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Department of Natural Resources
Illinois
Exotic Species:
coho
salmon Oncorhynchus kisutch
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 green on the back, silver on the sides and white on the belly. Also
called the "silver salmon," this fish's average life span is
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. Native to
the Pacific northwest, this fish was introduced to Lake Michigan in 1967.
Although some reproduce naturally, stocking of fish raised in hatcheries
is necessary to maintain population levels.
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