Odobenus rosmarus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Carnivora Odobenidae

Scientific Name: Odobenus rosmarus (Linnaeus, 1758)
Infra-specific Taxa Assessed:
Regional Assessments:
Common Name(s):
English Walrus
French Morse
Spanish Morsa
Phoca rosmarus Linnaeus, 1758
Taxonomic Notes: The Walrus, Odobenus rosmarus, was in the past divided into three subspecies: the Atlantic Walrus (O. r. rosmarus), the Pacific Walrus (O. r. divergens), and the Laptev Walrus (O. r. laptevi) (Rice 1998). However, the status of the Laptev Walrus has always been somewhat uncertain, animals from that region are described as being intermediate in size between the Pacific and Atlantic forms, with skull morphology most similar to the Pacific subspecies (Fay 1982). Recent analyses of mitochondrial DNA and morphometric data suggest that the taxon O. r. laptevi should be abandoned (Lindqvist et al. 2009). The walruses found in the Laptev Sea are in all probability the westernmost part of the Pacific Walrus population.

The IUCN Pinniped Specialist Group has assessed the status of the Atlantic and Pacific Walrus subspecies separately. This assessment combines those two analyses to assess the global status of the Walrus as a species.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A3c ver 3.1
Year Published: 2016
Date Assessed: 2016-02-05
Assessor(s): Lowry, L.
Reviewer(s): Kovacs, K.M.
Facilitator/Compiler(s): Ahonen, H., Pollock, C.M., Chiozza, F. and Battistoni, A.
While Walruses occur over a vast area and are common in some regions, their future is by no means secure. Climatic warming will surely require them to live in a much different environment as sea ice recedes and disappears from many of the areas they have used in past centuries (Kovacs et al. 2011, 2012, 2015; Laidre et al. 2008, 2015). All reasonable scenarios expect that such drastic changes to their habitats will cause Walrus populations to decline throughout most of their range. Because of the expectation of a decline the IUCN SSC Pinniped Specialist Group has recommended that the Atlantic Walrus be listed as Near Threatened under criterion C1, and they have recommended that the Pacific Walrus be listed as Data Deficient. Models suggest that Pacific Walrus abundance declined by 50% between 1980 and 2000 (Udevitz et al. 2009), and there is ongoing concern about female body condition and possible impacts on calf survival (Kovacs et al. 2015). Considering both the certainty of future decline in their habitat quality and the limitations of abundance and trend data, the Walrus as a species is listed as Vulnerable under criterion A3c.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Walruses have a discontinuous circumpolar Arctic and sub-Arctic distribution and are mostly found in relatively shallow continental shelf areas (Fay 1981, Rice 1998). The Atlantic Walrus occurs from the eastern Canadian Arctic to the western Kara Sea (Stewart et al. 2014). Within that region nine stocks are generally recognized. Historically, Atlantic walruses occurred south to the Gulf of Saint Lawrence in the northwestern North Atlantic, but they were extirpated in this region by excessive harvesting (McLeod et al. 2014). Vagrants have been reported from New England, Iceland, and from Norway south to the Bay of Biscay in France/Spain. The Pacific Walrus normally ranges from the Bering and Chukchi Seas, which constitute the center of its range, to the Laptev Sea in the west and the Beaufort Sea in the east, with vagrants south into the North Pacific Ocean to Japan and southcentral Alaska (Fay 1982).
Countries occurrence:
Canada; Greenland; Russian Federation; Svalbard and Jan Mayen; United States (Alaska)
FAO Marine Fishing Areas:
Arctic Sea; Atlantic – northwest; Atlantic – northeast; Pacific – northeast; Pacific – northwest
Additional data:
Estimated area of occupancy (AOO) - km2:4838872Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:25746932
Continuing decline in extent of occurrence (EOO):NoExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):5Lower depth limit (metres):250
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The Pinniped Specialists Group assessed the abundance and trend of the two Walrus subspecies as follows:
  • Atlantic Walrus--total abundance likely >25,000, some subpopulations increasing but overall trend unknown
  • Pacific Walrus--total abundance likely >200,000, trend unknown
Considering these results, the abundance of the Walrus species as a whole is likely >225,000 and the trend is unknown.
Current Population Trend:Unknown
Additional data:
Number of mature individuals:112500Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:The Walrus’s most distinctive feature is the external tusks, which are possessed by both males and females. The tusks can grow to be a meter long and can weigh 5 kg in large bulls. They are one of the largest pinnipeds with Pacific Walrus males reaching 3.6 m in length and weighing 880-1,557 kg; adult females are about 3 m and 580-1,039 kg. Atlantic Walrus adults are slightly shorter and lighter. Newborns are 1-1.4 m long and weigh 33-85 kg (Fay 1981, Kovacs and Lydersen 2006).

