Skip Navigation

Coho Salmon


Adult coho may measure more than 2 feet (61 cm) in length and can weigh up to 36 pounds (16 kg). However, the average weight of adult coho is 8 pounds (3.6 kg).  Coho salmon have dark metallic blue or greenish backs with silver sides and a light belly and there are small black spots on the back and upper lobe of the tail while in the ocean. The gumline in the lower jaw has lighter pigment than does the Chinook salmon. Coho spend approximately the first half of their life cycle rearing and feeding in streams and small freshwater tributaries. Spawning habitat is small streams with stable gravel substrates. The remainder of the life cycle is spent foraging in estuarine and marine waters of the Pacific Ocean.  Spawning fish in inland rivers are dark with reddish-maroon coloration on the sides.
 
Coho salmon adults migrate from a marine environment into freshwater streams and rivers of their birth in order to mate (called anadromy). They spawn only once and then die (called semelparity).  Adults return to their stream of origin to spawn and die, usually at around three years old. Some precocious males known as "jacks" return as two-year-old spawners. Spawning males develop a strongly hooked snout and large teeth. Females prepare several redds (nests) where the eggs will remain for six to seven weeks until they hatch.
The species was historically distributed throughout the North Pacific Ocean from central California to Point Hope, Alaska, through the Aleutian Islands, and from the Anadyr River, Russia, south to Hokkaido, Japan. Coho probably inhabited most coastal streams in Washington, Oregon, and central and northern California. Some populations, now considered extinct, are believed to have migrated hundreds of miles inland to spawn in tributaries of the upper Columbia River in Washington, and the Snake River in Idaho. Coho still occur in Alaska as well.
 
Habitat: 
Coho spend approximately the first half of their life cycle rearing and feeding in streams and small freshwater tributaries. Spawning habitat is small streams with stable gravel substrates. The remainder of the life cycle is spent foraging in estuarine and marine waters of the Pacific Ocean.
 
Critical habitat was designated on May 5, 1999 for the Central California Coast and Southern Oregon/ Northern California Coast coho salmon.
 
Distribution: 
The species was historically distributed throughout the North Pacific Ocean from central California to Point Hope, Alaska, through the Aleutian Islands, and from the Anadyr River, Russia, south to Hokkaido, Japan. Coho probably inhabited most coastal streams in Washington, Oregon, and central and northern California. Some populations, now considered extinct, are believed to have migrated hundreds of miles inland to spawn in tributaries of the upper Columbia River in Washington, and the Snake River in Idaho. Coho still occur in Alaska as well.
 
Population Trends: 
The long term trend for the listed populations is still downward, though there was one recent good year with an increasing trend in 2001. 
 
Threats: 
Salmonid species on the west coast of the United States have experienced dramatic declines in abundance during the past several decades as a result of various human-induced and natural factors.
 
There is no single factor solely responsible for this decline, given the complexity of the salmon species life history and the ecosystem in which they reside. For more information, please visit our Pacific salmonids threats page.
 
Conservation Efforts: 
A variety of conservation efforts have been undertaken with some of the most common initiatives including captive-rearing in hatcheries, removal and modification of dams that obstruct salmon migration, restoration of degraded habitat, acquisition of key habitat, and improved water quality and instream flow.
 
The Pacific Coast Salmon Recovery Fund (PCSRF) was established by Congress in 2000 to support the restoration of salmon species. The fund is overseen by NMFS and carried out by state and tribal governments. The 2006 PCSRF report summarizes their work in detail.
 
More information about the Coho Salmon can be found here.
 
Last Updated: Mar 25, 2013
Return to main navigation