How would you react to a suggestion that we grow alewives in hatcheries and release them into Lake Michigan? Doubtless you know about alewives, the silvery little fish from the Atlantic Ocean that invaded our lake a few decades back. In the late 60s, it seemed like alewives were put on earth to die and wash ashore in great stinking heaps. This spring they worked a variation on that morbid task by dying and floating into the quiet corners of our harbors.
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Of course there are other small fish in the lake, and as alewife numbers were reduced, native fish like bloaters and yellow perch showed good population growth. Some fisheries biologists began predicting that the salmonids–salmonids, or salmonines, is a general term that describes both salmon and the closely related lake trout–would change their eating habits and go after the more abundant species. Theory says that predators act like people playing the stock market. They look for a maximum return in calories for the time and energy they invest. Rather than spend all day searching for scarce alewives, the salmonids would conserve their energy by eating bloaters or smelt.
But so far all indications are that the salmonids have not made the switch. Alewife numbers continue to decline, and perch and bloater populations to burgeon.
So you take millions of hatchery fish–fish that grew up in a situation where they were never hungry, never faced danger, never had to worry about competition, never had to work for a living. Dan Quayle fish. And you let them loose in the wild. It should not surprise you that they are not as flexible or adaptable as fish that came up the hard way.
But the perch also protected themselves by hiding. According to Allen’s thesis, they would “take up positions along walls, in the corners, behind the cooling coil, or near the surface and remain absolutely motionless for hours. Sometimes for days.”
Allen Feldman is a lake trout supporter. “We have to manage everything,” he told me. “Nothing is pristine anymore. But we should try to manage toward more natural balance. Managing for salmon is labor intensive and not good for the ecological community. We should be managing in the long term–over the next century–for a self-sustaining lake trout population.”
