The last line of defense against Asian carp entering Lake Michigan isn’t impenetrable, according to a new report by the U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service.
Fish can pass through the electric barrier unharmed when they get caught in the wakes of barges passing through. And that’s not all. Metal barges can deplete the charge, and small fish aren’t always susceptible.
"Initial findings indicate that vessel-induced residual flows can trap fish and transport them beyond the electrical barriers, and that certain barge configurations may impact barrier electric field strength,” says an interim report based on laboratory and field experiments.
“Additionally, the preliminary (sonar camera) findings identified the potential for small fish (between 2-4 inches in length) to pass the barrier array in large groups, or schools."
The Corps emphasizes that the findings are preliminary, with more work to be done with the barge community and the Coast Guard to see how the barrier can be strengthened.
“There is no evidence that Asian Carp are bypassing the barriers; nor is there any indication Asian carp are in the vicinity of the barriers,” the agency says. “The closest adult Asian carp found in the Illinois River are about 55 miles from Lake Michigan, and no small Asian carp have been observed closer than 131 miles from Lake Michigan.”
Critics point out that water samples taken near the barrier and in a canal on the lake side of the barrier have tested positive for the exotic fish. Plus, poisoning of the canal in 2009 revealed an Asian carp carcass.
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(This article appeared originally in B.A.S.S. Times.)