Bowhead whale

Name and taxonomy

Carl Linnaeus described the species in 1758 in the tenth edition of Systema Naturae. At the time, naturalists lumped the bowhead with the right whales of the Atlantic, Pacific and Southern Oceans as one species. John Edward Gray proposed a separate genus for the bowhead in 1821, and Balaena now holds this one species alone. Debate over how many species the family Balaenidae held ran on for about 180 years. Genetic studies in the 2000s settled it: the three right whales form their own line in the genus Eubalaena.

The common name describes the bow-shaped curve of the mouth, where the lower jaw wraps around the upper jaw in a U shape. Older names include Greenland right whale, Greenland whale, Arctic whale and polar whale. GBIF lists vernacular names in many languages, among them arviq in Inuktitut and baleine boreale in French.

Evolution and relatives

The bowhead belongs to the baleen whales, the group that strains food through keratin plates instead of teeth. Its closest living relatives are the three right whales, which share the same family, Balaenidae. The fossil record of the family goes back to Morenocetus, found in South American rocks about 23 million years old. Balaena fossils from the Pleistocene have turned up in Italy and North Carolina, far south of the present range. Bones once credited to a mystery Swedenborg whale proved, on DNA testing, to be bowhead bones.

A whale believed to be a cross between a bowhead and a right whale has been found, which suggests the two lines can still interbreed. DNA from living whales and from old baleen shows that Arctic bowheads lost much genetic diversity over the past 500 years. Whaling and the cooling of the Little Ice Age probably shrank the summer habitats that once let Atlantic and Pacific whales mix.

Appearance

The bowhead is a rotund whale with a smooth back, no dorsal fin, broad flippers and wide, triangular flukes. Adults measure 14 to 18 metres, and females, at 16 to 18 m, run longer than males. Males average 14 to 16 metres. Weight ranges from 75 to 100 tonnes, which makes this the second heaviest whale after the blue whale. The largest reliable female measured about 19 metres.

The head takes up nearly 40% of the body length, the largest share of any cetacean. Between 230 and 360 baleen plates hang from each side of the upper jaw, and the longest reach 2.97 to 5.2 metres. The skin is black, with white patches on the chin, around the eyes and near the tail that spread with age. A blubber layer of 40 centimetres or more wraps the body against the cold. The twin blowholes send up a V-shaped blow that can rise 6.1 m.

Habitat and range

The bowhead is the only baleen whale that stays in Arctic and subarctic water all year. It lives among the pack ice and rarely swims south of 45 degrees north. Five stocks are recognised: Bering-Chukchi-Beaufort, Hudson Bay-Foxe Basin, Baffin Bay-Davis Strait, Sea of Okhotsk and Svalbard-Barents Sea. Genetic and tagging data now suggest that the two eastern Canadian stocks are one population.

The whales follow the ice edge, moving north as it melts in spring and south as it forms in autumn. The Alaskan population winters in the south-west Bering Sea and moves into the Chukchi and Beaufort Seas as leads open. Satellite tags on whales off West Greenland showed stays of 3 to 6 weeks at one site between offshore journeys of 1 to 2 weeks. In summer the whales enter bays, straits and estuaries.

The range once reached farther south, and bowheads were common off Labrador and Newfoundland into the 17th century. Strays have reached Japan, the Gulf of St Lawrence and Massachusetts. GBIF holds records from 18 countries, including a stray calf caught in Osaka Bay in 1969.

Diet and feeding

The bowhead is a filter feeder. It swims forward with its mouth open, and water streams through the fine bristles of the baleen. Copepods, krill, mysid shrimps and amphipods stick to the bristles, and the tongue pushes them back to be swallowed. The large upturned lower lip supports the plates so that water pressure does not bend or break them. Stomach studies have found more than 60 prey species, but copepods of the genus Calanus and krill dominate.

An adult eats about 1.8 tonnes of food a day. A whale can strain roughly 50,000 copepods a minute. Bowheads skim the surface, feed in mid-water and also feed at the sea floor. Feeding dives typically last 5 to 15 minutes. Groups of up to 14 whales sometimes feed together in a V formation, moving at one speed. Most feeding takes place on the summer and autumn grounds, and the whales live off blubber during long migrations.

Behaviour and social life

The bowhead is not a social animal. It usually travels alone or in groups of up to six, though larger gatherings form on feeding grounds and during migration. Migrating whales sort themselves by age and size, with subadults, mid-sized adults and large adults in separate waves. Mothers and calves often lead the spring movement. The sexes also use different areas: in Foxe Basin, mother and calf pairs dominate, while adult males use north-western Hudson Bay.

The whale swims slowly, at about 2 to 5 kilometres per hour, and can reach 10 km/h when it flees. During feeding the pace rises to 4 to 9 km/h. Most dives last 9 to 18 minutes, but a bowhead can stay under for up to an hour. It is not a deep diver, and 150 metres is a typical limit, though one tagged whale reached 352 m.

Bowheads break through ice of 20 centimetres from below with their heads, and Inuit hunters report ice of 60 cm being broken. Belugas often travel with bowheads, probably because the larger whale opens breathing holes that they can use. Bowheads rub on rocks to scrape off dead skin, and a moulting site was found off Baffin Island in 2012. They also breach and slap their flukes at the surface.

