Updated: May 2019
The walrus is one of the largest members of the Pinnipeds (the group that contains all types of seals and walrus), and is the largest member of this group to live in the Arctic. Two distinct subspecies are recognised: Atlantic and Pacific walrus. The Atlantic walrus is the slightly smaller of the two, with males reaching weights around 1200 to 1500 kg and lengths of close to 3 m. Females are smaller than males. Walrus are a cinnamon-brown colour overall, and are characterised by their mustache and long tusks. This is a social animal that can be found in groups from several individuals to several hundred animals. In NAMMCO countries it is found in Greenland and Arctic Norway.
There are several stocks of Atlantic walruses. The largest are found in Arctic Canada and West Greenland, where walruses number around 20,000 animals.
Atlantic walruses are found in Arctic waters, in areas that are seasonally ice-covered. They are found in the northern waters of Canada, Greenland, Norway and Russia.
Walrus are hunted by native peoples for food, leather and tusks in Canada and Greenland. Populations were reduced in the past by commercial hunting in all areas.
Management in Greenland is conducted by the Government of Greenland with scientific and management advice from NAMMCO. Canada and Russia also participate in NAMMCO Scientific Working Groups on walrus. Management in other areas is done by national authorities.
In the most recent assessment (2016) the species is listed as ‘Vulnerable’ bordering ‘Near Threatened’ for the Atlantic stock on the global IUCN Red List. It is listed as ‘Vulnerable’ on the Norwegian red list.
Scientific name: Odobenus rosmarus rosmarus
English: Atlantic walrus
The origin of the name “walrus” is uncertain, but it may be derived from the Old Norse word hrossval, meaning “horse-whale”.
Up to 40 years
One calf every 2-3 years from 5-12 years of age
Mainly bivalve mollusks (clams) and other benthic (sea bottom) invertebrates. Some walrus, particularly large males, hunt and kill seals, birds and even narwhals and belugas
Male Atlantic walrus reach weights of 1200 to 1500 kg and lengths of close to 3 m. Females are smaller than males, weighing up to around 600 – 700 kg and reaching lengths of 2.5 m (Born et al. 1995)
The walrus belongs to the Odobenid family (Odobenidae), which includes one species with two subspecies, the Atlantic walrus (O. rosmarus rosmarus), the Pacific walrus (O. rosmarus divergens) and maybe a third one in the Laptev Sea (O. rosmarus laptevi).
The Atlantic walrus is the slightly smaller of the two, with males reaching weights around of 1200 to 1500 kg and lengths of close to 3 m. Females are smaller than males, weighing up to around 600–700 kg and reaching lengths of 2.5 m (Born et al. 1995). A male Pacific walrus can weigh up to 1700 kg and be nearly 4 m long.
Throughout their range, walrus inhabit cold Arctic and subarctic waters. They live amongst pack ice, in leads and polynyas (open water areas within the ice) in winter and occupy coastal areas with access to shallow water during the spring, summer and fall.
Walrus are a cinnamon-brown colour overall. After a long period in cold water, they may appear almost white, as blood vessels to the skin constrict to conserve body heat. A walrus’ skin is very tough, and may be from 2 to 4 cm thick. Both male and female walrus have long ivory tusks, which are modified upper canine teeth. Male walrus tusks tend to be longer and thicker than those of females. Another distinguishing feature of walrus is the presence of many stout vibrissae or whiskers on the snout. The vibrissae are attached to muscles, are supplied with blood and nerves, and are used mainly to feel for food in bottom sediments.
Walruses are social animals and can be found in groups from several individuals to several hundred animals, depending on the time of year and the particular population being observed. When hauled out on land, walruses prefer to maintain body contact with one another, and tend to form a group which is roughly circular (Salter 1979). New additions to the group will walk around the periphery trying to find their spot or attempt to displace other animals (Salter 1979). Tusk displays and jabbing are particularly often seen in walruses hauled out on land, although walruses with comparatively short tusks struck much less frequently than did walruses with longer tusks (Salter 1979).
Walruses are also very vocal animals capable of producing a wide variety of sounds. Males especially produce long and repetitive vocalizations of various types, with bouts of “singing” that can last up to 65 hours (Sjare et al. 2003). One type of sound produced is short, sharp pulses, termed taps and knocks. The rate at which they are given can vary from 1 to 15 per second (Stirling et al. 1983). Taps and knocks are given in at least four different patterns: double knock, tapping or knocking sequence, coda, and diving vocalization (Stirling et al. 1983).
The double knock is a distinctive call given by some males before surfacing to breathe during a stereotyped vocalization cycle. In the long tapping or knocking sequences, pulses are usually given at a rate of about 1 to 3 per second. The sequences start slowly in some cases but quickly in others. The last few taps or knocks are often given in a rapid burst, termed the “coda”, sometimes followed by a bell call. During stereotyped vocalizing cycles, the male always gives a distinct call, which was termed the diving vocalization, immediately after taking his last breath and descending from the surface (Stirling et al. 1983).
Vocalizations are an important part of the breeding behaviour of walruses. Breeding takes place in the winter, from January to mid April, in polynyas (open water areas within the ice) or areas of unconsolidated pack ice. The mating system of walruses is best described as “female defense polygyny” (Sjare and Stirling 1996). A large mature male walrus, probably at least 15 years old, will “attend” or monopolize access to herds containing potentially reproductive females for extended periods of time, chasing away other males that approach. Any females that come into estrus during that time will mate with the attending male.
Vocalizations appear to mediate at least some interactions between males during the breeding season. When attending a herd of females, a single male may continuously repeat a complex, stereotyped song (Sjare and Stirling 1996). It is thought that these vocalizations convey his social status. Other sexually mature males in the area behave as silent herd members, vocal satellite males, or sometimes both. In some cases, males become silent and move out of the area when a singing attending male approaches them (Sjare and Stirling 1996). Sometimes these interactions escalate into fighting: if a young adult male approaches a female closely or vocalizes, the attending male will attack and chase him away (Sjare and Stirling 1996).
Walruses are long-lived animals with a low reproductive rate. A walrus can live to be 40 years old. Females reach sexual maturity between 4 and 10 years of age, males at 6-10 years, although males likely cannot compete successfully for females until they are older, about 15 years of age. Mating takes place in the water, and occurs in areas of drifting pack ice or polynyas (areas of open water surrounded by stable landfast ice) during the winter, usually from January to April (Sjare and Stirling 1996). The implantation of the embryo is delayed for 3 or 4 months, after which the gestation period is 12 months (Richard 2001). The pregnancy therefore lasts 15 or 16 months, meaning that females can only give birth a maximum of once every two years, though it is more commonly 3 years between calves. The result is that the walrus pregnancy rate is much lower than that of other pinnipeds (seals).
Walrus calves are born on land or on the pack ice between late April and early June. The calf is nursed solely on milk for the first 6 months or so, before beginning to eat solid foods. Nursing mostly takes place in the water, but also sometimes on land or ice. The nursing period typically lasts for 2 years, with weaning occurring gradually over a period of time.
Walruses are primarily bottom feeders, foraging in sediments on the ocean floor for bivalve molluscs (clams) and other invertebrates (Outridge et al. 2003). The soft parts of clams, the feet and siphons, have been found to make up 95% of both numbers and weight of walrus food intake. The main species taken in Greenland are the bivalves Mya truncata, Serripes groenlandicus, Hiatella arctica and Macoma baltica (Dietz et al. 2013). A study of the fatty acid composition of walrus inner blubber from Svalbard found that its composition closely resembled the fatty acid composition of the lipids in the bivalves Mya truncata and Buccinum spp. (Lydersen and Kovacs 2013). Other invertebrates are eaten to varying extents, and fish may be rarely taken (Born et al. 1995).
