Harp seals migrate with the seasons and steer by the stars

The harp seal is one of 19 species of ‘true seal’. This marine mammal belongs to a group of animals known as pinnipeds (meaning fin-footed) and is the most abundant seal species in the Northern Hemisphere. The Latin name for the harp seal, Pagophilus groenlandicus, means ‘ice-lover from Greenland’, a nod to their icy habitat and northerly range.

Harp seals are strong swimmers, and although they are mostly depicted on the ice, they actually spend most of their time in the water. Their powerful flippers are able to propel them forwards with graceful, coordinated strokes. When on land, however, these furry mammals are somewhat less agile, using their clawed flippers in a cumbersome manner to drag themselves along the ice. The seals migrate great distances covering between 4,000 to 5.000 kilometres (2.485 to 3,106 miles), one of the largest migrations recorded, in terms of distance.

The seals move like ghostly apparitions through the chilly waters in response to their changing environment. Like most animals, their primary concern is finding food. They are excellent navigators and take the same routes each year, following the receding ice pack. Harp seals’ mam territory is the open ocean, with little in the way of landmarks, so how they manage to pick out their routes with such accuracy baffled scientists for a long time. It is now accepted that seals use their large bulging eyes to gaze at the stars for orientation, much like sailors of the past.

Harp seals meet in their tens and thousands for the breeding season, which lasts just two months (February and March). This is the only time of year where they congregate with their own kind, on the thick ice of the south. The rest of the year is spent alone, cruising the oceans in search of their next meal. In the relentless, churning slush of the Arctic seas, a harp seal’s diet is anything but regular. They must take advantage when opportunity arises and eat what is available. A plethora of fish – cod, herring, plaice and halibut – and crustaceans are all on the menu.

Once the ice packs of the south are behind them, they head north, en route to their summer feeding ground in the Arctic. Once summer is over in around late September, they start their southward journey again, arriving back at the southern pack ice by early winter, ready to start the cycle all over again.

Life at sea

Harp seals are adapted for harsh conditions, enduring subzero temperatures for most of their lives

The harps seal’s life cycle starts on the ice and plays out at sea. They have a tough start but if they can survive the first few uncertain weeks, a long life cruising the oceans awaits them.

Yellow Jacket

Newborn harp seals have a slight yellow coloration, the result of staining by amniotic fluid while in the womb. They stay this color for the first two to three days of their life.

Motherly love

For the first 12 days, harp seals make for caring mothers. They will shun food in an effort to focus all their attention on nursing their young.

A new white coat

Once the mothers leave, the pups lose their yellow tinge as it is bleached by the sun and washed off by the rain. The white coat helps them stay hidden in their icy habitat.

Going the distance

Harp seals spend most of their lives solitarily swimming the seas and navigating their way across long distances.

Fish supper

Much of their diet is made up of fish and crustaceans. Harp seals are skilled hunters and will dive to depths of 200m (600 ft) to catch their dinner.

A mother’s bond is not so strong

From doting parent to abandonment; harp seal mothers are very quick to give the cold shoulder

After migrating for the winter, the large expanse of unforgiving white tundra in the south is where the seals retire. Here, icy gales tear across frozen seas and the sun glares from the snowy ground. However, a habitat so seemingly lifeless holds much significance for harp seals. Crowds of thousands gather here once a year to focus on continuing the species.

Female harp seals are almost always pregnant when they arrive here and give birth to a single pup, usually in late February. While young pups are nursing, the mothers do not eat and lose up to three kilograms (6.6 pounds) of fat per day. After 12 days, each female abruptly leaves her pups and never returns. The ice is littered with stranded pups, crying for their mothers, alone and vulnerable to predators.

Mature males take this as their cue to roam the ice and look for a mate. When females leave their young, it’s not long before they are ready to copulate once again, and they waste no time in the search for a partner. Both males and females breed promiscuously, the rush to find a mate apparent before the pack ice melts and migration must begin.

