To understand why salmon are so important to the Great Lakes and the Michigan economy, you first have to understand some history.
It used to be the lake trout was the fish to catch. It was big. It was tasty. But, by the late 1950s, that fish and others had been severely over-fished. And, an eel-like, blood-sucking parasite called the sea lamprey further reduced lake trout numbers.
Those weren’t even the worst problems for lake trout. A fish called the alewife invaded the Great Lakes through manmade canals. Lake trout starting feeding on alewives. But alewives caused a thiamine deficiency in lake trout. A lack of vitamin B-1.
Mark Gaden is with the Great Lakes Fishery Commission
“The thiamine deficiency that the alewives cause is one of the top reasons why natural reproduction has been very slow to occur over the decades in the Great Lakes of these species.”
Catching a lake trout became rare.