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.
Biogeographic Regions: nearctic (Native ); palearctic (Native ); arctic ocean (Native )
Other Geographic Terms: holarctic
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.
Known Predators:
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.
Range mass: 200 to 430 kg.
Average length: 2.3 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
Although most bearded seals do not live over 25 years in the wild, some have been recorded to live as long as 31 years.
Range lifespan
Status: wild: 31 (high) years.
Typical lifespan
Status: wild: 25 (high) years.
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.
Range depth: 200 (high) m.
Habitat Regions: polar ; saltwater or marine
Terrestrial Biomes: icecap
Aquatic Biomes: pelagic ; benthic ; coastal
Other Habitat Features: intertidal or littoral
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).
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Molluscivore )
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.
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.
Commensal/Parasitic Species:
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).
Positive Impacts: food ; body parts are source of valuable material
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.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
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.
Communication Channels: visual ; tactile ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
There are no known adverse effects of bearded seals on humans.
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.
Mating System: polygynandrous (promiscuous)
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.
Breeding interval: Bearded seals breeds approximately once a year.
Breeding season: Bearded seals breeds in March through June.
Average number of offspring: 1.
Average gestation period: 11 months.
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.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous ; delayed implantation
Average birth mass: 35000 g.
Average gestation period: 259 days.
Average number of offspring: 1.
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.
Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
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.[3] 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,[3] giving the bearded seal a "raffish" look.
Bearded seals are the largest northern phocid. They have been found to weigh as much as 300 kg (660 lb) with the females being the largest. However, male and female bearded seals are not very dimorphic.[3]
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.[3]
Fossils first described in 2002 indicate that, during the Pleistocene epoch, bearded seals ranged as far south as South Carolina.[4]
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 2.1 to 2.7 m (6.9 to 8.9 ft) in nose-to-tail length and from 200 to 430 kg (441 to 948 lb) in weight.[5] 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.[6] They are also an important food source for the Inuit of the Arctic coast. The Inuit language name for the seal is ugjuk[7][8] (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.[9]
The body fat content of a bearded seal is about 25–40%.[10]
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[11] where they span from Bristol Bay on the Alaskan coast to the Sea of Okhotsk on the Russian coast,[12] up to but not including the northern coast of Japan.[12] In the Arctic Ocean, they are found along the northern coasts of Russia, Norway, Canada, and Alaska,[12] including the Norwegian Archipelago of Svalbard[13] and Canadian Arctic Archipelago.[14] 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.[15]
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.[12]
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 feelers[16] in the soft bottom sediments. Adults tend not to dive very deep, favoring shallow coastal areas no more than 300 m (980 ft) deep. Pups up to one year old, however, will venture much deeper, diving as deep as 450 m (1,480 ft). 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.[14] 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.[17]
Bearded seals give birth in the spring. In the Canadian Arctic, seal pupping occurs in May.[9] In Svalbard, bearded seals reach sexual maturity at 5 or 6 years of age.[18] Further south, in Alaska, most pups are born in late April. Pups are born on small drifting ice floes in shallow waters, usually weighing around 30–40 kg (66–88 lb). 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 3.3 kg (7.3 lb) per day. During this time, pups consume an average of 8 L (1.8 imp gal; 2.1 US gal) of milk a day. By the time they are weaned, the pups have grown to about 100 kg (220 lb).
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.[19]
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.[20]
Natural predators of the bearded seal include polar bears, who rely on these seals as a major food source.[21] 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.[22]
Bearded seals are believed to live up to 31 years.[23]
The vocalizations produced by the bearded seal are very 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.[24]
The 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.[24] 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.[25]
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.[26] Males use these sounds to establish mating territories and communicate their fitness,[25] but it is likely that females produce these sounds as well.[26]
Underwater, bearded seal trills can be heard from a distance of over 30 km, 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.[26]
On March 28, 2008, the U.S. National Marine Fisheries Service initiated a status review[27] 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.[2] 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.[28] Their main predators include polar bears, however, typically pups around age 2 are attacked within birthing lairs, leaving older juveniles and adults commonly unharmed.[29] 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.
There are two recognized subspecies of this seal:[1]
While the validity of these subspecies has been questioned, and is not yet supported by any molecular data,[4] analysis of the animals' calls does indicate a differentiation between different populations.[30]
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.[31]
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.[31]
Bearded seals belong to the subfamily Phocinae. This subfamily is thought to have evolved after the subfamily Monachinae. Alternative phylogenies show the bearded seal being most closely related to the ribbon seal or the hooded seal. However, molecular evidence suggests that hooded seals are their close relatives.[31]
{{cite journal}}: Cite journal requires |journal= (help) 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. 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.
Bearded seals are the largest northern phocid. They have been found to weigh as much as 300 kg (660 lb) 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.
