Whirling disease parasite found at Crystal hatchery
Colorado Division of Wildlife aquatic pathologists have detected the parasite that can cause whirling disease at the Crystal River Hatchery south of Carbondale.
Aquatic managers have already begun work to eliminate the spores and restore the hatchery to disease-free status.
The discovery is not expected to have a significant impact on fish production because the Crystal River Hatchery is primarily used to produce trout eggs for rearing in DOW hatcheries around the state.
The parasite does not infect trout eggs and is not transmitted from fish to egg.
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Though none of the hatchery’s trout have shown signs of disease, Wildlife Commission regulations require that any hatchery in which the parasite is found must be designated as positive for whirling disease.
The parasitic infection attacks the nervous system of some trout and salmon species, sometimes causing skeletal and cranial deformities so severe that young trout don’t survive into their second year.
The disease has had major impacts on wild populations of rainbow and brook trout in some streams in Colorado and other states in the West.
“We believe the parasite may have reached the hatchery’s raceways when an irrigation ditch that carries water from the Crystal River overflowed onto hatchery property where our springs are located,” said Rich Kolecki, the DOW’s chief of hatcheries and former manager of the Glenwood Springs Fish Hatchery on Mitchell Creek.
The parasite has previously been found in trout in the Crystal River.
“We have isolated the lot of fish where the infection was found and are assessing additional barriers to keep irrigation water from the hatchery site in the future,” Kolecki said.
The Crystal River Hatchery has thousands of large trout that serve as the brood stock for the eggs that the DOW needs to produce millions of trout that are stocked in Colorado’s lakes, streams and reservoirs each year.
The hatchery also produces about 35,000 catchable-sized trout each year.
“Those trout will be stocked in lower-elevation reservoirs in and around Grand Junction to provide fishing opportunity this spring and summer,” said Eric Hughes, the DOW’s aquatic wildlife manager.
Wildlife Commission regulations allow the stocking of trout exposed to the whirling disease parasite in waters that are too warm and intermittent for trout to reproduce and are well away from wild trout streams.
The same regulations forbid the stocking of exposed trout in any waters in which trout can reproduce, such as high-country lakes, streams and reservoirs.
Some DOW hatcheries that once tested positive for whirling disease have been renovated and are now free of the parasite. These include Durango, Finger Rock, Buena Vista, Mount Ouray, Bellvue, Mount Shavano and most recently, the state’s largest, Rifle Falls.
“While the discovery of the parasite at Crystal River is a setback in our efforts to rid hatcheries of the parasite, we don’t expect it to affect our overall trout production and stocking,” Hughes said.
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