|Scientific Name:||Erignathus barbatus|
|Species Authority:||(Erxleben, 1777)|
|Taxonomic Notes:||Rice (1998) lists two intergrading subspecies as recognizable: Erignathus barbatus barbatus and E. b. nauticus. However, Burns (1981) questioned the validity of the division.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Kovacs, K. & Lowry, L. (IUCN SSC Pinniped Specialist Group)|
|Reviewer(s):||Kovacs, K., Lowry, L. (Pinniped Red List Authority) & Stuart, S.N. (Global Mammal Assessment Team)|
Due to its large population, broad distribution, variable feeding habits and no evidence of a decline, the Bearded Seal should be classified as Least Concern. However, this species is likely going to be negatively impacted by climate change, and should be monitored over the coming decades.
IUCN Evaluation of the Bearded Seals, Erignathus barbatus
Prepared by Seal Specialist Group
A. Population reduction Declines measured over the longer of 10 years or 3 generations
A1 CR > 90%; EN > 70%; VU > 50%
Al. Population reduction observed, estimated, inferred, or suspected in the past where the causes of the reduction are clearly reversible AND understood AND have ceased, based on and specifying any of the following:
(a) direct observation
(b) an index of abundance appropriate to the taxon
(c) a decline in area of occupancy (AOO), extent of occurrence (EOO) and/or habitat quality
(d) actual or potential levels of exploitation
(e) effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites.
Similar to most northern phocid seals sexual maturity is reached in bearded seals between 3-5 years of age and maximum longevity is approximately 35 year of age. Thus, the average age of reproducing individuals should be at least 10 years. A population reduction of Bearded Seals has not been observed, estimated, inferred, or suspected in the past 30 years. However, population abundance is poorly known and has not been monitored.
A2, A3 & A4 CR > 80%; EN > 50%; VU > 30%
A2. Population reduction observed, estimated, inferred, or suspected in the past where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under Al.
A population reduction of Bearded Seals has not been observed, estimated, inferred, or suspected in the past 30 years.
A3. Population reduction projected or suspected to be met in the future (up to a maximum of 100 years) based on (b) to (e) under A1.
A population reduction of Bearded Seals is suspected in the future because of predicted reduction in sea ice habitats due to continued climate warming. The likely amount of population reduction has not been projected and is extremely difficult to predict. Because of the bearded seals broad distribution and current abundance (and perhaps also sufficient behavioral flexibility to use a variety of substrates) declines are unlikely to exceed 30% within the next 30 years. However, there is considerable uncertainty regarding this prediction and monitoring is strongly encouraged.
A4. An observed, estimated, inferred, projected or suspected population reduction (up to a maximum of 100 years) where the time period must include both the past and the future, and where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under A1.
A population reduction of Bearded Seals has not been observed, estimated, inferred, or suspected in the past 30 years.
B. Geographic range in the form of either B1 (extent of occurrence) AND/OR B2 (area of occupancy)
B1. Extent of occurrence (EOO): CR < 100 km²; EN < 5,000 km²; VU < 20,000 km²
The EOO of Bearded Seals is > 20,000 km².
B2. Area of occupancy (AOO): CR < 10 km²; EN < 500 km²; VU < 2,000 km²
The AOO of Bearded Seals is > 2,000 km².
AND at least 2 of the following:
(a) Severely fragmented, OR number of locations: CR = 1; EN < 5; VU < 10
(b) Continuing decline in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) area, extent and/or quality of habitat; (iv) number of locations or subpopulations; (v) number of mature individuals.
(c) Extreme fluctuations in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) number of locations or subpopulations; (iv) number of mature individuals.
C. Small population size and decline
Number of mature individuals: CR < 250; EN < 2,500; VU < 10,000
The current abundance of Bearded Seals is poorly known, but the number of mature individuals is certainly > 10,000.
