17 different species of whale live in the Arctic. However, only three species can be found there year-round: the narwhal (Monodon monceros), beluga whale (Delphinus leucas) and bowhead whale (Balaena mysticetus). These three species, which permanently live in the Arctic Ocean, differ greatly in terms of lifestyle and distribution. One critical factor for the whales of the polar seas is that there be open cracks in the drift ice and pack ice, and that the ice cover doesn’t significantly exceed 30 cm. As long as that’s the case, the bowhead whale, for instance, can use its sturdy head and back to break through it and make new breathing holes. None of the three species has a dorsal fin, which could greatly facilitate swimming below the ice. Having this flap of tissue on their backs, which fast-swimming rorquals and dolphins do and use as a stabiliser, would be a potential source of injury when it comes to manoeuvring in and under the ice (Deimer-Schütte, 2014). The bowhead whale belongs to the baleen whales (Mysticeti), whereas the other two species are classified as toothed whales (Odontoceti). As their names suggest, the two groups mainly differ in terms of their mouths – those with ‘beards’ and those with teeth. Another difference is the number of blowholes: toothed whales only have one, while baleen whales have two. Bearded whales are characterised by plates descending from both sides of their long and bowed upper jaw, the baleen plates. They are composed of a material similar to human fingernails or the exterior of cow horns and taper off into fine hair-like bristles. Whales use their baleen to filter small and very small organisms (chiefly plankton and small marine fauna) from the water. In the upper layers of the cold waters near the Earth’s poles, large swarms of these animals can be found. The whales glide through these swarms with their mouths open, taking in massive amounts of water. Then they close their mouths and press the water back out through their baleen with their tongues. The tiny fauna remain trapped in the baleen and are swallowed whole. Considering how large these whales can grow, and the fact that baleen filtering is their only means of feeding, it’s extremely effective. The animal with the longest baleen plates (up to 4.5 metres) is the bowhead whale. Its upper jaw is so bowed that it can accommodate even the longest baleen plates (Dow, 1992).
In contrast, toothed whales are active hunters, using their teeth to seize and hold onto their prey species. These species are generally far larger than those of the baleen whales and range from various species of fish, to squid, to other marine mammals. The majority of whales are gregarious creatures with highly developed social behaviour; few species live in pairs or individually. These groups of whales, known as pods, normally number between ten and 50 animals. Further information on many types of whale can be found here, at the website of the International Whaling Commission.
Narwhals (Monodon monceros) have a discontinuous distribution near the North Pole. In this regard, ‘discontinuous’ means they are chiefly found in the Atlantic part of the Arctic Ocean and rarely in the Pacific part. Male narwhals can reach lengths of ca. 5 metres and weigh up to 1,600 kilogrammes. The females are somewhat smaller and lighter. There are believed to be ca. 100,000 narwhals, though estimates can vary greatly from source to source (Laidre and Regehr, 2017). The narwhal’s most characteristic feature is its two to three-metre-long tusk, which most males but only few females have. Narwhals can be found in the eastern Canadian Arctic, West and East Greenland, near Svalbard, and off the archipelago Franz Joseph Land north of Russia. Over the course of the year, they follow the sea ice. They can dive to great depths and are perfectly adapted to life in the Arctic Ocean. They prey on the Arctic cod and Greenland cod, as well as deep-sea squid. Narwhals are the only whales that live in areas covered by thick sea ice for up to six months in winter. Here, they prefer deep waters along the continental slope. In summer, they tend to be found in the ice-free bays and fjords of the High Arctic but return to their overwintering areas in autumn. In summer, narwhals eat comparatively little. They take in the most food from November to March, hunting in pack-ice-covered waters. Their young are born in spring (Laidre and Regehr, 2017).
