Coho salmon are also known as silver salmon.
Description: Coho salmon are small, but powerfully built; averaging between 6 and 12 pounds (although they can grow to weigh up to 31 pounds and be more than 38 inches long). In the ocean coho have silver-grey flanks and silver-blue backs and they keep these ocean colors long after they have entered the freshwater to spawn, which has earned them the name “silver”. When in full spawning colors, the backs of the coho salmon turn dark and their bodies turn a deep red color. Like the Chinook, coho salmon have black spots covering their backs, but these only extend to the upper lobe of their tails. They also have black mouths, but their gums are bright white.
Range: San Joaquin River, California to Point Hope, Alaska; patchy in Asia to the Sea of Japan; successfully introduced to Chile and the Great Lakes.
Abundance: Although coho are widespread, they are less abundant than sockeye, pink, and chum salmon. They represent less than 10% of the commercial Pacific salmon harvest.
Life History: Juvenile coho salmon spend 1 or 2
years in freshwater habitats as
solitary, opportunistic predators. After moving out of the freshwater environment, coho typically spend
another 1 to 2 years at sea before leaving the saltwater to spawn.
Spawning Season: November to January.
Habitat Requirements: Because of their long juvenile freshwater residence, coho require small headwater tributaries where they compete with resident trout and juvenile steelhead. With winter flooding, coho juveniles use beaver ponds, side channels, and small tributaries to avoid the silt and currents of the freshet. The quality of both the water and riparian habitat in freshwater streams is especially important for this species.
In Our Local Watersheds: Coho salmon are present in almost every stream in the Nooksack River basin and several hatcheries in the area have supplemented the wild population with hatchery fish for many years. Coho are currently listed as a “Species of Concern” in Puget Sound and the Strait of Georgia and are a candidate for listing as an Endangered Species.
Did You Know? Juvenile coho salmon are known to migrate downstream in the spring shortly after they emerge from the gravel and spend the summer in brackish-water sloughs and marshes near river mouths. Rather than fully committing themselves to the ocean environment, some individuals migrate back upstream in the fall to spend the winter in the freshwater. Then, in the spring, these fish make their final downstream journey out to the ocean to mature.
For more information on Whatcom County's coho salmon click here.