Following the discovery of invasive round gobies in Lake Winnebago earlier this year, the Department of Natural Resources is asking anglers to report catches of the fish. The department is also considering a chemical treatment to kill the fish.
In the wake of the discovery of round gobies this year in Lake Winnebago, the Department of Natural Resources is attempting to determine how widely distributed the species is in the Winnebago System, asking anglers to report catches of the fish and even considering a chemical treatment to kill it.
The round goby is an aquatic invasive species. It can displace native fish populations and has the potential to impact Lake Winnebago's sport fish through competition for prey and by eating their eggs, according to the DNR.
The species is native to Eurasia and is believed to have have been transported to North America in the ballast tanks of transoceanic ships.
It has been in the Great Lakes region since at least 1990, according to a paper in the Journal of Great Lakes Research. Gobies have been commonly caught by anglers in Lake Michigan and Green Bay for the last 25 years.
However the Menasha and Neenah dams and the 2015 closure of the Menasha Lock helped stop or slow the spread of round gobies up the Lower Fox River and into Lake Winnebago.
However on June 2 an angler found a round goby in Lake Winnebago while fishing near the Bowen Street Fishing Pier in Oshkosh.
Since then 18 more round gobies have been caught on Lake Winnebago, including 13 through DNR sampling efforts and five from angler reports, according to data from the DNR's Winnebago Fisheries team. The total does not include any potential catches during sampling efforts the week of Sept. 22.
All of the gobies have been caught in the same location in Oshkosh, according to the DNR.
Though nearly impossible to eradicate once a species such as round goby has been introduced, the DNR said it will conduct intensive, targeted monitoring efforts in Lake Winnebago and may begin containment actions.
This may include using rotenone, a naturally derived chemical fish killing agent, within a specified area in an effort to prevent gobies from becoming established in the Winnebago System.
However, as of Sept. 26 no treatment was scheduled; the DNR was continuing to sample for and asking anglers to report gobies in the Winnebago System.
Prevention remains the best way to help protect Wisconsin’s waters, according to the DNR. It reminded anglers to never use round gobies as bait, never transfer fish from one lake to another and never throw unwanted bait into the water.
Under chapter NR 40, Wis. Admin. Code, the round goby is a restricted species in Wisconsin, meaning they cannot be transported, transferred or introduced. A deceased goby can be legally transported to a DNR office for identification.
The finding of round gobies in Lake Winnebago was "disheartening and probably inevitable" due to their abundance in the Lower Fox, Green Bay and Lake Michigan, said Mike Arrowood of Fond du Lac.
The gobies could harm the Winnebago recreational fishery, which has a $234 million annual impact on the local economy, according to a 2006 survey by the University of Wisconsin-Extension.
Round gobies are typically from 3 to 6 inches in length, have a blotchy gray appearance with a black spot on the front dorsal fin and feature frog-like raised eyes and thick lips. In addition, they have a single, scallop-shaped pelvic fin on the belly of the fish.
No native Great Lakes fish has such a pelvic fin.
Native species sometimes confused with gobies are the mottled sculpin and slimy sculpin. Both have separate pelvic fins, a scaleless body and are typically between 2 to 4 inches in length.
Angelo Cozzola, DNR fisheries supervisor in Oshkosh, said the Winnebago System receives lots of fishing effort and anglers will likely continue to play a key role in detection of the species.
If anglers catch or suspect they've caught a round goby on the Winnebago System they are asked to: place the dead fish in a plastic bag on ice; record specific information about where (GPS location if possible) and when it was caught; bring it to the DNR office at 625 County Road Y, Suite 700, Oshkosh, Wis. The office is open from 8:30 a.m. to 4 p.m., Monday through Friday. The office phone is (920) 420-9943.
The DNR also has a round goby reporting form on its website at dnr.wi.gov.
Round gobies captured downstream of the Neenah or Menasha dams or in Little Lake Butte des Morts do not need to be reported, as these waters are not considered part of the Winnebago System and are known to have a verified and established population of the invasive fish. Gobies captured in Green Bay or Lake Michigan also do not need to be reported.
This article originally appeared on Milwaukee Journal Sentinel: Invasive round gobies discovered in 2025 in Lake Winnebago
Category: General Sports