The Beluga whale (Delphinapterus leucas) can also be found near the North Pole. Reaching lengths of up to 5 metres and weighing up to 1,600 kilogrammes, the adults are snow-white, which has earned them the sobriquet ‘white whales’. Their total number is estimated at ca. 200,000, divided into at least 21 subpopulations (Lowry et al., 2017). There are large populations in the eastern Bering Sea, eastern Beaufort Sea and western Hudson Bay. Here Beluga whales can be found in estuaries and the waters over the continental shelf or continental slope. However, Beluga whales can sometimes also be found in deeper ocean basins – depending on whether they’re covered by seasonal sea ice or are open. Some beluga whales undertake long journeys between their summer and winter habitats, while others stay in the same area year-round. As a rule, the latter only leave the coastal waters when the coast freezes over in winter and fast ice begins to form. Migrating belugas have been spotted in the waters west and north of Alaska, and in the Canadian High Arctic. Beluga whales primarily feed on pelagic and benthic fish, squid and amphipods (Laidre and Regehr 2017). In summer they can be found in huge groups numbering several thousand. They have also been nicknamed ‘sea canaries’, due to their propensity for vocalising and broad range of calls.
The bowhead whale can reach lengths of 15 to 18 metres and weigh between 75 and 100 metric tons. Bowhead whales can be extremely long-lived – with an estimated lifespan of up to 200 years (George et al., 199; Keane et al., 2015; Wetzel et al., 2017). The total bowhead whale (Balaena mysticetus) population is estimated at 25,000, divided into four subpopulations: two larger ones in the Bering Sea / Chukchi Sea / Beaufort Sea region, and between Canada and Greenland; and two smaller ones in the region between Svalbard and the Barents Sea, and in the Sea of Okhotsk. Like the beluga whale, the bowhead whale can be found throughout the North Pole region and stays in the Arctic Ocean year-round. The largest group (ca. 17,000) lives in the region of the Bering, Chukchi and Beaufort Seas. The population in the waters off Greenland has been drastically reduced by whaling; in some areas, it has disappeared entirely.
Between winter and summer, bowhead whales migrate from subarctic to high Arctic waters. In the course of these migrations, they also pass through areas nearly completely covered with ice. In winter and early spring, they can mostly be found in polynyas or marginal ice zones. The whales are powerful enough to break through ice up to 45 centimetres thick. The bowhead whale is well adapted to its habitat in and on the ice. But in late summer and autumn, when the sea ice is far from the coasts, it also hunts in open water (Moore et al., 2010). Bowhead whales are baleen whales and feed on zooplankton. The largest and most dominant zooplankton consumers in the Arctic Ocean, their diet consists of crustaceans living in the water or on the seafloor, like copepods and amphipods (Laidre and Regehr, 2017).
Bowhead whales come to the surface to breathe – or spout – every 5 to 15 minutes. But they can also dive up to 40 minutes long . As a rule, their dives aren’t particularly deep, since their food sources don’t require them to be. Depending on the available food and time of year, bowhead whales can also dive far deeper (dives over 400 metres deep have been recorded). During their migrations, bowhead whales emit staccato tones in a frequency range of 50 to 300 Hz. Scientists believe they do this in order to acoustically gauge the surrounding ice cover and thickness – and can do it so precisely that they almost never lose their orientation.
Deimer-Schütte P. (2014): Warnsignale Walfang. In: Lozán, J.L., H.Grassl, D.Notz & D.Piepenburg eds.: Warnsignal Klima: Die Polarregionen. Wissenschaftliche Auswertungen, Hamburg. 376 Seiten. ISBN: 978-39809668-63, pp. 192-199.
Dow L. (1992): Wale Großtiere dieser Welt, Jahr-Verlag Hamburg, ISBN: 3-921789-58-3, Auflage 1992
George, J.C., J. Bada, J. E. Zeh, L. Scott, S. E. Brown, T. O'hara &R. S. Suydam (1999): Age and growth estimates of bowhead whales (Balaena mysticetus) via aspartic acid racemization. Canadian Journal of Zoology 77, pp. 571-580.
Keane, M., J. Semeiks, A. E. Webb, Y. I. Li, V. Quesada, & T. Craig (2015): Insights into the evolution of longevity from the bowhead whale genome. Cell Reports 10(1), pp. 112-122.
