Invasive rock snot found in Schoharie Creek

Above: The Schoharie Creek in Lexington, where the USGS recently found the invasive algae Didymosphenia geminata, also known as "rock snot." Photo by Flickr user Doug Kerr; published under Creative Commons license.

The invasive alga known as "rock snot" continues its march into Catskills trout streams. Today, the state Department of Environmental Conservation announced that Didymosphenia geminata has been found in the Schoharie Creek near Lexington. From a DEC press release:

Samples taken by the U.S. Geological Survey and examined by DEC have confirmed that didymo is present in the Schoharie Creek about 1.8 miles east (upstream) of the hamlet of Lexington. This is the latest recorded incident of this aquatic nuisance species, also called "rock snot,” in New York State.

Upper Schoharie Creek is a popular trout fishery and the discovery of didymo here is particularly troubling given its proximity to other trout streams and the tendency of anglers to fish multiple streams during the course of a day or weekend.

Once established in a stream, rock snot cannot be eradicated. It can bloom into thick mats, covering the stream bottom and displacing habitat for trout and their food sources. The algae can spread from stream to stream by hitchhiking on the boots and equipment of anglers, especially felt-soled waders, whose damp nooks and crannies are a perfect habitat for harboring tiny living organisms.

Because of the threat of rock snot, Maryland, Vermont and Alaska have already banned felt-soled waders.

Several other prime Catskills trout streams are already infected with the algae. The DEC's website lists the East and West Branches, the Delaware River, the Little Delaware, and the Esopus Creek as infected waterways.

For a trout stream, rock snot is a problem, but not a death sentence, columnist Morgan Lyle wrote for the Schenectady Daily Gazette this May:

Fortunately, however, infection with didymo does not mean a river is doomed. It is now known to inhabit the Battenkill River, Esopus Creek, Kayaderosseras Creek and probably many other streams, but seems to have receded on all of them and hasn’t ruined anything. Apart from fouled nymphs and streamers during the occasional outbreak, you don’t hear much about it.

“It hasn’t been nearly as bad as what has been seen in other locations around the world, so I think we’ve been fortunate,” said Michael Flaherty, the fisheries manager for Department of Environmental Conservation Region 3, which includes the Esopus and the main stem (but not the branches) of the Delaware.

“One year, it became really obnoxious in May, and we had a good month or month and a half of that stalk material being so present in the water column that it affected anybody who fished there,” Flaherty said. “But then we had a decent-sized storm in June, and it cleared it all out, and it really never came back to a level like it had been.”