bearded seal

{{Short description|Species of Arctic dwelling marine mammal}}

{{Speciesbox

| name = Bearded seal{{MSW3 Wozencraft | pages = | id = 14001032}}

| image = Bearded Seal.jpg

| status = LC

| status_system = IUCN3.1

| status_ref = {{cite iucn |author=Kovacs, K.M. |date=2016 |title=Erignathus barbatus |volume=2016 |page=e.T8010A45225428 |doi=10.2305/IUCN.UK.2016-1.RLTS.T8010A45225428.en |access-date=12 November 2021}}

| genus = Erignathus

| parent_authority = Gill, 1866

| species = barbatus

| authority = Erxleben, 1777

| range_map = Erignathus barbatus map.svg

| range_map_caption = Distribution of bearded seal

}}

The bearded seal (Erignathus barbatus), also called the square flipper seal, is a medium-sized pinniped that is found in and near to the Arctic Ocean.{{Cite book|url=https://books.google.com/books?id=2rkHQpToi9sC&q=bearded+seal&pg=PP1|title=Encyclopedia of Marine Mammals|last1=Perrin|first1=William F.|last2=Würsig|first2=Bernd|last3=Thewissen|first3=J. G. M.|date=2009-02-26|publisher=Academic Press|isbn=9780080919935|language=en}} It gets its generic name from two Greek words (eri and gnathos) that refer to its heavy jaw. The other part of its Linnaean name means bearded and refers to its most characteristic feature, the conspicuous and very abundant whiskers. When dry, these whiskers curl very elegantly, giving the bearded seal a "raffish" look.{{citation needed|date=July 2012}}

Bearded seals are the largest northern phocid. They have been found to weigh as much as {{cvt|300|kg}} with the females being the largest. However, male and female bearded seals are not very dimorphic.

The only member of the genus Erignathus, the bearded seal is unique in that it is an intermediate. Bearded seals belong to the family Phocidae which contains two subfamilies: Phocinae and Monachinae. The bearded seal possesses characteristics of both of these subfamilies.

Fossils first described in 2002 indicate that, during the Pleistocene epoch, bearded seals ranged as far south as South Carolina.{{cite journal |author1=Berta, A. |author2=Churchill, M. |name-list-style=amp | year = 2012 | title = Pinniped Taxonomy: evidence for species and subspecies | journal = Mammal Review | volume = 42 | issue = 3 | pages = 207–234 | doi = 10.1111/j.1365-2907.2011.00193.x}}

Description

Distinguishing features of this earless seal include square fore flippers and thick bristles on its muzzle. Adults are greyish-brown in colour, darker on the back; rarely with a few faint spots on the back or dark spots on the sides. Occasionally the face and neck are reddish brown. Bearded seal pups are born with a greyish-brown natal fur with scattered patches of white on the back and head. The bearded seal is unique in the subfamily Phocinae in having two pairs of teats, a feature it shares with monk seals.

Bearded seals reach about {{convert|2.1|to|2.7|m|ft|abbr=on}} in nose-to-tail length and from {{convert|200|to|430|kg|0|abbr=on}} in weight.[http://animaldiversity.ummz.umich.edu/site/accounts/information/Erignathus_barbatus.html Erignathus barbatus]. The Animal Diversity Web The female seal is larger than the male, meaning that they are sexually dimorphic.

