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IUCN 2008: T15106A4494577
Odobenus rosmarus, Walrus
Assessment by: Lowry, L., Kovacs, K. & Burkanov, V. (IUCN SSC Pinniped
Specialist Group)
View on www.iucnredlist.org
Citation: Lowry, L., Kovacs, K. & Burkanov, V. (IUCN SSC Pinniped Specialist Group). 2008. Odobenus
rosmarus. The IUCN Red List of Threatened Species 2008: e.T15106A4494577.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T15106A4494577.en
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THE IUCN RED LIST OF THREATENED SPECIES™
Taxonomy
Kingdom
Phylum
Class
Order
Family
Animalia
Chordata
Mammalia
Carnivora
Odobenidae
Taxon Name: Odobenus rosmarus (Linnaeus, 1758)
Synonym(s):
• Phoca rosmarus Linnaeus, 1758
Regional Assessments:
• Europe
Common Name(s):
• English:
• French:
• Spanish:
Walrus
Morse
Morsa
Taxonomic Notes:
There are three recognized subspecies: Atlantic Walrus Odobenus rosmarus rosmarus; Pacific Walrus O.
r. divergens (Illiger, 1811); and Laptev Walrus O. r. laptevi (Chapskii, 1940).
It has been well established that the Atlantic and Pacific Walrus' are separate subspecies, however, the
taxonomic status of the Laptev Walrus has been uncertain. It has been described as intermediate in size
between the Pacific and Atlantic forms, with skull morphology similar to the Pacific subspecies (Fay
1981). Recent analyses of mitochondrial DNA and morphometric data suggest that the taxon O. r. laptevi
should be abandoned and the Laptev Walrus should be recognized as the western most population of
the Pacific Walrus, O. r. divergens (Lindquist et al. ms).
Assessment Information
Red List Category & Criteria:
Data Deficient ver 3.1
Year Published:
2008
Date Assessed:
June 30, 2008
Justification:
Although the global population is undoubtedly still quite large, there is evidence of declining
populations in two of the subspecies. Climate change is expected to have negative consequences for
Walruses, and particularly severe consequences for the Pacific subspecies. Additionally, little recent
information is available regarding current population sizes and trends throughout much of the Walrus’s
range. At this time, this species must be classified as Data Deficient.
Previously Published Red List Assessments
1996 – Lower Risk/least concern (LR/lc)
© The IUCN Red List of Threatened Species: Odobenus rosmarus – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T15106A4494577.en
1
Geographic Range
Range Description:
Walruses have a discontinuous circumpolar Arctic and sub-Arctic distribution (Fay 1981, Rice 1998). The
Pacific subspecies is normally found from the Bering and Chukchi Seas to the Laptev Sea in the west and
the western Beaufort Sea in the east, with vagrants south into the North Pacific Ocean to Japan and to
southcentral Alaska (Fay 1982). The Atlantic subspecies occurs in numerous subpopulations from the
eastern Canadian Arctic and Greenland to the western Kara Sea, including the Barents, White and
Pechora Seas, and Svalbard and Franz Josef Land (Committee on the Status of Endangered Wildlife in
Canada 2006, North Atlantic Marine Mammal Commission, undated). Historically, Atlantic walruses
occurred south to the Gulf of St Lawrence in the northwestern North Atlantic. Vagrants have been
reported from New England, Iceland and in western Europe south to the Bay of Biscay. All subspecies of
Walruses are found in relatively shallow continental shelf areas and seldom occur in deeper waters.
