The alewife population in Lake Michigan has declined by 80 percent in the past 20 years, and the fisheries biologists who have been managing the lake during those two decades don’t know whether to laugh or cry.
What worries the biologists is, first, that this entire multibillion-dollar industry depends on the well-being of a dinky little fish that has trouble surviving a cold winter in Lake Michigan. And second, that the biologists are going to have to tell the politicians and the anglers that there may not be as many fish to catch next year as there were last year.
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Computer modeling of fish populations strongly supports the idea that alewives are not going to come back any time soon. Continuous heavy stocking of predators has built up their numbers to such high levels that even a complete shutdown of the hatcheries wouldn’t have any effect in the short term. And some of the introduced fish are reproducing successfully, so they could continue in the lake indefinitely.
Lake trout spend their entire lives in the open lake and lay their eggs on rocky reefs. These reefs are scattered around the lake–most are in the north–and there is no pattern to their distribution. Therefore there is no way except pure chance for a lake trout to find one.
It is wise in this situation to keep a long-term goal in mind and to judge today’s actions not by how well they address an immediate problem but by how they further that goal. You can’t think of just one thing at a time when you are dealing with nature.
