Some Great Lakes biologists forecast a mostly cloudy future for the Asian carp.
The open waters of the Great Lakes are too cold for silver carp to digest food and reproduce, said Gerald Smith, professor emeritus with the University of Michigan’s Ecology and Evolutionary Biology department and author of the Guide to Great Lakes Fishes.
That’s good news for the part of the $7 billion Great Lakes sports fishery supported by deep water fishing for salmon and trout. If the carp thrived, they could pull the rug out from under the deep-water food web.
But the bad news is that the lakes’ warmer near-shore area and tributary rivers, as well as the western basin of Lake Erie, are more likely to support an Asian carp invasion.
“I think that’s going to happen and there’s nothing we can do to stop it,” said Smith, who spoke Monday on a panel hosted by Michigan State University’s Master’s in Public Policy Program.
Smith is confident that the carp will make it into the lakes because politicians are busy with election-year posturing over closing the Chicago locks system and ignoring other invasion routes. Those include anglers moving live bait and markets that could sell live carp to mischief makers who later dump them in the lake.
But another panelist argued that the physical and ecological separation of the Great Lakes and Mississippi River basins is more than a hasty reaction to carp. It’s a long-term solution to keeping either system’s invasive species from getting into the other, said Dan O’Keefe, an extension educator with Michigan Sea Grant.
O’Keefe said that the electric fish-shocking barrier on the Chicago Sanitary and Ship Canal was originally built to keep the invasive round goby from sneaking out of the Great Lakes and into Chicago canal system and Grand Calumet River. That fish made it through anyway, which points to the need to separate the basins for the good of each of them.
There are plenty of species in the Great Lakes that have yet to invade the Mississippi River. O’Keefe named the New Zealand mud snail, viral hemorrhagic septicemia (sometimes called “fish Ebola”) and Eurasian ruffe as examples.
“The Mississippi basin has as much to lose as the Great Lakes basin,” he said.