Also called the purple mahogany clam, the varnish clam was probably introduced into the region via ballast water carried by ships from Asia. Since its introduction in the early 1990s, this clam has spread throughout much of the Puget Sound, the Strait of Juan de Fuca, the San Juan Islands, the southern Strait of Georgia, and the Gulf Islands. Very little is known about the dispersal patterns and invasive capabilities of this clam. There is concern that this clam may impact Manila clam (Venerupis phillippinarum), another introduced species that is commonly harvested for food. For more information on the varnish clam see Dr. Claudia Mill's (the University of Washington, Friday Harbor Laboratories) website on the Nuttallia invasion in Washington State: http://faculty.washington.edu/cemills/Nuttallia.html