Scientist Jim Lamer holds an invasive silver carp in the Illinois River. (Juanpablo Ramirez-Franco/WNIJ-Northern Public Radio)
Midwestern states spend millions each year trying to prevent a giant, wide-eyed fish from invading rivers and lakes, but the Asian carp has established itself firmly in the Mississippi River basin, and experts say it’s here to stay.
Now researchers hope that creating new markets for the invasive fish could be part of the solution.
Asian carp are native to Asia and are widespread in the Mississippi and surrounding rivers. Four species of 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 scientific doubts about their reproduction and now pose an ecological problem, especially the silver carp.
“They’re eating green phytoplankton, which is really the foundation of the aquatic food web,” said William Kelso, a professor of renewable natural resources at Louisiana State University. “They’re taking away everything that used to go into native fish, insects and invertebrates.”
While all the phytoplankton is used to fill the bellies of the silver carp, less reaches the other plankton-eating fish.
Silver carp, in particular, pose a major threat to Great Lakes fisheries. In June 2023, 408 carp were caught in Minnesota, baffling authorities. Millions of dollars are spent each year building electric barriers to prevent carp from entering the Great Lakes from the Mississippi River. The U.S. Army Corps of Engineers in Illinois is currently working on a billion-dollar development plan, but that still may not be enough.
“They’re doing everything they can to prevent them from establishing themselves in the Great Lakes,” Kelso said. “It would be a big mess because you just can’t get rid of them.”
Researchers say that just ten breeding pairs could flood the ecosystem.
Silver carp are on the rise. Barriers could slow their advance, but stopping them completely may be impossible. However, officials and researchers believe that creating consumer markets for silver carp could help keep their numbers under control.
“If we can build a successful market around fish, markets can also help manage it,” says Ben Meadows, assistant professor of economics at the University of Alabama Birmingham.
Making people eat them
One way to control the silver carp population seems relatively simple: eat the carp.
Meadows spent years researching how to make silver carp more valuable as a food product and thus control invasive species. He concluded that while it is virtually impossible to completely eradicate silver carp, their numbers can be controlled by “displacing demand” for the fish.
“A campaign to rebrand them could potentially drive up their price and make it more profitable for people to fish them,” he said.
The fish’s white, flaky flesh is rich in nutrients and is a popular commodity in Asian countries, where it remains a staple in Chinese cuisine. However, it is less popular among Americans.
“If we can get people to believe that (carp) is the food equivalent of tilapia, rainbow trout or catfish … that would set off a self-fulfilling cycle,” Meadows said.
Companies like Two Rivers, a Kentucky-based Asian carp processor, currently fish carp from the Mississippi River and surrounding areas, but the market for human consumption is complicated in the United States.
“They have an incredible number of bones,” Kelso said of the silver carp, and “are very difficult to fillet.”
This, and Americans’ general aversion to fish, make it difficult to develop a U.S. market for carp, according to Jim Garvey, a zoology professor at Southern Illinois University.
“The human consumers” in the United States, he said, “are tough.”
An attempt to counteract the carp’s bad reputation launched in 2022 with a fish-centric PR campaign. The Illinois Department of Natural Resources announced the Asian carp’s new name: Copi.
“We found that the only way that would have an impact is to actually remove them,” said Garvey, who was involved in the process of renaming the silver carp and studied how the renaming campaign could help increase demand.
Renaming a fish has worked before – Chilean sea bass and dolphinfish were once known as Patagonian hake and dolphinfish, respectively.
Inspired by the large numbers of the invasive fish in the Mississippi Basin and surrounding areas, the fish formerly known as carp was introduced as a new menu item in restaurants from Chicago to Louisiana. Lawmakers even held taste tests to promote the new fish.
But the campaign has not been a resounding success. American consumers are still not convinced that copi is a fish they want to buy, even at current prices of just $0.09 to $0.30 per pound in April. Compared to the price of largemouth bass in April of up to $7 per pound, the demand for copi just isn’t there.
Making dogs eat them
Other markets that have emerged in recent years offer interesting opportunities and are considered by researchers and authorities to be a better solution, such as the production of animal feed. Carp can be ground up with their bones and processed into pellets that are used as animal feed and dry pet food.
“Carp is a perfect food in many ways,” Garvey said.
Silver carp contain relatively few pollutants because they feed at the bottom of the food chain, where toxins cannot accumulate.
“This is an unwanted source of protein for millions of Americans that is literally jumping into their boat,” Meadows said.
Silver carp jump in the Fox River in Illinois. (Ryan Hagerty/US Fish & Wildlife Service via Invasive Carp Regional Coordinating Committee)
He said that while there may be various hurdles to getting the pet food industry to accept carp and help reduce the population, “this seems to me, in my mind, to be a perfect little merger.”
Silver carp are also very healthy for pets – omega-3 fatty acids in the meat ensure shiny fur in dogs and cats. Carp are also easy to digest for cats and dogs and are a rich source of protein.
Cash incentives
Promoting silver carp consumption in the form of government subsidies has worked temporarily in the past. According to Meadows’ research, Kentucky and Tennessee supported carp fishing with 5 to 7 cents per pound, while Illinois helped finance the construction of processing plants, spending $1.9 million to open a plant 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 for success.
Subsidies for processing plants could work, but problems such as inefficiencies in production and even bad smells pose obstacles – the Grafton plant even faced fines and eviction from the area because of the odor nuisance.
“It’s not 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.”
But there remains hope that controlling carp infestations is possible, and part of that hope has to do with consumer attitudes. People might pay a higher price for carp-based pet food if they knew the environmental benefits, Meadows says.
Creative cooking, such as making carp burgers with dill pickles and cheddar cheese or New Orleans-style carp po’boys, might be more palatable to Americans if combined with the knowledge that eating carp helps the environment.
“They continue to degrade the environmental health of the Mississippi,” Wellenkamp said. “I really hope the market approach can work.”
Although eradication is impossible, reducing the numbers of invasive carp, particularly silver carp, could have enormous ecological benefits.
The ideal, says Kelso, would be to reduce their numbers to 80 percent of their current level. “If we could reduce their population size by 50 to 75 percent, that would be good,” he says.
“That would probably be the best thing we could do.”
This story is a product of the Mississippi River Basin Agriculture and Water Departmentan independent reporting network based in University of Missouri in partnership with Report for Americawith major support from the Walton Family Foundation. The Mississippi River Cities and Towns Initiative is also a Walton grantee.
