Traverse City, MI-If huge, hungry Asian carp reach Lake Michigan, their long-dreaded invasion might turn out to be less ferocious than once expected because a tiny competitor is gobbling up their primary food source, some Great Lakes researchers say.
The quagga mussel, a thumbnail-sized foreign mollusk first spotted in the lakes two decades ago, has devoured so much plankton in southern Lake Michigan that the entire food web is being altered, federal and university scientists reported in a series of newly published articles.
Mussels have "beaten the Asian carp to the buffet table," Gary Fahnenstiel, senior ecologist with NOAA's Great Lakes Environmental Research Laboratory, said Tuesday. "While the public has been worried about Asian carp and the Chicago canal, another invader has fundamentally changed the lake and made it inhospitable to the Asian carp."
Some biologists and government officials say if the carp get a foothold in Lake Michigan, they could spread to most of the Great Lakes and vacuum up enough plankton to threaten collapse of the $7 billion fishery. But Fahnenstiel and other researchers said the quagga mussel is a greater danger.
Some types of microscopic plants have declined more than 80 percent with the mussel's arrival, they said, which probably explains a similar drop-off of a freshwater shrimp species that is a dietary staple for small fish pursued by prized sport varieties such as salmon and trout.
Other scientists and policymakers insisted the carp could survive and even thrive in a plankton-depleted environment.
"They can eat other things besides plankton," said Duane Chapman, a U.S. Geological Survey biologist.
But Fahnenstiel said that if carp evade electronic barriers and reach the lake, they'll probably find so little nourishment they'll either go back or starve.
Scientists say whitefish and salmon, two of Lake Michigan's most popular species, have gotten smaller in recent years, a probable sign of malnutrition from a deteriorating food web.
"We are really getting a genuine collapse in the third-largest freshwater lake in the world," Michigan Technological University biologist Charles Kerfoot said.
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