Walruses need to eat a lot of clams to meet their energy needs. One study in northeast Greenland was able to quantify the amounts of food eaten by walruses using a combination of divers observing the walruses and satellite-telemetry data on movement and diving activity (Born et al. 2003). On 10 occasions, divers were able to observe walrus feeding, and collect empty bivalve shells from the sea floor. An average of 53.2 bivalves were consumed per dive, corresponding to 149.0 g shell-free dry, or 2,576 kJ per dive (Born et al. 2003).
In the same study, one walrus was fitted with a satellite tag to record its foraging and diving activity. During a 74 hour period of foraging at sea, the walrus spent 57% of its time diving to depths of between 6 and 32 m, and made a total of 412 dives, each lasting between 5 and 7 minutes. It was estimated that this walrus ingested 57 kg (95% CI: 41–72 kg) wet weight bivalve biomass per day, or close to 5% of his total body mass (Born et al. 2003).
Also mammals and birds
Although they are primarily benthic (bottom) feeders, some walruses also eat seals and other large animals. Such predation seems to be largely carried out by older males. Ringed seal, bearded seal, as well as beluga and narwhal remains have all been found in adult walrus stomachs (Richard 2001). Walruses have also been documented hunting various species of birds. In Svalbard, walruses were observed hunting flightless pinkfooted geese (Anser brachyrhynchus) as well as bearded and ringed seals (Lydersen and Kovacs 2013).
Apart from humans, the main predators of walrus are killer whales (Orcinus orca) and polar bears (Ursus maritimus). Mainly calves and younger walrus are susceptible to such predation.
Walruses are found in all Arctic waters, in areas that are seasonally ice-covered, in the Atlantic (Atlantic walrus, O. rosmarus rosmarus), in the Pacific (Pacific walrus, O. rosmarus divergens) and off the North coast of Asia, particularly in the Laptev Sea (Laptev walrus, O. rosmarus laptevi), three subspecies being geographically isolated.
Atlantic walruses are found in the northern waters of Canada, Greenland, Norway and Russia.
Habitat use by walruses varies according to the season. For most of the year walruses are widely dispersed over vast areas where they usually occur in clumped groups (Heide-Jørgensen et al. 2013). In spring and summer, walrus are generally found in coastal areas throughout their distribution area, where water depths are relatively shallow and they can access their favoured benthic foods. Summer habitat use is also driven by available haulout areas (Freitas 2009). Proximity to human settlements is also a factor in habitat choice, as walruses that are disturbed or displaced from an area tend not to return.
Walruses prefer hauling out on sea ice when they can, rather than on land (Lydersen et al. 2008). In the summer when ice is not available, groups of walruses haul out onto land at traditional sites, called uglit in Inuktitut. These are often located close to their feeding grounds, although walruses have been observed travelling up to 100 km from these sites to feed (Witting and Born 2005). Some sites may be used year after year, while others are more transient. There is considerable variation in site use by walruses both within and between years (Stewart et al. 2013c).
Walruses seem to be fairly consistent across their geographic range in spending about 25% of their time hauled out, at least during late summer (Lydersen et al. 2008). Diurnal variation in haul-out patterns has also been observed, with a tendency for walruses to haul out during the afternoon and evening (Stewart et al. 2013a).
Off western Greenland, areas of preferred habitat are offshore banks (<200 m deep) with suitable food items. One such area is west of Disko Island (69.75° to 70.75° N) while another is Store Hellefiske Banke (66.50° to 68.25° N) in the Sisimiut-Aasiaat area (Andersen et al. 2013). Store Hellefisk Banke has water depths ranging from 20 to 200 m and is frequented by walruses during spring (Dietz et al. 2013). These two shallow areas are separated by the entrance to Disko Bay where water depths exceed 200 m and where walruses are generally not found (Heide-Jørgensen et al. 2013).
Walruses spend from fall to spring in these two areas, but are absent from them in summer. Once the sea ice has melted, walruses will migrate the roughly 450 km across Davis Strait towards SE Baffin Island (Andersen et al. 2013, Heide-Jørgensen et al. 2103).
Variation by sex
As well as varying by season, habitat use varies by sex. Males have larger home ranges than females, and tend to occur farther offshore, farther from the ice edge and at greater depths than females. Frietas et al. (2009) documented quite regular annual movement patterns for 17 male walruses around Svalbard. During summer, walruses were most often found in coastal areas with a median distance to the coast of 4.6 km. In the winter, most of the tagged males performed long distance movements, up to 840 km from the tagging locations, and returned sometime between late February and late June.
The choice of summer haulout sites also appears to differ between males and females. Adult females with calves occur more frequently at sheltered inshore haul-out sites whereas the off-shore exposed rocks facing deeper waters have a higher proportion of adult males (Dietz et al. 2013).
Similar results were seen in a more recent tagging study of adult male walruses from Svalbard. During the winter, they moved into areas of >90% ice concentration, traveling as far as 600 km from ice-free water (Lydersen and Kovacs 2013). It is thought that these males moved into their breeding areas in the winter, based on the timing of the occupancy and diving behaviour in that area. When the breeding season was over, walruses with satellite tags that were still transmitting locations returned to the Svalbard coast, showing high site fidelity to the previous year’s summering area (Lydersen and Kovacs 2013).
Winter habitat use, especially for males, seems to be driven by breeding needs and appears to be independent of water depth and distance to shore (Frietas 2009). Males seem to feed little during the breeding season and their habitat selection is probably mainly affected by the presence of females. (Lydersen and Kovacs 2013, Frietas 2009).
Differences between male and female habitat use is also seen in other areas. Along Southeastern Baffin Island in the fall, dispersal of walruses along the coast was more condensed and there was greater segregation seen between males and females. Females remained farther north and farther east, and males were more often located offshore in areas with greater water depths. Males had also had larger home ranges than females during both seasons (Dietz et al. 2013). Females and calves seem to prefer to remain in association with drifting ice as much as is possible, but they are also found in coastal areas in summer throughout the range of the species (Freitas et al. 2009). Another consideration for females which will influence their habitat choices is their need to feed throughout the year, including times when they are pregnant or nurturing young.
Sea ice is important habitat for walruses. In several studies, the preferred percentage ice for walruses in West Greenland was found to be 50-60% cover, with some variation according to sex, season and year (Dietz et al. 2013, Born et al. 1994). In the Svalbard-Franz Josef Land region some walruses winter in very dense pack ice (Lydersen and Kovacs 2013, Freitas et al. 2009). Walruses are unable to break through ice that is thicker than about 20 cm (Fay 1982) but in both West Greenland and SE Baffin Island shallow polynya and pack-ice areas with dynamic leads exist where walruses can overwinter.
North Atlantic Stocks
Currently there are 3 stocks of walrus recognised in Greenland (2 of which are shared with Canada), 6 stocks in Canada (2 of which are shared with Greenland), and 2 in the eastern North Atlantic. The location of the 9 recognised stocks can be seen on the maps above.
Historically, walrus occupied Canadian waters on the east coast from Nova Scotia to perhaps 85°N and from the boundary with Greenland to roughly 100°W, but their range now is smaller and their distribution more discontinuous. The Canadian Department of Fisheries and Oceans (DFO) and the North Atlantic Marine Mammal Commission (NAMMCO) currently recognize two “genetic populations” and seven walrus stocks in Canada: the High Arctic population which includes the Baffin Bay (BB), West Jones Sound (WJS), and Penny Strait-Lancaster Sound (PS-LS) stocks, and the central Arctic population which includes the north and central Foxe Basin (N-FB, C-FB) and Hudson Bay-Davis Strait (HB-DS) stocks (see map) (DFO 2013, Stewart et al. 2013c, NAMMCO 2013, Shafer et al. 2013, Stewart 2008). The relationship between these stocks and the seventh stock, the South & East Hudson Bay (S&E-HB) stock is not clear at the present time (DFO 2013).
