Erignathus barbatusbearded seal

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Geographic Range

Bearded seals, Erignathus barbatus, are found in the Arctic Ocean, where populations are geographically divided into two subspecies, E. barbatus barbatus and E. barbatus nauticus. Erignathus barbatus barbatus occupies portions the Arctic near the Atlantic Ocean, from the eastern seaboard of Canada at the Gulf of Saint Lawrence to the waters around Norway in the western Laptev Sea. Erignathus barbatus nauticus is found in the the Sea of Okhotsk and Bering Sea, and in areas of the Arctic Ocean not occupied by E. barbatus barbatus. Bearded seals have been regularly sighted as far south as the Japanese island of Hokkaido, and there have been sightings in China of E. barbatus nauticus and of E. barbatus barbatus in Portugal. It currently unknown why some animals travel so far south outside their normal range. (Reeves, et al., 1992)

Habitat

Bearded seals prefer shallow, arctic waters less than 200 meters in depth. They also prefer areas heavy with ice floes or pack ice, as these are areas where adults "haul out." They generally segregate, with one adult per ice floe. Bearded seals ride drifting ice floes for great distances, and their "migration" is thus dependent on the season and distribution of ice floes. Bearded seals follow ice further south during the winter and further north during the summer. Riding drifting ice floes provides access to shallow water, in which they feed. However, they avoid ice floes on which walruses are abundant. Bearded seals rarely choose land over ice floes for hauling out. However, in summertime when ice floes are sparse, they have been known to haul out on land and gravel beaches. (Cameron and Boveng, 2009; Reeves, et al., 1992)

  • Terrestrial Biomes
  • icecap
  • Range depth
    200 (high) m
    656.17 (high) ft

Physical Description

Bearded seals on average measure 2.3 m in length and 200 to 250 kg in weight, with females larger than males. Between late fall and early spring, however, they can weigh up to 430 kg. At birth, pups average about 130 cm in length and 34 kg in weight. Adult bearded seals possess straight, evenly-colored light gray to dark brown hair, and their back is darker then the rest of their body. Their flippers and face are generally brick to deep rust in color. In contrast, bearded seal pups are born with lighter colored faces with assorted ribbon-like bands across their back and crown. Pups have soft, fluffy fur that tends to be a silvery blue, light brown or gray.

Bearded seals can be distinguished from other northern seals by their distinctive mustaches as well as their squared flippers. Their front and hind flippers have pronounced, pointed claws. Their head appears proportionally small compared to their long body. (Reeves, et al., 1992)

  • Sexual Dimorphism
  • female larger
  • Range mass
    200 to 430 kg
    440.53 to 947.14 lb
  • Average length
    2.3 m
    7.55 ft

Reproduction

Bearded seals are promiscuous, having more than one mate during the breeding season. Males leave after mating, providing no care to pups. Due to their solitary nature, bearded seals do not establish long-term bonds with mating partners. Occasionally, males fight over a female mate. Male bearded seals also sing, which may be a courtship routine and/or a territorial warning during the breading season. (Kirlin, 2005; Kovacs and Lavigne, 1986; Nelson, 2008)

Bearded seals breed once a year, though this varies with seasonal ocean productivity. They mate between March and June, and males are at peak potency during May. Due to delayed implantation and a long gestation period (11 months), female bearded seals do not give birth until the following summer. During gestation, females gain weight to build up a supply of milk. Females give birth on pack ice between mid-March and May. Unlike their close relative, ringed seals, bearded seals do not use or assemble subnivean birth lairs. Bearded seals give birth to 1 pup, which weighs approximately 34 kg at birth. Within several days, pups enter the water. Weaning occurs in 18 to 24 days, and pups weaned by late summer have ample time to create blubber before the winter. Females reach sexual maturity at 3 to 8 years of age and males at 6 to 7 years. (Gjertz, et al., 2000; Kovacs and Lavigne, 1986; Kovacs, et al., 1996; Reeves, et al., 1992)

  • Breeding interval
    Bearded seals breeds approximately once a year.
  • Breeding season
    Bearded seals breeds in March through June.
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    11 months
  • Average gestation period
    259 days
    AnAge
  • Range weaning age
    18 to 24 days
  • Range age at sexual or reproductive maturity (female)
    3 to 8 years
  • Range age at sexual or reproductive maturity (male)
    6 to 7 years

Male bearded seals leave females after mating and provide no parental care to pups. Like many arctic seals, female bearded seals give birth to their pups on ice floes. Unlike their close relative ringed seals, however, they do not use or assemble subnivean birth lairs. While weaning her pup, a mother does not leave the ice flow. She does not eat until her pup is weaned and can be left alone. (Gjertz, et al., 2000; Kovacs and Lavigne, 1986; Reeves, et al., 1992)

