Whirling Disease Parasite Found in Ten Sleep Fish Hatchery

CASPER, April 1, 2008 -- The Wyoming Game and Fish Department announced today that Myxobolus cerebralis, the causative parasite of whirling disease, has been detected in fish raised at the Ten Sleep Fish Hatchery.

During the annual fish health inspection by the Wyoming Game and Fish Department's Fish Health Laboratory in Laramie, fish tested positive for the parasite. Officials have not yet determined the source and are currently conducting tests on the spring water supply for the hatchery as well as extensive sampling of all fish lots.

The parasite penetrates the head and spinal cartilage of young trout, causing the fish to swim erratically. The disease is often fatal to fish, but has no known health effects for humans. Although spores of the parasite have been found, the infected fish at Ten Sleep Hatchery appear healthy with no outward signs of the disease.

Once established in the wild, eradication of the parasite is not feasible. To reduce the risk of spreading the disease, the Game and Fish does not stock positive fish into the wild.

"This infection at Ten Sleep is both surprising and disappointing," says Steve Sharon, fish culture supervisor for the department. "Our assumption is that surface water from nearby Ten Sleep Creek contaminated the shallow collections connected to the main hatchery spring system. But our number one priority is maintaining the health of all the fish in the hatchery system and our wild fish populations. Fish production for stocking will be suspended at Ten Sleep until adequate protection from the parasite can be planned, funded and constructed. Upgrades to the hatchery were under our ten year plan, but this situation has put Ten Sleep as our number one priority to remove the fish health problem and bring the facility to full production again."

Like most Game and Fish hatcheries, Ten Sleep often transfers fish to other stations. According to Sharon, the department is also currently testing fish transferred from the Ten Sleep Hatchery. Of these transferred lots, rainbow trout at the Wigwam and Boulder Fish Rearing Stations have tested positive for the parasite and will be destroyed.  Although all samples have not yet been completed at Ten Sleep, brook trout and splake lots that have been confirmed positive for the parasite will also be destroyed. The possibility of these fish infecting the others at Wigwam and Boulder is extremely remote due to the life cycle of the parasite.

At this time, the extent of the infection and its impact on the number of production fish are not known. The testing process takes several weeks and there are a substantial number of samples still being processed. The Game and Fish is also getting confirmation from an independent lab. Further information will be forwarded once these samples are complete. To ensure the Game and Fish is still meeting the needs of the Wyoming angler, the entire fish inventory in the other nine hatcheries will be assessed and, once the number of infected fish is known, fish will be allocated to meet the shortage and at the same time still meet all stocking requests statewide. Game and Fish personnel may also make up for infected fish by altering species and sizes as appropriate.

In the meantime, Ten Sleep will continue work with their Yellowstone cutthroat trout brood stock to produce eggs. Those eggs will be transported to other hatcheries to be raised and then stocked in Wyoming waters. "Proper egg disinfection and water-use removes any possible transmission of the whirling disease parasite through spawned and incubated eggs," explains Sharon.

Anglers can take several steps to help control the spread of whirling disease. Mud should be washed from boats, trailers, waders and float tubes before leaving a river or lake. No water, mud, fish or fish parts should be transported from one river basin to another. Fish heads, skeletons or entrails should not be thrown in any body of water.

For more information on the Game and Fish hatcheries, visit the department's Web site at http://gf.state.wy.us .

(Contact: Steve Sharon, (307) 473-3407)