Laidre K. & E. V. Regehr (2017): Arctic marine mammals and sea ice., In: D. N. Thomas (ed), Sea Ice, 3rd edition, Chapter 21, pp. 518-521
Lowry, L., R. Reeves & K. Laidre (2017): Delphinapterus leucas. The IUCN Red List of Threatened Species 2017: e.T6335A50352346. http://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T6335A50352346.en
Wetzel, D.L., J. E. Reynolds III, P. Mercurio, G. H. Givens, P. L. Pulster, & J. C. George (2017): Age estimation for bowhead whales (Balaena mysticetus) using aspartic acid racemisation with enhanced hydrolysis and derivatisation procedures. Journal of Cetacean Research and Management 17, pp. 9–14
The whales of the Antarctic can be classified according to their habitat: the pack ice, fast ice or open ocean. In the following, only those whale species with close ties to the fast ice and pack ice as habitat will be described in more detail. The southern minke whale (Balaenoptera bonaerensis), southern bottlenose whale (Hyperoodon planifrons) and killer whale (Orca orcinus) can be found in the Antarctic sea-ice zone year-round, whereas the blue whale (Balaenoptera musculus intermedia), sperm whale (Physeter macrocephalus) and southern beaked whale (Berardius arnuxii) live near the ice edge. The previously mentioned whale species belong to different families, which in the following are listed in brackets: the southern minke whale (rorquals, Balaenopteridae) and the (Antarctic) blue whale (rorquals, Balaenopteridae) are species belonging to the parvorder of baleen whales (Mysticeti), whereas the sperm whale (sperm whales, Physeteridae), killer whale (dolphins, Delphinidae), southern beaked whale (beaked whales, Ziphiidae) and southern bottlenose whale (beaked whales, Ziphiidae) belong to the parvorder of toothed whales (Odontoceti). There are also other species, which chiefly live in the subarctic waters and will not be described in more detail here.
These include the humpback whale (Megaptera novaeangliae) and fin whale (Balaenoptera physalus), which can be found in all oceans and migrate to subtropical, temperate-warm waters in winter to mate and bear their young. In summer, they migrate to the colder waters of the Arctic or Antarctic to hunt but are rarely sighted near the ice. Other species not described here include: the hourglass dolphin (Lagenorhynchus cruciger), sei whale (Balaenoptera borealis), southern right whale (Eubalaena australis), and short- or long-finned pilot whale (Globicephala melas). They mainly live in the open ocean, can be found throughout the Southern Ocean, and are only rarely sighted near the pack ice (Bester et al., 2017). Further information on many types of whale can be found here, at the website of the International Whaling Commission.
The southern minke whale (Balaenoptera bonaerensis) is the only baleen whale species in the Southern Ocean that can constantly be found in the ice-covered regions, from the marginal ice zone to areas with heavy ice cover. Some overwinter in the Antarctic, while others migrate to warmer waters. Little is known about their mating or reproduction. Their young are mostly born in warmer waters between July and August, while mating takes place between August and November.
Compared to other baleen whales, southern minke whales, at a length of ca. 9 metres, are quite small. They can weigh up to 10 metric tons and live up to 40 years. Southern minke whales make brief and shallow dives to hunt kill, which are normally found near the surface. They are often found individually or in small groups of two to three. In higher latitudes, large groups of more than 400 have occasionally been observed. The size of the total population is difficult to estimate, as in the past 40 years, three different surveys have produced very different figures: from ca. 270,000 to 777,000 (Bester et al., 2017). The most recent estimate is ca. 500,000 (International Whaling Commission 2013).
Balaenoptera musculus intermedia
In the whaling era, the blue whale (Balaenoptera musculus) was one of the most intensively hunted species. Especially after the advent of the harpoon cannon in the 20th century, the population of ca. 239,000 shrank to just 1 percent of its original size, making the species virtually extinct. In 1966, the international community banned blue-whale hunting. Since the ban on commercial whaling via the moratorium declared by the International Whaling Commission, the blue whale has enjoyed complete protection. As a result, the stocks in the higher latitudes of the Antarctic have recovered to some extent. In 1998, the number was estimated at 2,280 (Branch, 2007).
The blue whale is the largest animal on our planet. Blue whale cows can grow to 26 metres long; bulls to roughly 24 metres. Adult whales weigh between 50 and 150 metric tons. The largest female blue whale ever weighed was 190 metric tons. Their life expectancy is between 65 and 90 years, but it is surmised that they can grow even older.
(Antarctic) blue whales can be found throughout the Antarctic and live south of 60°S. In summer, they can frequently be found near the ice edge. In the higher latitudes, they can migrate nearly half-way around the Antarctic continent. In winter, the majority of blue whales migrate to their breeding grounds farther north, while a few overwinter in the Antarctic. Their young are born in warmer waters farther north, between March and early July. (Antarctic) blue whales are chiefly solitary or found in small groups of two to five. However, larger groups of up to 50 have been sighted in the higher latitudes. Like southern minke whales, blue whales only make brief and shallow dives to hunt their prey near the water’s surface – primarily krill, but also copepods and amphipods. That being said, they also occasionally dive to depths of up to 140 metres, remaining underwater for up to 15 minutes (Bester et al., 2017).
