Alasmidonta_heterodon shell USFWSThe Dwarf Wedgemussel is the only freshwater mussel listed under the Federal Endangered Species Act that is found in Vermont. Threats include pollution, habitat degradation, dams, and reductions in host fish ranges. Its lifespan is relatively short compared to other freshwater mussels – about 12 years.

Key Characteristics

Dwarf_Wedgemussel USFWS

Conservation Status

This is the only federally endangered freshwater mussel in New England. Historically, it was found in nearly 70 locations in 15 watersheds along the Atlantic seaboard, but its range and population sizes have dramatically decreased in the last century.  Only 54 populations remain globally; 41 of these are estimated to contain fewer than 50 individuals. Recent surveys in the Ashuelot and Connecticut Rivers indicate an apparent decline and therefore further reason for concern.


A large river species, it is found in stable mud, silty sand, sand, or gravel where the current is sufficient to keep the substrate free of surficial silt. Prefers stable substrates in slow or moderate currents. It is often found near the banks among roots.

Host Species

Fish hosts in Vermont include the Tessellated Darter (Etheostoma olmstedi) and Slimy Sculpin (Cottus cognatus). Storm-assisted dispersal could be an important dispersal mechanism for this species too.


Only found in the Connecticut River basin on the mainstem of the Connecticut River, and slightly upstream into some larger tributaries. Historically found from Bloomfield to Brattleboro. More recently known from Hartland to Springfield, and from Guildhall to Lunenburg.

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