The most abundant seal on Sable island is the Gray Seal which has increased at some 13% per cent over the past years.

Research on Sable Island has been carried out to access the foraging habits of Gray Seal using satellite-linked radio tags, small underwater videocams attached to seals, blubber samples to identify diet sources, and other modern techniques. Gray Seals also carry adults of Sealworms, the younger stages of which occur in groundfishes, especially Cod. Successful research has been carried out on Sable Island to develop antiferility vaccines that is injected into females during the breeding season.

The Harbour Seal is much scarcer on the Island coinciding with the great increase of Gray Seals. The Harbour Seal has been subjected to great losses from shark predations in recent years.

Other more northern seals have become common during the winter and spring on the Island’s beaches, especially Harp Seals and to a lesser extent Hooded Seals from the ice fields off Newfoundland. A few of the arctic Ringed Seals have also occurred. The island once held large herds of Walruses that were exterpiated soon after the arrival of Europeans. Only the occasional skull or other bone, is exposed by storms.