The high Arctic stocks are differentiated from each other in a number of ways. The Baffin Bay stock can be separated from West Greenland walruses through genetics. The West Jones Sound (WJS) stock, is differentiated from the Baffin Bay by seasonal distribution and tag movements, and the Penny Strait-Lancaster Sound (PS-LS) stock, is separated from West Jones Sound by distribution and tag movements and from Baffin Bay by limited lead isotope data (Stewart 2008).
The two stocks in Foxe Basin are distinguished from each other and from HB-DS on the basis of lead isotope and trace element profiles (Outridge and Stewart 1999, Outridge et al. 2003). Local Inuit also distinguish between two types of walrus in Foxe Basin on the basis of size, colour and distribution (DFO 2002). However, there is a lack of genetic differentiation between Foxe Basin and HB-DS stocks. There may be some male-mediated genetic exchange between FB and the HB-DS and SE-HB Bay stocks, which could indicate a single interbreeding population (Shafer et al. 2013).
In the summer, walruses from each of these stocks are found along the coasts in the area they are named for. In the winter, their distribution is more limited. Wintering areas for the high Arctic stocks are in the Cardigan Strait–Fram Sound area at the west end of Jones Sound, around Dundas Island, the floe edges of Jones and Lancaster sounds, and in the North Water polynya between approximately 69° and 77° N on the Greenland coast (Stewart 2008).
Further south, walrus from the HB-DS stock winter in Cumberland Sound and other areas around south Baffin Island (Stewart et al. 2013b), while some south Baffin walrus winter off west Greenland (Dietz et al. 2013). Walrus in Foxe Basin generally winter at the floe edge around Rowley Island (Stewart 2008).
As in Canada, walruses were previously much more abundant in Greenland than they are today, and were part of one large population (Witting and Born 2005). Currently, three stocks of Atlantic walrus occur in Greenland: the northwest, or Baffin Bay stock, the West Greenland-Southeast Baffin Island “component” of the Hudson Bay-Davis Strait stock, and the East Greenland stock. (Wiig et al. 2014). The three stocks have been differentiated on the basis of genetics, distribution and migration patterns (Witting and Born 2013). Two of these stocks, the northwest/Baffin Bay and the West Greenland, are shared with Canada.
The northwest/Baffin Bay stock are found in the coastal waters of Northwest Greenland and the northern reaches of the Canadian Arctic Archipelago. This stock is a subunit of the former North Water population (Andersen et al. 2013).
These walruses, however, are absent from coastal areas of Northwest Greenland during the open water season in August- September, as they spend the summer along the eastern and southern coast of Ellesmere Island (Canada) and in the Canadian High Arctic archipelago (Stewart et al. 2013a). It is not known whether these walruses travel into Jones or Lancaster Sounds. Sometime in the fall they reappear in the Qaanaaq area of Greenland.
A survey in the North Water in May of 2009 and 2010 found most of the walruses distributed roughly in a belt from Greenland across to Ellesmere Island in the southern part of the North Water at a latitude of about 76° 30’N over both shallow and deep (>500m) water. Only three sightings were made north of 77° N (Heide-Jorgensen et al. 2012).
West Greenland-Southeast Baffin Island
The West Greenland stock of walrus occurs off the central coast of West Greenland at the edge of the Baffin Bay pack ice from about 66° N to 70° N from fall to spring (Witting and Born 2005). Based on satellite tracking data, it is now clear that walruses in West Greenland are part of the larger Hudson Bay – Davis Strait population that summers primarily around Baffin Island (Dietz et al. 2013).
Along the eastern coast of Greenland, walruses occur year-round, and are mainly distributed inside the National Park of North and Northeast Greenland, north of the entrance to Scoresby Sound (about 71° N) (Witting and Born 2013). There is very limited exchange between the East Greenland walruses and neighbouring populations, such as the West Greenland, North Water, and the Svalbard-Franz Land populations (Witting and Born 2005).
Norway / Svalbard
Information on distribution and studies of movement and genetics have shown that there is a common stock of Atlantic walruses found in the Svalbard and the Franz Josef Land archipelagos in which most of the males summer in Svalbard and most females and calves remain in north-eastern parts of Svalbard and the Franz Josef Land area (Wiig et al. 2014, Lydersen and Kovacs 2013, Freitas et al. 2009).
While there has been a single documented exchange of walrus from East Greenland to Svalbard (Born and Gjertz 1993), this is likely rare. Walruses from East Greenland and Svalbard-Franz Josef Land differ genetically and are distinct stocks (Wiig et al.2014).
The relation between the Svalbard-Franz Josef Land stock and walruses found further east around Novaya Zemlya, and in the Laptev, south-eastern Barents, Pechora and White Seas is uncertain.
As mentioned above, Atlantic walruses in Franz Josef Land (Russia) and Svalbard (Norway) belong to a single population (Freitas et al. 2009). Walruses are also found south and east of Franz Josef Land, around Novaya Semlya and into the southern Barents, Pechora and Kara Seas (Wiig et al. 2014, Glazov et al. 2013). In a recent survey of the Pechora Sea, male walruses were found hauled out at three sites: one on Vaygach Island and two sites on Matveyev Island (Lydersen et al. 2012). Since no females or calves were seen during the survey, the population must be using a larger area than that surveyed.
Walruses found further east in the Laptev Sea are more closely related to the Pacific walrus than the Atlantic (Lindqvist et al. 2008).
Aerial surveys are most commonly used to estimate the abundance of walruses. However, walruses are definitely one of the most difficult species to survey, because of their clumped distribution throughout remote areas, and their simultaneous occurrence on sea ice, land and in the water at some times of the year. In addition, large annual variations in sea ice distribution and extent affects their distribution and makes survey planning challenging.
When they are hauled out on land or ice floes, walruses tend to lie piled on top of one another, making it hard to see all individuals, or even to count them in a photograph (Stewart et al. 2013c). If walruses are disturbed for some reason at their haulout shortly before the survey, a large number of animals can be dispersed and not counted. Since walruses also spend time in the water, correction factors must be applied to any count to correct for the proportion of the population unavailable to be counted during the survey. These factors are difficult to obtain simultaneously with the survey. Because of these difficulties, walrus abundance estimates therefore tend to be imprecise and probably underestimate the true stock size (negative bias) in most cases (Heide-Jørgensen et al. 2013).
