Statesman

Issue date: 3/3/10 Section: Outdoors

Media Credit: Paul Bowser/Cornell University This walleye was infected with the VHS virus, now present in Lake Superior, as shown by bulging eyes and hemorrhages of the fins and body.

The viral hemorrhagic septicemia virus (VHSV) has been coursing its way through the great lakes water system for years without infecting Lake Superior, but according to a recent announcement by Cornell University researchers, this is no longer the case.

"On a worldwide basis, VHSV is considered one of the most serious pathogens of fish, because it kills so many fish, is not treatable and infects a broad range of fish species," said Paul Bowser, professor of aquatic animal medicine at Cornell's College of Veterinary Medicine.

As the recently detected Lake Superior infection grows fish will begin to show "widespread hemorrhages throughout body surface and within the internal organs," according to officials at the Minnesota Department of Natural Resources (DNR). Eyes of infected fish will bulge and gills will appear pale. Fish movement will become listless and infected fish will often be seen by the surface of the water, swimming in circles.

Prior to the announcement Lakes Huron, Erie, Ontario and Michigan had all reported VHSV infections-Lake Superior was the last to go.

The eastern lakes VHSV, now identified in 28 freshwater fish species in the Great Lakes watershed, has reached epidemic proportions and threatens New York's sport-fishing industry, said Bowser.

Amongst the freshwater fish species susceptible to the virus, VHSV has caused large-scale mortality in fish such as black crappie, bluegill, great lakes muskellunge and yellow perch, according to the DNR. But these fish are nothing to fear because the virus only affects fish and cannot be transmitted to humans. Direct contact and consumption of fish contaminated with VHSV is still safe.

The virus travels from one fish to another, especially when fish are schooled together. "It has been found on the surface of newly spawned eggs, so it can be transmitted between generations. Fish can also contract it through virus-contaminated water," according to DNR officials.

If while out fishing on Superior or walking the shores you see a fish with bulging eyes, hemorrhaged fins and body, and potentially pale gills, the DNR requests that you, "place the fish in a clean plastic bag and keep it in an iced cooler or refrigerator as quickly as possible (do not freeze). Call the local DNR fisheries office or the DNR Pathology Lab at 651-259-5096 right away for instructions. Do not risk spreading the VHSV virus by bringing potentially diseased fish to DNR offices or hatcheries."

To prevent the spread of VHSV, the Minnesota DNR has outlined several precautionary tips to avoid transference to smaller lakes, which have are also beginning to show the disease.

-Do not move any live fish between water bodies. Dispose of unwanted baitfish in the trash.

-Do not move any water between water bodies. Drain water from boat, motor, bilge, live wells, and bait containers before leaving any water access.

-Power-wash and dry your boat, trailer, and recreational equipment in a car wash with hot water (preferably 140 degrees F). Or rinse your boat, trailer, and recreational equipment at home with a garden hose and dry completely for 12 hours if possible before going to the next water body.

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