Vermont Agency of Natural Resources staff have confirmed the presence of Asian clams (Corbicula fluminea) in Lake Bomoseen. This invasive species had been documented in the surrounding region, most notably in Lake George, NY, but had not been found in Vermont until now.

After a positively identified specimen was collected from southern Lake Bomoseen, Agency staff surveyed the lake to determine the extent of the Corbicula population. Likely introduction points, such as boat ramps and public beaches were surveyed, as was the area around the Green Mountain Conservation Camp docks where the initial specimen was found. Locations with sandy substrates, preferable Asian clam habitat, were also surveyed.

The relatively small, yellowish clam was found only in an isolated area of the southwestern part of the lake, which included sites directly adjacent to the Conservation Camp docks and part of the narrow channel leading to the dam. The area in which the species was confirmed measures approximately 14 acres, with depths up to 8 feet. No Asian clams were found at any of the other public access areas or beaches surveyed, suggesting that the species has not spread throughout the lake.  

Native to the eastern Mediterranean and other temperate regions of Asia, this species has spread through much of the eastern U.S. Several populations have recently popped up in western states as well. Able to quickly form dense populations under certain environmental conditions, Asian clams can clog intake pipes, industrial water systems, and irrigation canals. Like zebra mussels, another exotic invader, Asian clams are filter feeders, and can deplete benthic resources needed by native species.

It is unclear how or when the species was introduced to Lake Bomoseen, or exactly where the initial introduction occurred, but the presence of large, adult individuals (up to 2.4 cm diameter) and relatively high density in the affected area (approximately 240 individuals per square meter) likely indicate that the clams have been here for a year or more. Like most aquatic invaders, Asian clams can be transported from one body of water to another via small amounts of water or sediment. Boaters, anglers, and other lake users should always clean, drain, and dry their equipment after use to ensure that unwanted hitchhikers, like Asian clams, are not spread to new waterbodies.