Communication and senses

Bowheads are among the most vocal of the baleen whales. They use low-frequency sounds below 1,000 hertz to keep in contact while travelling, feeding and socialising. Loud calls peak during migration, when they may help the whales find their way under the ice. In the breeding season males sing long, complex songs that change from year to year. A population of about 300 whales near Greenland produced 184 different songs between 2010 and 2014.

Like other baleen whales, the bowhead probably relies on hearing more than sight in dark, ice-covered water. Its eyes sit above the corners of the mouth, low on the huge head. A ridge of blood-rich tissue on the palate is thought to shed heat when the whale opens its mouth in cold water. Two male brains weighed 2.072 and 2.280 kilograms, and both showed a strongly folded surface.

Reproduction and life cycle

Mating takes place in late winter and early spring, and most conceptions are thought to occur in March when song activity peaks. Mating groups often consist of one or two females with several males, and sperm competition is believed to decide paternity. Gestation lasts 13 to 14 months, and a female calves once every 3 to 4 years. Most calves arrive in May, during the northward migration.

A newborn measures about 4 to 4.5 metres and weighs roughly 1,000 kilograms. It is born with a thick layer of blubber and can swim on its own within 30 minutes. The calf grows to about 8.2 metres in its first year on its mother's milk. Weaning takes place between 9 and 15 months.

Sexual maturity comes late, at about 15 to 25 years, and the body stops growing at 50 to 60 years. Females may keep calving for 100 years, and the oldest pregnant female found was estimated at 121 years old. The bowhead is considered the longest-lived mammal, and one male was aged at 211 years. Genes such as ERCC1 and PCNA, which repair DNA, are thought to explain the whale's resistance to cancer and ageing.

Predators and threats

The orca is the only known natural predator. Bowheads seek ice and shallow water when orcas appear, and they can strike an attacker with the tip of the tail. In one 1995 study, a third of the Davis Strait stock carried scars from orca attacks. As sea ice shrinks, orcas reach the far north more often, so attacks are expected to rise. No shark attacks on bowheads have been recorded.

Commercial whaling was the main cause of decline, and it is over. Today the threats come from a warming Arctic: more shipping through open water, ship strikes and noise from drilling. Whales have been caught in fishing nets and have collided with vessels on rare occasions. Loss of ice also removes the shelter the whales use to hide from orcas.

Population and conservation

Before commercial whaling, about 50,000 bowheads swam the northern seas. The estimate today is 10,000 to 25,000, and one census range reaches 43,000. The Western Arctic stock recovered after commercial hunting stopped in the early 1900s, and it grew 3.7% a year from 1978 to 2011. A 2011 count put it at 16,820, and a 2019 survey found 12,505. The surveyors put the gap down to unusual conditions in 2019 rather than a real decline. The eastern Canada and West Greenland whales number about 6,000 or more, and their numbers are rising.

The Sea of Okhotsk stock probably holds no more than 400 whales. The Svalbard stock, once the largest, may now number only in the tens. The IUCN rates the species as Least Concern worldwide. Regionally it lists the Svalbard whales as Critically Endangered and the Okhotsk and Baffin Bay-Davis Strait whales as Endangered. The Hudson Bay-Foxe Basin stock, counted at 1,026 in 2005, is Vulnerable. CITES Appendix I bans commercial trade, and the United States lists the whale as endangered. Isabella Bay on Baffin Island became the first wildlife sanctuary in the world designed for bowheads.

Relationship with humans

Arctic peoples have eaten bowhead for thousands of years, and Paleo-Eskimo sites show use from perhaps 4000 BC. The whale gave meat, blubber for lamp fuel and baleen for tools. Basque whalers began the commercial hunt in the 16th century in the Strait of Belle Isle. The first whaling expedition sailed to Spitsbergen in 1611, and the whales there were nearly gone by mid-century. A whaler from Sag Harbor took the first Bering Strait bowheads in 1848, and about 18,600 died there by 1914.

A 1966 moratorium ended commercial hunting. Native hunters in Alaska, Canada, Greenland and Russia still take small numbers under quota. The IWC quota for the Western Arctic stock has stood at 67 strikes a year since 1998, about 0.5% of the stock. In 2024 hunters in Aklavik were allowed one whale to share meat among Inuvialuit and Gwich'in communities. Whale watching on the Shantar Islands in the Sea of Okhotsk now brings visitors to see the whales from shore.

In culture and myth

The bowhead sits at the centre of Inuit and Inupiat life in the Arctic. Inuit tradition holds that the whale offers itself to hunters who treat it with respect and waste nothing. One Inuit story says the Creator loved the great whales best but gave them to people in need, never to be killed for nothing. A hunted whale was given fresh water and a meal so that its spirit could travel home and return in a new body. Carved whale amulets were made to flatter the whale and call it to the hunters.

The qulliq, a stone lamp that burns whale or seal oil, remains a symbol of Inuit endurance. Inuit have a word for a bowhead that kills an orca with its tail, which shows the behaviour is old knowledge. The Alaska Eskimo Whaling Commission co-manages the hunt with NOAA, so tradition and science set the quota together.