Bearded seals, along with ringed seals, are a major food source for polar bears.{{cite episode | title = Arctic Bears | url = https://www.pbs.org/wnet/nature/arcticbears/index.html | series = PBS Nature | series-link = Nature (TV series) | air-date = 17 February 2008 | access-date = 24 August 2017 | archive-date = 9 February 2008 | archive-url = https://web.archive.org/web/20080209161313/https://www.pbs.org/wnet/nature/arcticbears/index.html | url-status = dead }} They are also an important food source for the Inuit of the Arctic coast. The Inuit language name for the seal is ugjuk{{cite book|last=Ohokak|first=G.|author2=M. Kadlun|author3=B. Harnum|title=Inuinnaqtun-English Dictionary|publisher=Kitikmeot Heritage Society|url=http://www.nald.ca/library/learning/nac/nac_dictionary/nac_dictionary.pdf|access-date=2013-03-20|archive-url=https://web.archive.org/web/20120904191006/http://www.nald.ca/library/learning/nac/nac_dictionary/nac_dictionary.pdf|archive-date=2012-09-04|url-status=dead}}{{cite web|url=http://www.livingdictionary.com/term/viewTerm.jsp?term=49164977792|title=Bearded seal|work=Asuilaak Living Dictionary|access-date=2013-03-20}}{{dead link|date=July 2017 |bot=InternetArchiveBot |fix-attempted=yes }} (plural: ugjuit) or oogrook or oogruk. The Inuit preferred the ringed seal for food and light; the meat would be eaten and the blubber burnt in the kudlik (stone lamp). The skin of the bearded seal is tougher than regular seal and was used to make shoes, whips, dog sled harnesses, to cover a wooden frame boat, the Umiak and in constructing summer tents known as tupiq.{{Cite web |url=http://www.arctic.uoguelph.ca/cpl/Traditional/traditional/animals/bearded_seal.htm |title=Ugjuk — Bearded Seal |access-date=2013-03-20 |archive-date=2021-04-27 |archive-url=https://web.archive.org/web/20210427115022/http://www.arctic.uoguelph.ca/cpl/Traditional/traditional/animals/bearded_seal.htm |url-status=dead }}

The body fat content of a bearded seal is about 25–40%.{{Cite journal|last1=Ryg|first1=Morten|last2=Lydersen|first2=Christian|last3=Markussen|first3=Nina H.|last4=Smith|first4=Thomas G.|last5=Øritsland|first5=Nils Are|date=18 January 1990|title=Estimating the Blubber Content of Phocid Seals|journal=Canadian Journal of Fisheries and Aquatic Sciences|volume=47|issue=6|pages=1223–1227|doi=10.1139/f90-142|bibcode=1990CJFAS..47.1223R |issn=0706-652X}}

Distribution

Bearded seals are extant in Arctic and subarctic regions. In the Pacific region, they extend from the Chukchi Sea in the Arctic, south into the Bering Sea{{Cite journal|last1=Lowry|first1=Lloyd F.|last2=Frost|first2=Kathryn J.|last3=Burns|first3=John J.|date=1980|title=Variability in the Diet of Ringed Seals, Phoca hispida, in Alaska|journal=Canadian Journal of Fisheries and Aquatic Sciences|volume=37|issue=12|pages=2254–2261|doi=10.1139/f80-270|bibcode=1980CJFAS..37.2254L |issn=0706-652X}} where they span from Bristol Bay on the Alaskan coast to the Sea of Okhotsk on the Russian coast,{{Cite journal|title=Erignathus barbatus: Kovacs, K.M.|date=2016-02-17|doi=10.2305/iucn.uk.2016-1.rlts.t8010a45225428.en|doi-access=free}} up to but not including the northern coast of Japan. In the Arctic Ocean, they are found along the northern coasts of Russia, Norway, Canada, and Alaska, including the Norwegian Archipelago of Svalbard{{Cite journal|last1=Hjelset|first1=A. M.|last2=Andersen|first2=M.|last3=Gjertz|first3=I.|last4=Lydersen|first4=C.|last5=Gulliksen|first5=B.|date=1999-02-23|title=Feeding habits of bearded seals ( Erignathus barbatus ) from the Svalbard area, Norway|journal=Polar Biology|language=en|volume=21|issue=3|pages=186–193|doi=10.1007/s003000050351|bibcode=1999PoBio..21..186H |s2cid=25532134|issn=0722-4060}} and Canadian Arctic Archipelago.{{Cite journal|last1=Finley|first1=K.J.|last2=Evans|first2=C.R.|date=1983-01-01|title=Summer Diet of the Bearded Seal (Erignathus barbatus) in the Canadian High Arctic|journal=Arctic|language=en-US|volume=36|issue=1|doi=10.14430/arctic2246|issn=1923-1245|doi-access=free}} In the Atlantic, Bearded seals are found along the northern coast of Iceland, the east and west coasts of Greenland and the Canadian mainland as far south as Labrador.{{Cite news|url=https://nammco.no/topics/bearded-seal/#1475843212917-9abc9066-9674|title=Bearded Seal - NAMMCO|date=2017-01-16|work=NAMMCO|access-date=2018-06-07|language=en-GB}}

Although the range typically only extends down into subarctic areas bearded seals have been seen in Japan and China as well as extremely far south of their range in Germany, Netherlands, United Kingdom, France, Spain and Portugal.

