
Sable Island grey seals gathered in the water just beyond the surf zone, observing the observer standing on the beach.

Five seal species occur on Sable Island: grey Halichoerus grypus; harbour Phoca vitulina; harp Phoca groenlandica; hooded Cystophora cristata; and ringed Phoca hispida. Two of these - grey and harbour seals - breed on the Island, and are year-round residents on the beach and in surrounding waters. The other three are "arctic" species which usually occur in winter and early spring. The number of seals on Sable is greatest during the grey seal breeding season in December and January. Seals belong to a group of marine mammals called pinnipeds. The term is derived from the Latin pinna meaning "fin", "wing" or "feather", and pedis meaning "foot". Thus pinniped means "fin-footed" or "wing-footed", and refers to the front and hind flippers which are long and flattened webbed hands and feet. Pinnipeds are divided into three groups: phocids (earless or hair seals), otariids (eared seals, e.g. sea lions and fur seals) and odobenids (walrus). All pinnipeds now found on Sable Island are phocids (i.e. seals). The global distribution of seals, sea lions and fur seals depends on availability of food resources and haul-out areas. There are a few pinniped species in freshwater habitats, but most are found in the oceans at temperate and polar latitudes, particularly in areas of high biological productivity along continental shelves, banks and oceanic islands. Marine productivity is greatest where nutrient enrichment is caused by river outflows, upwelling and ice melting, and convergence and mixing of oceanic water masses. Although all their food can be found in the ocean, pinnipeds must come ashore for certain activities: pupping, nursing, mating (in some species), resting, moulting and avoiding predators. Periods on ice or on land (beaches, sand bars, rocky ledges) are relatively brief, but these times are critical in the lifecycle of pinnipeds. The waters in the Sable Island region provide suitable marine habitat and resources for seals, and the Island itself offers extensive and safe haul-out areas. On the 40-km-long Island there is roughly 80 km of easily accessible and predator-free beach. Seals are not hunted on Sable. In Canada, seal management is the responsibility of the Department of Fisheries and Oceans (DFO), and seals are covered in the Marine Mammal Regulations of Canada's Fisheries Act. Another pinniped species - walrus - was common on Sable Island until the early 1700s. Although the walrus population is now long-gone, skull and tusk fragments occasionally wash ashore, and most of these are archived at the Nova Scotia Museum in Halifax. Whales, dolphins and porpoises are also marine mammals. They are members of the Order Cetacea, from the Latin word cetus meaning “whale”. Although cetaceans are found on Sable’s shoreline (on average about 10 to 15 individuals per year), they are not really part of the Island’s fauna. Unlike seals, cetaceans are fully aquatic - they spend their entire lifecycle in the ocean. Live cetaceans only come ashore when they are in trouble, and beaching is most often fatal. Many of those found on Sable are individuals which were cast ashore after dying at sea. However, the Scotian Shelf waters surrounding the Island host a diverse community of whales and dolphins, and evidence of this is provided by the long-term monitoring program for stranded cetaceans on Sable. Thus far nineteen species of whales and dolphins have been recorded.

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