Recent abundance estimates
|Stock||Year||Estimate||95% Confidence Interval||Source|
|East Greenland||2009||1,429||705 – 2,896||Born et al., 2009|
|Baffin Bay||2015||2,544||1,513 – 4,279||Heide-Jørgensen et al., 2015|
|West Jones Sound||2008||503||473 – 534||Stewart et al., 2013d|
|Penny Strait – Lancaster Sound||2009||727||623 – 831||Stewart et al., 2013d|
|Hudson Bay – Davis Strait||2006/07||2,502||1,660 – 3,345||Stewart et al., 2013b|
|Foxe Basin – North and South||2010||6,480||1,615 – 11,346||Stewart et al., 2013c|
|2011||10,379||N/A||Stewart et al., 2013c|
|Svalbard – Franz Josef Land|
|Svalbard||2012||3,886||3,553 – 4,262||Lydersen et al., 2014|
|Pechora Sea (Russia)||2011||3,943||3,605 – 4,325||Lydersen et al., 2012|
Historical population size
The total population of Atlantic walrus prior to the European discovery of North America must have been at least in the hundreds of thousands, and was found over a much larger range than is the case today. The population number is, of course, a very rough guess, and is based on recorded observations by early explorers and traders as well as known records from commercial walrus hunting. Walrus in all areas have been exploited for centuries, first by Inuit and later by European whalers and sealers. Hunting of walrus continues today to be an important part of Inuit culture in both Arctic Canada and Greenland. Walrus remains found at archaeological sites have been used to determine distribution of Atlantic walruses in Canada and Greenland in the past. In the later Paleo-eskimo period (2,500-1,000 BP) walrus remains are relatively common and occur in definite “diet-related” context (Wiig et al. 2014). Remains tend to be more common from the periods from around 2,500-2,300 BP and around 1,500-1,000 BP, than from the period in between. Paleo-eskimos appear to have abandoned the High Arctic between 2,300-1,500 BP, perhaps due to a cooling climate, which also may have affected the distribution of walruses.
Hunting by humans is considered to be the main cause of depletion of walruses during historic times (Born et al. 1995). The Norse hunted walruses in the Barents Sea and Greenland areas from sometime in the late 9th until the 15th century. Commercial hunting of walruses began in the late 1800s, roughly around the time of the end of the whaling era, and proceeded until the mid 20th century (Wiig et al. 2014). Walruses were hunted for their skins, blubber and ivory tusks. This hunt took a great toll on walrus populations, with the result that by the mid 20th century the population of Atlantic walruses had been reduced in nearly all areas and its range had shrunk substantially. At Svalbard, walruses were nearly completely extirpated (Wiig et al. 2000). Large herds which once hauled out on island and mainland beaches in cold temperate and subtemperate latitudes, for example as far south as Sable Island off Nova Scotia, Canada, have been exterminated, and walrus today are confined solely to the Arctic.
Great uncertainty exists about the numbers taken by European whalers and sealers for all three walrus stocks in Greenland, as harvests were not well documented. Previous to the 19th century, walruses were caught by the Greenlanders, the Norse from 985 until the latter half of 15th century, and European whalers and sealers from 17th century (Wiig et al. 2014 and references therein).
Until about 1910, Scottish whalers caught walruses in the Baffin Bay region including in West Greenland and the North Water areas. Norwegian sealers and whalers took walruses between about 1910 and 1923 offshore in West Greenland, and made large catches around the 1950s, presumably in northern Baffin Bay (Witting and Born 2005).
Hudson Bay/Davis Strait
This stock, which is shared by Canada and Greenland, likely declined greatly between 1930 and 1960. Catches in Greenland peaked in 1938 with more than 600 animals taken, and more than 9,400 animals were taken in total over those three decades (Witting and Born 2013). The result was that the number of walruses in Central West Greenland was reduced by about 80% between 1900 and 1960. Catches were relatively low after this, and the population increased to 3,100 (95% CI: 2,500-4,400) by 1993 (Witting and Born 2013). Catches again increased, and the population experienced a minor decline between 1994 and the early 2000s.
In central Greenland, joint research on walrus between the Canadian Department of Fisheries and Oceans and the Greenland Institute of Natural Resources was begun in 2005. Aerial surveys conducted off West Greenland in the spring of 2006, 2008 and 2012 produced population estimates of 1,105 (95% CI 610–2002) in 2006, 1,137 (95% CI 468–2758) in 2008 and 1,408 (95% CI 922–2150) in 2012 (Heide-Jørgensen et al. 2013).
Aerial and boat surveys of walruses from this stock that summer in the Hoare Bay area on southeast Baffin Island were carried out in 2006 and 2007. The estimate from those surveys was 2,533 (CV=0.17) (DFO 2013a, Stewart et al. 2013b), suggesting that not all the walrus accounted for in the Canadian surveys were available for the Greenland surveys (Stewart and Hamilton 2013). None of these surveys covered the entire range of the stock, so they should be considered underestimates. Based on population modelling, the population estimate for this stock for 2012 is about 3,900 (95% CI: 2,500–5,300) individuals (Witting and Born 2013).
Concerns about overexploitation led to quotas being introduced for the stock in 2007, to cover a three year period (Andersen et al. 2013, NAMMCO 2013). The approved quotas were designed to allow for a gradual reduction of catches to ensure that removals will be within the sustainable levels recommended by the Greenland Institute of Natural Resources. Annual catches were cut from 190 to the current quota of 61 animals for West Greenland hunters and 16 for southeast Baffin Island hunters (DFO 2013a).
The North Water-Baffin Bay stock was also subject to intense hunting during the late 19th and early 20th century, and by 2005 was estimated to have declined to a population of less than 10% of the 1900 level (Witting and Born 2005). As in other areas, the decrease caused by historical catches is unclear due to incomplete catch reporting prior to the 1950s. It is estimated that the population declined by 40% from the 1960s to 2005. Quotas were introduced for this stock in 2007, and the decline in harvest has likely led to an increase in the population.
Scientists from the Greenland Institute of Natural Resources have been satellite tagging walruses from the Baffin Bay stock to look at their movements to determine how far animals from this stock range. In 2015, 21 walruses were tagged in June 2015 in a collaboration with local hunters from Qaanaaq.
The tracking of the walruses showed that they left the Wolstenholme Fjord during June and moved west across the North Water to the east coast of Ellesmere Island. Some walruses moved north along Ellesmere Island, some went far west into Jones Sound and 3 walruses went south of Devon Island into Lancaster Sound where they headed west to Cornwallis Island. These new tracking data confirm that the Baffin Bay population of walruses extend far west into the Canadian high Arctic.
The Baffin Bay stock of walrus was surveyed in May of 2009 and 2010, as part of a larger survey of the North Water Polynya. Smith Sound and southern Kane Basin were surveyed from the air both years, resulting in a combined estimate for 2009/10 of 1499 (95% CI 1077–2087) (Heide-Jørgensen et al. 2012). Based on population modelling, the 2012 abundance estimate is 1,400 (95% CI: 1,000–2,000) individuals, and the annual natural growth rate of this population is estimated at 7.7% (95% CI: 6.7–8.9%) (Witting and Born 2013).
Another survey was conducted in April 2014 in the eastern part of the North Water Polynya. The resulting estimates suggested that 2,544 walruses (95% CI 1,513-4,279) wintered in the eastern part of the North Water polynya in April 2014 (NAMMCO 2015). The walrus estimate is larger than previous summer estimates and it emphasizes the importance of the habitat along the Greenland coast as a walrus wintering ground.
The East Greenland population was also heavily exploited late in the 19th century and during the first half of the 20th century. As in other areas, catches were not well documented, but at least 268 walruses were taken in 1889, and at least 573 walruses were taken between 1898 and 1908. Since that time harvests of this stock have been low, except for the period from 1925 to 1939 where a total of approximately 350 walruses were taken (Witting and Born 2013).
Based on an abundance estimate from 2009, population modelling suggests these takes caused only small changes in the population, with a maximum depletion to 80% of the estimated original population in 1890 (Witting and Born 2013). Some management measures were introduced fairly early on for the protection of this stock. In 1938 and 1939 some restrictions for the hunting of walruses for Danish hunters and trappers, but not Norwegians, operating in North East Greenland north of about 73° 30′ N were introduced by the Danish hunting company “Nanok”. In 1951, a decree from the Danish Ministry of State Affairs gave complete protection to walruses north of 74° 24’ N in North East Greenland (Wiig et al. 2014). Quotas were introduced for this stock in 2007, and currently allow 18 walrus to be harvested per year. The population has been increasing slowly and is now considered to be recovered with a current growth rate of 1.5% (95% CI: 0.5–3.9%) and a population estimate of 1,000 in 2005 and 1,430 (cv 0.45) in 2009 (Witting and Born 2013, NAMMCO 2013).
