Widened effort to eradicate invasive clams

ALBANY -- Dive teams that spread underwater mats to smother invasive Asian clams in an Adirondack lake this spring are now sifting the sandy bottom of a lake in New York's Finger Lakes wine country to determine how widely the water-befouling mollusks have spread there.

An interim report released last week on a $475,000 effort to eradicate Asian clams in Lake George said plastic mats spread on five acres of lake bottom have killed more than 97 percent of the clams. But it recommended additional work, such as suction harvesting, that could bring the cost to nearly $1 million.

A plan also is being developed to eradicate a new 5-acre colony of Asian clams discovered last month in another bay of 32-mile-long Lake George, where the clear, cold water, sandy beaches and mountain scenery have long made it popular for vacations and second homes.

The Asian clam, Corbicula fluminea, is known as the "good luck clam" in its native Southeast Asia. The thumbnail-size clams multiply rapidly because of their ability to self-fertilize and release up to 2,000 juveniles a day during breeding seasons in May and August.

Infestations of the clams usually occur when someone dumps a bait bucket or aquarium into a body of water. The mollusk's excretions feed algal blooms and the sharp shells from dead clams wash up on beaches in large numbers.

In Lake Tahoe, where a $1.4-million eradication effort was launched last summer, they have been blamed for algal blooms that have turned clear, blue bays a murky green.

Albany-based InnerSpace Scientific Diving, which is involved in the Lake George clam project, is now working to determine the extent of an infestation in Owasco Lake, about 25 miles southwest of Syracuse.

Divers plot their findings on a map, using GPS to pinpoint the location of clams. Populations also have been discovered in Cayuga and Seneca lakes.

In April, divers unrolled 825 50-foot-long plastic mats to cover the bottom of a five-acre bay of Lake George where the clams were discovered last fall.

Sandra Nierzwicki-Bauer, director of the Rensselaer Polytechnic Institute Darrin Fresh Water Institute on Lake George, said last week that more than 97 percent of clams were dead in areas where mats had been removed.

It is estimated than an additional $200,000 to $400,000 will be needed to finish work and pay for suctioning clams out of areas where mats can't be used.