State works to eradicate parasite deadly to trout

March 23, 2007|By Tom Pelton | Tom Pelton,Sun reporter

ACCIDENT -- Mark Harmon remembers the first hint of something funny with the trout at the state's Bear Creek hatchery in Western Maryland. The fish were swimming in circles.

"You ever see a puppy chasing its tail? That's what they looked like," said Harmon, the hatchery's assistant manager.

As it turns out, the fishes' spines and skulls were being deformed by a deadly parasite called Myxobolus cerebralis. The microscopic species causes an infection known as "whirling disease" that has decimated trout populations in Colorado, Montana and other Western states.

Since discovering the infected fish here last fall, state officials have begun an aggressive program of trying to contain the disease found at three hatcheries in Garrett County. The state this month destroyed 135,000 diseased trout at the Bear Creek and Mettiki hatcheries.

The dead fish - both rainbow and brown trout - were hauled by a pair of tractor-trailers to a rendering plant to be chopped into food for chickens.

The Department of Natural Resources is closing the hatchery at the Mettiki coal mine and another at the Jennings Randolf dam on the Potomac River. And the agency has temporarily shut down 12 of the 15 trout growing tanks here at Bear Creek, where the cement troughs will be scrubbed and twice disinfected with a lime solution, said Bob Lunsford, director of freshwater fisheries.

The result: The state will have about 20 percent fewer trout to stock into 126 streams and ponds this spring, and fishermen will have fewer to catch, Lunsford said. The health of humans or other animals isn't at risk, because the parasite infects only trout. But trout populations in the state could suffer for decades.

Officials acknowledge that they likely spread the disease when they ordered a load of 3,300 trout transferred here from Mettiki, not knowing the fish were contaminated.

"It never even crossed my mind when I authorized that transfer that fish from Mettiki could be infected," said Lunsford. "But I was clearly in error."

State workers are stepping up their efforts to disinfect trucks used for trout stocking and other equipment to prevent further spread of the disease, said Howard King, director of fisheries. And the department plans a publicity campaign to tell fishermen to disinfect their boots and waders.

Biologists know the parasite's spores can survive for 20 to 30 years. The spores are ingested by worms, which are eaten by trout. The spores are "virtually indestructible" and cannot be cleaned from streambeds once they take hold, according to the Montana-based Whirling Disease Foundation.

Beyond the three infected hatcheries in Western Maryland, state officials say the disease is also in the North Branch of the Potomac River. This spring, scientists will study other streams to see if it has also spread to the Youghiogheny River, Bear Creek, Savage River, Sand Run, Deep Creek Lake and Gunpowder River, among other waterways, Lunsford said.

Some fishermen worry that rainbow trout raised by the state and released could spread the parasite to native brook trout in Western Maryland, devastating some of the best fishing in the East. Some anglers are angry, with a few blaming the department for spreading the disease.

Ken Pavol, former western regional fisheries manager for the department, said the whirling disease was first detected in Maryland 12 years ago at the state hatchery near the Jennings Randolf dam.

Trout there are grown in floating net pens on the North Branch of the Potomac, said Pavol, who retired in 2005 and is now a fishing guide. Wild trout in the Potomac, already infected with the disease, apparently passed it to the fish being raised in the pens. How it got into the Potomac is unclear, but since its introduction from Europe 50 years ago it has spread to 22 states, including Virginia.

Instead of shutting down this infected hatchery in the 1990s and destroying the diseased fish, the state released the fish back into the Potomac River, Pavol said. The infected fish were also stocked into at least two ponds in Allegany County, state officials said.

By continuing to use the infected Jennings Randolf facility over the past decade, state workers may have accidentally spread the parasite's tiny spores to the Mettiki hatchery, Pavol said. From there, the state may have stocked infected fish into streams across Maryland, Pavol said.

"The state should stop the practice of rearing and stocking infected fish," said Pavol, now a vice president of Trout Unlimited, a conservation group. "Now we have a problem that's more extensive than it was. It could have been contained."

Lunsford, who used to be Pavol's boss, said birds, not state workers, may have spread the disease to the Mettiki hatchery.

At the Bear Creek Trout Rearing Station this week, 12 of the 15 mossy cement tanks that are normally brimming with fish in the spring were empty. The 90,000 trout they held were killed and trucked away earlier in the month.

Three other runs, gurgling with the creek's crystal waters, hold fish that tested negative for the disease. Dozens of golden-colored rainbow trout swirl in a 10-by-60-foot fiberglass-lined cement tank.

The trout churned the water and snapped for food as a state worker walked up and down with a bucket, scattering fish chow.

"There's no way we want this disease to spread any further," Harmon said.

tom.pelton@baltsun.com

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