Virginia has euthanized 40,000 trout after recent testing detected whirling disease among catchable-sized fish, officials said.
The Virginia Department of Wildlife Resources (DWR) said the commonwealth made the decision to euthanize the 40,000 catchable trout at the Marion Fish Hatchery to prevent the disease from spreading.
“DWR’s stringent fish-health protocols involve regular testing at state hatcheries to look for pathogens that are potentially harmful to hatchery raised and wild fish. DWR does not stock known whirling disease positive fish,” the DWR said in a press release.
“Regrettably, DWR has had to euthanize 40,000 catchable trout to control whirling disease. This represents about a 20% reduction in normal stocking levels for Southwest Virginia and a 5% reduction statewide. Consequently, trout anglers are likely to see a reduction in trout stocking, particularly in Dickenson, Buchanan, Wise, Lee, Scott, Russell, Washington, Smyth, Tazewell, and Grayson Counties.”
Myxobolus cerebralis, a microscopic parasite, causes whirling disease, according to DWR.
“This parasite penetrates the cartilage tissue of a trout’s head and spine, multiplying rapidly and causing skeletal deformities. Trout with whirling disease can show spinal deformities or a blackened tail, which can impact swimming ability and feeding habits,” it added.
Some fish infected by the disease swim in a circular motion, hence its “whirling” name.
The wildlife department said it was “working to reallocate fish as feasible to make up for shortfalls and is implementing measures to reduce the future impact of this parasite on trout production.”
According to DWR, whirling disease is fairly common and has been documented in more than 20 states.
The parasite and disease are native to Europe and were first detected in the United States in 1958. The parasite does not infect humans, even if consumed, DWR said.