The Wisconsin DNR confirms largemouth bass virus in smallmouth bass taken from the bay of Green Bay near Door County.
In September 2021, 14 smallmouth bass were collected from the waters surrounding Door County and examined by DNR fisheries staff. The fish had skin wounds that appeared red, ulcerated, and often had a cream-colored layer of dead tissue in the center of the wound. After testing, it was confirmed that largemouth bass virus was detected in all 14 fish.
Since 2008, smallmouth bass displaying similar skin lesions have been sampled during several outbreaks, but the test results were inconclusive.
Largemouth bass virus has been found throughout the Eastern United States and in Wisconsin’s Mississippi River Basin. The virus can cause weakness, abnormal swimming, swimbladder over-inflation, reddening, and death in largemouth bass populations.
While it is suspected that largemouth bass virus is involved in the development of the skin lesions on the 14 smallmouth bass, it’s not 100% known to be connected. DNR staff will continue to monitor smallmouth bass populations and collect additional samples to confirm largemouth bass virus in future outbreaks.
To avoid spreading largemouth bass virus:
- Drain all water from boats, motors and all equipment.
- Do not move live fish away from a waterbody.
- Handle bass as quickly and gently as possible if you intend to release them.
- Target smallmouth bass during cooler weather to reduce the stress on fish.
- Refrain from hauling fish in live wells unless fish are being harvested.
- Report smallmouth bass with skin lesions and dead or dying fish to local biologists or fish health staff.
While largemouth bass virus isn’t known to infect humans, the DNR wants anglers harvesting any fish to thoroughly cook their catch and to never consume dead or dying fish.