AND either C1 or C2:
C1. An estimated continuing decline of at least: CR = 25% in 3 years or 1generation; EN = 20% in 5 years or 2 generations; VU = 10% in 10 years or 3 generations (up to a max. of 100 years in future)
C2. A continuing decline AND (a) and/or (b):
(a i) Number of mature individuals in each subpopulation: CR < 50; EN < 250; VU < 1,000
(a ii) % individuals in one subpopulation: CR = 90–100%; EN = 95–100%; VU = 100%
(b) Extreme fluctuations in the number of mature individuals.
D. Very small or restricted population
Number of mature individuals: CR < 50; EN < 250; VU < 1,000 AND/OR restricted area of occupancy typically: AOO < 20 km² or number of locations < 5
The current abundance of Bearded Seals is poorly known, but the number of mature individuals is certainly > 1,000. AOO is > 20 km² and the number of locations is > 5.
E. Quantitative Analysis
Indicating the probability of extinction in the wild to be: Indicating the probability of extinction in the wild to be: CR > 50% in 10 years or 3 generations (100 years max.); EN > 20% in 20 years or 5 generations (100 years max.); VU > 10% in 100 years
There has been no quantitative analysis of the probability of extinction for Bearded Seals.
Listing recommendation — Past, poorly documented, estimates of bearded seal abundance suggest a total population size of more than 500,000. Current abundance and population trend are unknown. Based on reports from coastal hunters, and limited catch reporting in the Canadian Arctic Bearded Seals are still thought to be numerous and no major changes in abundance have been reported. Bearded Seals should thus be listed as Least Concern. However, climate warming and reduction in sea ice coverage are occurring and because Bearded Seals depend on sea ice for reproduction they are likely to decline in the decades to come. Because of the potential risk to Bearded Seals associated with global warming and loss of sea this species should be reassessed within a decade.
|Range Description:||Bearded Seals have a patchy circumpolar distribution throughout much of the Arctic and sub-Arctic, south of 85ºN (Kelly 1988). A disjunct population inhabits the Sea of Okhotsk, ranging south to Hokkaido, Japan (Rice 1998). Bearded Seals reach the southern Bering Sea and Bristol Bay to the limit of seasonally ice covered waters regularly (Kelly 1988). They also occupy all of Hudson Bay, are found throughout much of the eastern Canadian Archipelago, both coasts of Greenland and south to southern Labrador. They can also be found along the north shore of Iceland, within the Svalbard Archipelago and across much of the north within the Russian Federation (Kovacs 2002). Bearded Seal vagrants have been reported from many locations outside the Arctic including Portugal in the eastern North Atlantic (van Bree 2000), the Gulf of Saint Lawrence, northern Newfoundland, and Cape Cod, Massachusetts in the western North Atlantic (Gosselin 1994).
The ranges of the two putative subspecies are divided near the central Canadian Arctic in the West and the Laptev Sea in the East, with the Atlantic subspecies barbatus occurring from the central Canadian Arctic east to the central Eurasian Arctic and the Pacific subspecies nauticus occurring from the Laptev Sea east to the central Canadian Arctic, including animals in the Sea of Okhotsk (Rice 1998). Geographical variation does exist in the calls of Bearded Seals across their range, suggesting some population substructure (Risch et al. 2007).
