Wisconsin is testing more fish from Lake Michigan for a disease that can cause large fish kills. Viral hemorrhagic septicemia, or VHS, has been in the Great Lakes for at least six years.
In Lake Michigan, VHS has only been found on the Wisconsin side. Just this year it showed up in perch and another fish called gizzard shad.
Lately, large numbers of alewives have been washing up on Wisconsin beaches. Wisconsin officials have no reason to suspect VHS but they are testing for it and other diseases.
Alewives sometimes die in large numbers just because the fish is an invasive species and has trouble with quick changes in water temperature. The die off could actually be a sign that there are more young fish out there.
Alewives are the main food for salmon, the most popular sport fish in Lake Michigan.