The California Department of Fish and Wildlife (CDFW) recently learned Hot Creek Hatchery near Mammoth Lakes has tested positive for the parasite that causes whirling disease. Whirling disease was detected in wild trout populations in Inyo and Mono Counties more than 30 years ago. Therefore, continued fish stocking in these and other waters already known to have the whirling disease parasite should have little or no effect on those trout populations. Hot Creek, Lake Crowley and the Owens River provide blue ribbon trout fishing despite the presence of whirling disease in these waters.
“We will continue to operate Hot Creek Hatchery with no negative effects on wild fish in Inyo and Mono counties, where Hot Creek Hatchery normally stocks its fish,” said CDFW Fisheries Branch Chief Stafford Lehr.
Last week, two northern California hatcheries, Darrah Springs and Mt. Shasta, also tested positive for this parasite. Of the 22 hatcheries operated by CDFW throughout the state, only these three have tested positive. The disease was discovered as a result of routine annual checks for fish diseases which are conducted at all CDFW hatcheries.
Whirling disease is caused by Myxobolus cerebralis, a protozoan parasite that destroys cartilage in the vertebral column of trout and salmon. It is fatal or disfiguring to infected trout and salmon but does not affect humans. Fish infected with whirling disease are safe for human consumption.
At this time it is not known how the parasite entered Hot Creek Hatchery waters. The possibility the parasite was transferred to the hatchery from local nearby waters known to have whirling disease is likely, due to current drought conditions that cause wildlife to move to available waters sources. Some species of fish-eating birds can transmit the parasite.
For more information on whirling disease, please visit http://whirlingdisease.montana.edu.