Coho Salmon
Coho
Oncorhynchus kisutch
The Coho Salmon is a species of anadromous fish in the salmon family. Coho normally have silver sides and dark blue backs, but during their spawning phase they develop bright red sides, bluish green heads and backs, dark bellies with dark spots on their back and their jaws and teeth of become hooked. Mature Coho Salmon average 38 inches in length and seven to 11 pounds in weight, although Coho weighing up to 36 pounds have been reported.
The Coho is native to the North Pacific, but this fish has become a part of the Lake Superior fish population. After the Lamprey invasion of the Great Lakes, part of the effort to revive the lakes involved stocking them with other fish. This is how the Coho Salmon came to be in Lake Superior. These salmon have been planted in Lake Michigan and Lake Superior annually since 1966 and are now an important part of these lakes’ sport fishing industry.
Mature Cohos gorge themselves on alewives, smelt, and other forage fish. In Lake Michigan, Cohos attain an average weight of five to six pounds but often top out at 10 pounds or more. In Lake Superior, where forage fish are less abundant, Cohos average only two to four pounds.
Though smaller, Coho salmon are spawning successfully in most Lake Superior tributaries and thus have developed some limited but self-sustaining populations. There is some concern that this aggressive fish might disrupt the spawning of other valued species, such as brook, brown and rainbow trout.
Coho Salmon ordinarily return in their third year to the streams where they were planted to spawn and die. They reproduce naturally in many streams on the eastern side of Lake Michigan, but their general population must be sustained with hatchery-reared fish. Continual stocking has helped to improve the lake's predator-prey balance and given satisfaction to thousands of sport fishermen as well.
The Coho are an exotic species in Lake Superior, like the Lamprey. However, Coho were intentionally introduced to the lake. What are the benefits and drawbacks of bringing a new animal into an area that it has never lived in before?
