An idea to fight against the invasive Asian carp: eat them

Silver carp jumping in the Fox River, Illinois. (Ryan Hagerty/US Fish & Wildlife Service via Regional Invasive Carp Coordinating Committee)

Midwestern states spend millions each year to keep a giant, googly-eyed fish from invading rivers and lakes. But Asian carp has firmly established itself in the Mississippi River basin, and experts say it’s here to stay.

Researchers now hope that creating new markets for these invasive fish could be part of the solution.

Asian carp, four different species native to Asia, are widespread in the Mississippi River and surrounding waterways. These fish—grass carp, black carp, bighead carp, and silver carp—were introduced to the United States in the 1970s to feed on algae in aquaculture ponds. Once released into the wild, they spread rapidly despite scientific doubts about their reproduction, and today represent a huge ecological problem, particularly the silver carp.

“They feed on green phytoplankton, which is the base of the aquatic food chain,” says William Kelso, a professor of renewable natural resources at Louisiana State University. “They take all of that, which was once used by native fish, insects and invertebrates.”

While all the phytoplankton serves to satiate the bellies of silver carp, there is less left for other plankton-eating fish.

Silver carp pose a major threat to Great Lakes fisheries. In June 2023, 408 carp were caught in Minnesota, stunning authorities. Millions of dollars a year are spent building electric fences to prevent the carp from invading the Great Lakes from the Mississippi River, with a billion-dollar development plan being developed by the U.S. Army Corps of Engineers in Illinois, but it may still not be enough.

“They’re doing everything they can to make sure they don’t get established in the Great Lakes,” Kelso said. “That would be a disaster, a major disaster, because there’s no way to get rid of them.”

Researchers say just 10 breeding pairs could flood the ecosystem.

Silver carp are making an appearance. Barriers could slow them down, but stopping them altogether may be impossible. But officials and researchers believe that creating consumer markets for silver carp could help manage their numbers.

“If you can create a thriving market around fish, then markets can be a tool to manage them,” said Ben Meadows, assistant professor of economics at the University of Alabama at Birmingham.

Get people to eat them

One way to control the silver carp population seems relatively simple: eat the carp.

Meadows has spent years studying how making silver carp valuable as food could be a tool used to control invasive species. He has concluded that while it is virtually impossible to completely eradicate silver carp, it is possible to control their numbers by “pushing demand” for the fish.

“A rebranding campaign could potentially increase their price, making it more economically viable for people to go fishing for them,” he said.

The fish’s white, flaky flesh is nutrient-dense and a staple in Asian countries, where it remains a staple of Chinese cuisine, but it is less popular with Americans.

“If we can get people to believe that (carp) is the food equivalent of tilapia, rainbow trout or catfish … it starts to create a vicious cycle,” Meadows said.

Companies like Two Rivers, a Kentucky-based Asian carp processor, currently harvest carp from the Mississippi River and surrounding areas, but the market for human consumption in the United States is complicated.

“They’re incredibly bony,” Kelso said of silver carp, and “very difficult to fillet.”

This, combined with a general distaste for fish among Americans, according to Jim Garvey, a professor of zoology at Southern Illinois University, makes it difficult to develop a U.S. market for carp.

“Human consumers” in the United States, he said, “are tough.”

An attempt to counter the carp’s bad reputation began in 2022 with a public relations campaign focused on the fish. The Illinois Department of Natural Resources announced the new name for the Asian carp: Copi.

“The only way we’ve found an impact is to eliminate them,” Garvey said. He was involved in the silver carp rebranding process and conducted research into how the rebranding campaign could help increase demand.

Renaming a fish has worked before: Chilean sea bass and mahi mahi were once known as Patagonian toothfish and dolphinfish, respectively.

Inspired by the large number of invasive fish in and around the Mississippi River basin, the fish formerly known as carp has found its way onto restaurant menus from Chicago to Louisiana. Lawmakers have even held tastings to promote the new fish.

But the campaign has not had a resounding effect. American consumers are still not convinced that copi is a fish they want to buy, even at current prices as low as $0.09 to $0.30 per pound in April. Compared to the price of largemouth bass that hit $7 per pound in April, the human demand for copi is simply not there.

Feeding the dogs

Other emerging markets in recent years present an interesting opportunity that researchers and officials say could be a better solution, such as pet food manufacturing. Carp can be ground up, bones and all, and turned into pellets used in pet food and kibble.

“Carp are a perfect food in many ways,” Garvey said.

Silver carp are relatively low in contaminants because they eat at the very base of the food chain where toxins have not had a chance to accumulate.

“This is an unwanted protein source for millions of Americans who are literally jumping on board,” Meadows said.

He said that while there may be various obstacles to the pet food industry successfully adopting carp and reducing their numbers, “it seems, just in my mind, to be a perfect little fusion.”

Silver carp is also very healthy for pets: the omega-3 fatty acids present in the flesh help to make the coats of dogs and cats shine. Carp is also easily digestible for cats and dogs and is a rich source of protein.

Cash incentives

Supporting silver carp consumption in the form of government subsidies has worked temporarily in the past; Kentucky and Tennessee have given money to support carp harvests starting at 5 to 7 cents per pound, according to Meadows’ research, while Illinois has helped fund the creation of processing plants, spending $1.9 million to help a plant open in Grafton, Ill., in 2012.

However, many of these per-pound subsidies were too small to be effective in the long run. Meadows found that a subsidy of $1.13 per pound is the minimum amount needed to be successful.

Subsidies to processing plants could work, but challenges such as production inefficiency and even bad smells are obstacles – the Grafton plant has even had to pay fines and be evicted from the area because of the smell.

“It’s not an effective product,” said Colin Wellenkamp, ​​executive director of the Mississippi River Cities and Towns Initiative, a nonprofit advocacy group. “There are so many carp.”

Still, there is hope for carp control, and that hope rests partly on consumer attitudes. People might pay more for carp-based pet food if they were informed of the environmental benefits, Meadows said.

Creative cooking, such as making carp burgers with dill pickles and cheddar or New Orleans-style carp po’boys, coupled with the knowledge that eating carp helps the environment, might be more palatable to Americans.

“They continue to degrade the environmental health of the Mississippi River,” Wellenkamp said. “I really hope the market approach can work.”

Even if elimination is not possible, reducing the numbers of invasive carp, particularly silver carp, could have enormous ecological benefits.

While reducing their numbers to 80 percent of what they currently are would be ideal, Kelso said, “if we could reduce their population size by 50 to 75 percent, that would be good,” he said.

“That would probably be the best we could do.”

This story is a product of the Mississippi River Basin Bureau of Agriculture and Wateran independent reporting network based in University of Missouri in partnership with Report for Americawith major funding from the Walton Family Foundation. The Mississippi River Cities and Towns Initiative is also a Walton grant recipient.

Louisiana Illuminator is part of States Newsroom, a nonprofit news network supported by grants and a coalition of donors as a 501c(3) public charity. Louisiana Illuminator maintains its editorial independence. Contact Editor Greg LaRose with questions: info@lailluminator.com. Follow Louisiana Illuminator on Facebook and X.