Country Occurrence:
Native: Canada; Greenland; Norway; Russian Federation; Svalbard and Jan Mayen; United States
Vagrant: Belgium; Denmark; Finland; France; Germany; Iceland; Ireland; Japan; Netherlands; Spain;
Sweden; United Kingdom
FAO Marine Fishing Areas:
Native: Arctic Sea - , Atlantic - northeast, Atlantic - northwest, Pacific - northeast, Pacific - northwest
© The IUCN Red List of Threatened Species: Odobenus rosmarus – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T15106A4494577.en
2
Distribution Map
© The IUCN Red List of Threatened Species: Odobenus rosmarus – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T15106A4494577.en
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Population
The Pacific Walrus population recovered from a depleted state in 1950 to historical high levels in the
1980s (Fay et al. 1997). The Bering-Chukchi segment of the population was estimated at approximately
230,000 in 1985 (Gilbert 1989) and 201,000 in 1990 (Gilbert et al. 1992). However, characteristics of
Walrus behaviour and difficulties associated with conducting surveys resulted in estimates with low
precision (Gilbert 1999). The current population size in the Bering-Chukchi region is unknown (U.S. Fish
and Wildlife Service 2002). The number of Pacific Walrus in the Laptev Sea region was estimated at
4,000-5,000 animals according to a report cited in Fay (1982), but the current abundance in that region
is also unknown.
Changes in the abundance of Atlantic Walrus in various regions during the past 45 years are unclear
(Committee on the Status of Endangered Wildlife in Canada 2006, North Atlantic Marine Mammal
Commission undated). Modelling indicates that the Walrus populations in West Greenland and the
North Water have been in steady decline, while the population in East Greenland has been increasing
(Witting and Born 2005). Walrus numbers at Svalbard have increased slowly during 1993-2006 (Lydersen
et al. 2008). The current total abundance of Atlantic Walrus is very poorly known, but the most recent
information suggests a population size of perhaps 18,000-20,000 (Committee on the Status of
Endangered Wildlife in Canada 2006, North Atlantic Marine Mammal Commission undated). The current
global population trend is unknown.
Although female Walrus can ovulate at four years of age, the majority do not give birth until they are 7-8
years old and usually only produce one calf every three years. Gestation lasts 15 months, including a
delay of implantation time of 3-3.5 months. The period of calf dependency is long, regularly lasting two
years and sometimes longer. Males become sexually mature between 7-10 years old, but are not
physically and socially mature enough to successfully compete for breeding opportunities until they are
approximately 15 years old. Longevity is approximately 40 years (Fay 1981).
The Committee on the Status of Endangered Wildlife in Canada (2006) gives the generation time for
Atlantic Walrus, calculated as the average of ages of the youngest and oldest animal giving birth, as 21
years. However, because young animals are more common in the population and older females may
exhibit reproductive senility this does not correspond to the IUCN definition. The average age of female
Pacific walrus in the Alaska Native harvest is approximately 15 years (Garlich-Miller et al. 2006), which
provides a more reasonable estimate of the generation time.
Current Population Trend: Unknown
Habitat and Ecology (see Appendix for additional information)
Walruses are one of the largest pinnipeds. In the Pacific, males reach about 3.6 m in length and weigh
880-1,557 kg; adult females are about 3 m and 580-1,039 kg. In the Atlantic adults are slightly shorter
and lighter. Newborns are 1-1.4 m and weigh 33-85 kg (Fay 1981). Walrus are characterized by their
large tusks, which are well-developed in both males and females. Tusks are used for interspecific
aggression, defense against predators (Polar Bears and Killer Whales) and as an aid for hauling-out on
ice.
Courtship and mating occur in the winter. It is believed that Walruses are polygynous and that the males
© The IUCN Red List of Threatened Species: Odobenus rosmarus – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T15106A4494577.en
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establish small aquatic territories where they vigorously vocalize and display adjacent to females
hauled-out on ice floes (Fay 1981).
Walruses haul out on ice floes and beaches on islands or remote stretches of mainland coastlines. They
are very gregarious animals and are frequently found in tight groups that number from the tens to the
thousands. Pacific Walruses spend most of their lives associated with sea ice and migrate with the ice as
it expands and moves south in the winter and breaks up and retreats in the spring and summer. Males
often separate from the females in late spring and during the summer they use land haulouts some
distance from sea ice, while the females, their calves, and most of the juveniles follow the retreating sea
ice edge north (Fay 1982). The situation is somewhat different for Atlantic Walrus, with animals of all
sex/age categories using terrestrial haulouts during summer months (Born 2005). At sea, Walruses can
be found alone or in aggregations.
