One idea to curb the invasive Asian carp: Eat them

Silver carp jump in the Fox River in Illinois. (Ryan Hagerty/U.S. Fish & Wildlife Service via Invasive Carp Regional Coordinating Committee)

Midwestern states are spending millions every year to prevent a giant, goggle-eyed fish from invading rivers and lakes. But the Asian carp has firmly established a home in the Mississippi River basin, and experts say they are here to stay. 

Now, researchers are hoping that creating new markets for the invasive fish could be part of the solution. 

Asian carp, four different species originating from Asia, are widespread in the Mississippi River and surrounding streams. The fish – grass carp, black carp, bighead carp and silver carp – were brought to the United States in the 1970s to feed on algae in aquaculture ponds. When released into the wild, they spread rapidly despite scientists’ doubts that they would reproduce, and now present a huge ecological problem, especially silver carp. 

“They’re eating green phytoplankton, that’s really the basis of the aquatic food web,” said William Kelso, professor of renewable natural resources at Louisiana State University. “They’re taking all of that, that used to go into native fishes and insects and invertebrates.”

With all the phytoplankton going to satiate silver carp bellies, less goes to the other plankton-eating fish. 

Kasey Whiteman of the Missouri Department of Conservation holds proof that invasive silver carp can grow to large sizes. This one weighed close to 60 pounds. (Kasey Whiteman/Missouri Department of Conservation)

Silver carp particularly represent a huge threat to the fisheries in the Great Lakes. In June 2023, 408 carp were caught in Minnesota, stunning officials. Millions of dollars a year are spent on the construction of electric barriers to keep carp from invading the Great Lakes from the Mississippi River, with a $1 billion dollar development plan in the works from the U.S. Army Corps of Engineers in Illinois, but it still might not be enough. 

“They’re doing everything they can to try and make sure they don’t get established in the Great Lakes,” said Kelso. “That would be a mess, a big mess, because you really can’t get rid of them.”

Researchers say just 10 breeding pairs could inundate the ecosystem. 

Silver carp are coming. Barriers might slow them down, but stopping them completely may be impossible. Officials and researchers think, however, that the creation of consumer markets for silver carp could work to manage their numbers. 

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

Getting people to eat them

One way to get the silver carp population under control seems relatively simple – eat the carp. 

Meadows spent years researching how making silver carp valuable as food could be a tool used to control invasive species. He concluded that, while completely eradicating silver carp is all but impossible, controlling their numbers by “pushing out demand” for the fish is feasible. 

“A rebranding kind of campaign for them could potentially bring their price up, making it more economically viable for people to go fish for them,” he said.

The white, flaky flesh of the fish is rich in nutrients and a popular commodity in Asian countries, where it remains a staple food in Chinese cuisine, but it’s less popular with Americans.

“If we can get people to think that [carp] is the food equivalent of tilapia or rainbow trout or catfish … those would start to create the self-fulfilling cycle,” said Meadows. 

Companies such as Two Rivers, an Asian carp processor based in Kentucky, are currently fishing carp from the Mississippi River and surrounding areas, but the market for human consumption in the United States is complicated.

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

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

“Human consumers” in the U.S., he said, “are tough.”

One attempt to counteract the bad reputation of carp started in 2022 with a fish-centric PR campaign. The Illinois Department of Natural Resources announced the new name of asian carp: Copi.

“The only way that we’ve found has an impact is actually going out and removing them,” said Garvey. He was involved in the process of renaming silver carp, and conducted research as to 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 copious amounts of the invasive fish in the Mississippi River basin and surrounding areas, the fish-formerly-known-as-carp made its debut as a new menu item in restaurants from Chicago to Louisiana. Lawmakers even held taste-testing events to hype up the new fish.

But the campaign hasn’t been resoundingly effective. American consumers still aren’t convinced that copi is a fish they want to buy, even at current prices as cheap as $0.09 to $0.30 per pound as of April. Compared with the up to $7 per pound price of largemouth bass this April, human demand for copi simply isn’t there.

Dozens of invasive carp jump out of the water during an electrofishing demonstration at Barkley Dam in Kentucky on July 30, 2019. (U.S. Fish & Wildlife Service via Invasive Carp Regional Coordinating Committee)

Getting dogs to eat them 

Other markets emerging within the past few years present an interesting opportunity that researchers and officials feel could be a better solution, such as pet food manufacturing. Carp can be ground down, bones and all, and processed into pellets used in animal feed and pet kibble.

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

Silver carp are relatively low in contaminants, as they eat the very base of the food chain where toxins haven’t had the chance to accumulate.

“This is an unwanted protein source for millions of Americans that literally jumps in the boat,” said Meadows.

He said that while there may be different hurdles to the success of getting the pet food industry to embrace carp and help decrease numbers, “This seems, just in my head, to be a perfect little merger.”

Silver carp are quite healthy for pets, too – Omega-3 fatty acids in the flesh help promote shine on dog and cat fur. Carp is also easily digestible for cats and dogs and provides a rich source of protein.

Cash incentives

Support for silver carp consumption in the form of government subsidies has temporarily worked in the past; Kentucky and Tennessee gave money to support carp harvest from 5-7 cents per pound, according to Meadows’ research, while Illinois helped pay for the creation of processing plants, spending $1.9 million to help a plant open in Grafton, Illinois in 2012. 

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

Subsidies for processing plants could work, but difficulties such as manufacturing inefficiencies and even bad smells are barriers – the Grafton plant even faced fines and expulsion from the area because of the smell. 

“It isn’t an efficient product,” said Colin Wellenkamp, executive director of the Mississippi River Cities and Towns Initiative, a nonprofit advocacy group. “There are just so many carp.”

Hope still remains that carp control is possible, however, and some of that hope revolves around consumer attitudes. People might pay a higher price for carp-based pet food if they knew about the environmental benefits, said Meadows. 

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

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

Even if elimination is impossible, reducing the number of invasive carp, especially silver carp, could have huge ecological benefits. 

While reducing their numbers to 80% of what they are now would be ideal, according to Kelso, “If we could reduce their population sizes down … 50 to 75%, that would be good,” he said. 

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

This story is a product of the Mississippi River Basin Ag & Water Desk, an independent reporting network based at the University of Missouri in partnership with Report for America, with major funding from the Walton Family Foundation. The Mississippi River Cities and Towns Initiative is also a Walton grantee.