Asian carp could survive in Lake Michigan on the poop of invasive mussels, says a University of Michigan study that is disturbing news for the Great Lakes.
“It’s new and it’s troubling,” Canada Research Chair in Aquatic Invasive Species Hugh MacIsaac said Tuesday from the University of Windsor.
“Because the mussels are so common in Lake Michigan it suggests the carp probably wouldn’t have any difficulty finding sufficient food to survive.”
That increases the risk to the Great Lakes if the Asian carp aren’t stopped in the Chicago area and get into Lake Michigan, MacIsaac said.
MacIsaac was commenting on a study of Lake Michigan’s suitability for two species of Asian carp that was published online in Freshwater Biology Monday.
Lead author Peter Alsip said the analysis found the risk of bighead carp and silver carp surviving and establishing in Lake Michigan is higher than previously thought.
“Our study does indicate that their chances of surviving a journey across Lake Michigan and potentially into the other lakes is greater because of their ability to eat multiple foods,” said Alsip who did the work for his masters thesis and is now an ecological modeling data analyst at the University of Michigan’s Cooperative Institute for Great Lakes Research.
Bighead carp, which can reach 40 kilograms, and silver carp, the ones known for leaping out of the water, filter feed on plankton that had decreased in Lake Michigan in the last 50 years. There was less algae and other types of plankton because of the invasion of the filter-feeding zebra and quagga mussels and because less phosphorus was getting into the lake, Alsip said. That made some think there wouldn’t be enough food for Asian carp if they got into the lake.
But the large carp are capable of surviving on dead organic matter including mussel poop and partially digested material that is also excreted from the mussels. Once an analysis considered a varied diet and finding food beyond the lake surface, the study found there was 4.6 times as much suitable habitat for bighead carp and 2.3 times more for silver carp than previously thought, he said.
“It was surprising at first,” Alsip said although he soon learned from experts that Asian carp are very resilient and adaptive.
And if bighead carp and silver carp get into Lake Michigan, they would have an easier time finding a mate, he said. Since they can swim long distances and not eat for long periods of time, they would likely be able congregate where there’s more food in Green Bay and the mouths of rivers. That would make them more likely to find others than if the invaders were swimming randomly in the large lake, Alsip said.
MacIsaac, who is a professor at the University of Windsor and its Great Lakes Institute for Environmental Research, called the study huge news.
“This is a real surprise,” MacIsaac said. “I would have thought it (Lake Michigan) was almost like a biological desert because most of that food has been stripped out by the mussels but now we find out they’re able to access this mussel waste which is new. And it would be troubling because with the exception of Lake Superior we have very large mussel populations throughout all of the other Great Lakes.”
The risk to the Great Lakes only increases if bighead carp and silver carp get into Lake Michigan so it emphasizes the need to speed up efforts to keep carp from using the Chicago Area Waterway System to get from the Mississippi River drainage area to the lake, MacIsaac said.
The head of the U.S. Army Corps of Engineers sent a $778 million plan to Congress in May on creating a series of carp barriers at the Brandon Road Lock and Dam near Joliet, Illinois which is about 64 kilometres from Lake Michigan.
Alsip said the study does reinforce the importance of investing in prevention. “Once an invasive species becomes established, the cost and effectiveness of managing these species becomes a lot more expensive and a lot more difficult.”
Bighead and silver carp are considered the main species of Asian carp that threaten the Great Lakes because of their size and because they are voracious eaters of plankton that young fish eat.
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