The parasite that causes whirling disease in fish has been discovered in fish taken from portions of the Provo River, as far down as Deer Creek Reservoir, fish health specialists at the Division of Wildlife Resources' Fisheries Experiment Station announced recently.
Rainbow trout at Deer Creek and possibly Jordanelle reservoirs have tested positive. Fish at both locations are lightly infected and no physical deformities or other symptoms have been seen.
Investigators have sampled these waters and tested for whirling disease spores periodically since 1996. This first confirmed, positive detection was in fish collected in the winter of 1999. A presumptive diagnosis was made in fish directly above Jordanelle Reservoir, at the junction with the Weber-Provo Canal, in 1997.
The Provo River has been considered at high risk because of its connection with the Weber River drainage, which has been contaminated for several years.
Investigators believe the latest infection is a fairly recent downstream movement of the parasite.
There is no effective treatment for infected fish. Researchers are focusing much effort on finding ways to manage tiny tubifex worms, the intermediate host for the parasite, which are found on the bottom of most streams and reservoirs. The DWR has formed a response team to oversee further investigations to determine the extent and spread of the parasite and its impact on the sport fishery.
Biologists stress that fishing in Deer Creek and Jordanelle reservoirs, and the Provo River system, should remain good during the foreseeable future. Rainbow trout are stocked into both reservoirs at a large size, making them less susceptible to whirling disease. Wild brown trout in the river are more resistant to infection than rainbow and cutthroat trout.
Anglers are urged to clean their waders and gear after fishing in the river and to properly dispose of the remains of any harvested fish by placing them in garbage cans or by burning them completely.
Whirling disease does not infect humans and fish may be safely consumed.