Terrestrial Haul-out Research Articles

Protected area use by two sympatric marine predators repopulating their historical range

As large carnivores recover from over-exploitation, managers often lack evidence-based information on species habitat requirements and the efficacy of management practices, particularly where species repopulate areas from which they have long been extirpated. We investigated the movement and habitat use by 2 semi-aquatic carnivores (Australian fur seals Arctocephalus pusillus doriferus and New Zealand fur seals A. forsteri) at the northern end of their distributions in Australia, where after a long absence both are recolonising their historic range. We also assessed male fur seal habitat use overlap with terrestrial and marine protected areas (PAs). While at the margin of the range during winter and early spring, the males remained inshore close to terrestrial sites and where interactions with humans often occur. From early spring, the males from the range margin showed uniform movement toward colonies in the core of the species’ range prior to their breeding seasons. This contrasts with males tracked from the core of the species’ range that returned periodically to colonies during the year, and highlights the importance of range-wide monitoring of a species to inform conservation planning. Habitat use by some males included over 90% of a marine PA at the margin of the species’ range. Most terrestrial haul-outs used were within terrestrial PAs, while sites not protected were on the margin of the range. Despite wide-ranging habits, their dependence on coastal sites, where human access and activities can be regulated and more readily enforced, suggests that terrestrial and marine PAs will continue to play an important role in managing the recovery of these fur seals.

Daily and seasonal movements of Cape Cod gray seals vary with predation risk

White sharks Carcharodon carcharias and gray seals Halichoerus grypus are re-establishing their ecological roles within the Northwestern Atlantic Ocean, presenting an opportunity to understand gray seal movement and at-sea behavior under predation risk. As with other shark-seal hotspots, movements to and from terrestrial haul outs can be risky for gray seals, thereby eliciting antipredator strategies. We investigated the movement and coastal behavior of gray seals on Cape Cod (USA) in relation to seasonal and diel changes in white shark activity. Analyzing 412 trips to sea by 8 seals and more than 25000 acoustic detections from 23 individual white sharks, we observed seasonally homogeneous movements in seal behavior during months with greater shark presence. During riskier months, seal behavior manifested in near-exclusive nocturnal foraging, reduced offshore ranging, and limited at-sea activity. On these nocturnal trips to sea, seals returning to haul outs tended to avoid daybreak and traversed during diel minima in shark activity. However, seals tended to depart haul outs at dusk when shark presence was maximal. As conservation efforts succeed in rebuilding depleted populations of coastal predators, studying re-emerging predator-prey interactions can enhance our understanding about the drivers of movement and behavior.

Phenology of the Pacific Walrus (Odobenus rosmarus divergens) in Coastal Waters of Wrangel Island: The Impact of the Sea Ice Dynamics

Data on phenological events in the annual cycle of the Pacific walrus (Odobenus rosmarus divergens Illiger 1815) are presented, and their relationship with the dynamics of sea ice conditions is analyzed based on studies in the area of Wrangel and Gerald islands in the years 1989–1998 and taking into account the literature and unpublished sources. The duration of the feeding period ranged from 79 to 100 days at Wrangel and Gerald islands, from the appearance of the first groups of walruses to the registration of the last animals. The use of terrestrial haulouts during the second half of the 20th century occurred every 1.6–2 years, with the time of concentration of the animals to the departure of the last individuals taking up 33 to 52% of the entire presence period. Significant correlations have been obtained (p < 0.05) between the main parameters of haulout functioning (the beginning of the use of land habitats by walruses, the duration of haulout actions, the number of days the animals spent ashore) with the dates of sea ice disappearance and the duration of total sea ice absence. The results of this study allow recommending the use of phenological dates as an indicator reflecting the dynamics of walrus habitats in the northwesternmost area of the distribution range of the Pacific subspecies.

Key habitats and movement patterns of Pechora Sea walruses studied using satellite telemetry

The Pechora Sea in the western Russian Arctic is inhabited by Atlantic walrus (Odobenus rosmarus rosmarus). Until recently, walruses in this region remained the least-studied stock within the Atlantic subspecies. This benthic feeding pinniped requires careful management in this area because of the rapid industrial development that has taken place in the last decade in the region. In this study, 35 adult male Atlantic walruses were tagged with platform terminal transmitters (PTTs) on the western coast of Vaygach Island in the Pechora Sea in July–August 2012–2017. For the 30 PTTs that functioned, the average duration of the tracking records was 47 ± SE 6 days (maximum: 155 days). Most of the tagged animals (83%) stayed in the eastern part of the Pechora Sea between Pechora Bay, the southern tip of Novaya Zemlya and the western coast of Vaygach Island. The identified core range (4000 km2) was located between Vaygach Island and Matveev and Dolgiy islands; including a series of coastal haul-outs and a marine area which is likely an important feeding ground. Five of the tagged walruses left the Pechora Sea and moved to areas up to 1500 km away (maximum 2115 km by track distance) from the tagging location, including the northern part of Novaya Zemlya, the central Kara Sea and the northern part of the Severnaya Zemlya Archipelago. This is the first evidence that walruses from the southeastern Barents Sea occupy the Kara Sea. Eight terrestrial haul-outs in the Kara Sea were identified.

