It was a bad week for Asian carp. Which is good for the rest of us.
Last Tuesday, the Minnesota congressional delegation announced that a provision in a federal water resources bill that is expected to become law provides for the closure within one year of the Upper St. Anthony Lock in Minneapolis.
The intent is to develop an absolute barrier that prevents bighead, silver, grass and other invasive carp from swimming upstream of that point, thereby threatening the state’s northern rivers and lakes.
The action is unprecedented, and represents the diligence of U.S. Sens. Amy Klobuchar and Al Franken, and U.S. Reps. Keith Ellison, Erik Paulsen, Tim Walz and Rick Nolan.
Perhaps worse still — for carp — the Minnesota Legislature approved a bonding bill that includes $6 million to rebuild the laboratory at the Minnesota Aquatic Invasive Species Research Center on the U’s St. Paul campus.
As presently constructed, carp research undertaken there by Prof. Peter Sorensen and others is conducted amid a labyrinth of Rube Goldberg-like tanks, pumps and pipes. Home-video productions of Frankenstein have showcased fancier sets.
But progress in the carp war is being made. In coming weeks, five specially built underwater speakers — technically, “transducers” — will be installed on the downriver side of the downriver lock doors of Lock and Dam 8 near Genoa, Wis., near the Minnesota-Iowa border.
If you’re an Asian carp, swimming upstream, intent on moving toward Winona, Wabasha and other points north, sound that will blast from the speakers should keep you away from the lock, and perhaps even push you back downstream.
The transducers cost $7,000 apiece and are being built by an Ohio company that constructs similar speakers for U.S. Navy warships.
“We’ll probably blast motorboat sounds through the transducers,” said Sorensen, founder of the research center. “We think it might have the same effect on Asian carp as a dental drill does on people.”
Sorensen et al aren’t the only experts to find that Asian carp are sensitive to sound. It’s widely believed that silver carp — the ones that leap from the water when powerboats approach — go airborne because they’re frightened by sound.
This latest salvo in what likely will prove to be an endless carp war is just part of a complex set of actions Sorensen and other researchers at the U lab plan in coming years.
“We don’t think the speakers by themselves will keep 100 percent of Asian carp from coming upriver,” Sorensen said, noting that occasional “rogue” specimens have been found in the Mississippi and St. Croix Rivers since 1997. “But we have to try something. And if the speakers seem to be keeping carp downriver, we’ll install redundant systems farther upriver, at Lock and Dam 5 and Lock and Dam 3.”
Each speaker will be bolted to the lock doors by divers, Sorensen said, and electricity needed to power them will cost about $2,000 a year.
“We don’t think that fish native to the river will be affected by the sound,” Sorensen said. “Carp are capable of hearing as many as 100 times better than most other fish. So we doubt other fish will be bothered.”
Installing the speakers became an urgent option in recent months after federal researchers found Asian carp eggs in the Mississippi not far south of the Minnesota-Iowa border.
Fearing the further advancement of reproducing fish, Sorensen asked for the public’s help, which was forthcoming, to pay for the Lock and Dam 8 speaker system. Since then, the Legislative-Citizen Commission on Minnesota Resources (LCCMR) has shifted lottery funds from a previous allotment to help pay for the speakers.
“We have every reason to believe if the carp swim up this far [to the Twin Cities, and into the Minnesota and St. Croix rivers] that they’ll do well,” Sorensen said. “That’s perhaps especially true in the Minnesota River. And there’s no technology on the horizon that can control their numbers once they’re here.
“It would be a really horrible problem. People’s enjoyment of these rivers would be lost for the indefinite future.”
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Friday morning, Sorensen and postdoctorate research fellow Dan Zielinski, along with recent U fisheries graduate Daniel Krause, walked amid tanks large and small at the U’s research lab. Common carp swam in some, bighead carp in others. Cross the movie “Jaws” with Shark Week and you get the picture, creepy-wise.
In one tank, Zielinski was testing whether air bubbles can slow the advancement of carp (they can). He also hoped to determine how much water current is needed to forestall carp from swimming upstream.
This last is important because Sorensen believes Asian carp perhaps can be prevented from swimming upriver through dam gates — the “doors” in dams that allow water to flow downstream — if the velocity of water flowing through them is fine-tuned.
This could be accomplished by tamping down the gates to “squeeze” water and increase its speed.
If all dams between #1 (the Ford Dam in St. Paul) and #8 are adjusted to increase velocity and work as a “system,” Sorensen believes, then perhaps another battle in the carp war can be won.
“We’ve already done some swim tests of carp down in Mississippi,” Sorensen said. “We plan to do more. But the early results indicate that Asian carp aren’t particularly strong swimmers. They might even be pretty ordinary. More like a walleye, and less like a salmon that swims upstream to spawn.”
To model optimal water velocities flowing through multiple dam gates between the Twin Cities and Iowa, Sorensen and other U researchers will employ the U’s supercomputer, a project funded by the LCCMR that will begin July 1.
A parallel effort to determine swimming capacities and other traits of native fish such as sturgeon also will be undertaken to ensure they are unaffected.
“Even then it will probably take us a year of modeling to see how the gates can be modulated as a system so water flows can overwhelm the swimming capability of these fish,” Sorensen said.
Skeptics abound. Some believe even a highly regulated lock and dam system, replete with speakers, can be overwhelmed by Asian carp, particularly in spring and other times of high water.
Others believe only research leading to development of a pathogen — a species-specific poison, in effect — is the answer. And the recent, mysterious die-off of 500,000 Asian carp in Kentucky suggests such a killer might exist.
But Sorensen says the war against Asian carp is in danger of being lost in the near term, and that anything that will keep reproducing numbers of the fish far downstream is worth trying while other strategies are developed.
Toward that end, closing the Upper St. Anthony Lock will be effective. But it does nothing to save either the Minnesota or St. Croix rivers, whereas the speaker and gate-modulation system, if successful, would.
Sorensen, meanwhile, appears to be taking in stride his recent reassignment from director and research scientist at the center he founded to that of research scientist alone, his specialty.
“Nothing’s for sure in this fight,” he said. “Ultimately, a coordinated set of multiple tools will be needed. But I see a way forward.”
Dennis Anderson • firstname.lastname@example.org