Genus and Species: Halichoerus grypus
Male gray seals can grow to almost ten feet long.
Physical Description: Gray seal coloration varies from blackish with white specks and splotches to whitish with black markings. Generally, males are darker and females lighter. Pups are born white with a yellowish tint. Male gray seals have wrinkled necks, thicker necks and shoulders, and longer, broader, more rounded snouts than females.
Size: Male gray seals are much larger than females, weighing 375 to 880 pounds and growing to almost ten feet long. Females weigh between 220 and 572 pounds and reach lengths of up to seven and a half feet. The size difference between individuals can be even more striking than these averages: Some males weigh three times as much as some females. Seals living in Canadian waters grow the largest.
Geographic Distribution: Gray seals breed from eastern Canada to the Baltic Sea. Canadian breeding areas include the Gulf of Saint Lawrence and coastal Nova Scotia, Newfoundland, and Labrador. Colonies are also found in coastal Iceland, Great Britain, northern Norway, Denmark, southern Sweden, and Estonia. Young seals wander widely. For instance, Canadian gray seals are sometimes seen as far south as New Jersey.
Status: The gray seal's Baltic population is listed as endangered on the World Conservation Union's (IUCN's) Red List of Threatened Animals.
Habitat: Gray seals breed in a variety of habitats where disturbance is minimal, including rocky shores, sandbars, ice flows, and islands. They feed in cold open waters.
Natural Diet: Gray seals eat a wide variety of fish, squid, octopus, and crustaceans such as shrimp. Sometimes they eat a seabird or two. Small fish are swallowed whole, while larger ones are held in the seal's mouth and torn into smaller, more easily swallowed pieces with the claws on the front flippers.
Reproduction: Gray seal breeding seasons vary, but most breeding takes place between late September and early March. Males posture or fight for access to multiple females, which congregate at haul-out sites to bear and nurse their young. Gestation lasts ten months to a year, and pups are born at haul-out sites the season following mating. They wean about three weeks after birth. Adult females breed again at about the same time as their young wean. Females usually start breeding at three to five years old. Although males are ready to breed at four to eight years old, due to competition with older males they rarely do so before ten years old.
Life Span: In the wild, gray seal females live up to 40 years, while males live up to 30 years. In zoos, they can live into their forties.
Behavior: Gray seals congregate in large groups for breeding, pupping, and molting. During the four- to six-week-long breeding period, neither males nor females eat, drawing from their fat (blubber) for nutrition. Size and fat reserves play an important part in successful breeding. Male seals that can spend more time on land chasing females, and less time feeding at sea, have greater mating success. They also gather in small groups to rest on land. But when it comes to finding food, gray seals dive alone or in small groups.
Past/Present/Future: Over the centuries, gray seals were hunted commercially and for subsistence and many populations declined. In recent years, many have bounced back. Today, they are protected in many areas and their harvest is limited in others. In some areas, a bounty exists on these animals because they sometimes damage fishing nets, eat commercially valued fish, and carry a parasite called the codworm, the larvae of which live in fish and reduce their commercial value. Many gray seals, especially young ones, get tangled in fishing nets and drown. However, except for the Baltic population, gray seal populations are doing well—holding steady or increasing.
A Few Gray Seal Neighbors:
Harbor Seal (Phoca vitulina): One of the most widespread seals, this animal coexists with gray seals throughout much of the gray's range.
Killer Whale (Orcinus orca): Also called orcas, these predatory whales probably feed upon gray seals.
Northern Fulmar (Fulmarus glacialis): A gray, gull-like seabird that feeds on fish and other marine creatures in coldwater seas.
The gray seal's scientific name, Halichoerus grypus, derives from the Greek words meaning "hook-nosed sea pig."
Gray seal pups grow extremely fast on their mother's fat-rich milk, adding two and a half to over three pounds per day until they are weaned at around three weeks old.
Gray seals dive up to 475 deep and can remain underwater for up to 20 minutes at a time.
The Sierra Club Handbook of Seals and Sirenians, by Randall R. Reeves, Brent S. Stewart, and Stephen Leatherwood; Sierra Club Books, 1992.
The Natural History of Seals, by W. Nigel Bonner, Facts on File, 1990.
The Pinnipeds: Seals, Sea Lions, and Walruses, by Marianne Riedman; University of California Press, 1990.