Scientists turn invasive carp into traitors
Wildlife officials across the Great Lakes are looking for spies to take on an almost impossible mission: stop the spread of invasive carp.
Over the last five years, agencies such as the U.S. Fish and Wildlife Service and Minnesota Department of Natural Resources have employed a new seekand-destroy strategy that uses turncoat carp to lead them to the fish's hotspot hideouts.
Agency workers turn carp into double agents by capturing them, implanting transmitters and tossing them back. Floating receivers send real-time notifications when a tagged carp swims past. Carp often clump in schools in the spring and fall. Armed with the traitor carp's location, agency workers and commercial anglers can head to that spot, drop their nets and remove multiple fish from the ecosystem.
Kayla Stampfle, invasive carp field lead for the Minnesota DNR, said the goal is to monitor when carp start moving in the spring and use the tagged fish to ambush their brethren.
“We use these fish as a traitor fish and set the nets around this fish,” she said.
Four different species are considered invasive carp: bighead, black, grass and silver. They were imported to the U.S. in the 1960s and 1970s to help rid southern aquaculture farms of algae, weeds and parasites. But they escaped through flooding and accidental releases, found their way into the Mississippi River and have used it as a super highway to spread north into rivers and streams in the nation's midsection.
The carp are voracious eaters — adult bigheads and silvers can consume up to 40% of their bodyweight in a day — and easily out-compete native species, wreaking havoc on aquatic ecosystems. There is no hard estimates of invasive carp populations in the U.S. but they are believed to number in the millions.
State and federal agencies have spent a combined $607 million to stop the fish, according to figures The Associated Press compiled in 2020. Spending is expected to hit $1.5 billion over the next decade.
But wildlife and fisheries experts say it would be nearly impossible to eradicate invasive carp in the U.S. Just keeping them out of the Great Lakes and protecting the region's $7 billion fishing industry would be a success.
Fisheries experts have employed a host of defenses, including electric barriers, walls of bubbles and herding the carp into nets using underwater speakers.