Invasive golden clam found in Lake Champlain

Scientists uncertain if there is an infestation

By Mike Lynch

An invasive clam that can outcompete native species and is known to increase occurrences of algal blooms has been found in Lake Champlain for the first time. 

A single golden clam (also known as the Asian clam) was found by a volunteer at the South Bay Boat Launch near Whitehall last month during routine monitoring organized by the Champlain Aquatic Invasive Species Monitoring Program (CHAMP). 

“We are not surprised,” said Meg Modley, the aquatic invasive species management coordinator for the federally-funded Lake Champlain Basin Program (LCDP). 

The invasive species was found in the Champlain Canal in Hudson Falls in 2008, in Lake George in 2010 and Lake Bomoseen, Vt. in 2016. 

All three waterways drain into the southern portion of Lake Champlain. 

They aren’t known to be in any other Adirondack Park water bodies. 

Modley noted that the extent of a possible infestation is uncertain. A follow-up investigation by the state Department of Environmental Conservation found another full clam and parts of a third. Efforts to find infestations are expected this fall. 

“We’re not ready to say there’s a fully established population,” Modley said. “But unfortunately, the three known sources of Golden clam in the watershed all flow into the southern end of Lake Champlain.  

Golden clams are generally smaller than 1.5 inches in width and are hermaphrodites, meaning only a single clam is needed to reproduce. They can be spread through bait buckets, live wells in boats and other means. 

Native to Asia, Africa, and Australia, the clam can reproduce hundreds of offspring in a day or 35,000 per breeding season if they have optimal conditions. They prefer well oxygenated water above 60 degrees. Their larvae are free-floating so they can travel on currents in the water. 

In cases where they do proliferate, the clams can cause significant ecological and economic damage. 

They live on the surface or just under sandy or gravel bottoms and displace native mussels and other species. 

“The conditions in the southern end of Lake Champlain are not optimal for the species,” Modley said. “They like really sandy substrate, and they prefer shallow water. …They are able to adapt and find a way to survive.”

The same type of clams were found in Lake George in 2010, causing concern among state agencies, environmental groups and local communities, and spurring the formation of the Lake George Asian Clam Task Force. 

A task force project sought to eliminate the clams by smothering them using plastic mats held down by sandbags for seven years. 

Surveys showed that the nearly $2 million effort killed at least 96% and people were hopeful the clams would disappear. But that program was abandoned because the clams rebounded. 

The 2024 survey by the Lake George Park Commission found that clams now inhabit all large sandy areas along the western shoreline from the village of Lake George to Northwest Bay in Bolton Landing. 

There are now 50 locations in the lake where the clams can be found. However, the clams don’t seem to do well in areas where people use the beach frequently, such as roped swimming areas.  

The only major sandy area in the lake where clams haven’t been found is Huletts Landing in the town of Dresden. 

Fortunately, they “have not yet appeared to significantly impact Lake George ecology, water quality of recreation use,” according to the Lake George Park Commission’s September report on the invasive species.

The clams are the 52nd invasive species to be found in Lake Champlain. 

“The discovery of golden clam reinforces the need for all visitors to Lake Champlain to clean, drain, and dry their boats, trailers, and equipment to prevent the spread of aquatic invasive species,” Modley said.