Unlike the blue whale, the southern beaked whale (Berardius arnuxii) was never hunted. Consequently, very little is known about the species’ lifestyle; no data is available on its average weight, reproductive cycle or lifecycle, life expectancy or total population. It is assumed that females are somewhat larger than males. The largest recorded southern beaked whale to date was ca. 10 metres long. The beaked whale has a rounded head and long beak. Its lower jaw protrudes beyond its upper jaw and the larger two of its four teeth remain visible when it closes its mouth. The southern beaked whale can be found throughout the Antarctic, from the continent and the ice edge to ca. 34°S, but also swims far to the north, and has been sighted at ca. 24°S. When it’s summer in the Southern Hemisphere, it stays in Antarctic waters, and can frequently be sighted in the pack ice in August.
It remains unclear where southern beaked whales bear their young or where they overwinter. In ice-free areas in the pack ice, southern beaked whales make dives of 35 to 65 minutes in duration. Lone whales and small groups of five to ca. 20 have been sighted near Australia. In the Antarctic, larger groups of up to 80 have been observed (Bester et al., 2017).
The southern bottlenose whale (Hyperoodon planifrons) was never hunted either. Information on the species is extremely limited; nothing is known about its life expectancy, reproductive cycle or average weight. It has been speculated that it weighs ca. 3.4 metric tons. The cows reach lengths of ca. 7.5 metres, while the bulls, at 7 metres, are somewhat smaller.
The southern bottlenose whale can especially be found throughout the Antarctic from October to March. The total population is estimated at 600,000. The whales can be found at the sea-ice edge, but also in warmer waters as far north as 30°S; occasionally they swim even farther. The highest concentration of bottlenose whales can be found at a moderate distance (ca. 100 kilometres) from the ice edge. In the late southern summer (February to March), they migrate north, returning in the southern spring. Their exact whereabouts in winter (April to September) remain unknown. The southernmost sighting to date was at 73°S in the Ross Sea. These whales chiefly feed on oceanic squid.
Southern bottlenose whales tend to be solitary or are found in small groups of two to ten. That being said, larger pods of up to 25 have also been observed. Analyses of their stomach contents indicate that they mainly feed on squid and Patagonian toothfish (Bester et al, 2017).
The sperm whale (Physeter macrocephalus) is the world’s largest toothed whale. From the 18th century to 1979, it was intensively hunted. The estimated population before whaling began was more than a million; by the time whaling was banned (1986), that number had dwindled to ca. 360,000. Male sperm whales can grow to 20 metres, while cows grow to a maximum of 12 metres. Weights vary from 11 to 33 metric tons. Their life expectancy is 60 to 70 years.
In the Southern Hemisphere, sperm whales can be found both in tropical waters and near the ice edge. In this regard, the whales found at the ice edge are almost exclusively adult males. In the southern summer, the bulls migrate from the tropical or temperate regions to colder waters. In winter, they return to the lower latitudes and can be seen e.g. off the coast of South Africa. Their migrations are mainly for hunting purposes; the bulls go where the food is. In contrast, the females and young whales rarely venture farther south than 40°S, as they prefer water temperatures of ca. 15 degrees Celsius. The cows bear their young between January and April.
Sperm whales are deep divers, reaching 600 metres on average and remaining underwater for ca. 45 minutes. The longest sperm whale dive ever recorded was 2 hours and 18 minutes; the greatest depth was 2,035 metres. Sperm whales hunt giant squid and large Humboldt squid, as well as benthic and pelagic fish. Especially males hunt larger squid species, including the colossal squid, which lives in the waters of the Antarctic. Sperm whales hunt using echolocation, producing extremely loud clicks – in some cases more than 235 dB, making them the loudest sounds generated in the animal world. Female sperm whales are mostly found in groups of ten to fifteen adults, together with their young. Males are often solitary, though they can temporarily be found together with females and juveniles in mixed groups of 15 to 50 whales. In addition, there are groups of pregnant females and so-called ‘bachelor’ groups (Bester et al, 2017).
