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coho salmon

coho salmon (Oncorhynchus kisutch) [nonnative]
Photo © Paul Vecsei/Engbretson Underwater Photography

Features and Behaviors


The average size of a coho salmon is four to six pounds in weight and 11 to 26 inches in length. It may attain a maximum length of 38 inches. The gums of the lower jaw are white at the base of the teeth. Black spots are present on the back and the upper half of the tail. The breeding male has green on the back and head and a bright red side. An adipose fin is located near the tail fin. Nonbreeding males and females are steel-blue to greenish on the back, silver on the sides and white on the belly. The coho salmon is also called the "silver salmon." Its average life span is three to four years.


The coho salmon lives in Lake Michigan. This fish reaches maturity at an age of three to four years. Spawning occurs in fall. It moves to tributary streams on the eastern side of Lake Michigan to reproduce. The female deposits 3,000 to 5,000 eggs which are buried in gravel. Eggs hatch in 35 to 90 days. The coho salmon eats fishes such as alewives and smelt. The coho salmon is exotic to Illinois. Native to the Pacific northwest, it was introduced to Lake Michigan in 1967. Although some of these fish reproduce naturally, stocking of fish raised in hatcheries is necessary to maintain population levels.

Illinois Range


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Salmoniformes
Family: Salmonidae

Illinois Status: common, nonnative