While walrus have been harvested by Inuit in the Canadian Arctic for centuries, it was only with the advent of commercial whaling in the late 1800s that walrus started to be heavily exploited in the high Arctic. Walrus further south, in the Gulf of St. Lawrence, were hunted to extirpation in the 1700s. Very high numbers of walrus were taken further north in the late 1890s and early 1900s, as many as 1,400 in one year. Between 1885 and 1913, whalers harvested at least 4,000 walrus from Baffin Bay–Davis Strait. In northern Hudson Bay and the Cumberland Sound area between 1831 and 1914 at least 4,750 walrus were taken (DFO 2013b). This unrestricted commercial harvesting led to a serious decline in numbers for these stocks. The other result was a restriction of walrus distribution to more northerly areas, whereas previously walrus were found as far south as the Gulf of St. Lawrence and Sable Island off Nova Scotia (Wiig et al. 2014). In 1928, regulations were introduced under the Fisheries Act banning the commercial harvesting of walrus and limiting the harvest to Inuit (DFO 2013b).
It is difficult to say to what extent walrus populations have recovered since that time or what the population trends are, as there is little data available. As mentioned above, walrus are one of the most difficult animals to survey, and even the current population estimates carry a great deal of uncertainty.
Fairly recent surveys have been carried out on all walrus stocks in Canada, with the exception of the South and East Hudson Bay stock, and these are summarized in the table above. The two Foxe Basin stocks are by far the largest and together may number over 10,000 animals. The Baffin Bay stock is shared with Greenland, and population modelling indicates the 2012 abundance estimate to be 1,400 (95% CI: 1,000–2,000) individuals, and the annual natural growth rate of this population is estimated at 7.7% (95% CI: 6.7–8.9%) (Witting and Born 2013). Similarly the Hudson Bay–Davis Strait stock is shared between Canada and Greenland. Only a small portion of the Hudson Bay–Davis Strait stock range has been surveyed so existing estimates are almost certainly negatively biased. Population modelling suggests a 2012 stock size of 3,900 (95% CI: 2,500-5,300) individuals (Witting and Born 2013). Further investigations into the movement patterns between Canada and Greenland are required for this stock.
No stock identification information or recent estimates of population size are available for the South and East Hudson Bay stock.
It is difficult to estimate the size of the original population prior to hunting, but the Svalbard/Franz Josef Land population must have once been very large. The first recorded hunt of Atlantic walrus occurred in Svalbard in 1604 (Wiig et al. 2014), after which hunting continued for the next 200 years. By the middle of the 19th century the stock showed clear signs of decrease. The centuries of walrus hunting had brought the large herds in Svalbard to the verge of extinction. Because of this, all hunting was banned and walrus were given total protection in 1952 (Wiig et al. 2014).
Since that time, the population has been increasing slowly. A survey of all known terrestrial haul-out sites in Svalbard was carried out during August 2006. Overall, 2629 (95% CI: 2318–2998) walruses were estimated to be present in the Svalbard area during that period. A more recent survey of Svalbard was completed in 2012 and resulted in an estimate of 3886 (95% CI: 3553–4262) animals (Lydersen et al. 2014), which is a 48% increase from the 2006 survey (Kovacs et al. 2014). In addition to an increased abundance estimate, this survey also found more haul-out locations and more sites with mother-calf pairs.
The pre-harvest walrus population in the Barents Sea (Svalbard-Franz Josef Land) population was probably more than 30,000 but is only around 5,000 animals today (Lydersen et al. 2008). Walrus hunting in Franz Josef Land first became a significant mortality factor around 1900 (Gjertz et al. 1992). From then until the late 1920s Norwegian sealers harvested a considerable number of walruses at Franz Josef Land. The total registered catch for the period 1880 to 1950 was estimated to be about 5,900 animals (Gjertz et al. 1992). The original population size of walruses in Franz Josef Land in 1897 was estimated to be from 6,000 to 12,000 walruses (Wiig et al. 2014 and references therein). Walrus have been protected in the western Russian Arctic since 1956, and there has been no hunting of them in Russia since that time (Wiig et al. 2014).
In terms of current population levels or trends for the stock, little data is available for walruses along the Russian coast. The first investigation of walrus numbers in the Pechora Sea was carried out in 2011, through an aerial survey of 2,563 km of coastline which used a combination of infrared sensing and digital imagery. Hauled-out walruses were found at three sites: one on Vaygach Island and two on Matveyev Island. A total of 968 animals were counted on aerial photographs, all of which appeared to be males (Lydersen et al. 2012). Using an adjustment factor developed for male walruses in Svalbard to account for animals at sea during the survey, the number of walruses occupying this area was estimated to be 3,943 (95 % CI, 3,605–4,325). No females with calves were seen in this survey (Lydersen et al. 2012).
Walruses inhabit the waters of two NAMMCO member states: Greenland and Norway. Norway does not presently permit the harvest of walruses in its territory. West Greenland walrus stocks inhabit both Greenlandic and Canadian waters; therefore management is a shared responsibility between Greenland and Canada.
In Greenland, walrus hunting is controlled by various regulations, which vary by location. There is a year-round ban on walrus hunting south of 66° N, and walruses that are hauled out on land are completely protected. Greenlandic regulations also forbid the hunting of mature females and calves (except in the Qaanaaq area) (NAMMCO 2013b). In areas north of 66°, walrus hunting is restricted to people with a valid professional hunting licence, and transport used in connection with the hunt must be either a dog sled or vessels of 19.99 GRT/31.99 GT or less (NAMMCO 2013a). Sale of walrus products is limited to direct sales at open markets or for personal use only. Reporting of the sex, age class, and date of walrus harvested has been mandatory since 1994 (Wiig et al. 2014). Municipal authorities in Greenland also have the ability to implement further restrictions on walrus harvest if needed (NAMMCO 2013a).
Two of the Greenland stocks are shared with Canada. While there is cooperation on walrus research and stock assessment, there is currently no formal walrus co-management agreement between the two countries.
Science-based sound management gives results
Walrus quotas were introduced in 2007, and covered a 3-year period from 2007 to 2009. These quotas were designed to allow for a gradual reduction of catches so that by 2009 the walrus harvest would be within the sustainable levels recommended by NAMMCO and the Greenland Institute of Natural Resources (NAMMCO 2013a). The next quota blocks were set so that the probability of maintaining or increasing the population was at least 70% (NAMMCO 2013a, NAMMCO 2015). Recent harvests have been within these limits.
The walrus has been protected in Norwegian territory (Svalbard) since 1952, and walrus hunting by Norwegian citizens in other areas is prohibited (Lydersen and Kovacs 2013). Much of the walrus habitat on Svalbard has been included in nature reserves and national parks, and there are no known interactions of these walruses with any fishery (Wolkers et al. 2006). The walrus stock around Svalbard also inhabits Russian territory. While there is cooperation on walrus research between Russia and Norway, there is currently no formal co-management agreement between the two countries.
In Canada, walruses are managed by the federal Department of Fisheries and Oceans. The first regulations on walrus hunting were introduced in 1928 and have been amended several times since then (Wiig et al. 2014). Community quotas were enacted under the Walrus Protection Regulations of 1980, as was the limit of four walruses per year per Inuk. In 1993, the Walrus Protect Regulations were replaced by the Marine Mammal Regulations of the Fisheries Act, which stipulate that an Inuk or land claims beneficiary may, without a license, hunt for food, social or ceremonial purposes up to four walruses in a year. The Marine Mammal Regulations further stipulate requirements for hunting and established community quota levels for four communities in Nunavut: Arctic Bay, Clyde River, Coral Harbour and Sanikiluaq (DFO 2013b).