Native:Canada; Greenland; Iceland; Japan; Norway; Russian Federation; Svalbard and Jan Mayen; United States
Vagrant:China; Faroe Islands; France; Germany; Netherlands; Portugal; Spain; United Kingdom
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – northwest; Atlantic – western central; Pacific – eastern central; Pacific – northeast; Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The size of the global population of Bearded Seals is not known (Kovacs 2002). Crude published estimates for parts of the bearded seal’s range include: 200,000-250,000 in the Sea of Okhotsk, including 60,000-75,000 off eastern Sakhalin Island (1968 to1990) and 250,000-300,000 in the Bering Sea, including 83,000-87,000 in the western Bering Sea (Fedoseev 2000). A minimum estimate for Canadian waters of 190,000 animals was suggested by Cleator (1996), based on data collected over a 35-year period. Angliss and Outlaw (2005) state that there are no current reliable population estimates for the Bering Chukchi stock of Bearded Seals. No estimates exist for the population in the Atlantic Ocean (Reijnders et al. 1993), or the region from the Barents to the Chukchi Sea. Population trends are not known.|
|Habitat and Ecology:||
Bearded Seals are the largest northern phocid seal. Adults reach lengths of 2-2.5 m and weights of 250-300 kg (Andersen et al. 1999) with females typically being slightly larger than males (Kovacs 2002). In the Bering Sea, males have been recorded to reach 390 kg and females 361 kg (Kelly 1988). Weight fluctuates dramatically during the year and bearded seals are typically at their lowest weight from mid-summer to autumn, after which they regain lost weight lost during breeding and moulting (Andersen et al. 1999).
In Alaskan waters, sexual maturity is reached at 3-6 years in females, with 80% of females having had a pup by age 6. Males reach sexual maturity at 6-7 years (Kelly 1988). Final body size is reached at approximately 9-10 years (McLaren 1958), and they can live 20-25 years (Kovacs 2002).
Bearded Seal pups are born on small floes of annual ice and they swim within hours of birth (Kovacs et al. 1996). Peak birthing occurs between late March and mid-May, varying somewhat across the bearded seal’s range (Kovacs 2002). Pups in the Bering Sea average 132 cm and 34 kg in weight at birth and are weaned in an estimated 12-18 days when they weigh around 85 kg (Kelly 1988). Gjertz et al. (2000) estimated that in Svalbard pups are weaned in approximately 24 days. Prior to weaning their aquatic skills have developed to the degree that they spend about half their time in the water, diving for up to 5.5 minutes to depths of up to 84 m (Lydersen et al. 1994).
Adult females spend over 90% of their time in the water while caring for a dependent pup; about half this time is spent away from the neonate, presumably in foraging dives. Most female dives are relatively short and shallow. On average, there are 3 nursing bouts per day accomplished during the brief times the mother is out of the water. The amount of time mothers spend in the water is thought to be an adaptive response to polar bear predation, making the pair less conspicuous to hunting bears (Krafft et al. 2000).
Mating takes place at the end of lactation similar to other phocid seals. Males court females and display using elaborate downward trilling vocalizations that can travel many kilometers (Cleator et al. 1989). Individual males use distinct songs, and occupy the same territories over a series of consecutive years within constraints imposed by variable ice conditions, or they show a roaming pattern (VanParijs et al. 2001, 2003, 2004). In captivity singing males are attended by other satellite males similar to the male groups that have been observed for Harbour Seals in the wild (Davies et al. 2006).
Bearded Seals feed primarily on or near the bottom and most diving is to depths of less than 100 m (though dives of adults have been recorded up to 300 m and young-of-the-year have been recorded diving down to almost 500 m; Gjertz et al. 2000). They use their elaborate whiskers to search for prey on and in soft bottom substrates (Marshall et al. 2007, 2008). Because of their benthic feeding habits they live primarily in waters overlying the continental shelf, in shallow regions such as the Bering and Barents Seas (Burns 1981, Kovacs 2002). The availability of sea ice is a major habitat determinant for bearded seals. They are typically found in regions of broken free-floating pack ice; in these areas bearded seals prefer to use small and medium sized floes, avoiding large floes (Simpkins et al. 2003). They rarely haul out more than a body length from water and they use leads within shore-fast ice only if suitable pack ice is not available (Kovacs 2002). Bearded Seals naturally occur at quite low densities (e.g., Bengtson et al. 2005); they are typically solitary animals, but will form small, loose aggregations when ice availability is limited, such as at the time of moulting in midsummer.
