Coho salmon

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.

Description

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 and occasionally reaching . Mature females may be darker than males, with both showing a pronounced hook on the nose.

Reproduction

The eggs hatch in the late winter or early spring after 6 to 7 weeks in the redd. Once hatched, they remain mostly immobile in the redd as the alevin life-stage, which lasts for 6–7 weeks. Alevin no longer have the protective egg shell, or chorion, and rely on their yolk sac for nourishment during growth. The alevin life stage is very sensitive to aquatic and sedimental contaminants. When the yolk sac is completely resorbed, the alevin leaves the redd. Young coho spend one to two years in their freshwater natal streams,often spending...
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