Assessing site-use and sources of disturbance at walrus haul-outs using monitoring cameras

The rapid growth of tourism in Polar Regions stimulates a need for investigating potential impacts on targeted species and sensitive areas. This study examines effects of tourist visitations on haul-out dynamics and site use by walruses (Odobenus rosmarus) in Svalbard, Norway. Automated camera stations were established at five traditional haul-out sites that experience variable levels of tourist visitation. The cameras took one photograph each hour, throughout June–November from 2007 to 2015 (3 sites) and 2010–2015 (2 additional sites). A total of 66,365 images were analysed. The approximate number of walruses on shore, and % sea-ice cover was estimated for each image; additionally, the presence/absence of tourists, boats and polar bears (Ursus maritimus) were recorded. A log-linear regression model was run on residuals from an ARIMA model, fitted to each season of counts from each site. Use of the terrestrial haul-out sites was sometimes restricted by sea-ice cover, but walruses were also absent (or present rarely) at some sites, despite a lack of sea ice. Tourists on land and boats near the haul-out sites (with a single exception) did not disturb walrus haul-out behaviour significantly (p > 0.05) at any of the sites. In addition, most polar bear visits were not associated with detectable disturbances. However, polar bears did significantly disturb walrus herds at Andreetangen (p = 0.003) and Storoya (p = 0.002) in some years. These disturbances were likely associated with predation attempts on calves.

Walrus Movements in Smith Sound: A Canada–Greenland Shared Stock + Supplementary Appendix 1 (See Article Tools)

Fifty of 58 walruses (Odobenus rosmarus rosmarus) instrumented with satellite-linked transmitters in four areas in eastern Smith Sound, Northwest Greenland, during May and June of 2010 – 13 and 2015 provided data for this study. These animals departed from the feeding banks along the Greenland coast in June – July (average 14th June), simultaneously with the disappearance of sea ice from these areas. Most of them moved to Canadian waters in western Smith Sound. The most frequently used summering grounds were along the coasts of Ellesmere Island: on the eastern coast, the area around Alexandra Fiord, Buchanan Bay, and Flagler Bay (west of Kane Basin) and Talbot Inlet farther south, and on the southern coast, Craig Harbour. This distribution of tagged walruses is consistent with prior understanding of walrus movements in summer. In addition, however, nine tracks of these tagged animals entered western Jones Sound and four entered the Penny Strait-Lancaster Sound area, crossing two putative stock boundaries. Since these 13 tracks were made by 12 animals, one walrus entered both areas. It is possible that some of the tracked walruses used terrestrial haul-out sites in the largely ice-free areas of Jones Sound and Lancaster Sound for short periods during the summer, though this cannot be confirmed with certainty. The return migration from western Smith Sound to the wintering area in eastern Smith Sound takes place in October. The tracked walrus showed high affinity to coastal areas, while walruses moving between Greenland and Canada also used offshore areas in Smith Sound. This study demonstrates that the walrus population that winters along the northwestern coast of Greenland is shared more widely in Canada than previously thought and should be managed accordingly.

Source levels and call parameters of harbor seal breeding vocalizations near a terrestrial haulout site in Glacier Bay National Park and Preserve

Source levels of harbor seal breeding vocalizations were estimated using a three-element planar hydrophone array near the Beardslee Islands in Glacier Bay National Park and Preserve, Alaska. The average source level for these calls was 144 dBRMS re 1 μPa at 1 m in the 40-500 Hz frequency band. Source level estimates ranged from 129 to 149 dBRMS re 1 μPa. Four call parameters, including minimum frequency, peak frequency, total duration, and pulse duration, were also measured. These measurements indicated that breeding vocalizations of harbor seals near the Beardslee Islands of Glacier Bay National Park are similar in duration (average total duration: 4.8 s, average pulse duration: 3.0 s) to previously reported values from other populations, but are 170-220 Hz lower in average minimum frequency (78 Hz).

