No silver carp eDNA in new St. Joseph River samples

September 28, 2023

Contact:
Tammy Newcomb, newcombt@michigan.gov, 517-284-5832
Joanne Foreman, foremanj@michigan.gov, 517-284-5814

The Michigan Department of Natural Resources today announced that no silver carp environmental DNA was found in a Sept. 6 resampling of the St. Joseph River.

Following notification that one of 220 samples taken on the St. Joseph River in June by the U. S. Fish and Wildlife Service contained eDNA from invasive silver carp, the area was resampled.

A total of 220 new samples were collected from stretches of the river between Lake Michigan and Berrien Springs, and according to the USFWS, none of the samples tested positive for bighead or silver carp eDNA. These species of invasive carp are not known to be in the Great Lakes basin, and this sampling provides an early detection process for their potential presence.

Testing for eDNA involves collecting water samples throughout a river or lake and analyzing each sample for silver or bighead carp genetic material. Repeated sampling is used to verify results and to assess whether the detections may have come from a live fish.

“Based on all the available monitoring data, it is unlikely that live silver carp are present in the St. Joseph River,” said Lucas Nathan, Michigan Department of Natural Resources aquatic invasive species coordinator. “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.”

In addition to eDNA monitoring, the USFWS has conducted monthly electrofishing and netting in the St. Joseph River for the last two summers to capture and remove grass carp. No silver carp have been observed or captured in these efforts, which will continue through October and begin again next spring.

A history of partnership

Since 2013, the DNR has coordinated with the USFWS to implement the eDNA surveillance program in Michigan’s major tributaries to all the Great Lakes except Lake Superior, because it has been deemed very low-risk for the introduction and establishment of invasive carp. Results of these surveys are available at FWS.gov.

Boaters and anglers can help

Anglers across the state are encouraged to learn to identify invasive carp. Keep and report any suspected invasive carp captures. Identification and reporting information is available at Michigan.gov/InvasiveCarp.

Boaters and anglers are reminded to clean, drain and dry boats and gear and properly dispose of bait in accordance with state laws – measures that help limit the spread of invasive species and protect Michigan’s rivers, lakes and streams.