Mammals
Harp Seal
Pagophilus groenlandicus · also called saddleback seal, Greenland seal
The harp seal is the classic seal of the Arctic ice — silvery adults with a dark harp-shaped mark on the back, and impossibly fluffy white pups born on the drifting pack ice. Its whole breeding strategy is a race against that ice.
Overview
Harp seals live in the North Atlantic and Arctic, in three main populations that breed off eastern Canada (the Gulf of St Lawrence and “the Front” off Newfoundland), around Greenland and the island of Jan Mayen, and in Russia’s White Sea. They are strongly migratory, spending the summer feeding in high-Arctic waters and moving south each winter to the pack-ice zone to breed. They are highly social, gathering in enormous groups on the ice and at sea.
The 12-day childhood
Harp seal reproduction is built around unreliable ice:
- A female hauls out onto the pack ice in late winter and gives birth to a single white pup.
- She nurses it for only about 12 days, on milk that is roughly 48% fat — among the richest of any mammal.
- The pup gains over 2 kg a day, tripling its birth weight, while the mother loses condition fast.
- Then she leaves. The weaned pup stays on the ice, moulting its white coat, fasting, and losing up to half its body weight before it finally takes to the water and learns to catch fish on its own.
This crash course lets a pup become independent before the breeding ice disintegrates.
Diet and diving
Adult harp seals eat mostly schooling fish — capelin, Arctic cod, herring — along with krill and other crustaceans, diving to a few hundred metres and staying down for up to about 16 minutes. Their large numbers make them a significant part of the North Atlantic ecosystem and a point of friction with fisheries.
The hunt
Harp seals are the focus of the world’s largest marine mammal hunt, in Canada, Greenland, and Russia. The commercial killing of whitecoat pups was banned in the 1980s after international outcry, and the modern hunt takes older pups and adults under quota. The species remains Least Concern and its numbers are increasing past seven million; the controversy is about the ethics and welfare of the hunt, not about population survival.
Climate and the future
Because harp seals cannot breed without stable pack ice, the biggest emerging threat is sea-ice loss. In poor-ice years in the Gulf of St Lawrence, most or all of that region’s pups have died when the ice broke up early. As Arctic ice becomes thinner and less predictable, breeding failures are expected to become more frequent even while the overall population stays large.
Harp Seal: common questions
Why is harp seal milk so rich, and why is nursing so short?
Harp seals give birth on unstable drifting pack ice that can break up or melt at any time, so there is a strong evolutionary pressure to get pups off the ice fast. The mother's milk is about 48% fat — one of the richest of any mammal — and the pup gains around 2.2 kg a day, more than tripling its birth weight in under two weeks. The mother then simply leaves to feed and mate. The abandoned pup lives on its fat reserves, moulting its white coat and gradually entering the water on its own to learn to hunt, losing weight for weeks before it succeeds.
What is a "whitecoat" harp seal?
It is the newborn stage. Harp seal pups are born with a yellowish-white lanugo coat stained by amniotic fluid ("yellowcoat"), which whitens within a few days to the pure fluffy white "whitecoat" that lasts about two to three weeks. As the pup moults, it becomes a grey, dark-spotted "beater," then a "bedlamer" juvenile, and only develops the adult silvery coat with the black "harp" marking after several years. The white pup coat is camouflage against the snow and ice.
Are harp seals still hunted, and are they endangered?
Harp seals are the target of the largest marine mammal hunt in the world, conducted mainly in Canada, Greenland, and Russia for pelts, oil, and meat. Whitecoat pups have been protected from commercial hunting since the late 1980s, so the hunt now focuses on older pups and adults, under government quotas. Despite this, the species is Least Concern and increasing, with a population of over seven million; the hunt is controversial on animal-welfare grounds rather than because it threatens the species.
How does climate change affect harp seals?
Harp seals are entirely dependent on seasonal pack ice as a breeding platform. In years when the ice forms late, is thin, or breaks up early — increasingly common in the Gulf of St Lawrence and elsewhere — whole cohorts of pups can be crushed, separated from their mothers, or drowned before they can swim. Reduced and less predictable sea ice is now considered the main long-term threat to the species, even as overall numbers remain high.