Trophy Coho Return to Illinois
BY MIKE ROUX
"It is very possible that the Illinois state record for coho salmon may be broken this year" Bob Jenkins said.
Jenkins, who has operated a charter fishing boat on Lake Michigan out of Winthrop Harbor for about a dozen years, went on to say, "It's because of the ever-increasing number of bait fish, specifically the alewife, that the coho are getting big again. Not since 1978 have I seen coho this big, this consistently.
"When I mention big, or trophy-sized coho I mean those in the 10 to 15-pound range," he said. "Not until 1999 had I ever seen a coho over 7 pounds. Last year we caught three over 10 pounds in one day, the largest being about 17 pounds."
The alewife, a small fish, about 6 inches long, weighing about four ounces is getting most of the credit for these larger fish. It is silvery and has a blue-green metallic luster on back. Sometimes called a grey herring or golden shad, this small fish is common to lakes Michigan, Huron and Ontario. It was introduced into the Great Lakes in the mid 1950s.
The alewife is the primary species of forage eaten by coho salmon in the Illinois water Lake Michigan. A university study in 1994-95 examined the stomach contents of several thousand coho from Lake Michigan. In Illinois waters, 85 to 90 percent of the pre fish eaten by adult coho were alewife. Occasionally, a coho salmon might eat other types of fish like bloated chubs, stickle-backs, small perch or possibly a goby, but the occurrence of types of fish in the diet is rare pared to the overwhelming sumption of alewife.
The recent increase in alewife numbers is not unusual. Alewife and other forage fish populations can fluctuate greatly from year to year. It is likely that the abundance of alewife is greater now than in the recent past because of very suc-
Mike Roux is a free-lance writer living in Quincy.
Greg Nixon, Quincy, shows off a 12-pound coho salmon taken from Lake Michigan last summer.
cessful hatches in 1995 and 1998. Not since the 1960s and 1970s have so many alewife been available to our Illinois coho.
So how big will our coho salmon get? The size of a coho can depend on a number of things, but water temperatures can promote a good hatch of alewife. A combination of a good hatch of small prey fish for juvenile salmon to feed upon during their first year in the lake, and then a good number of adult alewife for adult coho to feed on during their second year promotes an increased growth rate.
During the early summer, alewife spawn in harbors and near shore waters. By late fall, they move into deeper water to feed. They migrate toward shore again in mid-March and April. This is commonly called the coho run in Lake Michigan, as the salmon follow the alewife to the shallows.
The coho itself is a remarkable fish. These Pacific Ocean transplants were introduced into Lake Michigan in 1966. Hatchery-raised fingerlings have been stocked annually since then. Lake Michigan coho can reach near 40 inches in length and weigh up to 30 pounds. The Illinois state record is a 20-pound, 9-ounce coho taken in 1972.
It is very easy to see how this small bait fish can have such a dynamic impact on a much larger species like the coho salmon. Will a new Illinois record be set for coho in 2000? Many experts say it is possible.
One fact is for certain. Many happy anglers will take home trophy coho salmon from the Illinois waters of Lake Michigan this season.
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