Under the Nunavut Land Claims agreement of 1993 the Nunavut Wildlife Management Board (NWMB) was established. The NWMB is a decision-making body within the Nunavut Settlement Area, with advisory authority in the adjacent waters. Ultimate responsibility for wildlife management, however, lies with the governments of Nunavut and Canada. These governments carry out NWMB decisions, once they are made.
In 1999 the NWMB created a walrus working group, which started developing a walrus management plan for Nunavut. This working group’s members have been studying traditional and scientific knowledge about the walrus, looking at problems with the current management system, and suggesting ways to better manage walruses. This new management plan is still under development, now with two working groups (one for Foxe Basin and one for Baffin Bay–High Arctic) currently drafting an Integrated Fisheries Management Plan (IFMP) for walruses in Nunavut (DFO 2013b).
Sport hunts for walruses began in Nunavut in 1995 and in Salluit (Nunavik) in 1996. Sport hunts are regulated by the annual issuing of licences, and hunts must be approved by the NWMB (Wiig et al. 2014). Sport hunts have been conducted in Cape Dorset, Hall Beach, Igloolik and Coral Harbour, with only a few walruses taken (DFO 2013b). During the 2012 walrus sport hunt season a total of 18 licences were issued but only 4 walruses were taken (DFO 2012). In Igloolik, sport hunts were suspended for two years, starting in 2008, over community concern that walruses were being disturbed (DFO 2013b).
In Russian territory, regulations curtailing walrus harvest were introduced in 1921. In 1956 hunting of the Atlantic walrus was prohibited for all Soviet citizens, excluding a limited subsistence harvest by aboriginal people (Wiig et al. 2014).
In 1971 the Novaya Zemlya population of walrus was included in the list of Rare Animals of the USSR. In 1975 regulations for protecting and harvesting of marine mammals prohibited sport hunting of walruses as well as any landing on or the littering of shore haul-outs at any time. It also prohibited the possession, manufacture, buying, selling, storage, and transportation of hides and tusks from walruses (Wiig et al. 2014).
Status according to other organizations
The walrus is listed in Appendix III of the Convention on International Trade in Endangered Species of Fauna and Flora (CITES). Appendix III concerns species which are not necessarily endangered, but which are managed by the listing nation. For walruses, the listing nation was Canada. A permit is required for any international trade in walrus parts.
On the IUCN “Red list” the walrus is listed as Data Deficient in an assessment made in 2008 (Lowry et al. 2008).
Walruses have long been a staple food resource for indigenous peoples throughout the Arctic, and continue to be an important part of northern diets today. Historically and currently, all parts of the walrus were used for food or other purposes. Walrus tusks remain a valuable commodity, and are used to make carvings and jewelry for sale, or sold in its raw form. Ivory carvings made from walrus tusk are an important source of income for some communities. The thick, strong hide of the walrus is used to make traditional footwear and strong, flexible rope for use as harpoon lines.
Walrus meat is a particularly important winter food for Inuit because it can be procured in large amounts in the late summer and fall, and especially because it can be preserved and stored for long periods of time. Igunaq, or aged, preserved walrus meat, is a well-loved delicacy in parts of Greenland and Nunavut. To make igunaq, the walrus is flensed, so that the skeleton is removed, leaving the skin, fat , meat and some organs in one thick sheet. This sheet is cut into smaller pieces and sewn into large sausage-shaped rolls, called ungirlak. The ungirlak are buried in gravel and left for several months to age and ferment. Experienced hunters know how to choose exactly the right type of gravel for burial, as it must be porous enough to allow some air circulation and to allow the hunter to dig up the bundles during the winter when the ground is frozen. Once dug up, the ungirlak are cut up and washed. Igunak is considered such a delicacy that it is often saved for special occasions and feasts, and traded to other communities that do not have access to walrus (Tigullaraq 2008).
In 2004, NAMMCO hosted a Workshop on Hunting Methods for Seals and Walrus, the report of which provides a wealth of information on walrus hunting techniques. The NAMMCO Workshop on Struck and Lost held in 2006 provides additional information relevant to this topic.
Several methods are used to hunt walruses in Canada and Greenland, depending on the season, the ice conditions and the size of the vessel that is used in open water. A favoured method that is used in the spring and summer is to hunt walrus that are hauled out on ice pans. The hunters approach walrus herds slowly from down-wind so that the animals cannot catch the hunters’ scent. Resting walrus can often be approached very closely in this way. The hunters then shoot the agreed-upon number of animals at close range, taking care to fire simultaneously so that the walruses cannot react to the noise. Large calibre rifles are used and the hunter attempts to kill the animal outright so it cannot re-enter the water. If an injured walrus does reach the water, it is harpooned with an attached line and float, because a dead walrus usually sinks rapidly. Once secured, the walrus is killed and retrieved.
When there is no ice around walruses can be hunted in open water, although this is more difficult and often less successful than hunting them on the ice. Walruses are harpooned with a line and float to prevent them from sinking before a killing shot is attempted. Walruses are agile and quick in the water, however, and it is often difficult to approach them closely enough for a successful harpoon strike. For this reason it is often necessary to shoot the walrus to injure it and slow it down so that it can be approached for harpooning. Once killed, the walrus is towed to shore or to an ice flow for processing, or brought on board if hunting from a larger vessel.
Walruses are also taken from the floe edge or as they breathe in holes in thin, young ice during the winter. In such hunts the walrus is first harpooned as it comes up for air, then shot through the head when it returns to breathe. In floe edge hunts, a small boat is used to retrieve the walrus.
As with all marine mammal hunts, struck-and-lost, the failure to retrieve an animal that has been killed or injured by the hunter, is a serious issue in walrus hunts. The problem is exacerbated because walruses generally sink when killed. Struck-and-lost rates for walrus hunts vary widely, depending on the type of hunt, environmental conditions and hunter experience among other factors, but have been estimated to average from 32% to 42% in Canadian and Alaskan hunts respectively (Orr et al.1986, Fay et al. 1994). The NAMMCO Workshop on Struck and Lost provided a wealth of information on this topic as well as recommendations to facilitate monitoring and reduce the incidence of struck-and-lost in all types of marine mammal hunts.
Reported catches of Atlantic walrus in Greenland
This database of reported catches is searchable, meaning you can filter the information by for instance country, species or area. It is also possible to sort it by the different columns, in ascending or descending order, by clicking the column you want to sort by and the associated arrows for the order. By default, 30 entries are shown, but this can be changed in the drop-down menu, where you can decide to show up to 100 entries per page.
Carry-over from previous years are included in the quota numbers, where applicable.
You can find the full catch database with all species here.
You can find a complete file with all comments and explanations here, under Overview Documents.
For any questions regarding the catch database, please contact the Secretariat at email@example.com.
Climate change and other human impacts
While over-hunting was the primary cause for decline in walrus numbers over the 20th century, other human activities may also have an impact on walrus populations. Walruses are very sensitive to human-caused environmental disturbances, such as the noise of boats and low-flying airplanes. Noise from increased industrial activity in the Arctic such as seismic surveys, exploration drilling, building of production facilities and other traffic related disturbances linked to oil exploration activities, including helicopter transport and intensified shipping, may potentially displace walruses from their wintering grounds or other important feeding grounds (Dietz et al. 2013). In the Canadian Arctic, walrus are likely to be exposed to greatly increased shipping associated with both reduced sea ice and increased exploration and extraction of minerals and hydrocarbons (DFO 2013b). Another concern is potential disturbance of walrus by scallop fishing off western Greenland, although the extent of the impact on walrus is not known (NAMMCO 2013). In Svalbard, increasing tourism is being monitored to ensure that it does not affect walrus distribution or behaviour.
