But they are keeping a close watch on lakes and rivers, particularly the Lake Winnebago and Lake Michigan systems where VHS has been found. Viral hemorrhagic septicemia, or VHS, is not a human health threat but it can infect 37 different fish species and has caused big fish kills in other Great Lakes waters.
Testing is underway for VHS on up to 70 lakes and rivers across the state, and Department of Natural Resources fisheries staff are expanding efforts to look at susceptible species in the Winnebago System.
“We’re entering our third year with VHS in pretty good shape due to the efforts we’ve taken to contain the disease and the cooperation we’ve had from people who can potentially spread the disease: boaters, anglers, bait harvesters, fish farmers and our own fisheries management staff,” says Mike Staggs, who leads the Department of Natural Resources’ fisheries management program. “We didn't find VHS in any new waters in 2008 testing and that’s a credit to everybody who followed the new rules and procedures.”
Staggs is concerned, however, that 2008 saw VHS expand its range much farther south in Lake Michigan, killing round gobies and yellow perch near Milwaukee.
The disease poses a threat to southern Lake Michigan fish as well as increases the chance that VHS will inadvertently be spread by boaters and anglers moving infected live fish and contaminated water back and forth between Lake Michigan and inland waters. Lake Michigan is the state’s most popular water and the one that people most often trailer their boat to and from, according to a 2007 DNR study of recreational boaters.
Sue Marcquenski, the DNR’s fish health specialist, is also closely watching what happens on Lake Winnebago and Lake Michigan to see if they exhibit the same pattern seen on some other Great Lakes waters where VHS has been detected.
“My hunch is that there may be a lag time of at least two years after VHS causes an initial outbreak before we see fish kills in new locations, or in new species from the same location,” she says.
Staggs says that DNR will be carefully monitoring state waters for VHS this year and working closely with the public to prevent the spread of the deadly fish disease.
Testing underway to learn where VHS is found
This spring, the DNR will conduct “surveillance” testing on 27 waters to continue to assess the prevalence of VHS. In addition, four hatchery water supplies and all wild fish DNR uses for broodstock for its hatcheries will be tested for VHS to make sure fish stocked from state fish hatcheries are VHS-free.
The DNR also will test fish from suspicious fish kills. All told, more than 50 waters and as many as 70 will be tested, says Tim Simonson, who coordinates VHS surveillance testing.
Those waters planned for surveillance testing are popular and highly trafficked waters by anglers and boaters, increasing the chances of VHS being spread by the movement of water and live fish, Simonson says. Mendota Lake in Dane County, Geneva Lake in Walworth County, Castle Rock Lake in Juneau and Adams counties, and Butternut Lake in Price County are among those on the list.
Sampling occurs while the water temperatures are below 60 degrees Fahrenheit, the period when the virus is most active. DNR fish crews will collect tissue samples from 170 individual fish from each of the 27 waters for surveillance testing, focusing on susceptible species. The Wisconsin Veterinary Diagnostic Laboratory in Madison, the La Crosse Fish Health Center and Microtechnologies, a private lab in Maine, will do the testing.
Working with the Minnesota Department of Natural Resources and the La Crosse Fish Health Center, sampling for VHS will also take place on Pools 9 and 10 of the Mississippi River, and the St. Louis Estuary on the St. Louis River.
The costs associated with the VHS testing is paid for with a grant from the U.S. Department of Agriculture, Animal and Plant Inspection Service as well as a grant from the U.S. Fish and Wildlife Service, Federal Aid in Sport Fish Restoration (SFR) and fishing license sales.
People finding fish with symptoms of VHS are encouraged to contact their local fish biologist. More information is available on the VHS Web site.
FOR MORE INFORMATION CONTACT: Mike Staggs (608) 267-0796; Tim Simonson (608) 266-5222.