The killer whale (Orcinus orca) or orca can be found around the globe and is especially abundant in the Antarctic. According to one estimate, there are 25,000 orcas south of 60°S, though this number is considered unreliable, since there are still no confirmed figures for many subpopulations (Branch and Butterworth, 2001). Adult bulls can reach lengths of up to nine metres. Cows are smaller and can grow to eight metres. Bulls have a life expectancy of 50 to 60 years; for cows, the number is 80 to 90 years. Adult weights are estimated at between three and eight metric tons. Males have a distinctive upright dorsal fin, which can be up to 1.8 metres tall.
In the Southern Hemisphere, killer whales can be found from the tropics to the Antarctic pack ice. In the waters of the Antarctic, to date five types – which differ not only genetically, but also in terms of their size, appearance (size and form of their characteristic colour pattern) and preferred prey – have been identified.
Type A prefers open water, is the physically largest type (8-10 m) and can often be found near the Antarctic Peninsula. It has specialised in hunting minke whales and most likely follows their migratory routes into and out of the Antarctic. Type B1, also known as the pack-ice orca, can be found in the loose pack ice and has specialised in seals. Type B2, the Gerlache orca (named for its abundance in Gerlache Strait), is somewhat smaller than Type B1 and hunts penguins as well. The smallest is Type C (6 m), which is mainly found in the ice-covered regions of the East Antarctic and mostly feeds on fish. However, it has also been sighted in the Weddell Sea (Schall and van Opzeeland, 2017). There is also Type D, found in subantarctic waters. More information can be found here.
Information on their migratory behaviour remains patchy, but it is believed that they migrate to warmer waters in the southern winter and return in the southern summer. Their migration southward begins in September or October and continues until January. Between February and late April, they begin the journey north. However, killer whales have also been sighted in the Antarctic in the southern winter. There are certain indications that this may mean there is a subspecies that doesn’t migrate. Alternatively, the wind can drive the ice together, or the ice can form very rapidly, leaving killer whales temporarily trapped in small areas of open water. Killer whale cows bear their young throughout the year, though mostly in autumn and spring. Here there would appear to be differences from location to location.
South of 60°S, killer whales normally live in pods of 12 on average. However, pods of 25 or even 200 have also been sighted. A pod consists of mature bulls and cows with their offspring. Solitary killer whales are rare (Bester et al, 2017).
As a rule, killer whales dive in shallow waters, and in the uppermost 20 metres of the water column. Occasionally they go to depths of 150 or even 300 metres. Their dives can last up to 30 minutes and their prey is diverse: they hunt various other whale species, seals and sea cows, as well as fish, birds and turtles. Killer whales hunt smaller animals alone, though they often cooperate to hunt larger prey. Killer whales also benefit from human fishing activities – e.g. from bycatch, which is thrown back overboard. They also eat fish caught with hook-covered longlines, tearing them off the hooks underwater (Bester et al, 2017).
Bester M. N., H. Bornemann & T. McIntyre (2017): Antarctic marine mammals and sea ice. In: D. N. Thomas (ed.), Sea Ice, 3rd edition, Wiley-Blackwell, Chichester (UK) Hoboken (NJ), pp. 534-555
Branch, T.A. & D. S. Butterworth (2001): Estimates of abundance south of 60°S for cetacean species sighted frequently on the 1978/79 to 1997/98 IWC/IDCR-SOWER sighting surveys. Journal of Cetacean Research and Management 3(3), pp. 251-270
Branch T.A. (2007): Abundance of Antarctic blue whales south of 60°S from three complete circumpolar sets of surveys. Journal of Cetacean Research and Management 9(3), pp. 253–262.
International Whaling Commission (2013): Reports of the subcommittee on in-depth assessments. J. Cetacean Res. Manag. 14, pp. 195–213.
Mizroch, S. A., D. W. Rice & J. M. Breiwick (1984): The Blue Whale, Balaenoptera musculus. Marine Fisheries Reviews. 46.
Schall E. & I. Van Opzeeland (2017): Calls produced by Ecotype C killer whales (Orcinus orca) off the Eckstroem Iceshelf, Antarctica. Aquat. Mamm. 43, p. 117. (doi:10.1578/AM.43.2.2017.117)