Rock Snot Hitches Ride on Fishing Gear

A handful of rock snot algae, scooped up from a New England stream. i i

A handful of rock snot algae, scooped up from a New England stream. NH DES hide caption

itoggle caption NH DES
A handful of rock snot algae, scooped up from a New England stream.

A handful of rock snot algae, scooped up from a New England stream.

NH DES
Rock snot coats a rock in a stream. i i

Rock snot coats a rock in a stream. Twenty years ago, the algae was found only in isolated mountain streams in western Canada. But a more aggressive version has spread to streams in the western United States and to the East Coast. Sarah Spaulding, USGS hide caption

itoggle caption Sarah Spaulding, USGS
Rock snot coats a rock in a stream.

Rock snot coats a rock in a stream. Twenty years ago, the algae was found only in isolated mountain streams in western Canada. But a more aggressive version has spread to streams in the western United States and to the East Coast.

Sarah Spaulding, USGS
A rock snot bloom coats the bottom of a stream. i i

A rock snot bloom can cover a stream from bank to bank and reach for miles. hide caption

itoggle caption
A rock snot bloom coats the bottom of a stream.

A rock snot bloom can cover a stream from bank to bank and reach for miles.

Serious fly fishermen may remember 2007 as the year that the invasive species known as "rock snot" turned into a national problem. For at a least decade, nasty carpets of this algae have been fouling up pristine fishing streams in the western United States. Then, last summer, it turned up in fishing streams in several eastern states.

Angler Paul Doscher of New Hampshire says it's useless to cast fishing lines into these sometimes giant blooms.

"You try to reel it back in, and you end up with a giant gooey cottony wad (on your hook)," he said. "There is nothing like that that I have experienced. It makes streams essentially unfishable."

Isolated Nuisance to Uncontrollable Monster

Twenty years ago, a mild version of the one-celled diatom that pumps out rock-snot blooms was found only in isolated mountain streams in western Canada. But in the 1980s, these blooms started getting larger and spreading into other streams.

"Something changed the diatoms in ways that made them more aggressive," said researcher Andrea Kirkwood of the University of Calgary. She says the change may have taken place when a European version of the rock snot diatom was accidentally brought to Canada. Kirkwood says it's also possible that the native version of this algae evolved in ways that created much more massive and more frequent blooms.

What's certain is that by the early 1990s, massive rock snot blooms were fouling cold, clear rocky mountain streams in western states such as Idaho, Wyoming and Colorado. Infestations sometimes stretched from bank to bank and covered several miles. Once the blooms appeared, it was impossible to make them go away.

East Coast Invasion

Rock snot seemed to be a strictly western problem until this past June, when a massive bloom appeared on the New Hampshire side of the Connecticut River. Before the summer, slimy carpets had fouled pristine fishing streams in New York, Vermont, Tennessee, Missouri and Virginia.

Anglers like Paul Doscher say it's now clear that fishermen who don't clean and dry their boots and fishing rods have helped spread these nasty blooms.

"The reality is that anglers and recreationists travel worldwide now to do what they do," he said. "When they travel they bring their equipment with them. Some of us don't sanitize that equipment properly when we're done fishing."

Doscher says he has no doubt that this is how the rock snot blooms got spread around the country. He also suspects that sloppy fishermen helped carry rock snot diatoms to streams on the south island of New Zealand.

Officials in New England have been posting signs near fishing streams that urge visiting anglers to clean and dry their gear.

"You find them nailed to trees near streams where anglers go," says Doscher. "They tell fishermen to 'Stop the rock snot.'

Whether these signs do any good won't be known until early next spring when scientists around the country begin looking for new rock snot hot spots.

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