In a recent development, routine tesing has uncovered traces of genetic material from invasive silver carp in Michigan’s St. Joseph River, according to authorities.
The discovery was made in a sample collected near Marina Island in June, where environmental DNA (eDNA) testing yielded a positive result for silver carp.
Although silver carp have taken over watersheds in other states, they have not yet established a foothold in the Great Lakes basin.
The Michigan Department of Natural Resources (DNR) is urging caution, emphasizing that genetic material does not necessarily indicate the presence of live fish.
It could result from boating and fishing equipment crossing state lines, potentially carrying genetic material from areas where invasive carp are more prevalent.
This positive finding was among 220 samples from the St. Joseph River, from Lake Michigan to Berrien Springs.
In response to this discovery, state and U.S. Fish and Wildlife Service (FWS) officials are conducting additional eDNA sampling in the river. The FWS uses electrofishing boats to remove invasive grass carp from the St. Joseph River each summer.
Since 2013, the FWS has been collecting eDNA samples to monitor the presence of invasive silver, black, and bighead carp in the Great Lakes and their tributaries.
So far, there has been no evidence of live bighead, silver, or black carp in the Great Lakes or Michigan rivers, including the St. Joseph River.
Moreover, none of the fish population assessments conducted in Michigan’s inland lakes have yielded any of these invasive carp species. These carp are in Illinois, Ohio, Indiana, Kentucky, and West Virginia.
A positive eDNA sample for silver carp sparked a fruitless search in Lake Erie’s Presque Isle Bay last summer.
The potential establishment of bighead and silver carp in the Great Lakes could have significant disruptive effects on sport fishing and recreational boating.
Silver carp, in particular, are known for leaping out of the water when disturbed, posing potential risks to people. Additionally, both species could compete with native fish for food and habitat, further complicating the ecosystem.
Authorities closely monitor the situation to prevent their establishment in this vital ecological region.