Currently present in Montana!

Whirling Disease begins as a spore on the bottom of a river. When bottom-dwelling worms eat the spore it is transformed into Triactinomyxon (TAM) which is then released into the water where it comes in contact with fish.  The TAM makes its way into the head and nervous system of the fish causing neurological damage.  Whirling disease causes fish to swim in a whirling motion making it difficult for the fish to feed and evade predators. 

Potential Harms:

Whirling disease can have devastating impacts on coldwater fisheries. All members of trout and salmon species as well as whitefish may be infected with the disease. When an infected fish dies the spores are released into the water, infecting all susceptible fish in the waterbody. The spores are almost impossible to kill.  They survive extreme water temperatures and may live for 20 to 30 years. 

Identification:

• Whirling Disease is identified by observing the fish with the disease.  
• Infected fish may have a swirl in their spine causing them to swim in a "whirling" motion.
• They may also have a black tail.

Prevention:

Because it is impossible to visibly see the disease, it’s best to assume that all bodies of water are infected.  Whirling disease is spread by the dispersion of infected fish, namely trout, whitefish, and salmon, to new bodies of water.  To prevent the spread of the disease, do not transport live fish to other bodies of water.  Also, do not use pieces of trout, whitefish, or salmon as live bait. Make sure to dispose of fish entrails and skeletons away from waterbodies.  And, always make sure to clean your fishing gear.

Links:

http://fwp.mt.gov/fishing/guide/ethics/whirlingDiseaseStory.html 

http://www.protectyourwaters.net/hitchhikers/others_whirling_disease.php 

http://whirlingdisease.montana.edu/default.asp