![]() Lake managers are considering stopping that hatchery program - something most biologists would have thought improbable just six or seven years ago. But since the alewife declines, the trout are again successfully breeding in the wild. The top native predator had been sustained on Lake Huron with hatchery plantings for decades. The thiamine problem has been known for years, but the extent that it was foiling federal efforts to restore lake trout in the Great Lakes was not grasped until the Lake Huron collapse. Alewives carry high levels of an enzyme that triggers a thiamine deficiency in trout, which causes their eggs to either not hatch or induces deadly development problems in trout offspring. They gobble up the eggs and young of native species and out-compete them for the zooplankton that is the foundation of the lake's food chain.īut alewives also doom lake trout in a manner that borders on subterfuge. It turns out alewives are death for the Great Lakes' native fish species in a number of ways. "And how can you call that a recovered fishery?"īiologists had long suspected that the massive schools of alewives were trouble for native species they just didn't know how much trouble until the alewives virtually disappeared on Lake Huron. "If you really want a native fish recovery, you're not going to fully achieve that in the presence of alewives, unless natives are sustained by hatcheries," said Fielder. One of them is Fielder, who proudly displays on his cluttered desk a framed "Tanner and Tody Award" received from the state for examining what's happened to Lake Huron's food chain since the alewife collapse. Some biologists on Lake Huron today are looking at alewives completely differently. "Maybe not as such a big nuisance, but that was the foundation of what you were trying to build. You wanted them there forever," said Tanner. "You wanted the alewife to be alive and healthy. Huron’s Saginaw Bay, where they have hit record numbersĮven though the stocking program ended in 2006. Walleye have already been declared “recovered” on Lake
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