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Overrun: Asian carp crisis on its way

Submitted/ "Overrun Dispatches from the Asian Carp Crisis" looks at four Asian carp species now found in North American waters. Reproducing populations are not believed to exist in the Minnesota River, but captures of Asian carp in 2016 and 2017 has led the Minnesota Department of Natural Resources to list the river as infested for bighead carp and grass carp from Granite Falls to the confluence with the Mississippi River. 1 / 3
Submitted/ Andrew Reeves devoted much of two years and traveled through 10 states and two Canadian provinces to gather information for his book, "Overrun" on Asian carp in North American waters. 2 / 3
Submitted A bowfisher took this bighead carp in a private gravel pit near Redwood Falls. It weighed 61.7 pounds and was 47 1/2 inches long. It was 80 miles upstream of the only other bighead carp caught in the Minnesota River at the time. 3 / 3

Environmental journalist and author offers look at what's coming

Andrew Reeves made a trip in 2014 to a public library in Cleveland, Ohio, to take in what he expected to be a quiet meeting hosted by the U.S. Army Corps of Engineers on what to do about Asian carp.

The place was packed with people, including local Congresswoman Marcy Kaptur.

"It was my first glimpse into how serious this issue was and how much people cared,'' said Reeves.

Two years of travels through 10 states and two Canadian provinces followed, and Reeves has now authored: "Overrun: Dispatches from the Asian Carp Crisis.'' His book tells the story of Asian carp since their introduction to American waters in 1963, in what was initially believed to be an environmentally-friendly means of controlling aquatic weeds. Today, the invasion of grass, bighead and silver carp is seen as a threat to fisheries throughout North America, including the Great Lakes.

Reeves, an environmental journalist in Toronto, Ontario, Canada, knows all the more how serious the issue remains. As he told the distributor of his now book, in areas affected by Asian carp, they are a "top of mind topic."

That's likely to be the case soon in Minnesota. Asian carp have been found in the Mississippi River in Minnesota. A silver carp was caught in the St. Croix River. Individual catches in 2016 and 2017 in the Minnesota River led the Minnesota Department of Natural Resources to list the river as infested waters for bighead and grass carp from Granite Falls to the confluence with the Mississippi River.

Reeves recently shared some of what he's learned about efforts to manage the Asian carp, as well as his own recommendations with the Tribune.

He said the once hoped-for idea of hydrological separation to keep the invasive species from reaching the Great Lakes is no longer being discussed. The $18 billion project was the topic for that meeting in Cleveland. Hydrological separation was shown to be technologically possible. But its costs, the long-time frame it required for implementation and, most importantly, the social buy-in needed proved too much to put together, he said.

The conversation has turned now to smaller scale solutions, including aggressive harvesting, as well as barriers using carbon dioxide bubbles, sound, light and electricity. One of the more recent proposals comes from the University of Minnesota Aquatic Invasive Species Research Center. It involves using pheromones to attract and congregate the fish, where they can be netted.

All of the technological solutions carry costs, and some risks, according to Reeves. The Army Corps of Engineers has some hesitation about what elevated carbon dioxide levels could do to locks and dams that were built 70 and 80 years ago, he pointed out.

Electric fences, as being used in the Chicago River, costs tens of thousands of dollars to operate, not to mention the costs of building them. "The question always comes down to who is going to pay for it and who is going to maintain it,'' said Reeves. "There's not a clear sense yet of whose responsibility these things are.''

Once Asian carp reach an area, there is an inevitable move towards finding ways to harvest and remove them. They are recent arrivals in Kentucky, and that state is now interested in establishing fish processing plants, he said.

The fish are more labor intensive than other so-called trash fish to process, as they have many bones to remove.

Creating a market for fish that environmental professionals would prefer to eradicate is problematic, to say the least. It's also been very difficult to find a market for their consumption by people in North America, Reeves explained.

In most cases, once the fish establish a reproducing population in a waterway they tend to dominate it, said Reeves. There is an initial population burst. In some parts of the Mississippi River, they represented 70 to 90 percent of the biomass at their population height, he said. In many places where they exist, native fish species can no longer find the food they need to grow larger than 16 inches, he said.

In time, the numbers of Asian carp settle into an equilibrium based on the food available, said Reeves.

They reproduce rapidly, and have advantages over many native species. Bighead and silver carp will eat phytoplankton and can switch to consuming zooplankton if needed. And as filter feeders, they need not chase down prey like most native fish species.

Reeves said he believes the best hope is to manage Asian carp, similar to the way that sea lamprey are limited in the Great Lakes.

Reeves said one of the more effective strategies he's seen is modeled after how they are harvested in China, where they are natives. It involves using teams with nets to work a reach of river over a two to three week period, purposely concentrating and isolating them for harvest.

But Reeves also cautions that he does not believe that Asian carp can be controlled by technological strategies alone. "Science can play a role, but I don't think it is coming to our rescue because it is only part of the issue," he said.

He recommends that people equally focus efforts on a "natural" fix to controlling their populations. Restoring spawning areas and improving habitat for native fish in rivers, and taking measures to improve water quality through practices on the land are critical.

Unfortunately, he can't say that people have rallied to clean up waterways once Asian carp have arrived in them. But he pointed out that the sight of silver carp jumping does more to focus public attention on the challenges ahead than zebra mussels plugging a water intake pipe. "It's a visual, visceral reminder that something has really gone wrong with these waterways. The fish are a part of that. They are a symptom. They are not the disease. That's the shift I am calling for people to sort of use then thinking about what we can do about this."

Reeves will speak about his book at 6 p.m. on Tuesday, April 9 at the Science Museum of Minnesota, St. Paul.

Tom Cherveny

Tom Cherveny is a regional and outdoor reporter with the West Central Tribune in Willmar, MN.

(320) 214-4335
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