Walrus
Odobenus rosmarus

The walrus (Odobenus rosmarus) resembles no other marine mammal. Four characters suffice for identification at distance: tusks, vibrissae, skin and body mass.

Tusks: Growth, Roles and Sexual Dimorphism

The tusks are elongated upper canines present in both sexes. In adult males they reach 60 to 100 cm and can exceed 1 metre in extreme cases; they grow throughout life. In females they are shorter and finer. These tusks are used primarily to haul out onto ice, establish social hierarchy among males and defend against polar bears (Ursus maritimus) or killer whales (Orcinus orca). They play no role in benthic foraging.

Mystacial Vibrissae: A Precision Sensory Organ

The walrus snout carries between 400 and 700 mystacial vibrissae, thick and rigid, forming a characteristic whisker pad. These are not simple hairs: each vibrissa is richly innervated and connected to mechanoreceptors capable of detecting minute pressure changes on the seabed. In the darkness or turbidity of Arctic waters, these vibrissae guide foraging with documented precision on bivalves buried several centimetres in sediment (Kastelein & van Gaalen, 1988).

Skin, Blubber and Thermoregulation by Vasodilation

Walrus skin is thick and wrinkled, covering a layer of subcutaneous blubber up to 15 cm thick. At rest in sunlight the skin changes from grey-brown to bright pink-red: this signals peripheral vasodilation, an active heat-dissipation mechanism. In the field this coloration is a useful behavioural cue: a pink-skinned group is resting thermally and potentially more vulnerable to disturbance.

Size, Mass and Differences Between Males and Females

Adult males measure 2.7 to 3.6 m and weigh 800 kg to 1.5 tonnes. Females are noticeably smaller: 2.3 to 3.1 m and 400 to 800 kg. This pronounced sexual dimorphism is visible from adolescence and increases until adulthood, around 15 years in males.

Current taxonomy recognises two main subspecies and a third whose status remains debated. Their ranges do not overlap, facilitating geographic identification.

Atlantic Walrus (Odobenus rosmarus rosmarus): Svalbard, Eastern Canada, Greenland

This is the subspecies most accessible to European observers. Svalbard populations were decimated by commercial hunting in the 17th–19th centuries, then began a slow recovery after total protection was granted in 1952 by Norway. Current numbers in Svalbard are estimated at a few thousand individuals, concentrated at well-documented coastal sites.

Pacific Walrus (Odobenus rosmarus divergens): Bering Sea, Chukchi Sea

This is the largest and most numerous subspecies. Populations move seasonally between the Bering Sea in winter and the Chukchi Sea in summer, following the ice edge. Local Alaskan operators report gatherings of tens of thousands of individuals on certain beaches on the west coast of Alaska, notably at Point Lay, when summer ice is absent.

Laptev Walrus (Odobenus rosmarus laptevi): Status Debated, Laptev Sea

Described on morphological criteria, this subspecies is sometimes regarded by taxonomists as a local population of the Pacific walrus rather than a distinct subspecies. Field data remain fragmentary due to difficult access to the Laptev Sea. Its conservation status is listed as Data Deficient by IUCN (2015).

The walrus is a specialised benthic predator. Its diet consists mainly of prey buried in sediments of Arctic continental shelves at moderate depths.

Benthic Diet: Bivalves, Gastropods, Polychaete Worms

Bivalves (mainly clams of the genera Mya and Serripes) form the dietary base. The walrus also consumes gastropods, polychaete worms and, occasionally, crustaceans or small fish. Cases of seal predation have been documented but remain anecdotal and limited to certain individuals.

Suction Technique and Role of Vibrissae in Detection

The common misconception that tusks are used to plough the seabed is false. The walrus locates prey with its mystacial vibrissae, which detect surface disturbances in the sediment. Once prey is located, it applies its fleshy lips and creates powerful suction by rapid tongue retraction, ejecting the mollusc from its shell. This technique works even in total darkness of winter waters.

Depth and Duration of Dives: Field Figures

Most foraging dives occur between 10 and 50 metres depth, where Arctic continental shelves offer the highest bivalve densities. Maximum recorded depth exceeds 80 metres. Typical breath-hold duration is 5 to 10 minutes; the documented record approaches 30 minutes (Fay, 1982). Between dives the walrus recovers at the surface for a comparable period.

Daily Consumption and Impact on Benthic Communities

An adult consumes 35 to 60 kg of prey per day during active feeding periods. At population scale this impact on bivalve communities is significant and contributes to mixing of surface sediments, with documented effects on seabed structure (Born et al., 2003).

The walrus is a highly social species. Its gatherings, hierarchies and acoustic repertoire are well documented yet little known to English-speaking audiences.

Group Structure: Sexual Segregation Outside Breeding Season

Outside the breeding season (winter–spring), walruses form groups segregated by sex. Females with young occupy different areas from adult males. This segregation reduces feeding competition and injury risk to calves. Young remain with their mother for 2 to 3 years.

Male Courtship Vocal Repertoire: Claps, Whistles, Bell-like Sounds

Males in rut produce a complex acoustic repertoire emitted from inflatable pharyngeal sacs that amplify sounds underwater. The repertoire includes claps, whistles and sounds likened to bell strikes, audible several kilometres away (Stirling et al., 1987). These vocalisations attract females at the surface and signal dominance to rival males. The complexity rivals that of some cetaceans, making it an active bioacoustics research topic.