Hauled out walruses disturbed by noise may panic and flee, which can sometimes lead to the death of animals, especially calves, by trampling. Repeated disturbance may cause walrus to abandon an uglit, or haul out site, forever.
Walruses are quite conservative in their choice of habitat and food, so any reduction in either of these may have detrimental effects on their numbers. Walrus numbers could be threatened by a loss of sea ice caused by global warming and accompanying environmental changes, with retreating sea ice reducing the availability of suitable habitat and food supply, and affecting walrus movement and behaviour (Dietz et al. 2013). Changes in sea ice extent and location could also affect human hunting patterns, providing hunters easier access to walrus.
Another potential threat to walrus populations is pollution from oil and gas exploration and extraction activities. Walruses are particularly at risk from oil spills as their staple diet items of benthic invertebrates are known to accumulate hydrocarbons (Born et al. 1995). Other pollutants of concern are heavy metals, such as cadmium, lead and mercury. Elevated levels of these metals have been found in Atlantic walrus tissues, though it is not clear what effect these might have on walrus health (Born et al. 1995). Relatively high levels of organochlorines such as DDT and PCBs have also been found in those walruses that eat seals, although in a fairly recent study in Svalbard, levels of these compounds were found to be substantially lower than those of animals sampled in the same area 10 years earlier (Wolkers et al. 2006). A surprising result from the same study was that individual variation in contaminant levels and patterns was very high, even though the walrus sampled were from a homogenous group which consisted solely of adult males from a restricted geographic area (Wolkers et al. 2006).
Research in NAMMCO Member Countries
Research on walrus populations in Greenland is ongoing, focusing on stock identification, walrus behaviour and population trends. Prominent in these research efforts has been the Greenland Institute of Natural Resources.
To study walrus behaviour and movements, a total of 35 walruses were fitted with satellite-linked transmitters in Smith Sound, Northwest Greenland, between 2010 and 2013 (NAMMCO 2013b). Tagging occurred in spring to coincide with aerial surveys, when the walruses are in Greenland. The last tags were put out in June 2013, and the analyses are still pending.
Aerial surveys were conducted off West Greenland in the spring of 2006, 2008 and 2012 (Heide-Jørgensen et al. 2013), in the North Water Polynya in the spring of 2009, 2010, 2014 and 2018 (Heide-Jørgensen et al. 2012; National Progress Report Greenland 2018).
Tagging walruses in Greenland
Research on the walrus population on Svalbard is ongoing. Future plans include aerial surveys at 5 year intervals of the Svalbard fraction of the Svalbard-Franz Josef Land population to monitor abundance trends. A synoptic aerial survey of the whole population including the Russian territories has high priority and has been planned, but for various reasons it has not yet been possible to conduct this work (Lydersen and Kovacs 2013). Prominent in these research efforts has been the Norwegian Polar Institute. The latest aerial survey flown in Svalbard was in August 2018 (National Progress Report Norway 2018).
Possible future dietary shifts, due to climate change induced changes in the marine ecosystem, will be assessed via analysis of walrus tissue for stable isotopes and fatty acids at regular intervals (Lydersen and Kovacs 2013). Walruses are also tracked over multiple years using tusk-mounted GPS loggers in order to study individual responses to changes in ice conditions. 20 animals were equipped with loggers both in 2014 and 2015, and data from these were collected from receiving stations in the summer of 2018. This project is mainly funded by the Norwegian-Russian Environmental Commission (National Progress Report Norway 2018).
Monitoring and genetic sampling
Walrus haul-out sites are being monitored by digital camera during the period late June- early October to study haul-out behaviour and the potential impact of visiting tourists to these sites (NAMMCO 2013a). It is hoped to continue this surveillance in order to get long enough time trends and large enough sample sizes to effectively monitor the status of the population (Lydersen and Kovacs 2013).
Research is also investigating the stock structure of Svalbard walruses. Currently, the genetic relationship between walruses in the Pechora and Kara Seas and those in the Svalbard-Franz Josef Land area is unknown. Material is currently being collected to address this issue (Lydersen and Kovacs 2013).
Andersen, L. W., Born, E. W., Stewart, R. E. A., Dietz, R., Doidge, D. W. and Lanthier, C. 2013. A genetic comparison of West Greenland and Baffin Island (Canada) walruses: Management implications. NAMMCO Scientific Publications. doi: http://dx.doi.org/10.7557/3.2610
Born, E. W. and Gjertz, I. 1993. A link between walruses (Odobenus rosmarus) in northeast Greenland and Svalbard. Polar Rec. 29:329. doi: http://dx.doi.org/10.1017/S0032247400023986
Born, E.W., Rysgaard, S., Ehlme, G., Sejr, M., Acquarone, M. and Levermann, N. 2003. Underwater observations of foraging free-living Atlantic walruses (Odobenus rosmarus rosmarus) and estimates of their food consumption. Polar Biology 26:348-357.
Born, E. W., Gjertz, I. and Reeves, R. R. 1995. Population assessment of the Atlantic walrus (Odobenus rosmarus rosmarus L.). Norsk Polarinstitutt Meddelelser Nr. 138. 100 pp.
Dietz, R., Born, E. W., Stewart, R. E. A., Heide-Jørgensen, M. P., Stern, H., Rigét, F., Toudal, L., Lanthier, C., Jensen, M. V. and Teilmann, J. 2013. Movements of walruses (Odobenus rosmarus) between Central West Greenland and Southeast Baffin Island, 2005-2008. NAMMCO Scientific Publications. doi: http://dx.doi.org/10.7557/3.2605
(DFO). Department of Fisheries and Oceans Canada 2013. Estimates of Abundance and Total Allowable Removals for Atlantic Walrus (Odobenus rosmarus rosmarus) in the Canadian Arctic. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2013/034. (DFO 2013a)
(DFO) Department of Fisheries and Oceans Canada 2013. Proceedings of the Pre-COSEWIC Peer Review Meeting for Atlantic walrus (Odobenus rosmarus rosmarus); February 28 to March 1, 2012. DFO Can. Sci. Advis. Sec. Proceed. Ser. 2012/041. (DFO 2013 b)
(DFO) Department of Fisheries and Oceans Canada 2012. DFO submission to the NWMB, October 2012. Available at www.nwmb.com
Fay, F.H., Burns, J.J., Stoker, S.W. and Grundy, J.S. 1994. The Struck-and-Lost Factor in Alaskan Walrus Harvests, 1952-1972. Arctic 47: 368-373.
Freitas, C., Kovacs, K. M., Ims, R. A., Fedak, M. A. and Lydersen, C. 2009. Deep into the ice: overwintering and habitat selection in Atlantic walruses. Mar. Ecol. Prog. Ser. 375:247-261. doi: http://dx.doi.org/10.3354/meps07725
Gjertz, I., Hansson, R. and Wiig, Ø. 1992. The historical distribution and catch of walrus in Franz Josef Land. Norsk Polarinst. Medd. 120:67-81.
Glazov, D. M. , Shpak, O. V., Kuznetsova, D. M., Solovyev, B. A., Udovik, D. A., Platonov,N. G., Mordvintsev, I. N., Ivanov, D. I., and Rozhnov, V. V. 2013. Observations of the Walrus (Odobenus rosmarus) in the Barents, Kara, and Laptev Seas in 2010–2012. Biol. Bull. 40:783-789.
