Bowhead whale

The bowhead whale is not a social animal, typically travelling alone or in small pods of up to six. It is able to dive and remain submerged under water for up to an hour. The time spent under water in a single dive is usually limited to 9–18 minutes.[16] The bowhead is not thought to be a deep diver, but can reach a depth down to 150 m (500 ft). It is a slow swimmer, normally travelling around 2–5 km/h (1–3 mph) [0.55–1.39 m/s].[25] When fleeing from danger, it can travel at a speed of 10 km/h (6.2 mph) [2.78 m/s (9 ft/s)]. During periods of feeding, the average swim speed is increased to 1.1–2.5 m/s (4.0–9.0 km/h).[26]

The head of the bowhead whale comprises a third of its body length, creating an enormous feeding apparatus.[26] The bowhead whale is a filter feeder, and feeds by swimming forward with its mouth wide open.[16] It has hundreds of overlapping baleen plates consisting of keratin hanging from each side of the upper jaw. The mouth has a large, upturning lip on the lower jaw that helps to reinforce and hold the baleen plates within the mouth. This also prevents buckling or breakage of the plates from the pressure of the water passing through them as the whale advances. To feed, water is filtered through the fine hairs of keratin of the baleen plates, trapping the prey inside near the tongue where it is then swallowed.[27] The diet consists of mostly zooplankton, which includes krill, copepods, mysids, amphipods, and many other crustaceans.[26][28] About 1.8 tonnes (2 short tons) of food are consumed each day.[27] While foraging, bowheads are solitary or occur in groups of two to 10 or more.[17]

Bowhead whales are highly vocal[29] and use low frequency (<1000 Hz) sounds to communicate while travelling, feeding, and socialising. Intense calls for communication and navigation are produced especially during migration season. During breeding season, bowheads make long, complex, variable songs for mating calls.[25] From 2010 through to 2014, near Greenland, 184 distinct songs were recorded from a population of around 300 animals.[30]

Sexual activity occurs between pairs and in boisterous groups of several males and one or two females. Breeding season is observed from March through August; conception is believed to occur primarily in March when song activity is at its highest.[25] Reproduction can begin when a whale is 10 to 15 years old. The gestation period is 13–14 months with females producing a calf once every three to four years.[21] Lactation typically lasts about a year. To survive in the cold water immediately after birth, calves are born with a thick layer of blubber. Within 30 minutes of birth, bowhead calves are able to swim on their own. A newborn calf is typically 4–4.5 m (13–15 ft) long, weighs roughly 1,000 kg (2,200 lb), and grows to 8.2 m (26 ft 11 in) within the first year.[21]

Bowhead whales are considered to be the longest-living mammals, living for over 200 years.[31] In May 2007, a 15 m (49 ft) specimen caught off the Alaskan coast was discovered with the 90 mm (3.5 in) head of an explosive bomb lance of a model manufactured between 1879 and 1885, so the whale was probably bomb lanced sometime between those years, and its age at the time of death was estimated at between 115 and 130 years.[32] Spurred by this discovery, scientists measured the ages of other bowhead whales; one specimen was estimated to be 211 years old.[33] Other bowhead whales were estimated to be between 135 and 172 years old. This discovery showed the longevity of the bowhead whale is much greater than originally thought.[34] Researchers at CSIRO, Australia's national science agency, estimated that bowhead whales' maximum natural lifespan is 268 years based on genetic analysis.[35]

A greater number of cells present in an organism was once believed to result in greater chances of mutations that cause age-related diseases and cancer.[36] Although the bowhead whale has thousands of times more cells than other mammals, it has a much higher resistance to cancer and aging. In 2015, scientists from the US and UK were able to successfully map the whale's genome.[37] Through comparative analysis, two alleles that could be responsible for the whale's longevity were identified. These two specific gene mutations linked to the bowhead whale's ability to live longer are the ERCC1 gene and the proliferating cell nuclear antigen (PCNA) gene. ERCC1 is linked to DNA repair and increased cancer resistance. PCNA is also important in DNA repair. These mutations enable bowhead whales to better repair DNA damage, allowing for greater resistance to cancer.[36] The whale's genome may also reveal physiological adaptations such as having low metabolic rates compared to other mammals.[38] Changes in the gene UCP1, a gene involved in thermoregulation, can explain differences in the metabolic rates in cells.

