U.S. Army Corps plans ‘zone of chaos’ to keep invasive carp from reaching the Great Lakes silver carp (NOAA Great Lakes Environmental Research Laboratory/WikiCommons)
The U.S. Army Corps of Engineers has an aquatic house of horrors planned for invasive Asian carp threatening the Great Lakes.
The gauntlet of irritation is part of a “layered defense” of Lake Michigan that the Corps is preparing to implement over the next several years to thwart the arrival of undesirable carp by way of Chicago-area rivers and canals.
If the noise won’t drive them away, then perhaps the curtain of bubbles will. And if neither are successful then ideally a shot of electricity will do the trick.
The plan received a boost last week when the Biden Administration awarded $225.8 million for partial design and construction of the Brandon Road Interbasin Project, which comes with an ultimate price tag of more than $850 million over several years.
The Corps hopes to award a construction contract for “increment one” in the summer of 2024.
Fish of concern
There are four primary species of Asian carp that worry the Corps and others concerned with the health of the Great Lakes.
The silver and bighead carp would be the two most destructive to Lake Erie, said Tory Gabriel, extension program leader and fisheries educator for the Ohio Sea Grant program at Ohio State University. That’s because they eat plankton and would crowd out native species such as walleye and perch.
The silver carp provide an added danger because they are known to jump out of the water in response to boat motors and cause injuries to humans.
Advocates for the Great Lakes have worried for years that Asian carp will make their way from the Mississippi River watershed into Lake Michigan, threatening the entire Great Lakes and its multi-billion dollar fishing and boating industries.
Connecting watersheds
The pathway for the carp was created more than a century ago after Chicago grew concerned about sewage flowing from the Chicago River into Lake Michigan and reversed the river’s course so that it instead connected to the Des Plaines River, part of the Mississippi River basin.
A similar rerouting of the Calumet River is also part of the extensive waterway system west of Chicago.
So far, only one silver carp has been caught upstream from the existing electric barriers located at the village of Romeoville on the Chicago Sanitary and Ship Canal, said Kevin Irons, assistant chief of fisheries for the Illinois Department of Natural Resources. That was in 2017, about nine miles west of Lake Michigan on the Little Calumet River.
“It’s rather odd that it appeared where it did,” Irons said, adding that it could have been pulled through the electric barriers by a barge “or a human could have put it in a bucket and taken it there.”
A single bighead carp was found in Lake Calumet, also part of the waterway system, in 2010.
What’s in store for the carp?
The Interbasin Project, which is planned for the Brandon Road Lock and Dam 27 miles southwest of Chicago on the Des Plaines River, would provide additional safeguards to keep carp from even making it to the existing electric barriers at Romeoville.
One of the planned deterrents will be speakers in the water that will emit noise designed to turn the fish away. Irons said researchers are still working on the right sounds.
“We know we could push fish with boat motor sounds,” he said, but blasting those could be inefficient because it’s probably just certain frequencies the fish are responding to.
“It won’t be music or any scripted sound,” he said, but probably something closer to white noise.
A second layer of deterrent will be a curtain of bubbles rising from an air-filled pipe along the bottom of the stream. It’s expected that the bubbles will turn the fish away, said Andrew Leichty, project manager for the Corps, but they may also be used to extract tiny carp caught in the hydraulic currents created between two barges as they approach the lock.
Also, an electric barrier will be installed as part of the project’s “increment two.” It’s expected to be most effective on larger carp.
Among the safety concerns with an electric barrier are stray voltage that can interfere with neighboring electrical systems and humans falling off boats and into charged water, Leichty said.
At Romeoville, all mariners must be inside the pilot house of their vessel while passing through the electrified area as a precaution against falling in the water, Leichty said.
Yet another technique to be employed later in the project’s development will be the ability to flush water downstream through the lock when boats pass through. The flushing would be designed to carry away any fish eggs or larvae floating in the water, Leichty said.
A price on their heads
In addition, as part of an overall inter-agency front to battle the carp, the Illinois Department of Natural Resources will continue to encourage fishermen to catch and remove the offending species from Illinois rivers so that they never reach the Chicago area. There’s a bounty of $100 per fish on black carp, which are the most difficult of the four to find, Irons said.
Also, fisherman can earn 10 cents for every pound of Asian carp they catch along an 80-mile stretch of the Illinois River, which is formed by the confluence of the Des Plaines and Kankakee rivers and flows into the Mississippi.
As of now, most carp do not swim very far up the Des Plaines River, Irons said, and one reason could be that they are turned off by pollutants, including chemicals and discarded medications, that they encounter in the water as they swim upstream toward Chicago.
While the Asian carp can be damaging to all the Great Lakes, Lake Erie could be especially harmed by Asian carp, according to a 2016 report by the Great Lakes Environmental Research Laboratory of the National Oceanic and Atmospheric Administration.
The only one of the four species found in Lake Erie so far is the grass carp. It was first detected spawning in the Sandusky River in 2013 and likely got there after having been stocked in ponds years ago, Gabriel said.
The grass carp is considered less harmful than the silver or bighead species because it feeds on aquatic vegetation, Gabriel said, and so far it has not been found in populations large enough to cause any damage.
Three bighead carp were found in Lake Erie, one in 1995 and two in 2000, while the silver carp has never been seen in the lake, Gabriel said.
Gabriel said he supports the Brandon Road Interbasin Project, which would basically create a “zone of chaos” that the fish would have to breach to reach Lake Michigan.
Asked how confident he is that the efforts will be able to keep the Asian carp at bay, Gabriel said that’s hard to say.
“The more things that we do like this the higher my confidence gets,” he said.
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