Walruses are primarily bottom feeders and shallow divers (Fay 1982, Born 2005). Most prey taken is
found in the upper few centimeters of sediment, or lives on or just above the bottom. A wide variety of
benthic invertebrates, with several species of clams, make up the majority of food for most animals.
Their diet also includes other species of molluscs, and many species of worms, snails, soft shell crabs,
amphipods, shrimp, sea cucumbers, tunicates, and slow-moving fish. Some individuals prey on seals,
small whales and seabirds and may occasionally scavenge marine mammal carcasses.
Systems: Terrestrial, Marine
Threats (see Appendix for additional information)
Native people of the Arctic have depended on Walruses for food, hides, ivory and bones since first
contact, and subsistence harvests of both subspecies continue today in most parts of their ranges. All
Walrus populations were severely depleted by episodic commercial hunting that was heaviest from the
18th through to the mid-20th centuries.
Direct conflicts with fisheries are uncommon (U.S. Fish and Wildlife Service 2002); however, trawl
fisheries could disturb important benthic feeding areas (Committee on the Status of Endangered Wildlife
in Canada 2006). Human disturbance at land-based haul-out sites, low-level aircraft over-flights and
near-shore passage of vessels can have serious effects on Walruses out of the water, as they are highly
susceptible to disturbance and easily panicked into stampedes (Fay and Kelly 1980).
Global warming and any associated reduction in the extent, timing, and characteristics of seasonal sea
ice cover could negatively affect Walruses, especially the Pacific population. Declining sea ice reduces
suitable strata for pupping and breeding aggregation and limits access to offshore feeding areas (Tynan
and DeMaster 1997, Moore 2005, Laidre et al. in press). In the Atlantic where the use of coastal
haulouts is more widespread, reduced sea ice cover could increase feeding opportunities for Walruses
(Born 2005).
Reduction in sea ice could also lead to the addition of commercial sea lanes in currently rarely visited
portions of the Walruses’ range, with increased risk of spills and discharge of pollutants, disturbance
and coastal development (Reijnders et al. 1993, Tynan and Demaster 1997, Moore 2005). A history of
poor international cooperation, crude population monitoring methods and delayed management
responses has led to speculation that future management actions in response to population declines of
© The IUCN Red List of Threatened Species: Odobenus rosmarus – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T15106A4494577.en
5
Pacific Walruses may not be taken soon enough to be effective (Fay et al. 1989).
Conservation Actions (see Appendix for additional information)
The population of Canada is listed on CITES Appendix III. Since 1972 coastal Alaska Natives have hunted
Walruses in the United States for subsistence purposes under an exemption provided in the Marine
Mammal Protection Act. No quotas or limits have been established, but all animals taken are required to
be harvested in a non-wasteful manner. Alaska Natives work with the responsible management agency
(U.S. Fish and Wildlife Service) to co-manage Walrus hunting. Regulations on harvest are in place in
Canada, the Russian Federation, and Greenland. Norway prohibits all hunting at Svalbard (North Atlantic
Marine Mammal Commission undated).
Credits
Assessor(s):
Lowry, L., Kovacs, K. & Burkanov, V. (IUCN SSC Pinniped Specialist Group)
Reviewer(s):
Kovacs, K. & Lowry, L. (Pinniped Red List Authority)
© The IUCN Red List of Threatened Species: Odobenus rosmarus – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T15106A4494577.en
6
Bibliography
Born, E. W. 2005. An assessment of the effects of hunting and climate on walruses in Greenland.
University of Oslo.
Committee on the Status of Endangered Wildlife in Canada. 2006. COSEWIC assessment and update
status report on the Atlantic walrus Odobenus rosmarus rosmarus in Canada. Ottawa, Canada Available
at: http://www.sararegistry.gc.ca/virtual_sara/files/cosewic/sr_atlantic_walrus_e.pdf.
