MADISON – Thousands of round gobies washed onshore on a Milwaukee beach last month were killed by the fish disease VHS, according to laboratory results returned today to Wisconsin fisheries officials.

The Department of Natural Resources received confirmation from the Wisconsin Veterinary Diagnostic Laboratory that viral hemorrhagic septicemia, or VHS virus, was isolated in three of four round gobies collected May 28 by DNR fish biologists. The four fish were among thousands of decomposing gobies piled up on the beach at Grant Park in Milwaukee along Lake Michigan, and were in good enough condition for testing, according to Sue Marcquenski, DNR’s fish health expert.

    VHS, which is not a human health threat but can infect a broad range of native  fish, was documented for the first time in Wisconsin in May 2007, including from fish in northern Lake Michigan near Algoma and Kewaunee.

    The diagnosis of the round gobies with VHS represents the first time the virus has been found in the southern basin of Lake Michigan and the first time the disease has been found in gobies from this lake. 

    Fisheries Director Mike Staggs said that the news was not a surprise, given that the virus was previously found in Lake Michigan and because round gobies are among the species most susceptible to it, based on fish kills caused by VHS in Lake Ontario and the St. Lawrence River.

     “The good news is that despite all the testing we’ve done this year and last year for VHS, we haven’t found the virus in waters beyond the Lake Michigan and Lake Winnebago systems,” he says. “And that the steps we’ve been requiring boaters, anglers and wild bait harvesters to take are working to contain the disease.

    However, Staggs says, the discovery of VHS in Lake Michigan gobies highlights that “VHS continues to be a potentially serious threat to Wisconsin fish and that we need everyone to continue following the rules to prevent the spread of this disease.”

    While gobies are an invasive fish, they are important prey for Lake Michigan yellow perch, walleye, lake trout and bass. Gobies also eat large numbers of quagga mussels and zebra mussels, helping control populations of these other invasive species that also can affect the amount and quality of food available to young fish, Marcquenski says.

    VHS can spread among fish when healthy fish eat sick fish or absorb VHS-contaminated water contaminated through their gills. Fisheries officials have said the main way VHS can spread to new waters is by anglers moving infected bait fish to a new lake or river, with moving large quantities of contaminated water a distant second.    

    VHS, which was documented as the cause of large fish kills in the lower Great Lakes in 2005 and 2006, can infect several dozen native game fish, pan fish and bait fish.

     This spring, DNR is testing fish from about 30 waters in the Wisconsin River basin for VHS as part of its monitoring program, and none have tested positive so far. Nor have any fish from other fish kills this spring tested positive for the virus so far.       In 2007, DNR tested more than 180 lots of wild fish from more than 50 waters and didn’t find the disease anywhere beyond Lake Michigan and Lake Winnebago. The state’s hatchery system also tested clean.

    The gobies’ diagnosis with VHS brings to seven the total number of sites from which the virus has been confirmed, representing five different fish species.  Drum from three different sites on the Lake Winnebago system, brown trout from Lake Michigan near Algoma, smallmouth bass from Sturgeon Bay, lake white fish from northern Green Bay and now the gobies from Lake Michigan near Milwaukee have all tested positive for the virus.

    For more information on the VHS fish disease and the rules boaters, anglers and others must follow to prevent the spread of VHS, go to dnr.wi.gov/fish/vhs.