All Hands On DeckStopping the Spread of Invasive Carp

Silver carp with white background
Silver carp. Photo by Sam Stukel/USFWS

Summer. A time to soak up the warmth of the sun, indulge in some cold treats, and of course — enjoy some exciting water recreation. During the summer, paddleboards, kayaks, fishing boats, and numerous other types of watercraft fill the Missouri River Basin. Anglers are hooked on opportunities to catch trout, walleye, bass, or perhaps even a hefty native paddlefish. The Missouri River Basin, composed of many tributaries and reservoirs, stretches from western Montana east to the Mississippi River near St. Louis, Missouri. If you want to know how big that is, it’s nearly a sixth of the continental United States! Recreation abounds in this basin oasis of fun outdoor activities, and it also generates millions of dollars each year for local communities through employment opportunities, tax revenues, and rising property values. Though the river is paradise for anglers, recreationists, and wildlife, a growing threat within the Missouri River Basin has the potential to wreak havoc with local economies and damage important aquatic resources. That threat is invasive carp.

A carp jumping out of water and slapping a man in the face with its tailfin while he’s in a boat
Carp jumping out of water by GIPHY

Holy Carp!

Invasive carp is a general term for a handful of non-native carp species that reproduce and spread rapidly, causing harm within their new environments. In other words — holy carp, they are bad! Bighead and silver carp specifically are a large concern within the Missouri River Basin due to their increasing numbers. Unprecedented flooding of the Missouri River in 2011 advanced the spread of invasive carp because higher water levels allowed the fish to move past normal barriers such as dams. Despite their growing numbers, there still isn’t enough information available to find a solution to stop the spread.

Close-up of juvenile bighead carp with white background
Close-up of juvenile silver carp with white background
Left Photo: Juvenile bighead carp by Sam Stukel/USFWS | Right Photo: Juvenile silver carp by Sam Stukel/USFWS

Schooling Together to Stop the Spread

To find solutions to this growing problem, U.S. Fish and Wildlife Service (FWS) biologists have teamed up with North and South Dakota Game and Fish Departments, the University of South Dakota, as well as several experts from the FWS Whitney Genetics Lab in Wisconsin to monitor invasive carp in the Missouri River Basin. The Missouri River Natural Resources Committee is at the heart of this collaborative effort. The committee released a control strategy framework in 2018 calling for the collection of information about the location, invasive carp numbers compared to other aquatic species in the area, carp behavior, and more to help find some solutions.

What is eDNA?

Stopping the spread of invasive carp relies on early detection of invasive carp in areas of concern. The key to early detection may lie in eDNA sampling. What is eDNA, you ask? eDNA, short for environmental DNA, involves testing water samples for evidence such as skin cells, mucus, or feces left behind by invasive carp. This method can help establish if invasive carp are present without having to physically capture one. This approach can help conserve resources and precious time, especially in areas where encroaching carp populations are sparse. When dealing with rapidly spreading invasive species, time is literally money.

5 people standing in or near a river collecting water samples
Biologists with U.S. Fish and Wildlife Service and University of South Dakota collect water samples from the Big Sioux River, near Sioux Falls, South Dakota, to test for eDNA from invasive carp. Photo by Tait Ronningen/USFWS

eDNA is attractively simple in theory and is becoming more popular in practice. This technique has been successfully used by the FWS La Crosse Fish and Wildlife Conservation Office for invasive carp monitoring in the Great Lakes Region for over a decade — talk about being tried and true! After months of delays due to the COVID-19 pandemic, eDNA is now being introduced within the Missouri River Basin thanks to the coordination ventures of Stephen Krentz, the Supervisory Fish Biologist at the FWS Missouri River Fish and Wildlife Conservation Office.

Swimming to New Waters of Research

In June 2021, biologists with the Missouri River Fish and Wildlife Conservation Office launched the first round of eDNA sampling in the Big Sioux River at Falls Park in Sioux Falls, South Dakota, and the Lake Vermillion Spillway near Canistota, South Dakota. The work done in June will be a blueprint for future eDNA sampling in the basin.

Over 200 water samples were collected and sent to the FWS Bozeman Fish Technology Center in Montana for testing. We will know if there are carp by the end of 2021, so stay tuned! Another round of sampling is taking place in fall 2021.

Man holding a tray with tubes of water samples. River and trees in background.
Two people holding tubes with water samples in a lab
Left: Biologist Jason Kral, carries water samples from the Big Sioux River near Sioux Falls, South Dakota, to be tested for eDNA from invasive carp. Photo by USFWS Right: Biologists Dan James (back) and Jenna Bloomfield (front) prepare water samples collected from the Big Sioux River for eDNA testing. Photo by Jason Kral/USFWS

The important research doesn’t just end with the cool, new eDNA sampling. There’s more work to be done! In places with lots of carp, the fish are being captured to learn more about the species including sex ratios, size, and reproductive capabilities. Emily Pherigo, the FWS Missouri River Basin Invasive Carp Coordinator, anticipates that this data accompanied by data about native fish species within the Missouri River can determine the impact of invasive carp if they continue to spread. But why does this matter?

The futures of more than just endangered American paddlefish, pallid sturgeon, and mussel species are at great risk if invasive carp continue to spread in the Missouri River Basin. Invasive carp are Darwinian nightmares that also threaten important game populations by outcompeting them for food and destroying aquatic habitats. As if the threat to native fish isn’t bad enough, the risk of getting seriously injured by a jumping silver carp scares away anglers and boaters. Support for aquatic conservation is massively reduced as recreational fishing disappears. Thus the future of the Missouri River as we know it is threatened by invasive carp.

Another important part of learning more about carp is tracking their movement and preferred habitats. Using a method known as telemetry, biologists record invasive carp throughout the Missouri River tributaries. But how does telemetry work? Transmitters are inserted into carp and emit signals that are picked up by receivers carried on FWS boats. Imagine the transmitters as microphones that amplify the activity of the fish so the receivers can track lots of carp across long distances without having to recapture the fish. Understanding their movement and habitat will help predict areas where carp are likely to spread in the future. Telemetry can also give special insight on how these carp may evade barriers in the basin, such as dams, and help determine areas where the spread of carp can be prevented.

Men in a boat surrounded by multiple silver carp jumping out of water. Green trees and blue sky in background.
U.S. Fish and Wildlife Service collecting invasive silver carp during telemetry study in South Dakota below Gavins Point Dam. Photo by Jason Kral/USFWS

The Fight Isn’t Over Yet

Monitoring is just one component of the FWS’s strategy to stop the spread of invasive carp, albeit an important one. Early detection and studies on existing populations will help efficiently contain and manage carp in the Missouri River Basin. In doing so, the basin, its species, and all its wonder can be preserved as an important habitat as well as an oasis providing the many recreational opportunities we all enjoy.

Story Written by Sarah Mastrian, Directorate Fellow, U.S. Fish and Wildlife Service

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