The diet of Bearded Seals varies by age, location, season, and possibly also changes in prey availability in marine communities (Kelly 1988). Their primary foods live on or near the bottom, but also include some infauna as well as schooling and demersal fish (Burns 1981, Hjelset et al. 1999). In the Kara and Barents seas, the diet is dominated by crustaceans (shrimps) and molluscs (gastropods and bivalves). Cod, other demersal fish, and worms are also regular components of the diet. A wide variety of prey has been reported from the Sea of Okhotsk with crabs and shrimps accounting for 87% of the total intake for animals in the north, and clams, worms, and gastropods making up 40%, 23%, and 12% respectively of the intake for animals in the south near Sakhalin Island. In the Bering and Chukchi Seas, snow crab was the most important prey, followed by the crab Hyas coarctatus, while the reverse was true farther north. Shrimp species, gastropods, and octopus are important in both the northern and southern Bering Sea and the Chukchi Sea. The diet is similar in the Beaufort Sea with the addition of Arctic cod (Boreogadus saida) (Burns 1981). Antonelis et al. (1994) found that 86% of Bearded Seals examined in the central Bering Sea in early spring, had fish in their stomachs. In order of importance these were capelin (Mallotus villosus), codfishes (Gadidae), and eelpouts (Lycodes spp.). Lowry et al. (1980) reported similar findings on percentage of the occurrence of fish in stomachs, but reported that fish as a percent of total volume was 16% from May through September, and dropped to 5% for October through April. In the eastern Canadian Arctic, Bearded Seals in the summer consumed a minimum of 12 fish species, dominated by sculpins (Cottidae) and Arctic cod with fish prey accounting for greater than 90% of the wet weight of the stomach contents (Finley and Evans 1983). At Svalbard, Bearded Seals eat a wide variety of prey (>50% of collected stomachs had 5 or more prey species). Polar cod (Boreogadis saida), sculpins (Cottidae spp.), spider crab (Hyas araneus), and the crustaceans Sabinea sptemcarinatus and Sclerocrangon boreas were the most frequent prey items (Hjelset et al. 1999).
In June, following the pupping and breeding season, Bearded Seals undergo their annual moult. During the moult they spend much of their time hauled out and are reluctant to enter the water (Kovacs et al. 2004). Animals can be found moulting from April to August with a peak in May to June (Burns 1981). Bearded Seals usually haul out on ice when it is available, but will haul out on land in the summer in the Sea of Okhotsk, along the Laptev, White, and Kara Sea coastlines and at Svalbard (Burns 1981, Kovacs et al. 2004).
Indigenous peoples of the Arctic have hunted Bearded Seals for subsistence for thousands of years, a practice that continues today. However, levels of subsistence harvest are not well known. Subsistence harvests of Bearded Seals in the United States were estimated to be approximately 6,800 in 2000 (Angliss and Outlaw 2005). Subsistence harvest levels are not closely monitored in Canada, but Cleator (1996) estimated that roughly 2,400 bearded seals were taken per year. Approximately 500-1,000 Bearded Seals are taken annually in Greenland (Reijnders et al. 1993). Rates of struck-and-lost are high for bearded seals in most months of the year, likely about 50% for gun-based harvests; these are not generally accounted for in hunting statistics.
The former Soviet Union historically had commercial harvests of Bearded Seals in the Sea of Okhotsk and the Bering, Chukchi, Barents and White Seas, with high harvest levels at times. Harvests grew from 9,000 to 13,000 from 1957 to 1964, and were 8,000 to 10,000 per year for the Bering and Okhotsk Seas combined from 1964-1967 (Reeves et al. 1992). This level of commercial harvesting was very likely unsustainable and in all probability depleted these populations (Kelly 1988). Bearded Seals are now harvested more on a subsistence basis for local use in Russia. Harvests in the Bering Sea of 1881 and 1418 were reported for 1988 and 1989 respectively (Reeves et al. 1992).
