The Softshell-clam is an introduced species in British Columbia that originates in Europe and along the Atlantic Coast of North America. It was first reported on the Pacific Coast in 1874 in Oakland, California (
Carl and Guiget 1958). By 1890 it was reported as abundant around Victoria, by 1895 it was reported from northern Vancouver Island, and by 1939 it was report from the Queen Charlotte Islands (Carl and Guiget 1958).