Hunting and diet

Primarily benthic, bearded seals feed on a variety of small prey found along the ocean floor, including clams, squid, and fish. Their whiskers serve as feelersSaundry, Peter. 2010. [http://www.eoearth.org/article/Bearded_seal Bearded seal] {{webarchive |url=https://web.archive.org/web/20100704151159/http://www.eoearth.org/article/Bearded_seal |date=July 4, 2010 }}. Encyclopedia of Earth. Topic editor C. Michael Hogan, Ed.in Chief: Cutler Cleveland, NCSE, Washington DC in the soft bottom sediments. Adults tend not to dive very deep, favoring shallow coastal areas no more than {{convert|300|m|abbr=on}} deep. Pups up to one year old, however, will venture much deeper, diving as deep as {{convert|450|m|abbr=on}}. In a study conducted during the summer months, the seals have been found to feed on invertebrates such as anemones, sea cucumbers, and polychaete worms. The same study found that sculpins and Arctic cod made up most of their summer diet. Sculpin were also found to be the largest fish consumed by the seals. Bearded seals are capable of preying on pelagic and demersal fish in addition to their benthic prey.{{Cite journal|last1=Finley|first1=K. J.|last2=Evans|first2=C. R.|date=1983-01-01|title=Summer Diet of the Bearded Seal ( Erignathus barbatus ) in the Canadian High Arctic|journal=Arctic|language=en-US|volume=36|issue=1|pages=82–89|doi=10.14430/arctic2246|issn=1923-1245|doi-access=free}}

Reproduction and lifecycle

Image:Beardedsealpup.jpg

Bearded seals give birth in the spring. In the Canadian Arctic, seal pupping occurs in May. In Svalbard, bearded seals reach sexual maturity at 5 or 6 years of age.{{cite journal | last1 = Andersen | first1 = Magnus | display-authors = etal | year = 1999 | title = Growth, age at sexual maturity and condition in bearded seals (Erignathus barbatus) from Svalbard, Norway | url = https://brage.bibsys.no/xmlui/bitstream/handle/11250/174308/AndersenPolarBiol1999.pdf?sequence=1 | journal = Polar Biology | volume = 21 | issue = 3| pages = 179–185 | doi = 10.1007/s003000050350 | bibcode = 1999PoBio..21..179A | hdl = 11250/174308 | s2cid = 37623370 | hdl-access = free }} Further south, in Alaska, most pups are born in late April.{{clarify|reason=See talk page|date=March 2013}} Pups are born on small drifting ice floes in shallow waters, usually weighing around {{convert|30|–|40|kg|abbr=on}}. They enter the water only hours after they are born, and quickly become proficient divers. Mothers care for the pups for 18–24 days, during which time the pups grow at an average rate of {{convert|3.3|kg|abbr=on}} per day. During this time, pups consume an average of {{convert|8|L|abbr=on}} of milk a day. By the time they are weaned, the pups have grown to about {{convert|100|kg|abbr=on}}.

Just before the pups are weaned, a new mating cycle takes place. Females ovulate at the end of their lactation period, but remain close to their pups, ready to defend them if necessary. During the mating season, male seals will "sing", emitting a long-drawn-out warbling note that ends in a sort of moan or sigh. This sound may attract females, or may be used by the males to proclaim their territory or their readiness for breeding. Males occupy the same areas from one year to the next.{{cite book | title = Encyclopedia of the Arctic | author = Nuttal | publisher = Routlelege | location = New York, NY | year = 2005|display-authors=etal}}

Like many Arctic mammals, bearded seals employ a reproductive strategy known as delayed implantation. This means that the blastocyst is not implanted for two months after fertilization, most often becoming implanted in July. Thus, the seal's total gestation period is around eleven months, though its active gestation period is nine months.{{cite book | author = Perry, Judith E. | title = Seals of the World | publisher = Comstock Publishing Associates | location = Ithaca, NY | year = 1983 | page = 103}}

Natural predators of the bearded seal include polar bears, who rely on these seals as a major food source.{{cite web|title=Erignathus barbatus – bearded seal|url=http://animaldiversity.ummz.umich.edu/accounts/Erignathus_barbatus/|publisher=Animal Diversity Web}} Killer whales also prey on these seals, sometimes overturning ice floes to reach them. Walruses also eat these seals, mainly pups, but such predation is rare.Folkens, Peter (2002). National Audubon Society Guide to Marine Mammals of the World. New York, pg. 117.

