Rifle hatchery hopes to be whirling-disease free by May of 2003 | PostIndependent.com
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Rifle hatchery hopes to be whirling-disease free by May of 2003

By this time next year, whirling disease could be a thing of the past at the Rifle Falls Fish Hatchery.

The state’s largest fish hatchery, which is operated by the Colorado Division of Wildlife, is expected to be whirling disease free by May.

“We’ve made a number of renovations there to keep it whirling disease free,” DOW spokesman Todd Malmsbury said.



One of those renovations includes using only subsurface water in its tanks. The hatchery needs to do that because water from nearby streams has whirling disease spores and just one spore can contaminate the entire facility.

“The problem with streams is once it’s in the stream, it stays there,” Malmsbury said.



The hatchery is not negative yet, but Malmsbury said he and other DOW officials are excited about the prospect of eradicating the decade-old problem.

“That will be the culminating achievement of the whole effort,” he said.

Once cleared of whirling disease, the hatchery is capable of producing more than a million catchable rainbow trout, and several hundred thousand sub-catchable trout, every year for Colorado streams.

“Then we should be able to get fishing levels to where they were before whirling disease,” he said.

The announcement about Rifle’s hatchery came Friday as the DOW announced its Mount Shavano hatchery, located in Salida, was the seventh hatchery to be cleared of whirling disease.

The cleanup efforts came after DOW biologists found in the mid-1990s that the parasite could impact wild fish populations. In a few places where the habitat supports a high level of whirling disease, young fish were unable to survive their first year in the river. Entire year classes of young rainbow trout were dying. Young fish are at greatest risk because the parasite attacks their soft cartilage.

Fish infected with whirling disease, which is caused by a tiny, water-borne parasite called Myxobolus cerebralis, can have spinal deformities, black tails and a decreased ability to feed. The parasite works its way into head and spinal cartilage, where it multiplies rapidly and causes fish to swim erratically in circles – hence the name “whirling” disease – and in severe cases, die.

When a fish dies, tiny spores of the parasite are released into the water, where they can live for long periods of time. The spores are eaten by a worm called Tubifex, the disease’s primary host, where they change into a highly infectious form that is passed back to trout through the water. Rainbow and cutthroat trout are the most susceptible to whirling disease, but it can infect all salmonid species.

Brown and lake trout are highly resistant. Trout and salmon native to the United States did not evolve in areas with the whirling disease spore, and consequently, most native species have little or no natural resistance.

Whirling disease, which is not harmful to humans, was first observed in the United States around 1958, and spread to Colorado in the 1980s. It has been found in 22 states and in New Zealand, central Europe, South Africa and northeast Asia.

The DOW’s Pitkin hatchery in Gunnison County will undergo final testing in February, and the Roaring Judy hatchery north of Gunnison is just now completing several years of construction. The 14-month program to monitor for the disease at Roaring Judy will begin early next year, with final certification expected in the spring of 2004.

The state legislature approved spending $13 million over five years from the DOW’s game cash revenues to modernize several of the state’s cold-water facilities and eliminate whirling disease where possible, a DOW news release said.

“I think this accomplishment speaks volumes of our division staff,” said DOW director Russ George. “They worked very hard to design the right projects and make them work.”


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