The harp-shaped pattern on the backs of adults explains the common name of these seals. Young pups are still controversially hunted for their fur. Harp seals are extremely social animals, congregating in huge numbers to give birth on ice floes in areas along the Arctic coastline.
Their sociability has led ultimately to their decline. The pups have soft, thick fur that is much sought after in some parts of the world. When the pups are gathered in large numbers, they make easy targets for hunters, who club them to death. Extensive hunting by humans reduced the total harp seal population from around ten million individuals to just two million by the early 1980s. Once their plight was understood, hunting pressure was reduced and the population is now gradually recovering. It will take a long time for harp seal numbers to reach their previous levels, because this species has a low rate of reproduction. Producing just one pup a year means that the population grows very slowly.
The luxuriant fur of harp seal pups keeps them warm as they grow up on the Arctic icepack. The pups are weaned after 10-12 days and abandoned by their mothers.
Harp seals spend most of the year in the ocean. They only return to the pack ice to give birth, congregating in large numbers at this stage, with up to 2000 seals per square kilometre (0.4 square miles). They are then particularly vulnerable to predation by polar bears. Young harp seals are pale yellow at birth, but by three days old their coat will have become snowy white. The pups grow very quickly, tripling their birth weight of 11 kg (24 lb) before they are weaned.
The harp seal is identified by its black head and the dark band along its flanks and over its back; the rest of the body is usually pale gray, but this is highly variable. It is an expert, fast swimmer, and spends much of the year at sea making regular north-south migrations. It can also move fast over ice if necessary. Fish and crustaceans are the harp seal’s main foods, and it is renowned for its ability to dive deeply and stay underwater for long periods in search of food. When feeding, adult harp seals may dive to depths of 200 m (655 ft) in search of herring and cod, which make up the bulk of this species’ diet.
Distribution: Occurs in the Arctic and northwestern Atlantic, breeding in the Gulf of St Lawrence off Newfoundland, east of Greenland and in the White Sea.
Habitat: Open sea for most of the year.
Weight: 130 - 160 kg (287 - 353 lb).
Length: 160 - 190 cm (63 - 75 in).
Maturity: Females 4 - 6 years; males 5 - 6 years.
Gestation Period: About 225 days; embryonic development only starts about 4.5 months after fertilization.
Breeding: 1; weaning occurs by 12 days.
Diet: Feeds on a variety of fish, including capelin, cod and herring, also crabs and cephalopods such as squid.
Lifespan: 16 - 35 years.
Females only nurse their young for about 10 minutes every four hours or so, otherwise the pups are left alone.
Adults have black heads, in addition to the harp-shaped marking on the back. Their fur is otherwise pale grey.
The seal moves these from side to side to provide propulsive power when swimming.
The darker areas of fur are slightly lighter in females than in males.
These tend to look more like paws than flippers.
ON THE MOVE
Eared seals and sea lions (left) use their front flippers for swimming, whereas members of this family use their hind ones.