Trout disease hits High Country

By Nathan Ham - [email protected]

BOONE — A deadly trout disease has hit the state of North Carolina for the first time and it hits way too close to home for many sportsmen.

The first occurrence was discovered in the Watauga River that flows through Avery and Watauga Counties before crossing into Tennessee and emptying into the Holston River.

Whirling disease affects fish in the trout and salmon family with rainbow and brook trout, two species found in North Carolina waters, being the most susceptible. The disease, caused by the microscopic parasite Myxobolus cerebralis, damages cartilage and skeletal tissue in a fish, causing it to swim in a whirling motion. While often fatal to juvenile fish, the disease does not infect humans or pets, and eating an infected fish is not known to cause any harmful effects.

The parasite that causes whirling disease was first discovered in Pennsylvania in 1956. Since then, whirling disease has been confirmed in other states, with varying degrees of severity. In some states, whirling disease has been observed in isolated cases and has had little impact while in other states, such as Montana and Colorado, the impacts on trout populations have been more pronounced.

According to the North Carolina Wildlife Commission, they are collecting fish from trout hatcheries and sending them to the Fish Disease Laboratory at Auburn University for testing.

“So far, we have no indications that trout at any of our hatcheries are infected with whirling disease, but we are being extra cautious and having fish tested before we resume stockings,” said Doug Besler, the Commission’s regional fisheries supervisor for the mountain region. “We hope to have test results back within the next few weeks and once we rule out whirling disease infection at our production facilities, we will resume planned trout stocking operations.”

Commission staff will also collect trout from the Watauga River and tributary streams to test for whirling disease and to determine its distribution in the watershed. In addition, Commission staff is working closely with N.C. Department of Agriculture and Consumer Services and N.C. State University to sample commercial aquaculture operations in the area where the infected trout were found.

Despite their concern, biologists acknowledge that the presence of whirling disease doesn’t necessarily equate to a dramatic loss of fish, given that other states where the disease has been present in waters for decades have been able to manage the disease so that impacts on both wild and stocked trout haven’t been nearly as devastating as previously thought.

“In the 1990s, whirling disease was relatively new to many states and there was broad uncertainty about trout population impacts from whirling disease,” Besler said. “Some western states, such as Montana, had substantial impacts from whirling disease early on, but many of those populations have since rebounded. On the other hand, some eastern states, such as Pennsylvania, do not appear to have experienced broad scale population level impacts from whirling disease.”

“In waters where whirling disease is found, how an outbreak affects trout populations depends on many factors in addition to water temperatures, such as the species of trout present and the quality and quantity of the substrate where the intermediate host resides,” he added.

Along with testing fish at its hatcheries, commercial aquaculture operations, and trout streams, the Commission is asking the public to help prevent the spread of the disease by:

—Cleaning and drying equipment, clothing and anything else that comes into contact with water;

—Never moving fish or aquatic life from one body of water to another without first obtaining a permit from the Commission;

—Disposing of fish parts carefully after cleaning fish by putting fish parts in the garbage, burying them deeply or burning them completely.

Anglers are asked to contact the N.C. Wildlife Commission if they observe deformities, strange swimming behaviors or other signs of disease in trout.

Nathan Ham can be reached at 336-846-7164 or followed on Twitter @NathanHam87

By Nathan Ham

[email protected]

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