Courtship begins on the ice through a fierce yet flamboyant display of dominance. In order to attract a female, males must fight one another using their sharp teeth and strong flippers. They will also call out to grab attention, shouting out over one another in a battle of vocal cords. Only the loudest and strongest seals make for potential suitors. What starts on the ice moves to the water, and copulation takes place submerged in the frosty ocean.

Once impregnated, females can delay implanting, meaning the fertilised egg becomes an embryo, but does not implant in the uterus wall immediately. This extends the gestation period from 7.5 to 11.5 months, allowing the seal enough time to complete migration and return to the pack ice before giving birth.

Small and vulnerable

Despite their chilly surroundings, pups are born with little to no protection from the cold. They have no blubber and a small body weight of 10kg (221b). This makes them extremely vulnerable and to compensate, the mother will stay by her pup’s side.

Binge eating

To increase in weight and put on much-needed fat to keep warm, the little harp seals will gorge on their mothers’ rich milk – which contains 50 per cent fat – for around 12 days. In this time, they will put on around 2.3kg (51b) a day.

Crash dieting

The mother leaves after 12 days, when the youngsters are still unable to swim or find food. The mortality rate is high, and pups will lose around 50 per cent of their body weight. They will stay here for around six weeks before they enter the water.

Sitting ducks

When the pups are left alone, there are a number of other animals they must be wary of. Polar bears, foxes, and wolves will all try to take advantage of the pup-buffet on display. Even orcas are able to snatch the unfortunate few sitting by the water’s edge.

Maternal instinct

In February, when the pack ice becomes a nursery there can be as many as 2,000 seals per square kilometre. This means the mothers need a special skill to determine which of the newborns is theirs! Amazingly they are able to identify their own pups among the masses by smell alone.

Harp Seal – Threats to Their Homes

Harp seals rarely set foot on land, but when they do come ashore, they board the Arctic ice pack. A thick layer of frozen water sitting atop the ocean, the ice pack undergoes a regular seasonal melt. The ice begins to melt in the spring and summer, with little left by mid-September. As autumn rolls back around, the ice starts to reform and doubles in cover for the winter. Not all ice melts, and some survives the warmer weather of the summers from year to year. Generally, sea ice consists of first-year ice, which is thin, and thicker ice that has accumulated in volume over time, called multi-year ice.

There has been a trend, in recent decades, for a decline in the thicker multi­year ice, due to a warmer global climate. Harp seals rely heavily on this ice for much of their life cycle and it is a vital feature of their landscape. Ice that melts too readily puts pups at risk of falling into the sea too early, before they are able to swim. And with no mother around to protect them, the results can be fatal. It is not just the weakest pups, or those with lower genetic diversity that are in danger. During seasons of extremely low ice cover, entire generations may be wiped out due to the harp seals’ reliance on the ice as a platform for giving birth and rearing their young.

A reduction in ice could also have an impact on reproductive success through a loss of breeding ground, meaning fewer pups being born. However, much of this is speculation and the long-term effects are unknown. At present, the species is listed as ‘Least Concern’ by the IUCN and there are currently an estimated eight million harp seals in the Northern Hemisphere.

A coveted coat

A quick search on the Internet for ‘harp seals and humans’, will tell you everything you need to know about the relationship we have with these intelligent creatures. Sadly, almost every page is awash with stories of hunting and sealing. The main attraction for the hunting industry is the snowy white pelts of the harp seal pups, an attraction that has led to more than one million deaths in the past five years. The number of seals killed each year is usually forecasted and regulated through the use of quotas. However, it’s estimated that many catches go unreported.

The fur is generally used for coat making, while the meat is used as an important source of protein for the inhabitants of small coastal communities. The blubber is broken down and used to make seal oil, which is then used as a fish oil supplement. The skin is also used in the fashion industry and tailored to make warm garments for colder climes. The act of harp seal hunting has gathered much debate and attention among conservationists about the appropriate course of action to safeguard the species for the future.