Fisheries interactions are low. Logbooks maintained by U.S. fishermen indicate 14 Bearded Seals killed and 31 injured in 1991 in the Bristol Bay, Alaska salmon drift net fishery. There were several incidents of incidental take, serious injury, or mortality in the Alaskan Bering Sea/Aleutian Islands flatfish and pollock trawl fisheries from 1999-2003, when annual mortality was estimated at 1.6 seals (Angliss and Outlaw 2005). Kelly (1988) mentions fisheries for snow/Tanner crabs (Chionoecetes opilio) and pink shrimps (Pandalus borealis), as possible sources of fisheries conflicts in the future, especially if these fisheries are renewed or expanded because both of these species are important foods for Bearded Seals.
Oil spills from offshore extraction and transportation could negatively affect bearded seals through direct contact with oil and damage to foraging areas and stocks of prey, particularly benthic invertebrates, which are vulnerable to oil contamination (Kelly 1988).
Global climate warming is currently causing major reductions in the extent and duration of sea ice cover in the Arctic, creating a threat to many species of marine ice-associated mammals. Pinnipeds, such as the Bearded Seall that are dependant on sea ice for pupping, moulting, resting and access to foraging areas, may be especially vulnerable to such changes (Tynan and DeMaster 1997, Learmonth et al. 2006, Kovacs and Lydersen 2008, Laidre et al. 2008). Stirling and Derocher (1993) suggest that climatic warming could result in more favourable conditions for Bearded, Harp, Harbour Seals and Walruses if it causes sea ice to become less consolidated in winter, and extends the summer open water period.
An increase in human-created noise in the arctic environment could cause marine mammals, including Bearded Seals which are very vocal during their breeding season (VanParijs et al. 2001, 2003), to abandon areas of habitat (Tynan and DeMaster 1997). A reduction in sea ice cover would likely lead to increased human activity in the Arctic in the form of shipping and extractive industries, and an associated greater threat of marine accidents and disturbance of marine mammals (Pagnan 2000).
Harp Seals, Hooded Seals, and Ringed Seals from the Canadian Arctic, where they overlap range with Bearded Seals, were all determined to carry antibodies to phocine distemper virus (PDV), with harp seals constituting the population with the largest percentage (83%) of positive tests. Although the disease has not been identified in Bearded Seals, the opportunity for exposure exists (Duignan et al. 1997).
Important natural predators of Bearded Seals include Polar Bears (Burns 1981), as well as Killer Whales, Walruses, and Greenland Sharks (Kovacs 2002).
Bearded Seals are protected by various laws in their range countries. Subsistence hunting by indigenous people of the Arctic is generally for personal use and not regulated unless populations are depleted (e.g., Cleator 1996, Angliss and Outlaw 2005).
Vessel-based commercial hunting in the former Soviet Union ended in 1975; after that time the harvest has taken place at much lower levels (similar to a subsistence harvest). Prior to the end of commercial harvesting, the Soviet Union used a system of quotas to regulate the take of Bearded Seals in an attempt to manage the population (Kelly 1988). Licensed (sport) hunters can shoot bearded seals in Svalbard, outside protected areas and not during the breeding season (Kovacs et al. 2004).
Andersen, M., Hjelset, A. M., Gjertz, I., Lydersen, C. and Gulliksen, B. 1999. Growth, age at sexual maturity and condition in bearded seals (Erignathus barbatus) from Svalbard, Norway. Polar Biology 21: 179-185.
Angliss, R. P. and Outlaw, R. B. 2005. Alaska marine mammal stock assessments. NOAA Technical Memorandum NMFS-AFSC.
Antonelis, G.A., Melin, S.R. and Bukhtiyarov, J.A. 1994. Early spring feeding habits of bearded seals (Erignathus barbatus) in the central Bering Sea, 1981. Arctic 47: 74-79.
Bengtson, J.L., Hiruki-Raring, L.M., Simpkins, M.A. and Boveng, P.L. 2005. Ringed and bearded seal densities in the eastern Chukchi Sea, 1999-2000. Polar Biology 28: 833-845.
Burns, J.J. 1981. Bearded seal Erignathus barbatus Erxleben, 1777. In: S.H. Ridgway and R. Harrison (eds), Handbook of marine mammals, Vol. 2: Seals, pp. 145-170. Academic Press, New York.