Heide-Jørgensen, M. P., M. S. Sinding, N. H. Nielsen, A. Rosing-Asvid and R. G. Hansen 2015. Large numbers of marine mammals winter in the North Water polynya. SC/22/17. Available from the NAMMCO Secretariat.
Heide-Jørgensen, M.P., Laidre, K.L., Fossette, S., Rasmussen, M., Nielsen, N.H. and Hansen, R.G. 2013. Abundance of walruses in Eastern Baffin Bay and Davis Strait. NAMMCO Scientific Publications. doi: http://dx.doi.org/10.7557/3.2606
Heide-Jørgensen, M. P., Burt, L. M., Hansen, R. G., Nielsen, N. H., Rasmussen, M., Fossette, S. and Stern, H. 2012. The significance of the North Water polyna to Arctic top predators. Ambio 42:596-610.
Kovacs, K.M., Aars, J., and Lydersen, C. 2014. Polar Research 33:26034, http://dx.doi.org/10.3402/polar. v33.26034
Lindqvist, C., Bachmann, L., Andersen, L. W., Born, E. W., Arnason, U., Kovacs, K. M., Lydersen, C., Abramov, A. V. and Wiig, Ø. 2008. The Laptev Sea walrus Odobenus rosmarus laptevi: an enigma revisited. Zoologica Scripta 38:113-127.
Lowry, L., Kovacs, K. and Burkanov, V. (IUCN SSC Pinniped Specialist Group) 2008. Odobenus rosmarus. The IUCN Red List of Threatened Species. Version 2014.2. http://www.iucnredlist.org/details/15106/0
Lydersen, C. and Kovacs, K. 2013. Walrus Odobenus rosmarus research in Svalbard, Norway, 2000- 2010. NAMMCO Scientific Publications. doi: http://dx.doi.org/10.7557/3.2613
Lydersen , C., Chernook, V., Glazov, D., Trukhanova, I. and Kovacs, K. 2012. Aerial survey of Atlantic walruses (Odobenus rosmarus rosmarus) in the Pechora Sea, August 2011. Polar Biol. 35:1555-1562.
Lydersen, C., Aars, J. and Kovacs, K. M. 2008. Estimating the number of walruses in Svalbard from aerial surveys and behavioural data from satellite telemetry. Arctic 61:119-128.
NAMMCO. 2015. NAMMCO Annual Report 2015. North Atlantic Marine Mammal Commission, Tromsø, Norway.
(NAMMCO) North Atlantic Marine Mammal Commission 2013a. NAMMCO Annual Report 2013. North Atlantic Marine Mammal Commission, Tromsø, Norway, 305 pp.
(NAMMCO) North Atlantic Marine Mammal Commission 2013b. Report of the 20th Meeting of the Scientific Committee.
Orr, J.R., Renooy, B. and Dahke, L. 1986. Information from hunts and surveys of walrus (Odobenus rosmarus) in northern Foxe Basin, Northwest Territories, 1982-1984. Can. Manuscr. Rep. Fish. Aqaut. Sci. 1899: vi +24 p.
Outridge, P. M. and Stewart, R. E. A. 1999. Stock discrimination of Atlantic walrus (Odobenus rosmarus rosmarus) in the eastern Canadian Arctic using lead isotope and element signatures in teeth. Can. J. Fish. Aquat. Sci. 56:105-112.
Outridge, P. M., Davis, W. J., Stewart, R. E. A. and Born, E. W. 2003. Investigation of the stock structure of Atlantic walrus (Odobenus rosmarus rosmarus) in Canada and Greenland using dental Pb isotopes derived from local geochemical environments. Arctic 56:82-90.
Reeves, R.R., Stewart, B.S. and Leatherwood, S. 1992. The Sierra Club Handbook of Seals and Sirenians. Sierra Club Books, San Francisco. 359pp.
Richard, P. 2001. Marine Mammals of Nunavut. Dept. of Education, Nunavut. 98pp.
Salter, R. E. 1979. Observations on social behaviour of Atlantic walruses (Odobenus rosmarus L.) during terrestrial haul-out. Can. J. Zool. 58:461-463.
Shafer, A., Davis, C.S., Coltman, D. W., and Stewart, R. E. A. 2013. Microsatellite assessment of walrus (Odobenus rosmarus rosmarus) stocks in Canada. NAMMCO Scientific Publications. doi: http://dx.doi.org/10.7557/3.2607
Sjare, B. and Stirling, I. 1996. The breeding behavior of Atlantic walruses, Odobenus rosmarus rosmarus, in the Canadian High Arctic. Can. J. Zool. 74(5):897-911.
Sjare, B., Stirling, I. and Spencer, C. 2003. Structural variation in the songs of Atlantic walruses breeding in the Canadian High Arctic. Aquat. Mamm. 29:297-318.
Stewart, R. E. A. 2008. Redefining walrus stocks in Canada. Arctic 61:292-308.
Stewart, R.E.A. and Hamilton, J.W. 2013. Estimating total allowable removals for walrus (Odobenus rosmarus rosmarus) in Nunavut using the potential biological removal approach. DFO Can. Sci. Advis. Sec. Res. Doc. 2013/031. iv + 13 p.
Stewart, R. E. A., Born, E. W., Dietz, R., Heide-Jørgensen, M. P., Rigét, F. F., Laidre, K., Jensen, M. V., Knutsen, L. Ø., Fossette, S. and Dunn, J. B. 2013a. Abundance of Atlantic walrus in western Nares Strait, Baffin Bay stock, during summer. NAMMCO Sci. Publ. doi: http://dx.doi.org/10.7557/3.2611
Stewart, R. E. A., Born, E.W., Dietz, R. and Ryan, A.K. 2013b. Estimates of Minimum Population Size for Walrus around Southeast Baffin Island, Nunavut. NAMMCO Sci. Publ. doi: http://dx.doi.org/10.7557/3.2615
Stewart, R.E.A., Hamilton, J.W. and Dunn, J.B. 2013c. Results of Foxe Basin walrus (Odobenus rosmarus rosmarus) surveys: 2010-2011. DFO Can. Sci. Advis. Sec. Res. Doc. 2013/017. iv + 12 p. (Erratum: February 2014)
Stirling, I., Calvert, W. and Cleator, H. 1983. Underwater vocalizations as a tool for studying the distribution and abundance of wintering pinnipeds in the High Arctic. Arctic 36:262-274.
Wiig, Ø., Born, E. W. and Stewart, R.E. A. 2014. Management of Atlantic walrus (Odobenus rosmarus rosmarus) in the arctic Atlantic. NAMMCO Scientific Publications. doi: http://dx.doi.org/10.7557/3.2855
Wiig, Ø., Berg, V., Gjertz, I., Seagars, D. J. and Skaare, J. U. 2000. Use of skin biopsies for assessing levels of organochlorines in walruses (Odobenus rosmarus). Polar Biology 23:272-278.
Witting, L. and Born, E. W. 2013. Population dynamics of walrus in Greenland. NAMMCO Scientific Publications. doi: http://dx.doi.org/10.7557/3.2612
Witting, L. and Born, E.W. 2005. An assessment of Greenland walrus populations. International Council for the Exploration of the Sea (ICES) Journal of Marine Science 62:266–284.
Wolkers, H., van Bavel, B., Ericson, I., Skoglund, E., Kovacs, K. M. and Lydersen, C. 2006. Congener- specific accumulation and patterns of chlorinated and brominated contaminants in adult male walruses from Svalbard, Norway: Indications for individual-specific prey selection. Sci. Total Envi. 370:70-79.