Boating crews took to the Lamine River in mid-Missouri last month, armed with two boats capable of scanning for fish, an electrified dozer trawl geared to stun them and more than 3,000 feet of net.
Their goal: to catch as many of an invasive species of carp as they could in a single day.
The trip was the final outing in a joint campaign between the Missouri Department of Conservation, the U.S. Fish and Wildlife Service and the state of Kansas. At the end of the day, the crews had a few dozen fish piled up – which is not much compared to their daily average of 7,000 pounds of carp earlier that week.
But their overall effort paid off, according to Kasey Whiteman, a fisheries researcher for the Missouri Department of Conservation who helped coordinate the project.
“43,000 pounds in eight days,” Whiteman said. “And that is the most that we've gotten in three years since doing this.”
For Whiteman, and other experts in the field, every fish counts in the fight to control the rapidly growing population of invasive silver carp.
“If you think about our river systems across the board and look at a map, it's like a giant interstate system,” Whiteman said. “So in that sense, these fish have lots of different places they can go and move. And so if it's impacting one part of one basin, eventually – if nothing happens – it can impact another part of the basin.”
Each year, states across the Midwest spend millions of dollars to reduce and control invasive Asian carp – which includes silver, bighead, black and grass carp. The fish were first introduced from Asia to the southeastern United States in the 1970s to combat algae blooms in aquaculture ponds and wastewater treatment facilities. In the years since, however, flooding allowed these carp to travel into smaller streams and rivers.
Experts say it's difficult to know exactly how many invasive carp there are, but the Missouri Department of Conservation previously estimated the species can make up almost 95% of the total biomass in local waterways.
“You could equate it to pollution, except in this case it's biological rather than trash or oil in the river,” said Chris Steffen, an aquatic invasive species coordinator with the Kansas Department of Wildlife and Parks. “It's just a whole bunch of unwanted biological pollution. And who wants to live in a place where people don't do anything about that?”
Today, silver carp especially threaten native aquatic life in the Mississippi River basin. That’s because they often outcompete native mussels, paddlefish and gizzard shad – which rely on the same vegetarian diet of plankton. If left unchecked, the fish could wreak havoc on local ecosystems and fishing industries.
“Folks are getting really concerned that this is not another background invasive species problem, but one that's a problem for the entire U.S. as well as Canada,” said Jim Garvey, a zoology professor and the director for Southern Illinois University’s Center For Fisheries, Aquaculture, and Aquatic Sciences.
Illinois and Michigan in particular have spent years trying to hold the invasive fish back from making their way into the world’s largest freshwater body, the Great Lakes, and disrupting a $7 billion-a-year fishing industry. There, state officials, scientists and the U.S. Army Corps of Engineers want to use electric barriers to keep the carp out.
“We're talking about a species that's like cancer – it just keeps spreading,” Garvey said. “And we’re trying to control it, but it's in so many different places. And so trying to come up with a sort of a silver bullet has been the challenge for resource managers throughout the U.S.”
Kevin Drews, a fisheries biologist with U.S. Fish and Wildlife Service, said that same challenge highlights the importance for his team to be out at places like the Lamine River, which is a tributary to the Missouri River.
“Tributaries are a really important habitat for carp. So this is a potential way that, with focused management actions like taking carp out over a week with a whole bunch of boats and people, we might be able to end up affecting some of those larger populations throughout the river,” Drews said.
With each successful outing, Whiteman said he’s hopeful that Missouri can learn more about the health of native species, all while efficiently removing the unwanted carp.
“So we'll continue to monitor those things, continue to monitor the condition of the native fish species, and we'll use all these data points to help understand the benefits that we're gaining and the response that we're seeing in these river systems to our removal efforts,” Whiteman said.
In the meantime, Midwestern states are also taking more creative steps to swing the pendulum back in the favor of native species. In Illinois, the Department of Natural Resources rebranded the invasive carp species as “copi” in hopes of encouraging more people to eat them.
“I mean, they’re here. It's not a problem we're going to fix overnight, so it's a great source of biomass for something,” Drews said.
Unlike Illinois, however, experts say it’s a bit more challenging to process the fish in states like Kansas and Missouri. The states lack infrastructure like fish processing plants that make producing goods and services from the carp difficult, said Mark Morgan, a retired professor from the School of Natural Resources at the University of Missouri.
For years, Morgan has been advocating for the consumption of invasive carp and has led an effort for it to be used as a supplement for malnutrition in developing countries.
“Right now, we probably don't have enough people to eat this on a regular basis, but I'm hoping things can change,” Morgan said.
The challenge, Whiteman said, has mostly to do with incentivizing processors to create a steady supply and demand for the fish, all while the state conservation departments have to focus on their ultimate goal of reducing the number of invasive carp in the years to come.
“That's the fine balance that we're working with right now,” Whiteman said.
For now, Whiteman said the Missouri Department of Conservation has a contract with FKF Fisheries, a company based out of northeastern Missouri, that will render the excess of caught invasive carp into bait for catfish anglers.
In addition to selling the bait, the company is interested in one day producing fertilizer out of the carp, said FKF Fisheries founder Darrick Garner, who is also a former Missouri Department of Conservation employee. He said it’s another way to make something useful out of the unwanted fish.
“That's our kind of pitch to folks,” Garner said. “It's something that's helping the ecosystem. It's getting an invasive species out of the river. So it helps our native species and also helps us create jobs.”
This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest. It reports on food systems, agriculture and rural issues.