Cleator, H. J. 1996. The status of the bearded seal, Erignathus barbatus, in Canada. Canadian Field Naturalist 110: 501-510.
Cleator, H.J., Stirling, I. and Smith, T.G. 1989. Underwater vocalizations of the bearded seal (Erignathus barbatus). Canadian Journal of Zoology 67: 1900-1910.
Davies, C. E., Kovacs, K. M., Lydersen, C. and van Parijs, S. M. 2006. Development of display behavior in young captive bearded seals. Marine Mammal Science 22(4): 952-965.
Duignan, P. J., Nielsen, O., House, C., Kovacs, K. M., Duffy, N., Early, G., Sadove, S., St. Aubin, D. J., Rima, B. K. and Geraci, J. R. 1997. Epizootiology of morbillivirus infection in harp, hooded, and ringed seals from the Canadian Arctic and western Atlantic. Journal of Wildlife Diseases 33: 7-19.
Fedoseev, G. A. 2000. Population biology of ice-associated forms of seals and their role in the northern Pacific ecosystems. Center for Russian Environmental Policy, Moscow, Russia.
Finley, K. J. and Evans, C. R. 1983. Summer diet of the bearded seal (Erignathus barbatus) in the Canadian High Arctic. Arctic 36: 82-89.
Gjertz, I., Kovacs, K. M., Lydersen, C. and Wiig, Ø. 2000. Movements and diving of bearded seal (Erignathus barbatus) mothers and pups during lactation and post-weaning. Polar Biology 23: 559-566.
Gosselin, J. and Boily, F. 1994. Unusual southern occurrence of a juvenile bearded seal, Erignathus barbatus, in the St. Lawrence estuary, Canada. Marine Mammal Science 10: 480-483.
Hjelset, A. M., Andersen, M., Gjertz, I., Lydersen, C. and Gulliksen, B. 1999. Feeding habits of bearded seals (Erignathus barbatus) from Svalbard, Norway. Polar Biology 21: 186-193.
Kelly, B.P. 1988. Bearded seal, Erignatus barbatus. In: J.W. Lentfer (ed.), Selected marine mammals of Alaska: Species accounts with research and managment recommedations, pp. 77-94. U.S. Marine Mammal Commission, Washington, DC, USA.
Kovacs, K. M. 2002. Bearded seal Erignathus barbatus. In: W. F. Perrin, B. Wursig and J. G. M. Thewissen (eds), Encyclopedia of Marine Mammals, pp. 84-87. Academic Press, San Diego, California, USA.
Kovacs, K. M. and Lydersen, C. 2008. Climate change impacts on seals and whales in the North Atlantic Arctic and adjacent shelf seas. Science Progress 91(2): 117-150.
Kovacs, K. M., Gjertz, I. and Lydersen, C. 2004. Marine Mammals of Svalbard. Norwegian Polar Institution, Tromsø, Norway.
Kovacs, K. M., Lydersen, C. and Gjertz, I. 1996. Birth-site characteristics and prenatal molting in bearded seals (Erignathus barbatus). Journal of Mammalogy 77(4): 1085-1091.
Krafft, B. A., Lydersen, C., Kovacs, K. M., Gjertz, I. and Haug, T. 2000. Diving behavior of lactating bearded seals (Erignathus barbatus) in the Svalbard area. Canadian Journal of Zoology 78: 1408-1418.
Laidre, K.L., Stirling, I., Lowry, L.F., Wiig, Ø., Heide-Jørgensen, M.P. and Ferguson, S.H. 2008. Quantifying the sensitivity of Arctic marine mammals to climate-induced habitat change. Ecological Applications 18: S97-S125.
Learmonth, J. A., Macleod, C. D., Santos, M. B., Pierce, G. J., Crick, H. Q. P. and Robinson, R. A. 2006. Potential effects of climate change on marine mammals. Oceanography and Marine Biology: An Annual Review 44: 431-464.
