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Evidence of Asian Carp DNA Detected in Green Bay Waters, Heightens Concern for Great Lakes

Asian Carp Regional Coordinating Committee, Flickr

Silver carp DNA was discovered in the Fox River, a tributary of Lake Michigan.

The Wisconsin DNR was quick to say that it was a single positive sample that the U.S. Fish and Wildlife Service detected. The federal agency took 200 samples last summer in the Fox River – starting at its mouth and subsequently five miles upstream. Teams picked up the positive reading in the heart Green Bay.

Scientists do not yet know the DNA’s source. A bird might have eaten a carp elsewhere and simply shed the DNA through mucus or waste; or a boat that did travel in other waterways where carp reside could have conveyed traces of the species.

The DNR has already returned to the Fox River to do additional testing. The agency is working closely with the U.S. Fish and Wildlife Service.

All eyes have been on the invasive fish since they escaped from ponds in the southern United States. Flooding in the 1990s released the carp into the Mississippi River and some migrated into Illinois waterways, threatening Lake Michigan. The initial area of concern occurred in Illinois, where the Chicago Sanitary and Ship Canal creates a connection - and potential passage of carp - between the Mississippi River and the Lake Michigan basin.

The ecological and economic threats Asian carp represent to the Great Lakes is daunting, both to its fisheries and ecology. Asian carp are ravenous eaters and the health of the Great Lakes are already compromised with nearly 200 invasive species occupying its waters.

Nearly a year ago, a water sample from Sturgeon Bay in Door County revealed one positive detection of Asian carp DNA. That was one positive sample – out of more than 280 taken from Lake Michigan waters bordering Wisconsin. Follow-up sampling uncovered no additional carp DNA.

As for monitoring, the Asian Carp Regional Coordinating Committee updated its plan last summer. Protocol now includes increased monitoring in northern Illinois waters, the initial area of concern. The Army Corps of Engineers manages a system of electric barriers within Chicago’s sanitary and ship canal designed to stop Asian carp passage into Lake Michigan. The first barrier went on line in 2002.

DNR officials describe the recent finding in Green Bay as important, but don’t want to jump to conclusions that Asian Carp have arrived. The agency says it takes multiple positive tests over a period of time to indicate the likelihood of a live fish swimming in the waters.

Susan is WUWM's environmental reporter.
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