Test Results Show VHS Fish Disease Hasn’t Spread in Wisconsin

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DNR fish health specialist Sue Marcquenski (center) collects ovarian fluid from a musky to test for VHS fish disease. - Photo Credit: David RoweMADISON – All planned testing of wild fish for VHS fish disease has been completed for 2008, and results show that so far, the deadly fish virus has not spread in Wisconsin and that state waters have not suffered the kind of fish kills once feared.

Fish from 67 different waters were tested for VHS in 2008, and the only positives were found in fish from Lake Michigan, where VHS was already known to exist. Round gobies found washed ashore on a Milwaukee Beach in June and yellow perch collected a short while later both tested positive. The diagnosis of VHS in the round gobies, an invasive fish species, represents the only instance this year in Wisconsin in which VHS was diagnosed as the cause of a fish kill.

“This is good news on all fronts,” says Wisconsin Fisheries Director Mike Staggs. “There was a lot of concern in 2007 that VHS was already widespread in Wisconsin and that it would spread rapidly,” he says. “Based on the sampling we’ve done last year and this year, it’s clear that’s not the case, and that’s a very good thing.”

Staggs says the test results affirm the DNR’s rules for boaters, anglers and people who harvest wild bait are working to avoid spreading the disease. VHS Prevention.

DNR hatchery crews collected ovarian fluids for VHS testing from a musky on the Minocqua Chain of Lakes earlier this year. - Photo credit: Bruce Underwood“We thought the virus could be contained if we could get boaters and anglers to drain their boats and not move live fish,” he says. “It seems we’ve been successful and we’re thankful for the public response.

“We need boaters and anglers to keep up the good work now and in the future to contain VHS and other invasive species.”

VHS, or viral hemorrhagic septicemia, was first detected in Wisconsin in Lake Winnebago system waters in May 2007 and later that month in Lake Michigan system waters. None of the other 50 waters tested that year were positive for VHS.

The virus does not affect humans but it can infect dozens of fish species, can spread rapidly, fish-to-fish and through the water, and it caused large fish kills in 2005 and 2006 in the lower Great Lakes.

To assess the prevalence of the disease in Wisconsin in 2008, DNR fisheries crews collected fish from 67 different waters for testing by the Wisconsin Veterinary Diagnostic Laboratory in Madison, the La Crosse Fish Health Center and Microtechnologies, a private lab in Maine, says Tim Simonson, the fish biologist who has been coordinating DNR’s VHS surveillance effort. VHS Distribution in Wisconsin.

Most of the work was done at the same time DNR crews were conducting fish population surveys and when water temperatures were below 60 degrees Fahrenheit, when the virus is most active. The fish collected for testing included walleye, musky, smallmouth bass and yellow perch, all anglers’ favorites and all species that are among the most susceptible to VHS.

“The samples had to be collected during a short period when the water temperatures were right and processed immediately,” Simonson says. “Our fisheries staff did a tremendous job getting this critical work done on top of their already scheduled fish sampling activities.”

Fish from the 67 waters were tested for one of three reasons: as part of the DNR’s planned surveillance for VHS that was funded in part by a federal grant; because the fish had symptoms consistent with VHS; and as part of DNR’s efforts to keep VHS and other diseases out of the state hatchery system. Reproductive fluids from all wild game fish that were spawned in spring to supply eggs for the hatcheries were screened for VHS and other viruses.

Waters tested included popular, high traffic waters such as Lake Du Bay, the Wisconsin River at several locations, the Minocqua Chain of Lakes, Little St. Germain Lake, Lake Kegonsa, Lake Koshkonong, Willow Flowage, Gile Flowage, and Lac Courte Oreilles. “We can’t say with 100 percent certainty that VHS is not somewhere outside these known waters, but it’s certainly not prevalent,” Simonson says. “We’ve looked at so many different places and so many different watersheds.”

Test results of fish taken from several Lake Winnebago and Fox River waters tested negative for VHS including Little Lake Butte des Morts and the Wolf River in Waupaca County.

The DNR is seeking another federal grant to help pay for VHS monitoring next year; waters planned for the project will be scattered across the state to continue to assess the prevalence of VHS.

FOR MORE INFORMATION CONTACT: Mike Staggs (608) 267-0796; Tim Simonson (608) 266-5222.