Local Seals at a Glance

enlarge image Gray seal, with its distinct "horse head" shape, off Jeremy Point in Wellfleet, Mass. in April 2008. (Credit: Meghann Murray/NOAA Fisheries) enlarge image A harbor seal has a blunt, round face and small flippers. (Credit: Woods Hole Science Aquarium, NOAA Fisheries) enlarge image Gordon Waring with a hooded seal pup in March 2005 on ice in the Gulf of St. Lawrence. Waring participated in studies of harp and hooded seals with colleagues at the Canadian Department of Fisheries and Oceans. (Credit: NOAA Fisheries)

Related Links Gray Seals Harbor Seals Harp Seals Hooded Seals

Four species of seals - gray, harbor, harp, and hooded - can be found seasonally in waters around Cape Cod and nearby islands, although gray and harbor seals are by far the most common with numbers in the thousands.  Harp and hooded, or “ice seals”, number less than 100 per year, possibly because Cape Cod is the southern end of their range. 

The highest numbers of gray, harp and hooded seals in New England coastal areas occur from late autumn through early spring. Harbor seals are most abundant during late spring through early fall, which overlaps with their pupping and molting seasons.

Gray and harbor seals can frequently be seen resting on rock piles, ledges, sand bars, and jetties exposed during low tides. They also rest on isolated beaches, in marshes, and on floating docks. 

Harbor seals are the most common seal seen along the U.S. East Coast, ranging from the Canadian Arctic to New Jersey, although some have been spotted as far south as the Carolinas. They also inhabit the U.S. West Coast, from Baja, California to Alaska and occur in the Bering Sea.

Gordon Waring of the Woods Hole Laboratory of NOAA’s Fisheries Service, who has been studying seals for the past two decades, has conducted a variety of ecological studies on harbor seals in Maine and gray seals on Muskeget Island. The two species do not interbreed and have very different birthing patterns. Their size and color differences make them easy to distinguish.

Along the U.S. East Coast, gray seals are known to give birth in winter at a few sites (known as colonies) on Muskeget Island, on Green Island in Penobscot Bay, and on Seal Island off the coast of Rockland, Maine. Mothers remain hauled out or ashore to nurse pups for about two weeks.  The pups remain in the colony for two to three more weeks, until they have shed their white birth coat and grown a darker one. 

Male gray seals have dark coats with lighter blotches, while female coats are lighter in color with dark spots.  Males can grow to eight feet in length and weigh 800 pounds, while females can grow to seven feet and weigh 500 pounds.  The head shape of a male gray seal is very distinct and is commonly referred to as a “horse head.” 

The much smaller harbor seals have their pups in late spring on scattered tidal ledges and small isolated treeless islands, particularly along the coast of Maine. Harbor seal mother/pup pairs may enter the water immediately following birth, and mothers nurse their pups for 25 to 30 days. Male and female harbor seals look similar, and can grow to a maximum length of about six feet and weigh up to 300 pounds. Their coat can vary in color from light gray to brown with spots and marks.

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