WHIRLING DISEASE FOUND IN
NEW MEXICO HATCHERIES
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News Release December
3, 1999 WILDLIFE
Four of seven lots of rainbow trout from the Lisboa Springs Hatchery tested positive for whirling disease. Two of three lots of rainbows transferred from Lisboa Springs, near Pecos, to the Seven Springs Hatchery in the Jemez Mountains also tested positive. "Lots" of fish are eggs from the same source and are hatched at the same time, said Mike Sloane, assistant chief of fisheries for the New Mexico Department of Game and Fish.
Tests also concluded the state's Glenwood Hatchery is free of the parasite.
All infected fish had at one time been kept in water taken from the Pecos River, the most likely source of the infestation, Sloane said. Fish living in spring water at both hatcheries, including Rio Grande cutthroat trout, tested negative for the disease.
Transfers and stocking of trout from Lisboa Springs and Seven Springs have been suspended while the Department determines what actions should be taken in response to the infestation. Preliminary tests of trout from the state's three other hatcheries-Rock Lake, Red River and Parkview-found those hatcheries free of whirling disease parasites. Results from a second round of tests have not been received.
Whirling disease, Myxobolus cerebalis, is spread by microscopic spores found on the bottom of ponds, lakes and rivers. It cannot be contracted by humans and fish carrying the spores are safe to eat.
In the life cycle of the disease, the spores are eaten by tubifex worms and develop into Triactinomyons while inside the worms. The Triactinomyons are released from the tubifex worms into the water, where they cling to the bodies of trout and burrow into the fish's nervous system. Another metamorphosis within the fish results in a mature spore attacking the cartilage right behind the fish's head. After several weeks, that results in spinal deformities and "whirling" motions by the fish. Black tails are additional evidence of a whirling-disease infection.
Young rainbow and cutthroat trout, birth to nine months, are particularly vulnerable to whirling disease, although brown trout are relatively resistant to it. Brown trout are native to Europe and evolved with whirling disease.
New Mexico has several alternatives for dealing with whirling disease. Seven Springs hatchery is scheduled for renovation, Sloane said, so the infestation should be controlled through that work. Renovating Lisboa Springs to eliminate the need to raise fish in Pecos River water could eliminate the problem there.
Covering raceways also could reduce the spread of whirling disease by birds and mammals, but human anglers also can take many steps to reduce its spread. Moving live infected fish, or parts of dead infected fish, is probably the biggest source of contamination. Anglers should never move live fish and always should dispose of fish entrails and skeletons properly in trash receptacles on land rather than throwing fish parts into the water. Do not use kitchen-sink disposals to dispose of fish parts.
Anglers also can thoroughly wash and dry their boots and other gear after fishing the Pecos River or infected waters in other states.
Impacts from whirling disease have ranged from disastrous to little or no impact elsewhere in the West. Sloane said the disease could have little impact in New Mexico because there is little natural reproduction of rainbow trout here.
New Mexico's six hatcheries produced and stocked almost 4 million rainbow trout in the last fiscal year. Sloane said the Game and Fish Department intends to check trout for whirling disease contamination in rivers, streams and lakes stocked with fish from either Lisboa Springs or Seven Springs hatcheries.
News Release December 22, 1999
Whirling disease, Myxobolus cerebralis, is spread by a parasite that attacks the cartilage of young trout and salmon, destroying the spine. Fish that survive infection exhibit a swirling, tail-chasing motion. There are no indications that whirling disease represents a human health threat.
Trout raised in river water at Lisboa Springs Fish Hatchery near Pecos twice tested positive for the whirling disease parasite. Trout transferred from Lisboa Springs to Seven Springs hatchery in the Jemez Mountains and Parkview Hatchery near Los Ojos also tested positive. Initial tests at Parkview were negative, but subsequent tests did find one lot transferred from Lisboa Springs was infected.
Two state hatcheries, Glenwood and Rock Lake near Santa Rosa, were found free of the parasite. Red River Hatchery fish also are being tested but results are not available at this time.
All lots of fish actually produced at Parkview were found free of the whirling-disease parasite, said Greg Friday, assistant hatchery foreman at Parkview. Fish produced in spring water at Lisboa Springs and Seven Springs, including Rio Grande cutthroat, also had negative whirling disease tests.
Until the Department and Commission prepare a comprehensive whirling disease policy, the Department has adopted the position of immediately destroying, in an appropriate manner, all fish that test positive. The Department will not knowingly contribute to the spread of whirling disease and is aggressively trying to eradicate known sources of the disease. Hatcheries will be retrofitted to maintain whirling disease-free facilities and eliminate sources of contamination.
The Department is preparing a priority list for testing 173 waters currently stocked with rainbow trout in order to develop a more effective and efficient stocking strategy.