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Coho Salmon Oncorhynchus kisutch


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Coho Salmon
credit: NOAA

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Alternate name: Silver Salmon

Family: Salmonidae, Trouts view all from this family

Description The Coho salmon, Oncorhynchus kisutch, (from the Russian кижуч kizhuch) is a species of anadromous fish in the salmon family. Coho salmon are also known as silver salmon or "silvers". It is the state animal of Chiba, Japan.

During their ocean phase, Coho have silver sides and dark blue backs. During their spawning phase, the jaws and teeth of the coho become hooked. They develop bright red sides, bluish green heads and backs, dark bellies and dark spots on their backs after they go in to fresh water. Sexually maturing coho 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 36 pounds (16 kg). Mature females may be darker than males, with both showing a pronounced hook on the nose.

Dimensions Up to 3'3" (99 cm).

Endangered Status The Coho Salmon is on the U.S. Endangered Species List. Certain naturally spawned populations in California and Oregon are classified as threatened. This salmon's numbers in Oregon dropped from 1.4 million in 1900 to 20,000 less than 100 years later. In Washington the Coho is virtually extinct, and in California the population has dropped from half a million in the 1940s to a few thousand today. Many factors have exterminated the Coho Salmon from its historic range, including alterations to its habitat caused by livestock grazing, mining, pollution, water-diversion, and urban development. The biggest impact has been dealt by the logging industry. Cutting of trees exposes the salmon's spawning streams to sunlight, which heats the water to temperatures that are lethal to these fish. Additionally, erosion from logging activies causes the steams to silt up and become too muddy for the fish and their eggs to survive in. The logging industry opposes measures that would help conserve salmon habitats and restore populations.

Habitat Rivers & streams, Estuaries, tidal flats & salt marshes, Ocean or bay shallows, Open ocean.

Range Rocky Mountains, California, Northwest, Western Canada, Alaska.