Walruses are extremely social animals, and when on land or ice they are normally found in tight groups ranging in size from a few individual up to thousands. At sea they usually travel in groups as well (Fay 1981, Kovacs and Lydersen 2006). There is significant sexual segregation outside the breeding season, with males often being found in areas away from females and their calves. Walruses have a narrow ecological niche. They depend on: 1) the availability of large areas of shallow water with suitable bottom substrate to support a productive bivalve community, 2) the presence of reliable open water over rich feeding areas, particularly in winter when access to feeding areas is limited by ice cover, and 3) the presence of haul out areas in reasonably close proximity to feeding areas. The preferred haul out platform is sea ice, although both subspecies routinely use terrestrial haul out sites in the summer and autumn (Fay 1981, Hamilton et al. 2015).

Because they feed in shallow, coastal areas Walruses usually perform only relatively shallow, short dives (Fay and Burns 1988, Born 2005). The Walrus’s main prey is bivalve mollusks that they search for using their sensitive whiskers on or in soft-bottom substrates. In addition to Clams, their diet can include Worms, Snails, soft shell Crabs, Amphipods, Shrimp, Sea Cucumbers, Tunicates, and even slow-moving Fishes (Born 2005, Sheffield and Grebmeier 2009). Some Walruses prey on birds and other marine mammals, eating a variety of Seal species (Lowry and Fay 1984, Fox et al. 2010, Seymour et al. 2014). Walrus make foraging trips that last from a few hours to several days; in the Pacific, trips are shorter in duration and distance when they originate from sea ice versus land (Udevitz et al. 2009).

Courtship and mating occur in the winter. Walruses are polygynous and the males establish small aquatic territories where they vigorously vocalize and display adjacent to females hauled-out on ice floes (Sjare and Stirling 1996, Sjare et al. 2003). Most births occur in May of the following year. Most female Walrus give birth at 7-10 years old and usually they only produce one calf every three years. 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 primary predators of Walrus are Polar Bears and Killer Whales (Killian and Stirling 1978, Fay 1981).
Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):15
Movement patterns:Not a Migrant
Congregatory:Congregatory (and dispersive)

Use and Trade [top]

Use and Trade: Native people of the Arctic have depended on Walrus for food, hides, ivory and bones since first contact, and subsistence harvests continue today in Canada, Greenland, Alaska, and Russia. All Walrus populations were severely depleted by episodic commercial hunting that was heaviest from the 18th through to the mid-20th centuries (Fay 1982). Since the 1970s, the Pacific Walrus has been managed under numerous international and national conservation programs that have eliminated commercial hunting and limited trade (Garlich-Miller et al. 2011). The Pacific Walrus continues to be an important subsistence resource for indigenous people in coastal Alaska (Robards et al. 2013), and harvests in recent years are likely to have been well within sustainable limits (Garlich-Miller et al. 2011, Udevitz et al. 2013). Atlantic Walruses are protected from harvest in Norway and in Russia (Boltunov et al. 2010, Henriksen and Hilmo 2015). Harvests are quota regulated in Canada and in Greenland, and additionally females are not supposed to be harvested in Greenland (Wiig et al. 2014).

Walrus are listed on Appendix III of the Convention on International Trade in Endangered Species of Wild Fauna and Flora which allows for control of global trade in Walrus ivory.

Threats [top]

Major Threat(s): Human harvests have had a major impact on abundance of Pacific Walrus over the past 200 years (Fay et al. 1997). The Pacific Walrus continues to be an important subsistence resource for indigenous people in coastal Alaska (Robards et al. 2013), and harvests in recent years are likely to have been sustainable (Garlich-Miller et al. 2011, Udevitz et al. 2013). The future, however, is uncertain, and as global warming and concomitant sea ice declines impact the Walrus population harvest levels could have an important influence on future abundance (Jay et al. 2011). A variety of mechanisms are available at the international, national, and local level that could be used to ensure that future harvests remain sustainable (Garlich-Miller et al. 2011, MacCracken 2012). Atlantic Walruses are protected from harvest in Norway (Henriksen and Hilmo 2015) and in Russia (Boltunov et al. 2010). Subsistence harvests are regulated by quotas in Canada and in Greenland and additionally, females are not supposed to be harvested in Greenland (Wiig et al. 2014). Recovery is the management target for all currently harvested Atlantic Walrus stocks so allowable takes are conservative.

