40,000 trout euthanized for ‘whirling disease’ at SW Virginia hatchery

Stock will drop, but state officials say they’ll try to adjust

Forty thousand catchable trout have been euthanized in Virginia over fears of a parasitic disease that causes them to swim in circles, officials said.

Now some local anglers have expressed concerns.

Whirling disease was detected among trout at the Marion Fish Hatchery in the southwest portion of the state, the Virginia Department of Wildlife Resources said in an Oct. 19 news release.

The disease can lead to spinal deformities and a blackened tail that may leave infected fish swimming in a “whirling” manner, according to DWR.

The disease only affects trout and salmon and cannot be passed to humans, even if they eat infected fish.

No fish with those symptoms have been reported in the wild in Virginia or at any of the state hatcheries, DWR said. There is no known treatment for the disease, so in order to prevent its spread, officials said they had to kill the fish.

“We utilized a form of carbon dioxide to quickly and humanely euthanize the trout,” Brendan Delbos with DWR told McClatchy News in an email.

The parasites first develop in a worm, then spores are released into the water, where they can make their way to fish. Delbos said officials believe a water source used at the Marion hatchery may have brought the parasite in.

The loss of the 40,000 trout will impact the fish’s stock in Southwest Virginia by about 20% locally and about 5% statewide, DWR said. Anglers in 10 counties will likely see the reduction in the stocking.

Trout fishers in Virginia rely heavily on stocking, according to DWR. About 80% of trout fishing in the state depends on the efforts of the Department of Game and Inland Fisheries to stock over a million catchable-size trout each year.

In order to make up for the loss, officials said they would work to “reallocate” fish to affected areas.

Whirling disease arrived in the U.S. from Europe and has been found in 25 states, the National Park Service reports.

It was first reported in the country in 1958 and can be found in most western states, according to wildlife officials.

As the weather cools off, prime trout season has started in Virginia, according to DWR. The state’s trout season is year-round.