by Spencer Hunt
THE COLUMBUS DISPATCH
LOUDONVILLE, Ohio -- State and federal officials are tracking an escaped killer. Armed with nets, a plastic dinghy and a 300-volt generator, a team of fish experts spent a day last week collecting fish from the Clear Fork Branch of the Mohican River, looking for a deadly disease called viral hemorrhagic septicemia.
Officials thought the contagious virus, which makes fish bleed to death, was contained in the Great Lakes. But the discovery of VHS in the Clear Fork Reservoir in Morrow and Richland counties has changed all that. It's the first discovery in a U.S. waterway that doesn't drain to the Great Lakes. "The bug is out," said Ken Phillips, a U.S. Fish and Wildlife Service microbiologist based in La Crosse, Wis. "In theory, it could make it all the way to the Mississippi River." Phillips and three other Fish and Wildlife biologists were in Ohio last week dissecting hundreds of fish shocked and netted from linked streams that flow from the Clear Fork to the Ohio River.
Although not a threat to humans, the disease can kill trout, perch, walleye and other fish by the thousands. There is no way to stop its spread or kill the virus. "It could be devastating," said Larry Mitchell Sr., president of the League of Ohio Sportsmen and the Ohio Wildlife Federation. In 2006, the virus killed tens of thousands of freshwater drum and yellow perch in the western basin of Lake Erie.
VHS is a threat to state hatcheries as well, where sport fish are bred for release in Ohio lakes and stream. Two hatcheries, one near London in Madison County and the other near Castalia in Erie County, are under quarantine while officials await results of VHS tests.
The London hatchery received virus-contaminated muskie eggs from the Clear Fork Reservoir in April. The hatchery sent about 55,000 potentially infected rainbow trout to Castalia, said Elmer Heyob, hatchery administrator for the Ohio Department of Natural Resources.
If tests for the virus are positive, the state would have to kill more than 400,000 muskies, brown trout, rainbow trout and steelhead trout at the hatcheries, Heyob said.
"Then we would have to decontaminate the hatcheries with chlorine," he added. The value of the fish at both hatcheries is more than $480,000, according to Ohio Department of Natural Resources estimates
First discovered in Europe, the disease somehow migrated to the Great Lakes. Researchers identified it after a fish kill in Lake Ontario in 2005 but now suspect it was in Lake St. Clair as early as 2003. VHS becomes deadly once fish are under stress because of spawning, another disease or low oxygen levels in water. Lower water temperatures also help VHS replicate.
The virus was discovered after routine tests of ovarian fluid from the Clear Fork muskie eggs. Heyob said he's hopeful that the disease hasn't spread among all the hatchery fish, which are kept in separate tanks and ponds.
However, he and others will have to wait some time to find out. It takes two to four weeks for test results, Phillips said.
Still, both are hopeful that tests on the stream-caught fish will show how far and how fast the disease has spread downstream.
"It could have been in the reservoir a year or two years ago and we're just now detecting it," Phillips said. "How long it could take to move is anybody's guess."
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Posted on Tue, December 29, 2015
by Brian plecas