By Drew YoungeDyke and Marc Smith, National Wildlife Federation with contributions from Patrick Kocovsky and Patrick Kroboth of the U.S. Geological Survey.

When you hear about invasive carp, you probably think of silver carp flying out of the water or bighead carp eating up all the phytoplankton that forms the base of the aquatic food chain. Maybe you think of grass carp, which damage wetlands and waterfowl habitat. While these well-known species of invasive carp are a huge threat and problem, there’s also a fourth species : the black carp. It is just as damaging to freshwater habitats, and particularly to threatened and endangered freshwater mussels and snails.

Black carp are an invasive molluscivore – which feeds on molluscs such as native mussels and snails – found in North America, originally imported to aquaculture facilities for their application as a biological control of snails the 1980s. Since their introduction to the United States, they have spread rapidly with reproductively viable populations established in the Mississippi River Basin, including the Ohio River.

Patrick Kroboth, Research Fish Biologist, describes the project and black carp identification.

“We know black carp are present and reproducing but have no data beyond commercial fisheries captures and a few biologist/recreational reports to know where the fish are throughout the year,” Patrick Kroboth, Research Fish Biologist with the U.S. Geological Survey. “We also lack the habitat specifics, such as depth and current velocities that the black carp use within a reach or their range. This information is needed for control.”

After the fish is anaesthetized, scales are removed for the initial insertion of a radio transmitter.

The U.S. Geological Survey is the lead research agency for Black Carp Monitoring, Assessment, and Control, a key project within the 2021 action plan for the Invasive Carp Regional Coordinating Committee, which is composed of multiple federal and state agencies working to together to stop invasive carp. This project is funded primarily by the Great Lakes Restoration Initiative, along with some agency funding. To better understand black carp habitat and movement, biologists use telemetry techniques. Black carp are captured and surgically implanted with telemetry tags and released back into the water to track their movements. The Illinois Department of Natural Resources and the U.S. Fish and Wildlife Service also work on black carp management and control.

“It may seem counterproductive to take an invasive species and put it back in the environment, but the information that can be gathered from a few individuals can help understand the behavior of the larger population for more effective control,” Krobath said.

Kroboth makes an incision to place the radio transmitter.

The greatest effect that black carp have on our freshwater resources is the direct predation of native mussel and snail fauna. This is even more problematic because many mussels and snails are already listed as threatened or endangered. They also eat small freshwater aquatic insects, at all stages directly competing with native fish, turtles, otters, and waterfowl for the same food sources.

“Black carp have the potential to negatively affect threatened and endangered mollusks, fish, turtles, and birds that rely on mollusks as a food source,” describes the U.S. Fish and Wildlife Service. “Based on its dietary habits, the black carp is likely to invade the habitat, feed on, and further threaten most of the federally listed freshwater mussels and about one third of the federally listed aquatic snails, as well as numerous potential candidates for Federal protection.”

A radio transmitter is inserted into the invasive black carp.

Currently, most information for management of black carp come from captures by commercial fishers and biologists. These data are potentially biased because of the methods, timing, and location of current fishing efforts. The U.S. Geological Survey is currently studying black carp life history in their invaded range to understand their effects on North American ecosystems and develop controls to combat them.  However, more information is needed on the habitat use and movements of the species.

This study will provide the first information on movement patterns and habitat use of black carp related to foraging and spawning behavior. Using these data, state and federal agencies can more effectively target prevention and eradication efforts to stop black carp.

While much attention is rightfully focused on the Brandon Road project to prevent bighead and silver carp from invading the Great Lakes through the Chicago Area Waterway System, this is a prime example of the ongoing work to monitor, prevent, control, and reduce invasive carp populations throughout their current range.  Combined, these efforts will help keep black carp from advancing closer to the Great Lakes, protecting  the freshwater river systems of the Midwest, and advancing the scientific understanding and technology needed to stop invasive carp throughout the nation.

Kroboth releases the black carp back into the water.

This project is funded primarily by the Great Lakes Restoration Initiative (GLRI); $450,000 in 2021, along with $95,000 in U.S. Geological Survey funding. In early 2021, the Great Lakes Restoration Initiative Act was signed into law which increases annual funding for the GLRI from $300 million to $375 million for FY 2022 and by an additional $25 million each year until it reaches $475 million in 2026 – a top congressional priority for the National Wildlife Federation Great Lakes Regional Center. On top of that, the bipartisan infrastructure package signed into law by President Biden in November adds an additional $1 billion in new funding to the Great Lakes Restoration Initiative, spread over five years.

Invasive carp are a national problem requiring a national solution. The ongoing work of the U.S. Geological Survey and their partner agencies are critical to reducing invasive carp populations where they already exist and preventing them from invading new waters to protect our freshwater economy and our fish and wildlife.

Great Lakes Conservation Coalition

About Great Lakes Conservation Coalition

The Great Lakes Conservation Coalition is an informal affiliation of conservation groups working in the Great Lakes region and collectively representing millions of hunters and anglers. Working together, we help advance solutions to the conservation challenges threatening our fish, wildlife, and outdoor heritage.