Bearded seals are believed to live up to 31 years.National Marine Mammal Laboratory [http://www.afsc.noaa.gov/nmml/education/pinnipeds/bearded.php#die Bearded Seals] Retrieved May 1, 2016

Vocalization

The vocalizations produced by the bearded seal are unique, possibly because their trachea is different from that of other Northern Pacific phocids. A majority of the rings in the trachea are incomplete with only a membrane attaching the two ends.{{Cite web|url=https://www.boem.gov/ESPIS/0/312.pdf|title=Natural History and Ecology of the Bearded Seal, Erignathus Barbatus|last=Burns|first=John J.|date=May 1979}}{{Dead link|date=June 2020 |bot=InternetArchiveBot |fix-attempted=yes }}

File:Svalbard_Sample_for_Wiki.oggThe sounds of the bearded seal usually consist of a long oscillating trill lasting for a minute or more followed by a short, deep moan. This "song" is often repeated frequently. The number of call types within a population can vary geographically, with four types found in Svalbard and eleven in the Western Canadian Arctic. The most frequent sounds are trills, moans, and sweeps. A sweep can be compared to a short trill.{{Cite journal|last1=Risch|first1=Denise|last2=Clark|first2=Christopher W.|last3=Corkeron|first3=Peter J.|last4=Elepfandt|first4=Andreas|last5=Kovacs|first5=Kit M.|last6=Lydersen|first6=Christian|last7=Stirling|first7=Ian|last8=Van Parijs|first8=Sofie M.|date=May 2007|title=Vocalizations of male bearded seals, Erignathus barbatus: classification and geographical variation|journal=Animal Behaviour|volume=73|issue=5|pages=747–762|doi=10.1016/j.anbehav.2006.06.012|s2cid=53187110|issn=0003-3472}}

Bearded seals produce distinct trills from late March to late June, with a decline in rhythmicity in late May and June. This timeline coincides with their breeding and pupping season, which is from April to May. The repetitive and transmittable nature of bearded seal trills leads researchers to believe that they are utilized for communication, likely during courtship and breeding.{{Cite journal|last1=Cleator|first1=Holly J.|last2=Stirling|first2=Ian|last3=Smith|first3=T. G.|date=5 July 1989|title=Underwater vocalizations of the bearded seal (Erignathus barbatus)|journal=Canadian Journal of Zoology|volume=67|issue=8|pages=1900–1910|doi=10.1139/z89-272|bibcode=1989CaJZ...67.1900C |issn=0008-4301}} Males use these sounds to establish mating territories and communicate their fitness, but it is likely that females produce these sounds as well.

Underwater, bearded seal trills can be heard from a distance of over {{convert|30|km|abbr=on}}, with some types of sounds traveling farther than others. This makes it possible for one animal to communicate with another animal that is far away, although acoustic degradation does occur as the sound passes through the environment. A seal must produce a trill with a sound-pressure of at least 100 dB at 1 m in order for the sound to propagate 30 km, meaning that bearded seals can likely produce sounds at this level.Image:beardedseal2.jpg]]

Conservation status

On March 28, 2008, the U.S. National Marine Fisheries Service initiated a status review[http://www.nmfs.noaa.gov/pr/pdfs/fr/fr73-16617-ribbonseal.pdf Federal Register /Vol. 73, No. 61 / March 28, 2008 / Proposed Rules]. National Marine Fisheries Service under the Endangered Species Act (ESA) to determine if listing this species under the ESA is warranted. All bearded seals are protected under the Marine Mammal Protection Act, and determined by the IUCN to be classified as a "least concern" for extinction. This classification was determined due to various factors including, widespread distribution, stable population size, as well as alternating prey resources. NOAA determined that the factors influencing any change in conservancy status of the bearded seal may include: loss of sea ice by climate change, bycatch from commercial fishing gear, and hunting.{{Cite web|url=https://www.fisheries.noaa.gov/species/bearded-seal|title=Bearded Seal {{!}} NOAA Fisheries|last=Fisheries|first=NOAA|date=2018-05-24|website=www.fisheries.noaa.gov|language=EN-US|access-date=2018-06-06}} Their main predators include polar bears; however, typically pups around age 2 are attacked within birthing lairs, leaving older juveniles and adults commonly unharmed.{{Cite journal|title=Canadian Science Publishing|doi=10.1139/z80-302 | volume=58 | year=1980|journal=Canadian Journal of Zoology|pages=2201–2209 | last1 = Smith | first1 = Thomas G.}} Due to climate change, factors such as loss of sea ice, as well as decrease in prey population may create negative results on the bearded seal population in the future. Therefore, monitoring of the species as well as influences of human activity, will be vital to ensure species stability.

