Erignathus barbatus (Erxleben, 1777)
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publication ID |
https://doi.org/ 10.5281/zenodo.6607185 |
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DOI |
https://doi.org/10.5281/zenodo.6606912 |
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persistent identifier |
https://treatment.plazi.org/id/464F694F-FFA2-A85F-FFB8-D0BA9E10F68E |
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treatment provided by |
Diego |
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scientific name |
Erignathus barbatus |
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Bearded Seal
Erignathus barbatus View in CoL
French: Phoque barbu / German: Bartrobbe / Spanish: Foca barbuda
Other common names: Squareflipper; Atlantic Bearded Seal (barbatus); Pacific Bearded Seal (nauticus)
Taxonomy. Phoca barbata Erxleben, 1777 View in CoL ,
“ad Scotiam atque Groelandiam australiorem, vulgaris circa Islandiam” (= North Atlantic Ocean, South Greenland).
Two subspecies are recognized.
Subspecies and Distribution.
E.b.barbatusErxleben,1777—NAtlanticandArcticoceansfromtheCCanadianArctictoBarentsandLaptevseas.
E. b. nauticus Pallas, 1881 — Arctic and subarctic oceans E of Laptev Sea to the C Canadian Arctic,also petion Sea and Sea of Okhotsk S to Hokkaido, Japan. View Figure
Descriptive notes. Total length 210-250 cm; weight 250-450 kg. Newborns are c.130 cm in length and weigh c.34 kg. Bearded Seals are large-bodied, with relatively small heads, long slender bodies, square front flippers, and prominent facial whiskers. Adult females are somewhat larger than males. Offspring have lanugo (fine, soft hair) in utero that is shed just before birth when they then have silver-blue to brown pelage. Adult Bearded Seals are uniformly gray to dark brown, slightly darker dorsally, and have scattered splotches over their bodies. Hair is short and shed in April-August, with a peak in May-June. One relatively unique characteristic, shared only with monk seals ( Monachus spp. ), is that Breaded Seals have four teats rather than two teats as in all other phocid carnivores.
Habitat. Widely but patchily distributed in Arctic and subarctic regions of the North Pacific and North Atlantic oceans. Bearded Seals are typically found in areas with broken free-floating pack ice, and because of their benthic feeding habits, they live primarily in shallow waters overlying continental shelves such as in the Bering and Barents seas. For example, south of Saint Lawrence Island, Alaska, in late winter, Bearded Seals avoided large ice floes (more than 48 m in diameter) and preferred areas of freefloating pack ice between large and small (less than 20 m in diameter) ice floes; they occurred in areas with 70-90% ice cover and selected areas of high benthic biomass. In contrast, sympatric Ringed Seals ( Pusa hispida ) and Walruses ( Odobenus rosmarus ) preferred large ice floes, and Spotted Seals ( Phoca largha ) preferred small ice floes. In Canadian waters, greatest densities appear to be in Hudson and Baffin bays and along the west coast of Banks Island.
Food and Feeding. Bearded Seals are not deep divers and eat a diversity of benthic and epibenthic prey at depths of 100 m or less, using a combination of waterjetting and suction feeding in soft bottom substrates. Their primary prey lives on or near the seafloor, but they also eat some infauna and schooling and demersal fish. Diets of Bearded Seals are dominated by mollusks (clams and sea snails), crustaceans (shrimps and crabs), fish ( Gadidae , Osmeridae , Zoarcidae , Cottidae , and flatfish), and cephalopods (squid). In the Bering and Chukchi seas region, Bearded Seals had the highest diversity of invertebrate prey types with most stomachs containing shrimps (71%) and molluscs (61%), and consume more flatfish and sculpin ( Cottidae ) than the sympatric Ringed Seals and Spotted Seals. Fatty acid composition of blubber of Bearded Seals from subsistence harvests near Little Diomede Island, Alaska (USA), differed from that of sympatric Ringed Seals, Spotted Seals, and Ribbon Seals ( Histriophoca fasciata ). The particular concentration of a monounsaturated fatty acid (16:1n-7) suggested that Bearded Seals ate a diet dominated by benthic mollusks. Such comparisons of fatty acids are not only useful as an index of diet but also as a benchmark to assess future climate change.
Breeding. Bearded Seals are born from mid-March through early May and are weaned at 2-3 weeks old. Estrous females mate from mid-March through mid-June. The fertilized egg develops briefly and then floats freely and dormant for about two months before attaching to the uterine wall and resuming development. Most females are sexually mature at 2-7 years old and almost all by eight years old. About 85% offemales give birth each year. Males are sexually mature at 6-7 years old. Structure of the breeding system of Breaded Seals is poorly known, although males have elaborate underwater vocalizations and bubble displays that may be used to attract estrous females or displace other males. Bearded Seals normally live 20-25 years.
Activity patterns. Nursing Bearded Seals can enter the water when they are only a few hours old, perhaps an adaptation to avoid predation by Polar Bears (Ursus maritimus). Diving abilities of young Bearded Seals develop quickly, and they can dive repeatedly for up to ¢.5 minutes to depths of more than 90 m within a couple of weeks after birth and to more than 450 m by the end of their first year. Mothers and their offspring spend about one-half of their time in the water during the brief lactation period, hauling out on ice only for offspring to suckle; females occasionally leave their offspring on the ice while they forage. Dives of adult Bearded Seals are usually less than 100 m in shallow coastal or continental shelf waters where they feed on epibenthic and benthic prey. Dives last ¢.10 minutes but can be as long as 25 minutes.
Movements, Home range and Social organization. Bearded Seals are thought to be year-round residents in some areas, but mobile in others areas, following the ice edge as it moves south in autumn and winter and then recedes in spring and summer. Some Bearded Seals overwinter in areas where persistent polynyas (open water surrounded by sea ice) occur. They are solitary and sparsely distributed throughout most of the year, even during the breeding season when they haul-out to give birth and mate. Bearded Seals are known to wander outside the Arctic and have been reported south to Spain and Portugal in the eastern North Atlantic Ocean, and to the Gulf of Maine and Cape Cod, USA, in the western North Atlantic Ocean.
Status and Conservation. Classified as Least Concern on The IUCN Red List. Bearded Seals have long been important prey for some Native Arctic human cultures for meat, skin and oil, and bones and teeth used to make tools and weapons. Harvests of Bearded Seals are generally small in all areas. Soviet sealers harvested somewhat larger numbers (up to 10,000 individuals in some years) in the 1940s and through at least the late 1980s in various areas of the Arctic. Population sizes have been difficult to estimate, but some researchers conclude that ¢.300,000 Bearded Seals occur off the coast of Alaska, with perhaps more than 500,000 Bearded Seals worldwide. In 2012, two Distinct Population Segments of the “Pacific Bearded Seal” (LE. b. nauticus) in Beringia (Bering Sea) and the Sea of Okhotsk were listed as threatened under the US Endangered Species Act.
Bibliography. Bengtson et al. (2005), Cleator et al. (1989), Cooper et al. (2009), Gjertz et al. (2000a), Kovacs (2009a), Kovacs, Lydersen & Gjertz (1996), Krafft et al. (2000), McLaren (1958a), Quakenbush & Sheffield (2007), Ray et al. (1969), Simpkins et al. (2003), Van Parijs et al. (2003b).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
