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Intensive method to remove Asian carp finds early success at Creve Coeur Lake

An aerial shot of wildlife officials from the U.S. Fish and Wildlife Service and the Missouri Department of Conservation removing Asian carp from Creve Coeur Lake in winter 2018.
Missouri Department of Conservation
Federal and Missouri state wildlife officials deployed a new method this winter that removed 85 percent of the Asian carp in Creve Coeur Lake.

Federal and Missouri state wildlife officials have successfully used a new technique to remove the majority of Asian carp from Creve Coeur Lake in St. Louis County. 

Earlier this year, the U.S. Fish and Wildlife Service, Missouri Department of Conservation and St. Louis County Parks and Recreation deployed a method to extract the invasive species from the lake.

Asian carp has invaded many Midwestern lakes and rivers, outcompeting native fish populations and tainting water quality. Traditional netting methods have not been effective, since the fish jump over the nets. Under the "unified method" developed in China, nets and electric barriers create a grid-like system where fish are herded and then removed.

In the United States, the technique had only been used in one area of the Illinois River. 

Wildlife officials worked for 28 days from the end of January into February to harvest the Asian carp, said Kevin Meneau, a fisheries management biologist at the Missouri Department of Conservation. They managed to capture 47,000 carp, about 85 percent of the lake's estimated population. 

"We didn't know how stubborn the fish would be," Meneau said. "We didn't know if they would try to do end runs around us. As it turns out, the techniques we tried turned out super." 

The cold temperatures also helped with herding the fish, Meneau added, since the species is more likely to jump over nets in warmer weather. Most were silver carp, which is one of four types of Asian carp. Officials mostly avoided capturing other species of fish. 

"We had no techniques to manage these fish, to harvest these fish," Meneau said. "Now we have one. It's very effective at just catching Asian carp without impacting those native species." 

The extracted Asian carp were disposed in a landfill because the state wildlife code prohibits commercial use of the invasive fish. However, Meneau is assembling a committee to change the regulation. 

In the next few weeks, state biologists plan to use hydroacoustic surveys and environmental DNA testing to see what species remain in the lake. 

It's still too early to see the benefits the carp removal will have on Creve Coeur Lake, Meneau said. It will take approximately three to five years to see recovery in the lake's crappie population. But it's very likely that wildlife officials will consider using this method in more floodplain lakes. 

"Now we can spread the word on how successful it was," Meneau said. 

Follow Eli on Twitter: @StoriesByEli

Eli is the science and environment reporter at St. Louis Public Radio.