  • Parental Investment
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

Although most bearded seals do not live over 25 years in the wild, some have been recorded to live as long as 31 years. (Reeves, et al., 1992)

  • Range lifespan
    Status: wild
    31 (high) years
  • Typical lifespan
    Status: wild
    25 (high) years

Behavior

Bearded seals are solitary animals; even in high densities, they keep separate from each other except during the breeding season. Generally, they maintain a density of one individual per ice floe or less. Bearded seals are territorial during the breeding season and fast-ice season when they haul out on separate ice floes. While hauling out, bearded seals face the water in order to spot predators. Bearded seals are diurnal and spend most of the year foraging in the coastal and shallow seas of the north Atlantic. During breeding season, they are more localized and spend more time on pack ice. Male bearded seals sing in what is believed to be either a courtship routine and/or a territorial warning during the breeding season. Occasionally, males fight over a female mate. (Kirlin, 2005; Kovacs and Lavigne, 1986; Nelson, 2008)

  • Range territory size
    0.27 to 12.5 km^2

Home Range

Bearded seals have a territory of 0.27 to 12.5 sq km. They become territorial during fast-ice season and during breeding season.

Communication and Perception

Of all the marine animals, male bearded seals are among the most vocally expressive, especially during spring breeding season. Their minute-long songs can be described as sinister and monotone but also harmonious. They are generally characterized as chirps, ascents, sweeps, or grumbles. During their song, bearded seals begin a slow, circular dive while emitting bubbles until resurfacing. It is believed that these songs are typical of courtship routines and or distinguishing breeding territory. Many underwater recordings of marine mammal communication in the Alaskan/Bering Strait region are predominately composed of songs of bearded seals. (Cleator, et al., 1989; Nelson, 2008; Reeves, et al., 1992; Terhune, 1999)

Food Habits

Bearded seals are primarily benthic feeders and dive to a maximum of 200 m to obtain food. They primarily eat local mollusks and crustaceans, and also commonly eat Arctic cod. They have also been known to eat benthic fishes such as sculpins and flatfishes, and also American Plaice (Hippoglossoides platessoides). (Cameron and Boveng, 2009; Finley, 1983; Lowry, et al., 1980; Reeves, et al., 1992)

  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans

Predation

Bearded seals have two main predators, polar bears and killer whales. Polar bears hunt seals by waiting near a breathing hole for their prey to surface. However, breathing holes of bearded seals usually form domes or caps of ice that they must dig through to reach the surface. This may serve as a defensive strategy, obscuring breathing hole positions and making them more difficult for polar bears to locate. Killer whales do not actively hunt bearded seals, but eat them opportunistically. Although rarely observed, pups of bearded seals are occasionally eaten by walruses. Bearded seals are also taken by humans through subsistence fishing by Native Americans in Canada and Alaska. (Reeves, et al., 1992; Smith, 1980)

Ecosystem Roles

Bearded seals are important predators of benthic mollusks, crustaceans, fish, and octopi. They compete with other seal species for food; however walruses tend to be their main food competitor. Bearded seals are also a secondary prey to polar bears (ringed seals are primary prey). Bearded seals also serve as prey to killer whales and walruses. (Bishop, 1979; Brattey and Stenson, 1993; Bristow and Berland, 1992; Nelson, 2008; Reeves, et al., 1992)

Bearded seals are the only know definitive host of the nematode Pseudoterranova decipiens, which resides in the animal's stomach and intestinal lumen. The parasitic nematode is transmitted when the seal eats the' intermediate host of the parasite, American Plaice (Hippoglossoides platessoides). The bearded seal also hosts the nematode Contracaecum osculatum, which also resides in the stomach.

Numerous trematode species reside in the pancreas and bile duct of the bearded seal, and other parasitic worms reside in the intestine. Abundance of these parasites varies among individual seals.

Protozoan parasites like Sarcocystis species (residing in the tongue) and Giardia species, such as Giardia duodenalis, are often found in the gut of the bearded seal. The protozoan species of Giardia found in bearded seals are not the same species of Giardia that can be transmitted to humans. (Bishop, 1979; Brattey and Stenson, 1993; Bristow and Berland, 1992; Nelson, 2008; Reeves, et al., 1992)

Commensal/Parasitic Species
  • Contracaecum osculatum A, B, C, a nematode
  • Pseudoterranova decipiens C, a nematode
  • Giardia duodenalis, a protozoan
  • Sarcocystis, a protozoan genus

Economic Importance for Humans: Positive

Bearded seals have been traditionally hunted by the Eskimo people for meat, blubber, and leather. Although Eskimos do not rely exclusively on bearded seals for subsistence, hunting pressure on bearded seals is increasing. Bearded seals are important seal species for many Alaskan villages, as native peoples utilize them for their oil, meat, and skin, which is used to make umiaks (boats) and maklak (boots). (Nelson, 2008; Reeves, et al., 1992)

  • Positive Impacts
  • food
  • body parts are source of valuable material

Economic Importance for Humans: Negative

There are no known adverse effects of bearded seals on humans. (Reeves, et al., 1992)

Conservation Status

Although bearded seals are not considered threatened, habitat destruction and overfishing of their prey species are their biggest threats. Additionally, global climate change may result in decreased ice floes, which would negatively impact habitat availability for bearded seals.

