: Pacific Salmon- Childerhose and Trim - Douglas & McIntyre Vancouver/Toronto