Asiatic clams finding home in local ponds

Ledyard - Residents and boaters on Long Pond are wondering what a new occupant of their neighborhood, the small, brown-shelled clams native to southeast Asia and Africa, means for their waterway.

"I first noticed them two years ago," said Robert Barnett, as he reached into the water Thursday to scoop up some of the Asiatic clam shells from a pile just past the end of the dock at his lakefront house.

Another Long Pond resident, Betsy Graham, said she first saw a few of the clams, about the size of a thumbnail, last summer. But this spring, she noticed huge piles of empty shells at her beachfront, at one of the dams on the lake and at the state boat launch there.

Graham, secretary of the Lantern Hill Valley Association, the organization of lake property owners, said she became concerned about a new invasive species in the lake, took some photos and sent them to the state Department of Energy and Environmental Protection.

"We have endangered mussels in our lake," she said. "They (the clams) are going to get transported downstream into Whitford Brook and Whitford Pond, and maybe the Mystic River."

Laura Saucier, wildlife biologist with DEEP, confirmed from Graham's photos that the shellfish were Asiatic clams, a non-native species first found in the Connecticut River in 1991. Since then, they have spread to several other rivers in the state, including the Shetucket and the Quinebaug, and other lakes including Amos Lake in Preston and Chapman Pond in East Haddam.

The pile of shells Graham and others noticed are probably due to a dieoff of the clams after the harsh winter, Saucier said. The clams cannot withstand temperatures below 36 degrees.

The U.S. Geological Survey lists the clams, also called golden clams and good luck clams, as a "nonindigenous aquatic species," and they were declared an invasive species in states such as Nevada after they multiplied rapidly in Lake Tahoe.

Lake Tahoe and Lake George in New York state are among waterways where eradication efforts are under way, according to Laury Parramore of the U.S. Fish and Wildlife Service. Asiatic clams are not, however, federally listed as "injurious wildlife," Parramore said.

Unlike zebra mussels, the more notorious non-native shellfish found in the western part of Connecticut, Asiatic clams are not officially designated an invasive species in this state, Saucier said.

"Further study is needed before a designation like that would be given," she said. "We are still trying to figure out what the actual distribution is."

She asked that anyone who thinks they see the clams in a lake or river send her a photo and contact her with questions.

The effects of the clams on native mussels and other aquatic species are unknown, Saucier said, although there is evidence that some native fish, ducks and crayfish have added them to their diets.

"There are lots of questions about their environmental impacts, and not a lot of data," she said.

The clams first turned up in this country in 1938 on the banks of the Columbia River, and since then have spread west and south to 38 states, according to the USGS. They were believed to have been brought to this country by Asian immigrants, who ate them in their home countries. Reproducing rapidly, the clams have caused millions of dollars' worth of damage to electric power plants on freshwater lakes and rivers, when the shells clogged intake pipes.

Saucier said the best way to prevent further spread is for boaters to make sure they rinse their vessels and gear after leaving a waterway.

Graham said she plans to raise the issue at the lake association's annual picnic later this month, and may suggest posting signs or taking other measures to alert lake visitors about the clams. Boaters, including kayakers and canoeists, should be made aware of the potential for carrying the clams to other waterways, she said.

j.benson@theday.com

Twitter: @bensonjudy

MORE INFORMATION

Photos and questions about Asiatic clams can be sent to Laura Saucier, wildlife biologist at the state Department of Energy and Environmental Protection, at laura.saucier@ct.gov.

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