News & Views Disease Management
Whirling disease discovered in New Mexico hatchery

(Photo: Rock Lake Fish Hatchery, New Mexico Dept. of Game & Fish)

An outbreak of whirling disease was discovered among the fish stock during an annual fish health testing at Rock Lake State Fish Hatchery in Santa Rosa, N. Mex., USA.

About 70,000 fish are being euthanized at the hatchery which has caused concern for stock levels around the state, according to a report in the National Fisherman. Rock Lake hatchery produces 300,000 trout per year, serving as the state’s primary catchable trout-rearing station. The hatchery also raises bass, walleye, catfish, bluegills and tiger muskies.

Whirling disease is caused by a microscopic parasite called myxobolus cerabralis and can affect both trout and salmon. The parasite attacks the cartilage tissue of a fish’s head and spine. Infected fish are edible and pose no health hazard to humans.

“A changeling microspore that alters form in each host, the disease can turn young trout into horror show aliens with blackened tails, bulging eyes and deformed humps by feeding on cartilage near their heads. The resulting damage to the nervous system and skeletal integrity launches young fish into a kind of permanent spin cycle that gives the disease its name,” wrote Marti Niman, media coordinator for New Mexico State Parks. “Fingerlings are particularly vulnerable to heavy infestations, since their soft cartilage has not yet hardened into bone. While adult fish are not visibly affected, they often serve as spore carriers.”

The New Mexico Department of Game and Fish said this is the first time since 2007 that this parasite was found in any state hatchery waters, however it has been found in other waters. The U.S. Forest Service stated that whirling disease is also present in waters of the Santa Fe National Forest.

Subsequent testing in the state’s other hatcheries found fish at Parkview Hatchery infected with whirling disease, although Red River, Glenwood and Rock Lake all were determined to be free of microspores caused by the disease. An estimated total of 225,000 fish have been culled across the state hatcheries.

The department is still investigating the cause of disease exposure, however, the Pecos River might be the most likely source of the contamination. Lisboa Springs Hatchery was using river water in some raceways and transfers of trout from those raceways to the Seven Springs and Parkview hatcheries appears to have spread the disease.

“Game and Fish biologists will certainly join forces with other agencies in order to maintain a viable trout fishery for the future of all New Mexicans,” said Niman.