Coho salmon are the wild things of Lake Michigan.  Often referred as silver salmon or just coho, they are nuts when on the line.  They are similar in appearance to kings, but quite different when it comes to the fight.  They like to roll and jump and do whatever else they can to get off the hook.  Their average size is smaller than kings, but their hyperactivity makes them a joy to catch.  They often feed in schools, so where there is one, there are often many more.  Fast limits can be obtained when a school of hungry coho are around.  They feed on baitfish and bugs alike, but for some reason have a hankering for anything orange.  Coho can be caught at all water depths and any time of the season, but they are most readily caught in early spring in shallower waters, and again in the fall while staging to spawn.  Their smaller size is no indication of attitude while battling one of these and their fillets are the tastiest you will put on the table.  They average size is 1-6# with larger specimens taken in good numbers in certain years.  2007 saw some good coho and 2008 looks promising as well.  Coho are very succeptible to the amount of forage in the lake since they spend the first year and half in a hatchery, they have limited time to feed.  Therefore, they make the most of it when food is abundant and they get noticably larger. 

This is the Michigan DNR description:

Coho Salmon Oncorhynchus kisutch 

Identifying characteristics: (Non-Native Fish) Two dorsal fins including one adipose fin, inside of mouth black and gums between teeth gray, small spots on upper tail, 13-15 rays in anal fin.

The average adult Great Lakes coho salmon weighs eight pounds. Like the chinook, coho are native to the Pacific coast of North America, and to parts of Asia. They were introduced into the Great Lakes in 1873 but the first successful plantings weren't until 1966. There was much excitement amount anglers and fish managers when coho made their first spawning run in the fall of 1967. Since that time, the coho has become a popular sport fish, in fact people come from all over the world to fish Michigan's great coho fishery.

Although coho do spawn in Great Lakes tributaries, present fish stocks are maintained mainly by fish culture and stocking. There simply aren't enough streams available to produce all the fish the Great Lakes can handle. Coho spawing runs up tributary rivers occur from early September to early October. Females excavate a nest in a tributary stream's gravel bed. Both adult die soon after spawning. The next spring the eggs hatch and the young remain in the gravel for 2-3 weeks. When they emerge (March to July), some migrate downriver almost immediatly. Most, however, wait a year or longer before descending to the lake.Once in the lake, they stay near shore for a few months, then seek deeper waters.

Young coho eat greedily and grow rapidly. Most coho spend about 18 months in the lake, then return to their parent streams to spawn (at age three or four). As soon as they are large enough, young coho begin to eat smaller fish, mostly of other fish species. In the Great Lakes, larger coho feed on smelt and alewives. They compete primarily with steelhead for food. Coho are preyed upon by predatory fish and birds while they are small, and residual numbers of sea lampreys also take their toll of coho populations.