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Fish disease upsets stocking plans

US - The spectre of viral hemorrhagic septicemia is likely to claim thousands of trout and salmon from Wisconsin's state-owned hatcheries in coming weeks without the disease actually infecting a single fish.

"We're going to end up with a surplus of fish that we don't have use for," said Mike Staggs, fisheries director for the Department of Natural Resources.

The fate of those excess fish appears to be burial in a landfill.

It's a conundrum for fisheries biologists.

Discovery of the VHS virus in Lake Michigan and the Lake Winnebago system this spring has the DNR taking steps to prevent further spread of the exotic disease, which can be fatal to a variety of fish species.

"Nobody is more concerned about spreading VHS than the department, and we won't do anything to knowingly spread this disease," Staggs stated.

DNR policy is not to "stock any group of fish in 2007 that have tested positive for, or show clinical signs of VHS, nor any group of fish for which testing of their parents or 'broodstock,' the hatchery water supply or the forage fish they were fed has shown a positive VHS result."

Fish from the DNR's old Wild Rose, Kettle Moraine and Lake Mills hatcheries were hatched from eggs collected from the Lake Winnebago system. The Bayfield hatchery uses water from Lake Superior, which is thought to harbor VHS.

Fish from all four hatcheries, as well as forage fish used at the hatcheries, have tested negative for VHS. As a precaution, however, the DNR has determined those fish will be stocked only in Lake Michigan or Lake Superior.

"There is no option that is risk-free but we have decided to err on the side of extreme caution," Staggs said.


Further Reading

Viral Haemorrhagic Septicaemia