Wausau - The Wisconsin Department of Natural Resources is investigating a large fish kill on Lake Du Bay and the Stevens Point Flowage.

The kill involved mainly black crappie, 3 to 4 years old, and was reported to DNR fisheries staff on April 25.

DNR biologists and fisheries technicians determined that the cause appears to be a virus primarily affecting 3-year-old black crappie.

In Lake Du Bay, the kill has been widespread and has covered many areas of the water body, with concentrations of dead fish along Seagull Drive and extending south.

In the Stevens Point Flowage, fish were reported dying Sunday. The fish kill there also is widespread and affects crappie in the 3- to 4-year-old range.

Samples of live fish from both lakes were sent to the DNR Fish Health Lab in Madison. Initial examinations indicated eroded fins, some internal abnormalities and poor quality gills. The fish secondarily are infected with a fungus that is visible on the dorsal fin. These symptoms are consistent with those observed in previous black crappie fish kills in the Madison area lakes and northwestern Wisconsin lakes in past years.

The symptoms are not consistent with VHS, viral hemorrhagic septicemia, but further laboratory results are pending. Fisheries personnel continue to investigate this fish kill.

Black crappie is an important and popular game fish on these water bodies.