Dynamics of Collective Haul-outs: Hierarchy and Density

Haul-outs (gatherings on land or ice) can comprise hundreds to several thousand individuals. Density is extreme: walruses huddle together to conserve heat and reduce predator exposure. A dominance hierarchy linked to tusk size regulates access to central, safest positions. Sea-ice retreat forces increasingly dense terrestrial haul-outs, with direct consequences for calf mortality by crushing.

Natural Predators: Polar Bear and Killer Whale

The polar bear (Ursus maritimus) and killer whale (Orcinus orca) are the main predators. Bears attack mainly on land or ice, targeting young or isolated individuals. Killer whales hunt at sea, sometimes in coordinated groups. Faced with these threats, the collective response of the haul-out is cohesion: an alerted individual triggers a chain reaction that can empty a site within seconds.

Three sites are referenced on the Whale Spotter map for the walrus. The observation season runs from May to September, peaking between June and August when coastal ice fragments and walruses concentrate on accessible beaches and floes.

Svalbard (Norway): May–September Season, Accessible Coastal Sites

Svalbard is the most accessible site for European observers wishing to see the Atlantic walrus. Operators from Longyearbyen offer zodiac or Arctic sailing trips to sites such as Poolepynten or Kapp Lee, where groups of males regularly gather from June to August. Local guide reports indicate stable groups of 20 to 150 individuals at these sites. Access is regulated by the Governor of Svalbard (Sysselmannen) and some areas are protected by nature reserves.

Eastern Canada and Greenland: Access Conditions and Local Operators

Atlantic walrus populations in eastern Canada (around Baffin Island and Hudson Strait) and Greenland are less accessible. Field observers report that trips require multi-day boat expeditions from bases such as Pond Inlet or Qaanaaq. Local Inuit operators offer guided access respectful of communities and wildlife. The optimal season is concentrated in July–August.

Bering Sea: Observation from Alaska and Russia

Pacific walrus populations (O. r. divergens) are observable from the west coast of Alaska, notably at Nome or Gambell, and from certain accessible Russian coastal zones on expedition. According to USFWS (US Fish and Wildlife Service) data and local operator reports, terrestrial gatherings in Alaska can reach tens of thousands of individuals in summer when the ice edge retreats beyond feeding areas. Logistics are complex and weather conditions require considerable flexibility.

Walrus observation demands strict discipline. Haul-outs are environments where an approach error can have lethal consequences for the animals.

Minimum Distances Recommended by the Governor of Svalbard (Sysselmannen)

Sysselmannen recommends maintaining a minimum distance of 30 metres from any resting walrus group, whether on ice or land. It is strictly forbidden to position oneself between a group and the water, as this blocks the animals’ natural escape route. These rules apply to both foot and zodiac approaches. Drones are subject to the same distance restrictions and are prohibited over haul-out zones in several Svalbard nature reserves.

Stampede Risks at Haul-outs: Documented Causes and Consequences

A stampede (collective panic flight to water) can be triggered by too rapid an approach, sudden noise or a low-altitude drone. In 2019 several incidents were documented in Svalbard, with calves crushed during collective rushes caused by unguided tourist boats. Young animals, unable to move as fast as adults, are the first victims. These incidents are recorded in Sysselmannen annual reports.

Principles of the High Quality Whale Watching Charter Applied to Pinnipeds

Although the High Quality Whale Watching (HQWW) charter was designed for cetaceans, its core principles apply directly to walruses: slow lateral approach, reduced engine, limited observation time, no encirclement, immediate withdrawal if animals show stress signs. Certified HQWW operators working in the Arctic incorporate these principles into their protocols.

Behaviour to Adopt in Zodiac or on Foot Facing a Resting Group

In a zodiac, cut the engine at 50 metres and allow the boat to drift. On foot, advance slowly, silently, without sudden movements, staying downwind. If an animal lifts its head toward you, stop immediately and wait. At the slightest sign of collective agitation (heads raised, alarm vocalisations), retreat without turning your back.

The walrus is a species whose conservation status is directly indexed to the state of Arctic sea ice. Recent trends are concerning.

IUCN Status: Vulnerable for Pacific Subspecies, Data Deficient for Laptev

The IUCN lists the Pacific walrus (O. r. divergens) as Vulnerable since 2015, with a re-assessment pending. The Atlantic walrus is also classified Vulnerable. The Laptev subspecies remains in the Data Deficient category (IUCN, 2015). These classifications reflect both uncertainty over exact numbers and the negative trajectory of habitats.

Retreat of Summer Sea Ice: Loss of Resting and Foraging Platforms

Summer sea ice plays a dual role for the walrus: a resting platform above benthic feeding areas and a refuge from terrestrial predators. The NSIDC (National Snow and Ice Data Center) documents continuous retreat of minimum Arctic sea-ice extent since the 1980s, with repeated record lows since 2007. When ice retreats beyond the continental shelf, walruses can no longer rest near hunting grounds and must swim long distances, increasing energy expenditure and calf mortality.

Historical Hunting and Partial Population Recovery

Intensive commercial hunting in the 17th–19th centuries reduced Atlantic populations to a few hundred individuals in some regions. Legal protection, granted progressively from the 1950s, has allowed partial recovery. Subsistence hunting by Inuit and Yupik communities remains authorised and regulated; managers consider it compatible with conservation when quotas are respected.

Pollution, Arctic Maritime Traffic and Increasing Anthropogenic Disturbance

The gradual opening of Arctic shipping routes linked to ice melt exposes walruses to sharply increased vessel traffic. Underwater engine noise disrupts rutting male vocalisations and can disorient diving individuals. Hydrocarbon pollution, in the event of an accident in these remote waters, poses a major risk to already fragile populations. Disturbance from unregulated tourism adds to these cumulative pressures.