Catch of day: didymo

With Memorial Day weekend about to begin, state biologists are racing to set up decontamination stations along six popular trout streams in an effort to stem the spread of an alien algae that destroys fish food supply and habitat.

Strong saltwater is the enemy of didymo, an algae that forms a thick mat on the bottom of rivers and streams and suffocates plants, insects and tiny creatures. Scrubbing fishing gear and waders for a minute with a brush dipped in a saltwater solution kills microscopic traces of algae, preventing it from getting a free ride to another trout stream.


The 13 primitive wooden stands are being set up statewide, from Gunpowder Falls in Baltimore County to the north branch of the Potomac River in Garrett County. Each stand holds a black plastic tub, a 5-gallon pail and a scrub brush. A sign explains the problem and gives instructions.

"The wader wash is as much to educate everyone who uses the river as it is to clean waders," said Jonathan McKnight, the Department of Natural Resources lead biologist on invasive species.


Yesterday, McKnight and Charlie Gougeon, a DNR fisheries manager, set up stands along the Gunpowder below Prettyboy Reservoir, at Falls, Masemore, Bunker Hill, York and Bluemount roads.

"The rain has helped break it up some," said Gougeon, who has been monitoring didymo outbreaks. "But it's so early in its establishment, we're likely to see it pop up elsewhere. So we're waving the flag and singing the song and doing whatever it takes to get the word out."

Didymo was identified in the 1890s in Great Britain, Scandinavia and China. It was detected on the West Coast a decade ago and on the East Coast in just the past few years.

Anglers discovered didymo on the Gunpowder this month, setting off alarms among invasive species experts and fisheries managers, who are concerned it might spread to Maryland's other premier trout streams.

The algae, which can grow to be a foot thick, seems to favor tailwaters - swift moving water below a dam - like the Gunpowder, Big Hunting Creek in Frederick County and Savage River in Garrett County.

With research in its early phases, scientists aren't sure how much damage didymo can do. But they are concerned about anything that upsets the balance of trout streams by destroying essential elements.

In South Dakota, where didymo was detected in 2005, officials blame massive algae blooms for the decline in brown trout in a popular stream. After the algae showed up in New Zealand in 2004, officials initiated a "biosecurity lockdown" that included checkpoints and penalties of five years in prison and $100,000 fines for anglers and boaters who failed to clean their gear.

With nearly 66,000 licensed trout anglers and a national reputation to uphold, Maryland officials and tackle shop owners aren't waiting for answers.


Mike Watriss, owner of Great Feathers fly-fishing shop in Sparks, not far from the Gunpowder, has a fact sheet on the counter and counsels customers about proper gear cleaning.

"Panic is not what we need. Common sense is what we do need," Watriss said. "It's our obligation at the lowest level to educate people as to what didymo is and what it has the potential to do."

Anglers who fish in areas without scrubbing stations should carry in their vehicle a 5-gallon pail, 1 pound of salt and brush and use water from the river to make a saline solution. If that proves impractical, they should disinfect boots, waders and other gear at home in a solution of 1 pound of salt to 5 gallons of water or scrub them down in hot water and dish detergent and then air-dry. The organism can survive on moist surfaces for two days.

Boaters and tubers should take similar precautions.

McKnight said he is hoping fishing clubs will agree to build and maintain more scrubbing stations.

"Thirteen is not enough. We'd like to have more," he said. "But we're going forward with the resources we have to try to stop this in its tracks."