The coho salmon is a species of anadromous fish in the salmon family. Coho salmon are also known as silver salmon or "silvers".
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. Some stocks of coho salmon migrate more than 1,000 miles in the ocean, while other stocks remain in marine areas relatively close to the streams where they were born.
During their ocean phase, coho salmon have silver sides and dark-blue backs. During their spawning phase, their jaws and teeth become hooked. After entering fresh water, they develop bright-red sides, bluish-green heads and backs, dark bellies and dark spots on their backs. Sexually maturing fish develop a light-pink or rose shading along the belly, and the males may show a slight arching of the back. Mature adults have a pronounced red skin color with darker backs and average 28 inches (71 cm) and 7 to 11 pounds (3.2 to 5.0 kg), occasionally reaching up to 36 pounds (16 kg). Mature females may be darker than males, with both showing a pronounced hook on the nose.
The traditional range of the coho salmon runs along both sides of the North Pacific Ocean, from Hokkaidō, Japan and eastern Russian, around the Bering Sea to mainland Alaska, and south to Monterey Bay, California. Coho salmon have also been introduced in all the Great Lakes, as well as many landlocked reservoirs throughout the United States.
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