VHS disease expanding in Lake Michigan

Spiel · April 11, 2009

VHS disease expanding in Lake Michigan

April 09 2009

These gizzard shad died from VHS disease on the lower Great Lakes.

Fish-killing VHS disease has not been found in more inland lakes in Wisconsin, but the virus is spreading to more parts of Lake Michigan and into the Mississippi River system in Ohio.

Wisconsin Department of Natural Resources fisheries officials this week highlighted the results of last year’s testing for the disease, viral hemorrhagic septicemia.

Fish experts say cooperation by the public in not moving water, bait or fish out of infected areas appears to have helped slow the spread of the virus to additional lakes.

But Mike Staggs, who heads the DNR’s fisheries management program, said it’s bad news that VHS has for the first time broken into the Mississippi River system and has spread hundreds of miles in Lake Michigan.

Last year “was a quiet year across the Great Lakes as far as major die-offs being reported,’’ Staggs said. “But what I think is troubling is the major expansion that we’ve seen in the past year. We now have VHS confirmed in an Ohio reservoir on the Mississippi River system, … and now we have it as far south as Milwaukee and into Illinois in Lake Michigan.’’

Staggs said it’s not clear if the lack of fish die-offs in Wisconsin over the past year is a sign of good luck or simply that the disease takes time to settle in.

“There’s a theory that there’s a lag time of a few years from when it first shows up and from when you get the larger levels of fish dying … so we’re going to be back out in the field this year looking as much as we can,’’ Stagg said.

Wisconsin and Minnesota fisheries officials will work together in coming weeks to test fish in the St. Louis River, said Dennis Pratt, Wisconsin DNR fisheries biologist in Superior.

“We’ll be out there shortly after that ice goes out looking for goby, perch and shiners. Those are fish that have been susceptible to VHS in other areas,’’ Pratt said. “We have to assume it’s here. We just haven’t found it yet. … We may not find it until after it starts killing off some larger numbers of fish.’’

VHS, which does not affect people, was first detected in Wisconsin in May 2007 in Lake Winnebago and Lake Michigan near Green Bay. Staggs said the DNR will go back to Lake Winnebago this year to re-test for the disease and compare fish population trends to past years.

“Seeing a few dead adult fish is not pleasant,’’ Staggs said. “But I’m worried most about finding a long-term, chronic reduction in reproduction.’’