USDA Forest Service, Pike & San Isabel National Forests, Cimarron & Comanche National Grasslands

Whirling Disease
Flyer
Produced by
Trout Unlimited
and placed throughout
Region 2 Forests

Whirling disease is a potentially fatal condition affecting trout that is caused by a microscopic parasite. The parasite has a two-host life cycle involving trout and a common bottom-dwelling tubifex worm. The spore stage of the whirling disease parasite is extremely persistent and easily spread.

Whirling disease has led to major declines in several Rocky Mountain fisheries, including some located on the Pike & San Isabel National Forests. Symptoms of the disease are skeletal deformities and discolored “black tail”. Some infected fish exhibit “whirling” motion when swimming, caused by pinched nerves and damage to their cartilage. Young rainbow trout are at greatest risk, and other trout species can also suffer effects from the disease.

Due to the severe shortage of whirling disease free fish available for stocking in the state of Colorado, we do not expect any stocking to take place during 2000 in any of the rivers and streams listed on this web site. For more information link to the Colorado Division of Wildlife whirling disease web-page.

Pike & San Isabel National Forests Cimarron & Comanche National Grasslands

Whirling Disease

Pike & San Isabel National Forests
Cimarron & Comanche National Grasslands