Invasive Species Task Force Recommends Actions to Control Invasive Asian Clam in Lake Bomoseen, VT

The Lake Champlain Basin Aquatic Invasive Species Rapid Response Task Force has recommended actions to contain, control, and prevent the spread of Asian clams (Corbicula fluminea) in Lake Bomoseen, Vermont.

A camp counselor discovered Asian clams near the Green Mountain Conservation Camp docks in Lake Bomoseen in August 2016. After this discovery, the Task Force surveyed the entire lake to identify other areas of infestation, and found no other sites with the invasive clam.

After conducting a risk assessment, the Task Force recommends the use of benthic barrier mats—large nylon mats used to cover the lake bottom—to contain and control the invasive clam population by smothering them. They also have determined that increased education and outreach efforts are necessary to prevent the spread of the invasive clams within the lake and to other water bodies.

The bivalves, which are native to the eastern Mediterranean and temperate areas of Asia, prefer sandy areas and can crowd out native species and increase occurrences of algae blooms. The hermaphroditic clam needs only one individual to start a population, and the species reproduces quickly.

Lake Bomoseen is the first lake in Vermont with a confirmed population of Asian clams. Asian clams were discovered in the Champlain Canal in New York in 2008 and in Lake George, NY in 2010, but have not yet been found in Lake Champlain. Lake Bomoseen is a popular destination for in-state and out-of-state boaters. Asian clams may have been transported by watercraft or associated gear, or by aquarium dumping or other means.

The discovery of Asian clam in Lake Bomoseen, also home to zebra mussels and several species of aquatic invasive plants, reinforces the need for all visitors to Clean, Drain, and Dry their boats, trailers, compartments, and equipment to prevent the spread of aquatic invasive species.

The Task Force’s Spread Prevention Recommendations include:

1. The lead agency, the Vermont Agency of Natural Resources, should pursue a general rapid response permit to use benthic barrier mats to contain and control the population of Asian clams in Lake Bomoseen.
2. Further delineation of the Asian clam population at the known infestation site in Lake Bomoseen is required to identify areas for treatment, develop cost estimates, and determine treatment feasibility.
2. Measures to prevent the spread of Asian clams within Lake Bomoseen due to disturbance from traffic and anchoring should be considered.
3. Spread prevention measures should include enhancement of the VT Greeter program to ensure that all boats arrive clean, drained and dry and leave clean and drained from Lake Bomoseen to prevent the spread of Asian clams and other AIS. Watercraft decontamination stations should be made available to remove AIS from high risk vessels.
4. Ensure that signage is posted at all public access sites to Lake Bomoseen as part of an education and outreach campaign and continue to promote the “Clean, Drain, and Dry” message to all users of Lake Bomoseen to prevent the transport of Asian clams, zebra mussels, and other aquatic invasive species to other water bodies.
5. Incorporate surveillance for Asian clam into early detection programs in the Basin including through the Lake Champlain Long Term Monitoring Program and the Vermont Invasive Patrollers programs. Develop a standard operating procedure for early detection of Asian clam and target lakes with suitable habitat for early detection surveys.

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