The bowhead whale is the only baleen whale to spend its entire life in the Arctic and subarctic waters.[39] The Alaskan population spends the winter months in the southwestern Bering Sea. The group migrates northward in the spring, following openings in the ice, into the Chukchi and Beaufort seas.[40] The whale's range varies depending on climate changes and on the forming/melting of ice.[41]

Historically, bowhead whales' range may have been broader and more southerly than currently thought. Bowheads were abundant around Labrador, Newfoundland (Strait of Belle Isle) and the northern Gulf of St Lawrence until at least the 16th and 17th centuries. It is unclear whether this was due to the colder climate during these periods.[42] Distributions of Balaena spp. during the Pleistocene were far more southerly as fossils have been excavated from Italy and North Carolina, thus could have overlapped between those of Eubalaena based on those locations.[43]

Generally, five stocks of bowhead whales are recognized: 1) the Western Arctic stock in the Bering, Chukchi, and Beaufort Seas, 2) the Hudson Bay and Foxe Basin stock, 3) the Baffin Bay and Davis Strait stock, 4) the Sea of Okhotsk stock, and 5) the Svalbard-Barents Sea stock. However, recent evidence suggests that the Hudson Bay and Foxe Basin stock and the Baffin Bay and Davis Strait stock should be considered one stock based on genetics and movements of tagged whales.[44]

The Western Arctic bowhead population, also known as the Bering-Chukchi-Beaufort population, has recovered since the commercial harvest of this stock ceased in the early 1900s. A 2019 study estimated that the Western Arctic population was 12,505; although it was lower than the 2011 value of 16,820, the surveyors believed there was no significant decline in 2011-2019 due to the unusual conditions of whale migration and observation in 2019.[45] The yearly growth rate of the Western Arctic bowhead population was 3.7% from 1978 to 2011. These data suggest that the Western Arctic bowhead stock may be near its precommercial whaling level.[44] Migration patterns of this population are being affected by climate change.[46]

Alaskan Natives continue to hunt small numbers of bowhead whales for subsistence purposes. The Alaska Eskimo Whaling Commission co-manages the bowhead subsistence harvest with the National Oceanic and Atmospheric Administration. The Alaskan villages that participate in the bowhead subsistence harvest include Barrow, Point Hope, Point Lay, Wainwright, Nuiqsut, Kaktovik, Gambell, Savoonga, Kivalina, Wales, and Little Diomede.[47] The annual subsistence harvest of the Western Arctic stock has ranged from 14 to 72, amounting to an estimated 0.1-0.5% of the population.[44]

In March 2008, Canada's Department of Fisheries and Oceans stated the previous estimates in the eastern Arctic had undercounted, with a new estimate of 14,400 animals (range 4,800–43,000).[48] These larger numbers correspond to prewhaling estimates, indicating the population has fully recovered. However, if climate change substantially shrinks sea ice, these whales could be threatened by increased shipping traffic.[49]

The status of other populations is less well known. About 1,200 were off West Greenland in 2006, while the Svalbard population may only number in the tens. However, the numbers have been increasing in recent years.[50]

The Hudson Bay – Foxe Basin population is distinct from the Baffin Bay – Davis Strait group.[51] The original population size of this local group is unclear, but possibly about 500 to 600 whales annually summered in the northwestern part of the bay in the 1860s.[52] It is likely that the number of whales that actually inhabit Hudson Bay is much smaller than the total population size of this group,[53] but reports from local indigenous people indicate that this population is increasing over decades.[54] Larger portions of the bay are used for summering, while wintering is on a smaller scale. Some animals winter in Hudson Strait, most notably north of Igloolik Island and north eastern Hudson Bay. Distribution patterns in these regions are affected by the presence of killer whales, and bowheads can disappear from normal ranges in the presence of atypical numbers of orcas. Increased mortality caused by killer whale attack is a possible outcome of climate change, as reduced ice coverage is expected to result in fewer areas that the bowheads can use for shelter from attack.[54] Whaling grounds in the 19th century stretched from Marble Island to Roes Welcome Sound and to Lyon Inlet and Fisher Strait, and whales still migrate through most of these areas.

Distribution within Hudson Bay is mostly restricted to the northwestern part[51] along with Wager Bay,[55] Repulse Bay,[56] Southampton Island (one of two main know summering areas),[56][57] Frozen Strait, northern Foxe Basin, and north of Igloolik in summer.[54] Satellite tracking[58] indicates that some portions of the group within the bay do not venture further south than Whale Cove[56] and areas south of Coats and Mansel Islands. Cow – calf pairs and juveniles up to 13.5 m (44 ft 3 in) in length make up the majority of summering aggregation in the northern Foxe Basin, while matured males and noncalving females may use the northwestern part of Hudson Bay.[54] Fewer whales also migrate to the west coast of Hudson Bay and Mansel and Ottawa Islands.[54] Bowhead ranges within Hudson Bay are usually considered not to cover southern parts,[53][59] but at least some whales migrate to locations further south such as Sanikiluaq and Churchill river mouth.[60][61][62]

Congregation within Foxe Basin occurs in a well-defined area of 3,700 km² (1,100 sq nmi) north of Igloolik Island to Fury and Hecla Strait and Kapuiviit and Gifford Fiord, and into Gulf of Boothia and Prince Regent Inlet. Northward migrating along western Foxe Basin to eastern side of the basin also occurs in spring.[54]