Fay, F.H. 1981. Walrus Odobenus rosmarus (Linneaus, 1758). In: S.H. Ridgway and R. Harrison (eds),
Handbook of Marine Mammals, Vol. 1: The walrus, sea lions, fur seals, and sea otter, pp. 1-23. Academic
Press.
Fay, F.H. 1982. Ecology and biology of the Pacific walrus, Odobenus rosmarus divergens Illiger. North
American Fauna 74:1-279.
Fay, F.H. and Kelly, B.P. 1980. Mass natural mortality of walruses (Odobenus rosmarus) at St. Lawrence
Island, Bering Sea, autumn 1978. Arctic 33:226-245.
Fay, F.H., Eberhardt, L.L., Kelly, B.P., Burns, J.J. and Quakenbush, L.T. 1997. Status of the Pacific walrus
population, 1950-1989. Marine Mammal Science 13(4): 537-565.
Fay, F.H., Kelly, B.P. and Sease, J.L. 1989. Managing the exploitation of Pacific walruses: a tragedy of
delayed response and poor communication. Marine Mammal Science 5: 1-16.
Garlich-Miller, J.L., Quakenbush, L.T. and Bromaghin, J.F. 2006. Trends in age structure and productivity
of Pacific walruses harvested in the Bering Strait region of Alaska, 1952-2002. Marine Mammal Science
22(4): 880-896.
Gilbert, J., Fedoseev, G., Seagars, D., Razlivalov, E. and Lachugin, A. 1992. Aerial census of Pacific walrus,
1990. U.S. Fish and Wildlife Service Administrative Report R7/MMM 92-1.
Gilbert, J. R. 1989. Aerial census of Pacific walruses in the Chukchi Sea, 1985. Marine Mammal Science 5:
27-28.
Gilbert, J.R. 1999. Review of previous Pacific walrus surveys to develop improved survey designs. In:
G.W. Garner, S.C. Amstrup, J.L. Laake, B.F.J. Manly, L.L. McDonald and D.G. Robertson (eds), Marine
Mammal Survey and Assessment Methods, pp. 75-84. A.A. Balkema, Rotterdam, The Netherlands.
IUCN. 2008. 2008 IUCN Red List of Threatened Species. Available at: http://www.iucnredlist.org.
(Accessed: 5 October 2008).
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.
Lindqvist, C., Bachmann, L., Andersen, L. W., Born, E. W., Arnason, U., Kovacs, K. M., Lydersen, C.,
Abramov, A. V. and Wiig, Ø. Unpublished. The Laptev Sea walrus Odobenus rosmarus laptevi: an enigma
revisited.
Lydersen, C., Aars, J. and Kovacs. K. M. 2008. Estimating the number of walruses in Svalbard based on
aerial surveys and behavioural data from satellite telemetry. Arctic 61(2): 119-128.
Moore, S. E. 2005. Long-term environmental change and marine mammals. In: J. E. Reynolds III, W. F.
Perrin, R. R. Reeves, S. Montgomery and T. J. Ragen (eds), Marine Mammal Research Conservation
Beyond Crisis, pp. 137-148. Johns Hopkins University Press., Baltimore, USA.
© The IUCN Red List of Threatened Species: Odobenus rosmarus – published in 2008.
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7
North Atlantic Marine Mammal Commission. Undated. Status of marine mammals in the North Atlantic:
the Atlantic walrus. Available at: http://www.nammco.no/webcronize/images/Nammco/654.pdf.
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.
Stirling, I. and Derocher, A. E. 1993. Possible impacts of climatic warming on polar bears. Arctic 46: 240245.
Tynan, C. T. and DeMaster, D. P. 1997. Observations and predictions of Arctic climate change potential
effects of marine mammals. Arctic 50: 308-322.
U.S. Fish and Wildlife Service. 2002. Pacfic walrus (Odobenus rosmarus divergens): Alaska stock.
Available at: http://alaska.fws.gov/fisheries/mmm/walrus/pdf/Final_%20Pacific_Walrus_SAR.pdf.