Subspecies

There are two recognized subspecies of this seal:

class="wikitable "
ImageSubspeciesDistribution
120pxErignathus barbatus barbatus {{small|(Erxleben 1777)}} – Eastern bearded seal
120pxErignathus barbatus nauticus {{small|(Pallas 1811)}} – Western bearded seal

While the validity of these subspecies has been questioned, and is not yet supported by any molecular data, analysis of the animals' calls does indicate a differentiation between different populations.{{cite journal | author = Risch, D. | year = 2006 | title = Vocalizations of male bearded seals, Erignathus barbatus: classification and geographical variation | journal = Animal Behaviour | volume = 73 | issue = 5 | pages = 747–762 | doi = 10.1016/j.anbehav.2006.06.012| s2cid = 53187110 |display-authors=etal}}

File:Bearded Seal (Erignathus barbatus), Baltasound marina - geograph.org.uk - 2323394.jpg

Evolutionary history

Bearded seal fossils have been found to be as old as the early to mid Pleistocene. These early fossils were found in northern regions like England, Alaska, and Sweden, as well as the North Sea and the Champlain Sea.{{Cite journal|last=Harington|first=C. R.|date=March 2008|title=The Evolution of Arctic Marine Mammals|journal=Ecological Applications|language=en|volume=18|issue=sp2|pages=S23–S40|doi=10.1890/06-0624.1|issn=1051-0761|pmid=18494361|doi-access=free|bibcode=2008EcoAp..18S..23H }}

Bearded seals, like all true seals, belong to the family Phocidae which is one of the three families in the clade Pinnipedia, along with Otariidae and Odobenidae. Pinnipeds are thought to have originated 27 to 25 million years ago during the late Oligocene period. One hypothesis for the evolution of pinnipeds is that pinnipeds are a diphyletic group and otariids and odobenids are more closely related to bears, and phocids are more closely related to mustelids like weasels. Another hypothesis suggests that pinnipeds are a monophyletic group that descended from a single ancestor. This has been more supported by phylogenetic analysis than the diphylectic hypothesis. One such study suggests that phocids are sister taxa to the common ancestor to both otariids and odobenids.

Bearded seals belong to the subfamily Phocinae (Northern Hemisphere seals). Phocinae can be further divided into three clades: Erignathini (bearded seals), Cystophorini (hooded seals), and Phocini (all remaining genera). Bearded seals are the sister taxa to the common ancestor of Cystophorini and Phocini.{{cite journal | last1=Berta | first1=Annalisa | last2=Churchill | first2=Morgan | last3=Boessenecker | first3=Robert W. | title=The Origin and Evolutionary Biology of Pinnipeds: Seals, Sea Lions, and Walruses | journal=Annual Review of Earth and Planetary Sciences | publisher=Annual Reviews | volume=46 | issue=1 | date=2018-05-30 | issn=0084-6597 | doi=10.1146/annurev-earth-082517-010009 | pages=203–228| bibcode=2018AREPS..46..203B | s2cid=135439365 | doi-access=free }}

See also

  • Tama-chan, an individual bearded seal which became a minor celebrity in Japan after being sighted in Tokyo's Tama River

References

{{Reflist}}

Further reading

{{Refbegin}}

  • [http://www.nmfs.noaa.gov/pr/species/mammals/pinnipeds/beardedseal.htm U.S. National Marine Fisheries Service bearded seal webpage]
  • Heptner, V. G.; Nasimovich, A. A; Bannikov, Andrei Grigorevich; Hoffmann, Robert S, [https://archive.org/details/mammalsofsov231996gept Mammals of the Soviet Union], Volume II, part 3 (1996). Washington, D.C. : Smithsonian Institution Libraries and National Science Foundation

{{Refend}}