Lowry, L.F., Frost, K.J. and Burns, J.J. 1980. Feeding of bearded seals in the Bering and Chukchi seas and trophic interaction with Pacific walruses. Arctic 33: 330-342.
Lydersen, C. and Kovacs, K. M. 1999. Behaviour and energetics of ice-breeding, North Atlantic phocid seals during the lactation period. Marine Ecology Progress Series 187: 265-281.
Lydersen, C., Hammill, M.O. and Kovacs, K.M. 1994. Diving activity in nursing bearded seal (Erignathus barbatus) pups. Canadian Journal of Zoology 72: 96-103.
Marshall, C. D., Amin, H., Kovacs, K. M. and Lydersen, C. 2006. Microstructure and innervation of the mystacial vibrissal follicle-sinus complex in bearded seals, Erignathus barbatus (Pinnipedia: Phocidae). Anatomical Record 288(A): 13-25.
Marshall, C. D., Kovacs, K. M. and Lydersen, C. 2008. Feeding kinematics, suction, and hydraulic jetting capabilities in bearded seals (Erignathus barbatus). The Journal of Experimental Biology 211: 699-708.
McLaren, I. 1958. Some aspects of growth and reproduction of the bearded seal, Erignathus barbatus (Erxleben). Journal of the Fisheries Research Board of Canada 5: 219-227.
Pagnan, J. L. 2000. Arctic marine protection. Arctic 53: 469-476.
Reeves, R.R., Stewart, B.S. and Leatherwood, S. 1992. The Sierra Club handbook of seals and sirenians. Sierra Club Books, San Diego, CA, USA.
Reijnders, P., Brasseur, S., van der Toorn, J., van der Wolf, P., Boyd, I., Harwood, J., Lavigne, D. and Lowry, L. 1993. Seals, fur seals, sea lions, and walrus. Status survey and conservation action plan. IUCN Seal Specialist Group.
Rice, D.W. 1998. Marine Mammals of the World. Systematics and Distribution. Society for Marine Mammalogy, Lawrence, Kansas.
Risch, D., Clarke, C.W., Cockeron, P.J., Elepfandt, A., Kovacs, K.M., Lydersen, C., Stirling, I. and Van Parijs, S.M. 2007. Vocalizations of male bearded seals, Erignathus barbatus: classification and geographical variation. Animal Behavior 73: 747-762.
Simpkins, M.A., Hiruki-Raring, L.M., Sheffield, G., Grebmeier, J.M. and Bengtson, J.L. 2003. Habitat selection by ice-associated pinnipeds near St. Lawrence Island, Alaska in March 2001. Polar Biology 26: 577-586.
Stirling, I. and Derocher, A. E. 1993. Possible impacts of climatic warming on polar bears. Arctic 46: 240-245.
Tynan, C. T. and DeMaster, D. P. 1997. Observations and predictions of Arctic climate change potential effects of marine mammals. Arctic 50: 308-322.
van Bree, P. J. H. 2000. A review of recent extralimital records of the bearded seal (Erignathus barbatus) on the west European continental coast. Marine Mammal Science 16: 261-263.
Van Parijs, S. M., Kovacs, K. M. and Lydersen, C. 2001. Spatial and temporal distribution of vocalizing male bearded seals – implications for male mating strategies. Behavior 138: 905-922.
Van Parijs, S. M., Lydersen, C. and Kovacs, K. M. 2003. Vocalizations and movements suggest alternative mating tactics in male bearded seals. Animal Behavior 65: 273-283.
Van Parijs, S. M., Lydersen, C. and Kovacs, K. M. 2004. The effects of ice cover on the behavioural patterns of aquatic mating male bearded seals. Animal Behavior 68: 89-96.
|Citation:||Kovacs, K. & Lowry, L. (IUCN SSC Pinniped Specialist Group) 2008. Erignathus barbatus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 30 January 2015.|
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