GRAND RAPIDS, Mich. (WOOD) — The Michigan Department of Natural Resources says one sample in the St. Joseph River shows DNA evidence of silver carp, a member of a group of invasive fish that pose a major threat to the Great Lakes.
The sample was taken as a part of routine surveillance by the DNR and the U.S. Fish and Wildlife Service. The DNR says one out of the 220 water samples collected in June tested positive.
“A positive eDNA sample does not necessarily indicate the presence of live fish,” DNR Fisheries Research Program manager Seth Herbst said in a statement. “It is possible for genetic material to be introduced from other sources, such as boats or fishing equipment used in another state where invasive carp are present, then transported and used in Michigan waters.”
The positive sample was taken near Marina Island, which serves several marinas and a public boat launch. Herbst said his team started another round of sampling this week to check for any other evidence of invasive carp.
The USFWS has been conducting DNA monitoring around the Great Lakes and its tributaries since 2013 and no samples show an established population of any invasive carp.
“To date, there is no evidence of any live bighead, silver or black carp in the Great Lakes or Michigan rivers such as the St. Joseph River. Similarly, no bighead, silver or black carp have been caught in any of the thousands of fish population assessments conducted in Michigan’s inland lakes during that same time frame,” the DNR said in a statement.
Invasive carp — formerly known as Asian carp — are considered a major threat to the Great Lakes because they could upend the natural ecosystem. Invasive carp are voracious eaters and would devour the food sources for several popular Great Lakes fish, including walleye and rainbow trout, key players in the region’s billion-dollar fishing industry.
Invasive carp were used as a tool in the 1970s, controlling algae, weed and parasite growth on aquatic farms. But the fish eventually made their way into the Mississippi River basin and now dominate that ecosystem.
The U.S. Army Corps of Engineers has worked with environmental agencies for years to monitor carp in the Mississippi River basin and ensure they don’t make it to the Great Lakes. The two systems only have one permanent connection point — the Chicago-Area Waterway System. Several tools are in place along that system, most notably at the Brandon Road Lock and Dam about 27 miles southwest of Chicago.
There are plans for a major upgrade to the Brandon Road facility to strengthen the tools there. Designs are mostly set, but negotiations for covering the estimated $1.1 billion price tag remain unsettled.