Witting, L. and Born, E. 2005. An assessment of Greenland walrus populations. ICES Journal of Marine
Science 62: 266–285.
Citation
Lowry, L., Kovacs, K. & Burkanov, V. (IUCN SSC Pinniped Specialist Group). 2008. Odobenus rosmarus. The
IUCN Red List of Threatened Species 2008: e.T15106A4494577.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T15106A4494577.en
Disclaimer
To make use of this information, please check the Terms of Use.
External Resources
For Images and External Links to Additional Information, please see the Red List website.
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8
Appendix
Habitats
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Habitat
Season
Suitability
Major
Importance?
9. Marine Neritic -> 9.1. Marine Neritic - Pelagic
-
Suitable
Yes
10. Marine Oceanic -> 10.1. Marine Oceanic - Epipelagic (0-200m)
-
Marginal
-
12. Marine Intertidal -> 12.1. Marine Intertidal - Rocky Shoreline
-
Suitable
Yes
12. Marine Intertidal -> 12.2. Marine Intertidal - Sandy Shoreline and/or
Beaches, Sand Bars, Spits, Etc
-
Suitable
Yes
Use and Trade
(http://www.iucnredlist.org/technical-documents/classification-schemes)
End Use
Local
National
International
Food - human
Yes
No
No
Wearing apparel, accessories
Yes
No
No
Handicrafts, jewellery, etc.
Yes
No
No
Threats
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Threat
Timing
Scope
Severity
Impact Score
5. Biological resource use -> 5.4. Fishing & harvesting
aquatic resources -> 5.4.1. Intentional use:
(subsistence/small scale)
Ongoing
-
-
-
Stresses:
2. Species Stresses -> 2.1. Species mortality
Past,
unlikely to
return
-
Stresses:
2. Species Stresses -> 2.1. Species mortality
Ongoing
-
Stresses:
2. Species Stresses -> 2.2. Species disturbance
Ongoing
-
Stresses:
1. Ecosystem stresses -> 1.1. Ecosystem conversion
1. Ecosystem stresses -> 1.2. Ecosystem degradation
2. Species Stresses -> 2.2. Species disturbance
2. Species Stresses -> 2.3. Indirect species effects ->
2.3.8. Other
5. Biological resource use -> 5.4. Fishing & harvesting
aquatic resources -> 5.4.2. Intentional use: (large
scale)
6. Human intrusions & disturbance -> 6.3. Work &
other activities
11. Climate change & severe weather -> 11.1. Habitat
shifting & alteration
© The IUCN Red List of Threatened Species: Odobenus rosmarus – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T15106A4494577.en
-
-
-
-
-
-
9
Conservation Actions in Place
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Conservation Actions in Place
In-Place Land/Water Protection and Management
Conservation sites identified: Yes, over entire range
In-Place Education
Included in international legislation: Yes
Subject to any international management/trade controls: Yes
Conservation Actions Needed
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Conservation Actions Needed
2. Land/water management -> 2.1. Site/area management
3. Species management -> 3.1. Species management -> 3.1.1. Harvest management
Research Needed
(http://www.iucnredlist.org/technical-documents/classification-schemes)
Research Needed
1. Research -> 1.2. Population size, distribution & trends
1. Research -> 1.5. Threats
3. Monitoring -> 3.1. Population trends
Additional Data Fields
Population
Population severely fragmented: No
© The IUCN Red List of Threatened Species: Odobenus rosmarus – published in 2008.
http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T15106A4494577.en
10
The IUCN Red List Partnership
The IUCN Red List of Threatened Species™ is produced and managed by the IUCN Global Species
Programme, the IUCN Species Survival Commission (SSC) and The IUCN Red List Partnership. The IUCN
Red List Partners are: BirdLife International; Botanic Gardens Conservation International; Conservation
International; Microsoft; NatureServe; Royal Botanic Gardens, Kew; Sapienza University of Rome; Texas
A&M University; Wildscreen; and Zoological Society of London.
THE IUCN RED LIST OF THREATENED SPECIES™