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One of the first local leaders to recognize that something needed to be done was Mayor Richard M. Daley. In May 2003, he and the U.S. Fish and Wildlife Service convened the two-day Aquatic Invasive Species Summit in Chicago. The carp were about 55 miles from Lake Michigan.
As luck would have it, just the year before, the Army Corps of Engineers had completed an electric barrier on the canal near Romeoville. Its original purpose was to repel yet another finned menace: the mollusk-munching round goby, a Eurasian native, which was moving south from the Great Lakes. (The electric barrier functions like an invisible dog fence: creatures approaching it receive a shock that, theoretically, keeps them from advancing.) Unfortunately, by the time the barrier was up and running, the goby had already slipped by. But at least the barrier could stop the carp from going north, right?
Wrong, concluded the 60-plus experts who had traveled from around the world to attend Daley’s conference. They worried that the barrier wasn’t reliable enough to keep the carp out. There was, the attendees concluded in a postconference report, only one “essential” solution: “Completely separate the waters of the Great Lakes and Mississippi River basins by creating a physical or other type of barrier in the Chicago Canal System.” Without such a move, the experts foresaw “irreversible damage to these remarkable ecosystems.”
Amid corporate and government fears about the economic impact—an estimated $16 billion in cargo annually travels through the Chicago Area Waterway System—not much happened. The Illinois DNR did what it could—for example, hiring fishermen to catch carp in the Illinois River. Last summer, the DNR hauled in 240 tons of carp, which was turned into fertilizer; commercial fishermen caught tons more, most of which were shipped to China under an agreement signed in July 2010 by Governor Pat “If You Can’t Beat ’Em, Eat ’Em” Quinn. But that wasn’t enough to quell the threat. (Mayor Rahm Emanuel declined to comment for this article.)
Rather than rethinking electric barriers in the wake of the experts’ warnings, the Corps of Engineers kept building more. There are now three on a 1,150-foot-long span of the canal, all near Romeoville, all designed, built, evaluated, and maintained by the corps at a cost thus far to taxpayers of about $75.4 million.
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In the fall of 2009, David Lodge made an unsettling discovery. The director of the Environmental Change Initiative at the University of Notre Dame, Lodge had been hired by the corps to help assess the carp threat. He soon realized that the corps did not seem to know exactly how far toward Lake Michigan the fish had traveled. “If you don’t know where they are, you can’t fight them,” he says. “It occurred to us that, rather than capture the fish [as the corps had been doing], maybe we could figure out where they were using indirect genetic means.”
With his colleagues, Lodge began collecting water samples from the canal and testing for environmental DNA, or eDNA, cellular material the carp had left behind. “We did not expect to see evidence of the carp north of the electric barrier,” Lodge remembers. “We were astonished and very disappointed to find it there.”
In November 2009, state and federal officials announced that eDNA evidence of the Asian carp had been found on the Calumet River near the T. J. O’Brien Lock and Dam, more than 20 miles above the barrier (see map, page 94). (In addition to that lock, water from the canal passes into Lake Michigan via four sources: the Wilmette Pumping Station; Chicago’s downtown locks, officially known as the Chicago River Controlling Works; the Indiana Harbor and Canal; and the Burns Waterway Harbor in Indiana.)
To Henry Henderson, Midwest program director for the NRDC, discovery of carp eDNA past the electric barriers is proof that “the barriers don’t work.” Lodge agrees. Because DNA decomposes quickly, he rules out the possibility that the eDNA arrived in the river after passing through the digestive system of a bird or human who had consumed the carp. Other scenarios seem equally unlikely. “All the evidence that exists points to the most plausible explanation for the positive DNA findings,” Lodge says. “There are Asian carp above the barrier.”
Don’t tell that to John Goss, President Obama’s so-called carp czar (he heads the Asian Carp Regional Coordinating Committee, which comprises 21 local, state, and federal agencies). “Right now, there’s a lot of uncertainty about what traces of eDNA mean,” says Goss, who formerly worked at the Indiana Wildlife Federation. “We don’t know if it’s evidence of a live or a dead fish or if it comes from fish scales or from a barge [traveling in the Chicago canal]. We need further research.” He adds: “All evidence shows that we are succeeding in keeping Asian carp out of the Great Lakes.”
The Illinois DNR, for its part, took Lodge’s news very seriously. Within days, its biologists poured 2,200 gallons of the fish toxin Rotenone into a six-mile stretch of the canal below the barriers. The operation yielded between 30,000 and 40,000 dead or surfaced fish; only one of them was an Asian carp, and it was found five miles below the barriers. A month later, commercial fishermen hired to search for carp above the barriers netted a three-foot bighead in Lake Calumet—a worrisome development, especially since officials couldn’t say how it got there. Over the next 11 days, fishermen deployed ten miles of nets in Lake Calumet and captured more than 15,000 fish. None of them were an Asian carp.
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