Thursday, November 10, 2011

Lake George Survey Finds No Additional Asian Clams

The Lake George Asian Clam Rapid Response Task Force (Task Force) has conducted a lake wide survey to identify any additional sites of infestation since the discovery of Asian clam in Lake George waters in late summer of 2010.

Populations have been found at Boon Bay, Treasure Cove, Norowal Marina, and a small population at Shepard’s Park just adjoining the first infestation near Lake George Village where substantial treatment actions were taken this year.
The Task Force’s lake-wide survey of all known suitable Asian clam habitat in Lake George was designed to prioritized management, according to Walt Lender, Executive Director of the Lake George Association. “While new infestations could appear in the future the lakewide survey assures that for now resources are being spent in the most critical areas. If we had found other infestations we would have to consider prioritizing management based on the size of the infestation and the resources and control technologies available to us,” he said in part of a prepared statement presented here:

When the Lake George Village infestation was first discovered in August 2010, a survey was conducted around the southern end of the lake from Diamond Point on the western shore to Dark Bay (just south of Dunham’s Bay) on the eastern shore. Forty-five sites were surveyed within 10 miles of shoreline of the infestation, and no additional clams were found. A site north of that survey area, 6 miles up the lake on the western shore in Boon Bay was discovered in mid-July and then another site north of that at Norowal Marina in Bolton Landing at the end of July. These additional sites prompted the need for the lake-wide survey.

Over 60 marinas and public beaches were surveyed by members of the Task Force in early August. A fourth site was found at Treasure Cove, just south of Boon Bay, as well as a small expansion of the Lake Avenue Site in front of Shepard’s Park in Lake George Village. This first round of surveys covered high use areas, such as marinas and public beaches, but with 176 miles of shoreline on Lake George, there were still many more locations that could be suitable for
Asian clams.

Members of the Task Force next mapped out the known suitable habitat for Asian clams in Lake George. Large areas of shoreline on Lake George, especially in the middle of the lake, are very rocky and drop off quickly, not providing suitable habitat for Asian clams. So it didn’t make sense to try to survey the entire shoreline of the lake. Instead, sites of suitable habitat were identified by a combination of on-the-ground reconnaissance and office technology. Sandy, shallow sites were identified from on the water by boating long distances of
the shoreline very slowly and very close to shore and marking any locations found that met the criteria. Satellite imagery was also used. Over 100 sites were identified that still needed to be surveyed in addition to the more than 60 sites that had already been surveyed in August.

Asian clams prefer shallow warm water and sandy substrate. The survey focused on high use areas where there might be the risk of introduction of the clam from overland transport, bait introduction, or aquarium dumping and the most suitable habitat. Marinas, boat launches, public beaches, and all sandy shallow areas were surveyed.

AE Commercial Diving was contracted by the Lake George Association to survey the over 100 sites identified as suitable Asian clam habitat that had not yet been surveyed. It took four weeks to complete the work. At each site, divers carefully swam side by side parallel to shore over all shallow sandy lake bottom shoreline at 3ft and 6ft depths. They conducted a visual survey and sieved sediment samples on the lake bottom for the presence or absence of adult and juvenile clams at 10 ft intervals. In addition to swimming parallel to shore at 3 and 6 ft
depth sieving every 10 ft along the shore, divers swam a transect perpendicular to shore every 50 ft out to 10 ft depth and sieved at intervals along the transects as well.

As of the end of October, 2011, more than 160 sites around the perimeter of the lake have been surveyed by AE divers, Rensallear Polytechnical Institute Darrin Freshwater Institute (DFWI), and the Lake George Association.

The Lake George Asian Clam Rapid Response Task Force is managing the eradication effort. This Task Force includes a wide variety of organizations, scientists and agencies. The Task Force includes the Rensselaer Polytechnic Institute Darrin Fresh Water Institute, Adirondack
Park Invasive Plant Program, FUND for Lake George, Lake Champlain Basin Program, Lake George Association, the NYS Lake George Park Commission, The Nature Conservancy’s Dome Island Committee, Lake George Watershed Coalition, the NYS Department of Environmental Conserva-
tion, NYS Adirondack Park Agency, Bateaux Below, Inc., InnerSpace Scientific Diving, Scientific Diving International, and the Vermont Department of Environmental Conservation
as well as researchers from Lake Tahoe.

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