Contributors

Anthony Neuberger (author), San Diego Mesa College, Laurel Popplewell (author), San Diego Mesa College, Hillary Richardson (author), San Diego Mesa College, Paul Detwiler (editor), San Diego Mesa College, Tanya Dewey (editor), University of Michigan-Ann Arbor, Gail McCormick (editor), Animal Diversity Web Staff.

Glossary

Arctic Ocean

the body of water between Europe, Asia, and North America which occurs mostly north of the Arctic circle.

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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acoustic

uses sound to communicate

benthic

Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

food

A substance that provides both nutrients and energy to a living thing.

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

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Found in northern North America and northern Europe or Asia.

intertidal or littoral

the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.

migratory

makes seasonal movements between breeding and wintering grounds

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

piscivore

an animal that mainly eats fish

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Andersen, M., A. Hjelset, I. Gjertz, C. Lydersen, B. Gulliksen. 1999. Growth, age at sexual maturity and condition in bearded seals (Erignathus barbatus) from Svalbard, Norway. Polar Biology, 21(3): 179-185.

Bishop, L. 1979. PARASITE-RELATED LESIONS IN A BEARDED SEAL, Erignathus barbatus. Journal of Wildlife Diseases, 15: 285-293.

Brattey, J., G. Stenson. 1993. Host specificity and abundance of parasitic nematodes (Ascaridoidea) from the stomachs of five phocid species from Newfoundland and Labrador. Canadian Journal of Zoology, 71(11): 2156-2166.

Bristow, G., B. Berland. 1992. On the ecology and distribution of Pseudoterranova decipiens C (Nematoda: Anisakidae) in an intermediate host, Hippoglossoides platessoides, in northern Norwegian waters. Internation Journal for Parasitology, 22.2: 203-208.

Cameron, M., P. Boveng. 2009. "Seasonal Movements, Habitat Selection, Foraging and Haul-out Behavior of Adult Bearded Seals" (On-line). Accessed May 26, 2010 at ftp://ftp.afsc.noaa.gov/posters/pCameron05_adult-bearded-seal-pups.pdf.

Cleator, H., I. Stirling, T. Smith. 1989. Underwater vocalizations of the bearded seal (Erignathus barbatus). Canadian Journal of Zoology, 67.8: 1900-1910.

Finley, K. 1983. Summer diet of the bearded seal (Erignathus barbatus) in the Canadian High Arctic. Artic, 36.1: 82-89.

Gjertz, I., K. Kovacs, C. Lydersen, Ø. Wiig. 2000. Movements and diving of bearded seal (Erignathus barbatus) mothers and pups during lactation and post-weaning. Polar Biology, 23.8: 559-566.

Hjelset, A., M. Andersen, I. Gjertz, C. Lydersen, B. Gulliksen. 1999. habits of bearded seals (Erignathus barbatus) from the Svalbard area, Norway. Polar Biology, 21.3: 186-193.

Kirlin, M. 2005. "The Bearded Seal - Mating System" (On-line). Accessed May 08, 2010 at http://www.bio.davidson.edu/people/vecase/Behavior/Spring2005/Kirlin/Mating.html.

Kovacs, K., D. Lavigne. 1986. Maternal Investment and Neonatal Growth in Phocid Seals. Journal of Animal Ecology, 55.3: 1035-1051.

Kovacs, K., C. Lydersen, I. Gjertz. 1996. Birth-Site Characteristics and Prenatal Molting in Bearded Seals (Erignathus barbatus)”. Journal of Mammology, 77.4: 1085-1091.

Lowry, L., K. Frost, J. Burns. 1980. Feeding of Bearded Seals in the Bering and Chukchi Seas. Artic, 33.2: 330-342.

Nelson, M. 2008. "Bearded Seal" (On-line). ADF&G Wildlife Notebook Series. Accessed May 01, 2010 at http://www.adfg.alaska.gov/index.cfm?adfg=beardedseal.main.

Reeves, R., B. Stewart, S. Leatherwood. 1992. The Sierra Club Handbook of Seals and Sirenians. San Francisco, CA: Sierra Club Books.

Smith, T. 1980. Polar bear predation of ringed and bearded seals in the land-fast sea ice habitat. Canadian Journal of Zoology, 58: 2201-2209.

Terhune, J. 1999. Pitch separation as a possible jamming avoidance mechanism in underwater calls of bearded seals (Erignathus barbatus). Canadian Journal of Zoology, 77: 1025-1034.