These large seals inhabit remote islands and shoals on both sides of the northern Atlantic. In North America most live along the Canadian Maritime provinces, although smaller numbers are found along the shores of New England.
Grey seals have a similar, but bolder, color pattern to harbor seals.
Males grow to 8 feet and weigh about 800 pounds, while females are smaller, growing to 7 feet and weighing about 400 pounds. Female grey seals are estimated to live to at least their mid 30's. Males are estimated to reach only their mid 20's, which may be a result of the fierce competition between males for mating rights with the females. Breeding takes place on rocky or sandy islands or land fast ice after pups are weaned. Newborn pups averaging 3 feet and weighing about 35 pounds are born in January and February.