Fly fishers serving as transport for little invaders

For fly fishers who pride themselves on a conservationist ethic, it hurts to discover that they may be trampling on that ethic every time they wade into a trout stream.

Blame their boots — or, more precisely, their felt soles. Growing scientific evidence suggests that felt, which helps anglers stay upright on slick rocks, is also a vehicle for noxious microorganisms that hitchhike to new places and disrupt freshwater ecosystems.

That is why Alaska and Vermont recently approved bans on felt-soled boots and Maryland plans to do so soon.

"If you were trying to design a material to transport microscopic material around," said Jack Williams, an expert on invasive species with the environmental group Trout Unlimited, "felt on the bottom of someone's boots in a stream would be as close to perfection as you could find."

The response among fishermen threatened with the loss of soles that cling to slippery rocks parallels the five stages of grief.

There is denial (the science is wrong), anger (why should I fall on my tail for the good of the planet?), bargaining (I will wash them, I will disinfect them, I will dry them), depression (I cannot afford new boots) and, finally, acceptance (I will go feltless if I must).

John Berry, a fishing guide in Cotter, Ark., switched to studded rubber-soled waders this year, after the streams near his house, by the White River in the Ozark Mountains, became infected with Didymosphenia geminata, or didymo.

A single-celled organism also known as rock snot, didymo has done as much as any invasive species to prompt calls for a ban on felt soles.

"I first thought it was toilet paper or something," Berry said of his first encounter with the algae, which resembles soggy tissue. "I wondered, Is someone upstream having a problem with their water treatment? Then we started hearing about didymo."

Didymo, which is native to British Columbia, migrated first to Vancouver Island — scientists say that its smothering blooms had been discovered there by 1989 — and then headed south and east, crossing the Rocky Mountains and hitting Plains states like South Dakota before arriving in Vermont in 2008.

Didymo has also been found (and felt soles banned) in New Zealand, possibly introduced by a North American angler's gear, scientists suggest. Once its pioneer cells are established, clumps of the algae bloom first on rocks, then cover river bottoms with a fibrous mat that can choke out the insect life that is trout food.

"We people are clearly the vector for its spread," said Jonathan McKnight, a wildlife biologist with the Maryland Department of Natural Resources who is trying to protect streams like the Youghiogheny River from didymo, whirling disease and other aquatic invaders.

"It's fly fishermen who are doing it," McKnight said. "The people who love and appreciate those rivers the most have got to be the ones protecting them." He said his department planned to ban felt soles this fall.

Bans or no bans, it can be a challenge to separate an angler from his felt soles when he believes the alternative is a bath in an icy stream. Fishing the Duchesne River in Utah while wearing rubber-soled boots about three years ago, Arvey McFarland, 56, a musician from Salt Lake City, took a hard fall.

"In all these years, the number of times I've fallen wearing felt soles, I can count them on one hand," he said. "When I've tried various rubber and pleated soles, I've opened my right elbow and dislocated my shoulder. No more for me."

Gerard Haines, 48, of Wyoming, Minn., who manufactures construction equipment, said that after wearing felt-bottomed soles for almost 20 years in the Brule and Kinnikinnick rivers, he switched last spring. He worked on a river-cleaning project in waders without felt soles, he said.

"It was hard to negotiate the stream bottom," Haines said. "The streams I'm fishing are not dangerous water, but you still want to keep your balance."

Wildlife biologists and local and national fishing groups like Trout Unlimited have spread the word about the threat of didymo and felt. On fishing blogs, anglers persistently debate the merits and drawbacks of the new rubber soles and the felt bans approved this spring by Vermont's Legislature and Alaska's Board of Fisheries. (Vermont's ban takes effect next April and Alaska's in January 2012.)

Orvis, the fly-fishing retailer, has switched its boot lineup from 80 percent felt-soled to 80 percent rubber-soled over the last two years, said Tom Rosenbauer, the marketing director for the company's rods and tackle.

The store's website urges, "Change your boots and help fight the spread of invasive species."