State wildlife officials have announced the discovery of the whirling disease parasite in brown, cutthroat, rainbow and brook trout and whitefish in the Duchesne River in Duchesne County.
Positive samples were taken three miles downstream from Tabiona and at the confluence of the West and North Forks of the Duchesne. The infected portion of the Duchesne River is dominated by brown trout, one of the most resistant of the trout and salmon impacted by the disease.
Although samples taken last fall on the West Fork of the Duchesne came back negative, there is still the possibility the whirling disease has found its way into an important population of pure strain Colorado cutthroat trout which live there.
Even more alarming is the possibility that, through a series Central Utah Water Project diversions, the trout disease could be spread to the state's most popular fishery: Strawberry Reservoir.
"Natural recruitment is a very important component of our management plan at Strawberry. Whirling disease could have a serious impact," said Roger Wilson, sport fishing coordinator for the DWR. "Up to 60 percent of our population [at Strawberry] has been provided by natural reproduction."
Whirling disease is most deadly to young trout and salmon born into a system as the parasite attacks the cartilage of their head and spine. Deformed fish have a hard time swimming, making it difficult for them to feed and making them easy targets for predators.
According to the 2005 Utah Angler Survey prepared by Utah State University and the DWR, Strawberry had 525,917 angler days that year. That's nearly double the next closest Utah fishery.
Officials say there is no health risk to humans from eating infected fish.