Novel terrestrial haul-out behaviour by ringed seals (Pusa hispida) in Svalbard, in association with harbour seals (Phoca vitulina)

ABSTRACTRinged seals (Pusa hispida) are the most ice-associated of all Arctic pinnipeds. In the Svalbard area, this species has always given birth, moulted and rested on sea ice. In addition, much of their food has been comprised of ice-associated prey. Recently, ringed seals have been reported to be using terrestrial substrates as a haul-out platform in some fjords on the west coast of Spitsbergen. In many cases the seals involved are harbour seals (Phoca vitulina), which are extending their distribution into new areas within the Svalbard Archipelago and which are being misclassified as ringed seals. However, this study reports that terrestrial haul-out by ringed seals is also now taking place on rocks exposed at low tide as well as on the coastline. Recent intrusions of warm Atlantic Water (with associated prey) have extended deep into the fjords of western Spitsbergen, resulting in deteriorated ice conditions for ringed seals and expanded habitat for harbour seals. Over the last decade, ringed seals ha...

Leveraging constraints and biotelemetry data to pinpoint repetitively used spatial features.

Satellite telemetry devices collect valuable information concerning the sites visited by animals, including the location of central places like dens, nests, rookeries, or haul-outs. Existing methods for estimating the location of central places from telemetry data require user-specified thresholds and ignore common nuances like measurement error. We present a fully model-based approach for locating central places from telemetry data that accounts for multiple sources of uncertainty and uses all of the available locational data. Our general framework consists of an observation model to account for large telemetry measurement error and animal movement, and a highly flexible mixture model specified using a Dirichlet process to identify the location of central places. We also quantify temporal patterns in central place use by incorporating ancillary behavioral data into the model; however, our framework is also suitable when no such behavioral data exist. We apply the model to a simulated data set as proof of concept. We then illustrate our framework by analyzing an Argos satellite telemetry data set on harbor seals (Phoca vitulina) in the Gulf of Alaska, a species that exhibits fidelity to terrestrial haul-out sites.

Use of Multiple Methods to Estimate Walrus (&lt;i&gt;Odobenus rosmarus rosmarus&lt;/i&gt;) Abundance in the Penny Strait-Lancaster Sound and West Jones Sound Stocks, Canada

Surveys to estimate walrus abundance at terrestrial haulout sites in the Penny Strait-Lancaster Sound (PS-LS) and West Jones Sound (WJS) stocks were conducted in 1977 and 1998-2009. The Minimum Counted Population (MCP) was similar in 1977 (565) to recent years (557) for the PS-LS stock. The MCP for the WJS stock was higher in recent surveys (404) than in 1977 (290). Regression analysis of MCP and density (number of walrus divided by number of haulouts surveyed) showed no significant trends over time. We also calculated bounded count estimates for comparison. Finally, we used broad-scale behavioural data to estimate the proportion of the total stock that could be considered countable, to produce two adjusted estimates. We selected recent surveys with good coverage and ignored adjusted estimates that were lower than MCP. For the PS-LS stock, the adjusted MCP (with 95% CL) was 672 (575-768) and 727 (623-831) walrus in 2007 and 2009, respectively. For WJS, the best estimates were the adjusted MCP of 503 (473-534) in 2008 and the adjusted bounded count of 470 (297-1732) in 2009. While both stocks appear to have remained stable over three decades, differences in survey coverage and possible differences in walrus distribution make precise population estimation difficult.

The influence of ice conditions on terrestrial haulouts of the pacific walrus Odobenus rosmarus divergens Illiger, 1815 in the Gulf of Anadyr, Bering Sea

The boundaries of the area of appropriate depths for feeding by the Pacific walrus were determined. Based on the ice maps for the period of 1997–2011, the long-term dynamics of ice breakup and formation in the Gulf of Anadyr (Bering Sea) were analyzed. There was a tendency towards a reduction in the ice-cover period in the Gulf of Anadyr, especially during 2007–2011. In 2008, the number and duration of stay of walruses at terrestrial haulout sites on Meeskyn Spit Island and on Retkyn Spit continued to decrease. Walruses also used other haulouts located in the Gulf of Anadyr at Cape Gek and Cape Retkyn. The age and sex structure of the walrus herd changed: the proportions of adult males and young animals decreased, while the proportion of females with calves increased.

