The European flat oyster, Ostrea edulis, a native of Europe, occurs naturally from Norway to Morocco in the North-Eastern Atlantic and in the whole Mediterranean Basin; It has been a harvested species for at least 6000 years. Natural populations are also observed in eastern North America, from Maine to Rhode Island, following intentional introductions in the 1940s and 1950s. The species was also introduced in Canada for aquaculture purpose 30 years ago and some populations naturalised in Nova Scotia, New Brunswick and British Columbia. These stocks were imported from naturalised populations in Maine whose ancestors originated in the Netherlands.