In response to the detection of Asian carp DNA in a single water sample from Sturgeon Bay, the U.S. Fish & Wildlife Service will collect additional water samples from the waters around Sturgeon Bay on Tuesday, Nov. 12, at the request of the Wisconsin Department of Natural Resources.
“We were notified last week of this single positive detection of Asian carp DNA out of more than 280 water samples collected from Wisconsin’s Lake Michigan waters,” said Bob Wakeman, aquatic invasive species coordinator for the DNR. “Right now, we are unsure if the DNA came from a live fish. It is possible that it washed off from a boat, came from droppings from a bird that ate a silver carp, or from some other temporary source.”
Wakeman said the U.S. Fish & Wildlife Service will collect 100 to 150 samples for analysis for the presence of Asian carp DNA. Results are expected before the end of the year.
Environmental DNA, or eDNA, is released into water with the urine, feces and scales of live fish. Other possible sources could include a bait bucket that accidentally contained young silver carp (a type of Asian carp), water transported in the live well of a recreational boat that had recently been used in silver carp-infested waters, or feces from a migrating bird that had eaten a silver carp.
“That’s the problem with eDNA. It doesn’t tell where it’s from,” Wakeman said.
The DNR was notified of the single positive sample Oct. 28 by researchers at the University of Notre Dame, Central Michigan University and The Nature Conservancy, who conducted the genetic testing with funding from the U.S. Fish and Wildlife Service.
A total of 282 water samples also were collected in spring and summer 2013 from the Milwaukee, Menomonee, Twin, Fox and Menominee rivers and none of these samples tested positive for Asian carp DNA. An additional 600 water samples were collected from other Great Lakes waters in 2013 and again there were no positive eDNA results, Wakeman says.
Mike Staggs, DNR’s fisheries director, notes that the researchers also screened the one positive sample from Sturgeon Bay with a newly developed genetic test and that the result was negative for Asian Carp DNA. “At this point we have no other physical or anecdotal evidence to confirm the presence of Asian carp, which included a variety of already planned netting, electroshocking and trawling operations in and around the Green Bay area during 2013 which captured no Asian carp.”
Asian carp species introduced into the southern United States in the 1970s are headed toward the Great Lakes, a serious concern because they can aggressively compete with native commercial and sport fish for food and can potentially disrupt entire ecosystems. Also, silver carp can injure boaters when the fish leap out of the water.
Wakeman encourages anglers and others to review Asian carp identification materials, to report any sightings of Asian carp, and to make sure their bait buckets don’t inadvertently contain the fish because young Asian carp resemble popular bait species. Photo identification tools and more information on Asian carp can be found on the DNR’s website, dnr.wi.gov.
“While research is showing some promising new methods, there currently are no technologies to eradicate Asian carp and prevention remains the most cost effective tool to protect the Great Lakes,” Wakeman says. “We encourage anglers and others who encounter a bighead or silver carp while fishing in Wisconsin to keep the fish, put it on ice and call the local DNR. Anglers are also asked to make sure any baitfish they purchase or catch are not Asian carp.”