Fish Caught in June 2025, Downstream of De Pere Dam

From the WI Department of Natural Resources

On June 1 of last year, a grass carp was captured by a bow angler on the lower Fox River, downstream of the De Pere Dam. The fish was positively identified by fisheries biologists from the Wisconsin Department of Natural Resources (DNR) and the U.S. Fish and Wildlife Service (USFWS). The fish was an adult female; however, it is unclear if it was diploid (able to reproduce) or triploid (sterile) as the fish was disposed of by the angler prior to obtaining a sample. Grass carp have been detected in low numbers in Lake Michigan. In recent years, individual grass carp were found in the Milwaukee River estuary. Additional sighting data is available through the USGS Nonindigenous Aquatic Species Database.

This individual confirmation does not indicate that there is an established population in the river.

This fish is different from the common carp that anglers have been catching in the region for years. Check out how to tell the difference between these two fish!

So what’s happening next?

The USFWS is leading grass carp specific monitoring efforts as part of their routine invasive species program fieldwork including metabarcoding, electroshocking, and gillnetting in the lower Green Bay and Fox River up until the De Pere Dam.

In addition, Fox-Wolf is helping coordinate outreach and education to local bait shops, marinas, and other stakeholders about the finding and the next steps. Signs will be placed at local boat launches to raise awareness and support early detection.

If you’re fishing and think you caught a grass carp, keep the fish! Place it on ice (DO NOT FREEZE THE FISH). Then contact the Wisconsin DNR and the U.S. Fish and Wildlife Service Fisheries Biologists to get them the fish. 

Photo Credit: WI DNR

Questions? Comments? Contact Chris Acy, the AIS Coordinator covering Brown, Outagamie, Fond du Lac, Calumet, and Winnebago Counties at (920) 460-3674 or chris@fwwa.org!

Follow the Fox Wolf Watershed Alliance on our Fox-Wolf Watershed Alliance Facebook page or @fox_wolf_watershed_alliance on Instagram! You can also sign-up for email updates at fwwa.org.

The Fox-Wolf Watershed Alliance is an independent nonprofit organization that identifies and advocates effective policies and actions that protect, restore, and sustain water resources in the Fox-Wolf River Basin.

Reporting invasive species is a first step in containing their spread. Maintaining and restoring our waters and landscapes can reduce the impacts even when we don’t have other management options to an invasive species.