GRAND RAPIDS, Mich. (WOOD) — The Michigan Department of Natural Resources says a second round of testing found no evidence of silver carp DNA in the St. Joseph River.
The DNR ordered a second round of sampling after routine surveillance over the summer found silver carp DNA in one of the 220 water samples collected in the area. The positive sample was taken near Marina Island, which serves marinas and a public boat launch.
The DNR suspected the sample came from carp DNA coming off of a boat or equipment that had been previously used in water where silver carp reside. That appears to be the case.
“Based on all the available monitoring data, it is unlikely that live silver carp are present in the St. Joseph River,” DNR aquatic invasive species coordinator Lucas Nathan said in a release. “Even with this good news, we will continue to work with our Fish and Wildlife Service partners to monitor the river for any signs of invasive carp.”
Besides DNA monitoring, the U.S. Fish and Wildlife Service conducts monthly electrofishing and netting along the St. Joseph River to capture and remove grass carp. No silver carp have been spotted during those exercises.
Silver carp are one of four species of invasive carp that are considered a major threat to the Great Lakes. They are voracious eaters and could devour food sources, hurting several popular Great Lakes fish, including walleye and rainbow trout, key players in the region’s billion-dollar fishing industry.
Invasive carp — formerly known as Asian carp — were used as a tool in the 1970s to control algae, weed and parasite growth on aquatic farms. But the fish eventually made their 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.