Whale spyhops in Ulbansky Bay, northwestern Okhotsk Sea[63]

Not much is known about the endangered Sea of Okhotsk population. To learn more about the population, these mammals have been regularly observed near the Shantar Islands, very close to the shore, such as at Ongachan Bay.[64][65] Several companies provide whale-watching services, which are mostly land-based. According to Russian scientists, this total population likely does not exceed 400 animals.[63] Scientific research on this population was seldom done before 2009, when researchers studying belugas noticed concentrations of bowheads in the study area. Thus, bowheads in the Sea of Okhotsk were once called "forgotten whales" by researchers. The WWF welcomed the creation of a nature sanctuary in the region[66]

Possibly, vagrants from this population occasionally reach into Asian nations such as off Japan or the Korean Peninsula (although this record might be of a right whale[67]). The first documented report of the species in Japanese waters was of a strayed infant (7 m or 23 ft) caught in Osaka Bay on 23 June 1969,[68] and the first living sighting was of a 10 m (33 ft) juvenile around Shiretoko Peninsula (the southernmost of ice floe range in the Northern Hemisphere) on 21 to 23 June 2015.[69] Fossils have been excavated on Hokkaido,[70] but it is unclear whether the northern coasts of Japan were once included in seasonal or occasional migration ranges.

Genetic studies suggest Okhotsk population share common ancestry with whales in Bering-Chukchi-Beaufort Seas, and repeated mixings had occurred between whales in the two seas.[71]

The most endangered but historically largest of all bowhead populations is the Svalbard/Spitsbergen population.[72] Occurring normally in Fram Strait,[73] Barents Sea and Severnaya Zemlya along Kara Sea[50] to Laptev Sea and East Siberian Sea regions, these whales were seen in entire coastal regions in European and Russian Arctic, even reaching to Icelandic and Scandinavian coasts and Jan Mayen in Greenland Sea, and west of Cape Farewell and western Greenland coasts.[74] Also, bowheads in this stock were possibly once abundant in areas adjacent to the White Sea region, where few or no animals currently migrate, such as the Kola and Kanin Peninsula. Today, the number of sightings elsewhere is very small,[75] but with increasing regularities[76] with whales having strong regional connections.[77] Whales have also started approaching townships and inhabited areas such as around Longyearbyen.[78] The waters around the marine mammal sanctuary[79] of Franz Josef Land is possibly functioning as the most important habitat for this population.[80][81]

It is unclear whether this population is a remnant of the historic Svalbard group, recolonized individuals from other stocks, or if a mixing of these two or more stocks has taken place. In 2015, discoveries of the refuge along eastern Greenland where whaling ships could not reach due to ice floes[82] and largest numbers of whales (80–100 individuals) ever sighted between Spitsbergen and Greenland[83] indicate that more whales than previously considered survived whaling periods, and flows from the other populations are possible.

During expeditions by a tour operator 'Arctic Kingdom', a large group of bowheads seemingly involved in courtship activities was discovered in very shallow bays south of Qikiqtarjuaq in 2012.[84] Floating skins and rubbing behaviours at sea bottom indicated possible moulting had taken place. Moulting behaviours had never or seldom been documented for this species before. This area is an important habitat for whales that were observed to be relatively active and to interact with humans positively, or to rest on sea floors. These whales belong to Davis Strait stock.

Isabella Bay in Niginganiq National Wildlife Area is the first wildlife sanctuary in the world to be designed specially for bowhead whales. However, moultings have not been recorded in this area due to environmental factors.[85]

In 1978 the International Whaling Commission (IWC) introduced a hunting strike quota for the Bering-Chukchi-Beaufort Sea (BCB) bowhead.[86] The quota has remained at 67 strikes per year since 1998 and represents about 0.5 percent of BCB population.[86] The population of bowheads in West Greenland and Canada is estimated to be 6,000 and rising, and hunts in this are minimal (<0.001 percent).[86] Both stocks are rising, and the indigenous hunts seem to be self-sustaining.[86]

Killer whales are also known predators.[87] There is no consensus on the number of deaths by killer whales.[86] Bowheads seek the ice and shallow waters' safety when threatened by killer whales.[25] The Inuit have a traditional word for this behavior to give historical context that this is not a new phenomenon.[86] Global warming is increasing the frequency that killer whales are observed in the far north. A once-rare event, killer whales are now seen more frequently.[86]

There are no reports of attacks on bowheads by sharks.[86]

Some Alaska Natives continue by tradition to hunt bowhead and beluga whales on a subsistence level, with low annual bowhead total quotas set by the International Whaling Commission in conjunction with individual village limits set by the Alaska Eskimo Whaling Commission.[96]

Bowhead hunting is limited to whaling crews who are:

• Iñupiat
• St Lawrence Island Siberian Yupik

This bowhead subsistence hunting occurs during the northward spring migrations based from the ice and from small boats during the returning fall migrations.[97]