BALTIMORE (Map, News) - State officials plan to kill 80,000 trout from hatcheries in western Maryland that are infected with a deadly parasite.

Myxobolus cerebralis, the parasite, is not a risk to humans or other fish. It deforms the spines and skulls of trout. It causes trout to swim in circles until they die — a symptom commonly called “whirling disease.”

The infected fish were discovered last month at the Bear Creek Rearing Station and a contract trout-rearing operation at the Mettiki Coal Co., both in Garrett County, said H. Robert Lunsford, director of freshwater fisheries.

The Department of Natural Resources will test for the parasite in Maryland waterways that hold wild trout in hopes of learning how far the organism has spread, he said.

The population of the fish should remain similar to previous years because the department can increase the numbers produced in other state hatcheries and purchase trout from other states, said Mike Slattery, assistant secretary of the Maryland Department of Natural Resources.

“We have flexibility and a relationship with hatcheries in other states. We can manage this so the public services aren’t undermined,” he said.

The fish to be killed are all between 1/2 pound to 1 pound, which results in a loss of about $100,000 for the department, Slattery said.

Last year, the state’s five hatcheries stocked 197 streams and ponds with 418,000 trout.

The parasite has long been known to exist in the Potomac River’s North Branch, which is about 20 miles from Bear Creek and several miles from Mettiki. Lunsford said it might have been spread to the hatcheries from mud on the feet of birds or bears.

It has decimated wild rainbow trout populations in the West and is now found in 22 states, according to the Whirling Disease Foundation.

The DNR said anglers can help stop the spread of whirling disease by:

» Not moving caught fish from one stream to another

» Not discarding fish carcasses in a stream or on a stream bank

» Removing mud from boots and equipment before moving from one stream to another.

The Associated Press contributed to this report.

lgreenback@baltimoreexaminer.com