Yes, harp seals are highly migratory marine mammals that undertake one of the longest annual journeys of any sea creature, traveling thousands of kilometers between feeding and breeding grounds. The harp seal, named for the dark, harp-shaped pattern on the backs of adults, is common throughout the North Atlantic and Arctic Oceans. These animals follow the seasonal movements of pack ice, which is essential for reproduction and molting, driving a predictable, large-scale movement cycle. Their extensive migration routes connect sub-Arctic waters to the high Arctic.
Distinct Population Stocks
The global population of harp seals is divided into three major, genetically distinct stocks, each centered around a unique breeding area. These separate groups have their own annual migration routes and do not significantly mix. The largest stock is the Northwest Atlantic population, which breeds in the waters off eastern Canada. This group is further divided into two main breeding herds: the “Front” herd off Newfoundland and Labrador and the “Gulf” herd in the Gulf of St. Lawrence.
The second major stock is the Greenland Sea population, which utilizes the pack ice near Jan Mayen Island, north of Iceland. The third population is the White Sea stock, which breeds on the ice within Russia’s White Sea.
These three geographical stocks establish the starting points for three entirely separate migration systems. The Northwest Atlantic stock is by far the largest, estimated to be in the millions, while the other two stocks number in the hundreds of thousands to over a million combined.
Seasonal Drivers of Movement
The migration cycle is driven by two biological requirements: reproduction and the annual molt. Harp seals are dependent on sea ice to haul out for these critical life stages. In late winter and early spring, the seals migrate south to the stable pack ice on the southern edge of their range for whelping, or giving birth.
For the Northwest Atlantic stock, this occurs in late February and early March, when females give birth to a single pup on the ice. The pups are nursed for a brief period of about 12 days before being weaned and abandoned by the mother.
After the breeding and nursing period concludes, the annual molt begins. The seals then gather on the ice to shed their entire fur coat over a period of about four weeks, typically from April into May. During the molt, the animals rarely feed and can lose over 20% of their body fat.
Once both breeding and molting are complete, the seals undertake the return migration north to the Arctic feeding grounds for the summer and fall months.
Navigating the Migration Corridors
The seasonal biological drivers propel the seals along highly predictable, long-distance migration corridors that can cover between 3,000 and 5,000 kilometers annually for a round trip. For the Northwest Atlantic stock, the southward migration begins in late September, with the animals traveling along the Labrador coast toward their breeding areas.
After molting in April and May, this population begins its northward journey, dispersing to summer feeding grounds in the eastern Canadian Arctic and western Greenland. The routes are so well-defined that researchers use satellite tracking technology to monitor the specific paths and timing of these movements.
The Greenland Sea stock follows a similar north-south pattern, migrating from their Jan Mayen breeding area to summer feeding grounds between Svalbard and Greenland. The White Sea stock travels north from their Russian breeding ground to the Barents and Kara Seas for their summer foraging period. These animals utilize the rich Arctic waters, feeding on small fish and crustaceans throughout the summer and fall before the cycle reverses and they begin the southward trek again with the advancing winter ice.