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Fish-Killing Aquatic Virus Spreads Among Great Lakes

A fast-spreading aquatic virus that threatens the Great Lakes fishing industry has been detected in Lake Huron for the first time, Michigan officials said.

The Department of Natural Resources said Thursday it had confirmed the presence of viral hemorrhagic septicema, or VHS, in fish samples from waters as far north as Cheboygan, Michigan — only about 15 miles (24 kilometers) from where Lake Huron meets Lake Michigan.

VHS previously had been found in only two Great Lakes — Ontario and Erie — and in Lake St. Clair, which links Erie and Huron. But officials have predicted the virus eventually would spread across the entire system, where the $4.5 billion (euro3.47 billion) fishery is a crucial segment of the economy.

How damaging the virus turns out to be will depend largely on whether fish develop immunity, said Kelley Smith, chief of the DNR's fisheries division.

The virus poses no danger to people but is usually deadly to fish. It targets some of the region's most popular sport and commercial species.

Analyses completed this week found VHS in whitefish and walleye, and in Chinook salmon from a DNR station, Smith said.

Originally a saltwater virus, VHS made its first known appearance in the Great Lakes in 2005, killing the likes of freshwater drum and muskellunge.

Cheboygan-area whitefish were collected in 2005 during a survey for bacterial kidney disease, Smith said. They were examined again more recently and found to have carried VHS.

How VHS arrived in the lakes is uncertain. But fishery managers say a likely culprit is ballast water dumped by ocean freighters, widely considered a leading source of exotic species in the lakes.

"These new discoveries are extremely unfortunate and further highlight the problems created by the constant introductions of new diseases from outside the Great Lakes region," DNR Director Rebecca Humphries said.