The Harp seal is a sea mammal of the fin-footed animal group and the Phocidae family (true seals with no external ears). The adult male has an irregular horseshoe-shaped black band across its back. This ‘harp’ joins across the shoulders and curves toward the abdomen, then goes back up toward the hind flippers, where it disappears.
In this post, Pritish Kumar Halder takes a brief look at Harp seal – distribution, lifestyle and habits.
The main colour of its coat is pale grey when dry and steel blue when wet. Its head and tail are black, and its front flippers and stomach are whitish. Adult females have the same pattern, except that their head, tail, and the ‘harp’ are usually lighter in colour. Some females have irregular dark spots on their backs with no clear ‘harp’ pattern. Sometimes very dark ‘smutty’ seals can be seen, which are usually males believed to be melanistic or darkly pigmented colour forms.
Harp seals live in the North Atlantic and the Arctic from the Barents and Kara Seas to the waters around Newfoundland and Greenland. There are three Harp seal populations: one breeds off the coast of Newfoundland in the Gulf of St. Lawrence, another breed in the Greenland Sea north of Jan Mayen Island, and the third breeds in the White Sea. These seals spend most of their time near pack ice in coastal ocean waters. On land, they favour rough ice at least 0.25 meters in thickness.
Habits and Lifestyle
Harp seals are solitary creatures except during the mating season when tens of thousands congregate together. There is no social organization for these groupings. They spend most of their lives in open water, but “haul out” or come onto land on a regular basis to spend some time there. Hauling out is usually at night. The longest haul-outs are the one during the breeding season and the other at molting time.
If they stay on the ice for extended periods of time, the seals form holes in the ice to enable them to access water easily and for breathing when they swim under the ice. These seals are highly migratory, undergoing a migration each year of 6,000 – 8,000 km. The north migration starts after the breeding season, the seals returning around late autumn to the breeding grounds in large, noisy groups.
Diet and Nutrition
Harp seals are carnivorous (piscivorous) animals, eating fish, including capelin, herring, cod, Arctic cod and halibut, and crabs and other invertebrates.
Harp seals exhibit polygynous mating systems. The male courting rituals involve making pawing gestures, calling, blowing bubbles, and chasing females across the ice. They also fight for mating access by beating one another with their flippers and biting. Dominant males mate with a few different females. The mating season takes place from February to March. After a gestation of 11 months, a single pup is born, which will be nursed and looked after by its mother for a period of 10 to 12 days.
When the pup is nursing, the mother leaves the pup on its own for a long time. The pup will remain near the place where its mother entered the water. Once weaned, the pup is left on its own on the ice, where it will shed its white coat and grow a silver-gray one. In about four weeks pups are fully independent and will forage for their own food. Harp seals are sexually mature at 3 to 8 years old.
Over-exploitation, especially in the northwest Atlantic, along with an unregulated and expanding trade in seal products, is the single largest threat to the Harp seal. Other threats are global warming, accidental catches in fishing equipment, oil spills, and other environmental contaminants. Oil development located in the Barents Sea is a future threat.
According to the IUCN Red List, the global population size of the Harp seal is around 9 million animals, with the following estimates for the three distinct populations of this species: the northwest Atlantic stock – 7.5 million seals; the Greenland Sea population – 627,000 animals; and the White Sea breeding group – 1.4 million seals. Overall, Harp seal numbers are increasing today and this species is classified as Least Concern.
- Harp seals get their name from the harp-shaped mark on their back.
- Fossils of harp seals show that they were alive during the mid-Miocene, about 20 million years ago.
- These seals are very strong high-speed swimmers, moving quickly on ice and diving more than 270 m.
- The main method of communication over both short and long distances underwater is calling, which may be used to coordinate herds and to attract mates. They may use trills, clicks and other chirping sounds on land, also to attract a mate or in response to a predator coming too near to a pup.
- Immediately after giving birth, mother seals smell their newborn, and from that time on will only feed their own pup, as they remember the scent.
- Seals wandering off from the herd are called “vagrants.”