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Fish-killing disease raises concerns

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A fast-acting fish-killing disease that's moved as close as Lake Huron is raising concern among local scientists and natural resource experts who will discuss the issue Thursday in Duluth.

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Fisheries experts from Minnesota and Wisconsin will talk about the invasion of viral hemorrhagic septicemia (VHS), which has infected 27 species in the Great Lakes in the past two years.

Some biologists are calling VHS among the most devastating of the 180 foreign species that have invaded the Great Lakes, mostly because of its ability to kill large numbers of fish quickly.

Just last month VHS was discovered in fish in Lake Huron, near Cheboygan, Mich., and experts believe it's probably in Lake Michigan, just 15 miles from there.

So far, the disease hasn't been found in Lake Superior. But because it probably has moved within the Great Lakes in the ballast water of ships, the disease could already be here, undiscovered, or could be just one ship's arrival away.

Susan Marcqueski is fish health specialist for the Wisconsin Department of Natural Resources and a member of the Great Lakes Fishery Commission's fish health committee. Marcquenski will join Duluth scientist Gary Glass at Thursday's event, along with Dennis Pratt, senior fishery biologist for the Wisconsin Department of Natural Resources in Superior, and Don Schreiner, Duluth area fishery manager for the Minnesota Department of Natural Resources. U.S. Coast Guard officials also have been invited.

Glass organized the event for the Izaak Walton League of America's Duluth chapter.

In January in Lake Huron, VHS was found in whitefish and walleye, and in Chinook salmon from a DNR station. Farther east, it has killed muskie, perch, drum, emerald shiners and 20 other species, in some cases in huge numbers.

VHS was believed to be a cold-water, mostly saltwater disease killing species like salmon in European streams. But it has spread to the U.S. and, for the first time, is killing cool and warm water species. The variation found in the Great Lakes has never been seen before. It flourishes when water is between 32 and 59 degrees Fahrenheit -- generally when many fish are spawning and are most vulnerable to disease.

The impact of VHS on shallow water fishing hotspots such as the Twin Ports harbor and lower St. Louis River could be potentially devastating, Glass said.

Marcquenski said it's unclear how VHS got into the Great Lakes. Many researchers believe it came in the ballast of oceangoing ships. But it also may have arrived inside a fish migrating out of the Atlantic Ocean, she said.

Glass is calling for immediate changes in federal regulations to mandate sterilization of ballast water in ships moving into and within the Great Lakes.

That almost certainly won't happen, port and regulatory officials note, because no system has been developed or proven, and it would take years to retrofit lakers and salties with the new technology.

Officials so far have focused on keeping commercially caught baitfish and hatchery fish from spreading the disease outside the Great Lakes, including a federal ban on the movement of bait out of the region. Marcquenski also said state, federal and provincial fisheries managers are working to make sure they don't spread the disease through their own research netting, egg-taking efforts and hatchery releases.

Marcquenski noted that recreational boaters and anglers will be reminded to not move water, bait or fish out of any Great Lake or connected water to any inland water. The same education effort aimed at keeping zebra mussels and spiny waterfleas out of inland lakes also will work for VHS.

"We're trying to make sure we aren't the vector for any spread, especially to inland lakes," she said. "We're going to need people's help, especially boaters and anglers."

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