Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Temperate and subarctic regions of the North Atlantic Ocean. Three distinct populations, centered on the Baltic Sea (most common in the northeastern Gulf of Finland, the archipelago separating the Gulf of Bothnia from the Baltic proper, and off southeastern Sweden), eastern North Atlantic (mainly Iceland to northern Norway, with the largest rookeries in the British Isles), and western North Atlantic from Labrador to Massachusetts. In the western North Atlantic, principal breeding/birthing areas are Sable Island, the Basque Islands, Camp Island east of Nova Scotia, Amet Island in Northumberland Strait, Deadman Island in the Gulf of St. Lawrence southwest of the Magdalen Islands, and newly forming pack ice in the eastern portion of Northumberland Strait and between eastern Prince Edward Island and western Cape Breton Island; a few females may give birth south to Muskeget and Tuckernuck islands in Nantucket Sound, Massachusetts, and on Monomoy Island south of Cape Cod (Reeves et al. 1992). Major spring molting sites include Anticosti Island in the Gulf of St. Lawrence and Sable Island. See Reeves et al. (1992) for further details on distribution in the Baltic region and eastern North Atlantic.