This species is found throughout much of the
Atlantic and
Gulf coastlines of eastern North America, from
New York south to
Cuba, east to
Bermuda, and west to
Texas. It also has a fragmented distribution along the
Mediterranean shoreline of southern Europe, including parts of coastal
Spain &
Italy, the
Balearic Islands, and
Corsica. Populations in northern Italy are thought to be introduced. One very small population is known from
Georgia, on the coast of the
Black Sea. It is also found along the western and southern shorelines of the
Caspian Sea in
Iran and
Azerbaijan. This species is also found along the
Volga and
Don Rivers in southwestern
Russia, but it is unknown whether these populations have natural origins. == Threats ==