Statistics

Coho (Silver) Salmon
Oncorhynchus kisutch

Other names: silver
Average size: 6-12 lbs, up to 31 lbs

Coho salmon are a very popular sport fish in the Puget Sound. The species uses coastal streams and tributaries; often being present in small neighborhood streams. They can even be found in urban settings if their need for cold, clean, year-round water is met.

Spawning

Coho spawn in small coastal streams and the tributaries of larger rivers. They prefer areas of mid-velocity water with small to medium sized gravel. Because they use small streams with limited space, they must use many streams to successfully reproduce. As a result, coho can be found in virtually every small coastal stream with a year-round flow.

Returning coho frequently gather at the mouths of streams and wait for the water flow to rise, often after a rainstorm, before heading upstream. The higher flows and deeper water enable the fish to pass obstacles such as logs or beaver dams that would otherwise be impassable.

Rearing

Coho have a very regular life history. It takes them about 18 months to go from egg to smolt. In the fall they are deposited in gravel as eggs, emerge from the gravel the next spring, and then rear in the stream for a year before making their way to the ocean.

Body

• Mouth is light with a white gum line
• Medium size, sharp teeth
• Spots only on upper lobe of tail
• Spots on back
• Wide caudal peduncle

Jaw

The mouth is white and the gum line is almost white, but the tongue may be black. The teeth are sharp and strong.

Tail

The coho tail has just a few scattered spots, usually on the upper lobe, with silver streaks. It has a wide caudal peduncle.

Terminology

Alevin - The lifestage of a salmonid between egg and fry. An alevin looks like a fish with a huge pot belly, which is the remaining egg sac. Alevin remain protected in the gravel riverbed, obtaining nutrition from the egg sac until they are large enough to fend for themselves in the stream.

Anadromous - Fish that live part or the majority of their lives in saltwater, but return to freshwater to spawn.

Emergence - The act of salmon fry leaving the gravel nest.

Fry - A juvenile salmonid that has absorbed its egg sac and is rearing in the stream; the stage of development between an alevin and a parr.

Kype - The hooked jaw many male salmon develop during spawning.

Parr - Also known as fingerling. A large juvenile salmonid, one between a fry and a smolt.

Smolt - A juvenile salmonid which has reared in-stream and is preparing to enter the ocean. Smolts exchange the spotted camouflage of the stream for the chrome of the ocean.

Substrate - The material which comprises a stream bottom.