Researchers announced this month that Asian carp DNA was positively identified in both Lake Michigan’s Sturgeon Bay in Wisconsin and Pennsylvania’s section of the Ohio River. The announcement came on the heels of another worrying development, as it was just late last month that scientists confirmed the existence of breeding grass carp in the Lake Erie basin.
According to the Associated Press, a collective effort by the University of Notre Dame, Central Michigan University, and The Nature Conservancy found silver carp DNA in one of the 50 samples taken from Sturgeon Bay. Silver carp, along with bighead, are among the most feared invasive species to hit American waters. Asian carp were imported to the country in the late ’60s and early ’70s for their tremendous benefits to aquaculture. Unfortunately, the fish soon escaped and began colonizing the Mississippi River. Currently, Asian carp pose an ecological problem in many states by out-competing native fish.
“These fish could destroy the Great Lakes ecosystem, as well as boating and fishing industries and hundreds of thousands of jobs,” said Michigan Senator Debbie Stabenow (D-MI).
Wildlife agencies have been worried for years that Asian carp will enter the Great Lakes, which support a $7 billion commercial and sport fishing industry. However, the finding of carp DNA does not always mean that carp are actually present. Carp DNA can be found in discarded scales and other forms of waste, and in bird droppings. Researchers are quick to mention that their findings do not absolutely mean carp are in the waters.
Similarly in Pennsylvania, Fish and Boat Commission Executive Director John Arway said there can be sources of carp DNA other than a live, breeding population.
“We don’t know if the eDNA came from live or dead fish or if it was transported from other sources, like bilge water or storm sewers, or even waterfowl visiting the basin,” Arway told pennlive.com.
The Pennsylvania Fish and Boat Commission found silver carp DNA in one sample out of 200 taken from the Ohio River in Beaver County. A second positive sample was confirmed in Hancock County as well. Arway stated that while it could be an early warning sign for the presence of silver carp, the agency is not drawing any conclusions until further evidence is collected. Researchers warn that if more DNA samples are found, the likelihood of live carp increases.
“One sample is a smoke detector,” said Notre Dame University biologist Chris Jerde. “A couple of more samples is a fire.”
Image courtesy U.S. Geological Survey