Professor has cheap plan to stop invasive carp, but needs money now
ST. PAUL -- The carp invading Minnesota up the Mississippi River can be stopped — at least for several years.
It’ll only cost $60,000.
But the man with the plan — University of Minnesota researcher Peter Sorensen — doesn’t have the money.
And he needs it now for it to work.
“We’ll take money from wherever we can get it,” said Sorensen, who heads the Minnesota Aquatic Invasive Species Research Center at the university’s St. Paul campus. “We need to put these things in the water as soon as possible.”
Those “things” are five transducers — underwater speakers — that Sorensen and his team want to install at Lock and Dam No. 8 near Genoa, Wis.
Bighead or silver carp, possibly both, are successfully breeding below the dam, researchers discovered last month. But there’s no evidence the fish, often called Asian carp, are breeding above it in Pool 8, which extends north along the Minnesota-Wisconsin border to La Crosse, Wis.
Sorensen and his team, including Ph.D. student Dan Zielinski, have discovered that the carp are sensitive to — and annoyed and deterred by — sounds not heard by most other fish. The speakers would play those sounds just downstream of the lock, which is the carp’s most likely doorway farther into Minnesota.
“Our goal is to design a deflector shield around the lock,” Sorensen said.
Time is of the essence, he said, because bighead and silver carp swim upstream to spawn, and spawning will begin this summer.
Sorensen’s traditional sources for money — the university and the state legislature — don’t turn around funding rapidly, so Sorensen is now hat-in-hand, asking for donations, which would be handled through the University of Minnesota Foundation (giving.umn.edu).
The transducers are part of a larger plan developed by Sorensen to slow or halt the spread of the carp, based on research by his team that discovered two vulnerabilities of the fish: They have sensitive ears and they don’t swim that fast.
Carp have “hearing” that’s 10 to 100 times better than all native fish except catfish, thanks to a rib bone that vibrates against the fish’s swim bladder, essentially turning the organ into a large eardrum. Using live carp and a tank that looks like a hot tub, Zielisnki discovered that by playing combinations of louder and softer low-frequency sounds — a din similar to a boat motor — he could not only annoy carp but deflect them.
“I started researching bubble curtains for common carp, but what I found out was they were likely responding to the sound of the bubbles more than the bubbles themselves,” Zielinski said. Silver carp, known for spectacular leaps from the water when boats speed by, likely are fleeing the sound of the motor, he said.
Meanwhile, Sorensen’s lab and the university worked with the U.S. Army Corps of Engineers to find out how fast carp can swim. No one knew.
“It turns out their swimming capabilities are very normal,” Sorensen said. “Similar to a walleye but much slower than a salmon.”
That meant that if the Army Corps, which operates the lock-and-dam system, could keep water flowing fast enough through the dam’s gates — which it can by tweaking procedures — carp would be unable to swim through.
Which leaves the lock. The underwater motorboat sound would protect that.
The plan might sound similar to a much pricier proposal — $12 million to $19 million — to build an acoustic, bubble and light barrier at the Ford Dam in St. Paul.
But the goal of that proposal, which hasn’t yet been funded, was to get as close as possible to a 100-percent barrier.
“We’re not saying (we expect) 100 percent (success) for our plan,” Sorensen said. “We’re saying maybe 90 percent, maybe better. We’re just talking about a simple cheap thing that can brush them off. … As long as they don’t have the numbers to establish themselves, we’ve bought time. Once they establish themselves as a breeding population, we have absolutely nothing to get rid of them.”
Both the underwater speakers and the changes in the dam’s gate procedures need formal approval from the Army Corps, but neither would threaten navigation or the structure of the lock and dam, so the agency doesn’t expect any delays, said Shannon Bauer, public affairs chief for the Army Corps’ St. Paul district.
The cost — $45,000 for the speakers and $15,000 for a contractor to install them — is a pittance compared to the tens of millions of dollars being spent to battle aquatic invaders that range from zebra mussels to curly leaf pondweed.
Bighead and silver carp are seen as a major threat to the health of Minnesota’s waters and the state’s fishing. The fish voraciously eat plankton, the base of a water’s ecology, and where they’ve established themselves, native fish suffer.
Lawmakers generally have supported spending money to battle aquatic invaders, which continue to spread.
A $16 million project is underway to make the Coon Rapids Dam a more effective barrier against Asian carp.
The state Senate earlier this month approved a plan to dole out $5 million this year — and $10 million annually after that — from the state’s general fund to counties statewide to battle aquatic invasive species. The provision wasn’t part of the accompanying tax bill approved by the House, so it remains unclear whether it will become law.
Sen. Rod Skoe, DFL-Clearbrook, who introduced the plan, said it dovetails with a larger philosophy that the Department of Natural Resources act as a central clearinghouse for programs that work. To that end, the Legacy Amendment bill moving through the legislature contains $4 million from the Outdoor Heritage Fund for the DNR to develop and evaluate pilot projects to battle aquatic invaders.
And Sorenson’s underwater speakers are actually already on track for state funding as part of an $800,000 request supported by the Legislative-Citizen Commission on Minnesota Resources, which recommends a portion of lottery proceeds for the environment.
But by law, that money cannot be appropriated until July 1, and university rules prohibit spending money until a grant has been fully approved. Bottom line, Sorensen said: “It would be another year before we got this done via the official channels. The machinery can only move so fast.”
Jumping out of the laboratory and pleading for donations is an unusual role for Sorensen, who frequently preaches that the campaign against invasive species is long term and requires years of research.
But he said his perspective changed in March when federal scientists discovered that Asian carp had fertilized eggs downstream of Lock and Dam No. 8 near Lynxsville, Wis.
“It kind of kills me because it’s not really research and we’re still studying how to make sure we do as much as we can to not affect native fish,” he said. “But when the news came out about the eggs, I thought about it for a while and came to the conclusion that I just needed to do something.”
He went ahead and ordered the underwater speakers.
“I really need that money because they’re building them on spec.”
The Pioneer Press is a media partner with Forum News Service.