Observations of incidental take of Pacific Walrus indicate that direct conflicts with fisheries are uncommon (US Fish and Wildlife Service 2010); however, trawl fisheries could disturb important benthic feeding areas (COSEWIC 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 hauled out Walruses, as they are highly susceptible to disturbance and easily panicked into stampedes that can result in high mortality, particularly among calves (Udevitz et al. 2013). Walruses feed low in the trophic web, so generally have relatively low levels of contaminants in their tissues, though individuals that consume marine mammal prey are likely at higher risks (Wolkers et al. 2006, Skoglund et al. 2010). Sedimentation from industrial development can cause degradation of their prey populations and oil pollution can negatively impact the filter-feeding Clams that make up most of their diet.

Global warming and associated reduction in the extent, seasonal persistence, and characteristics of sea ice are likely to negatively affect Walrus (e.g., Huntington 2009; Kovacs et al. 2011, 2012, 2015). The seasonal duration of ice cover is shrinking throughout their range, and at the extreme the Barents Sea region has lost 42 days of ice coverage per decade during 1979-2013 (Laidre et al. 2015). Declining sea ice reduces suitable strata for pupping and breeding aggregations and limits access to offshore feeding areas (Laidre et al. 2008, Kovacs et al. 2011). Global climate models suggest moderate changes in winter-spring ice conditions in the Bering Sea by the mid-2000s (20-30% ice loss) and major changes by the late-2000s (60-90% loss). Summer sea ice in the Chukchi Sea is predicted to show major losses (>80%) by the mid-2000s (Garlich-Miller et al. 2011). In prior years, Walrus in the Chukchi Sea spent the summer hauling out mostly on sea ice and foraging over a wide area on the shallow continental shelf (Fay 1982). In recent years with little or no summer ice cover, animals have begun to haul out on land in large groups and go to sea to forage from there (Robards and Garlich-Miller 2013). Coastal haul-outs are less suitable because of increased energy required to reach prey resources and mortality due to crowding, disturbance events, and predation (Jay et al. 2011, Garlich-Miller et al. 2011, MacCracken 2012). Reduction in sea ice has already lead to increased shipping and development of oil and gas fields in the southern parts of the Walrus’s range, bringing increased risk of spills and discharge of pollutants and disturbance (Semyonova et al. 2015), and oil and gas exploration is moving north rapidly with exploration licenses having already been granted in East Greenland.

Conservation Actions [top]

Conservation Actions: Atlantic Walruses are protected from harvest in Norway and in Russia; they are on the Norwegian Red List (Henriksen and Hilmo 2015) and they are listed in the Russian Red Book (Boltunov et al. 2010). Harvests are quota regulated in Canada and in Greenland (Wiig et al. 2014). The Committee on the Status of Endangered Wildlife in Canada designated the Atlantic Walrus as a species of “special concern”, which acknowledges that they are at risk of becoming threatened in this region; this classification is attributed to climate change impacts on sea ice (COSEWIC 2006).

Within the USA, the Marine Mammal Protection Act (MMPA) generally prohibits taking of Walrus unless it is by an Alaska Native for subsistence or production of handicrafts. MMPA regulations are used to control impacts caused by commercial fishing, oil and gas development, and other human activities. The Pacific Walrus is currently under consideration for listing under the US Endangered Species Act which would provide additional protections. Within the US there are currently no legal mechanisms to regulate discharge of greenhouse gas emissions, the primary cause of climate warming and sea ice loss (Garlich-Miller et al. 2011).

In Russia, Walruses were commercially harvested through the 1980s, but harvests ended in 1991 due to economic collapse of the industry. The “Law of Fisheries and Preservation of Aquatic Resources” provides for subsistence harvest of Pacific Walruses by aboriginal Russian peoples, and a quota is determined annually. Russian legislation prohibits sport hunting of Pacific Walruses, and a variety of types of protection are afforded to major haulout sites along the Russian coast (Garlich-Miller et al. 2011).

Citation: Lowry, L. 2016. Odobenus rosmarus. The IUCN Red List of Threatened Species 2016: e.T15106A45228501. . Downloaded on 18 September 2018.
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