Natal site fidelity by breeding female southern elephant seals in relation to their history of participation in the winter haulout

Of the four types of terrestrial haulout periods undertaken by southern elephant seals Mirounga leonina, only the purpose of the winter haulout is unknown. Returning to a haulout site from distant pelagic foraging grounds bears significant costs in terms of increased energy expenditure, reduced foraging time and increased exposure to predation; therefore, each haulout must serve a purpose. We examined the hypothesis that the winter haulout serves to maintain familiarity with the natal site, thereby increasing site fidelity. To this end, we analysed a long-term mark-recapture dataset for female southern elephant seals at Marion Island, Southern Ocean. Results indicate that, whereas greater natal site fidelity as primiparous females was associated with recorded presence ashore at the study site during the winter haulout as immatures, this was not the case for multiparous females. Furthermore, recorded presence ashore during both the moult haulouts as immatures, and all haulouts as immatures, irrespective of haulout type, was also associated with increased site fidelity. This suggests that any haulout at the natal island as an immature seal, whether for the moult or winter haulout, assists in maintaining site fidelity. Therefore, while the winter haulout facilitates greater natal site fidelity, whether this is the sole reason for this terrestrial period remains uncertain.

Foraging distribution of Pacific harbor seals (Phoca vitulina richardii) in a highly impacted estuary

Assessing the relative importance of environmental and anthropogenic influences on the distribution of wild populations is an important step in designing spatially explicit plans for their management and protection. We examined environmental variables correlated with the spatial distribution of eastern Pacific harbor seals (Phoca vitulina richardii), a marine mammal common to coastal waters, in a large, highly urbanized estuary. We assessed the relationship between prey abundance, depth, bottom relief, proximity to terrestrial haul-out sites and 3 potential sources of anthropogenic influence, and the in-water spatial distribution of seals. We identified locations of seals using satellite-linked telemetry, and used partial Mantel tests to assess which environmental variables were most strongly linked to seal foraging distribution, given spatial autocorrelation within variables. Mann-Whitney tests were used to compare environmental characteristics of locations of seals with a random distribution of locations. Because harbor seals are central-place foragers, we incorporated spatial distribution of seals relative to the central place into our analyses. High prey abundance and proximity to the haul-out site were strongly associated with the spatial distribution of seals. Harbor seals also tended to use deeper waters and areas of high bottom relief within the estuary. There was no consistent spatial relationship between the 3 anthropogenic factors and the distribution of seals, although seals tended to be found closer than expected to sites of high human activity. In highly impacted coastal areas where limited alternate suitable habitat exists, foraging seals may need to rely on disturbed (suboptimal) areas, and as a result may habituate to human presence in areas rich in food resources.

Estimating the Number of Walruses in Svalbard from Aerial Surveys and Behavioural Data from Satellite Telemetry

All known terrestrial haul-out sites for walruses in Svalbard (n = 79) were surveyed during the period 1–3 August 2006, and sites that were in use (n = 17) were documented using digital photography. A total of 657 walruses were counted on land in the resultant images. An extensive behavioural data set from walruses equipped with satellite relay data loggers, covering August 2002 to August 2005, was used to account for walruses that were in the water. The proportion of walruses at sea during the survey was calculated to be 0.750 on the basis of 28 thirty-day periods from 23 male walruses. Time of day and wind chill did not significantly affect haul-out behaviour. However, a logistic regression model revealed both a correlation among haul-out patterns of individuals within years, and a year effect (chi-square = 6.42, df = 2, p = 0.04). Because the survey was not flown in a year when satellite tags were deployed, the interannual variance was retained in a model (with no other explanatory variables). The overdispersion parameter from this model was 2.02 (deviance = 28.33, df = 14). Thus, variance in proportions of time individuals spent at sea was multiplied by this parameter to achieve a corrected SE around the estimate. The 95% CI based on this SE corresponded to a proportion of walruses at sea during the survey between 0.717 and 0.781, resulting in an estimated total number of walruses in Svalbard in August 2006 of 2629 (95% CI: 2318– 2998).

Haulout site selection by southern elephant seals at Marion Island

Using data from an ongoing mark–resight programme at Marion Island, we tested empirically whether southern elephant seals prefer certain terrestrial sites to others during the breeding, moulting and winter haulouts, and whether the pattern of site use is the same for different age and sex groups. Southern elephant seals preferred some sites, while discriminating against other sites, with different age and sex classes using different sites for certain haulout events. Wintering young animals did not show strong site selection. Some popular sites were used for all haulouts by all age and sex groups, and apparently have all the requirements of a good site for terrestrial haulout by southern elephant seals. Site selection becomes more apparent with age, suggesting the role of haulout experience in site selection.

Haulout site selection by southern elephant seals at Marion Island

Using data from an ongoing mark–resight programme at Marion Island, we tested empirically whether southern elephant seals prefer certain terrestrial sites to others during the breeding, moulting and winter haulouts, and whether the pattern of site use is the same for different age and sex groups. Southern elephant seals preferred some sites, while discriminating against other sites, with different age and sex classes using different sites for certain haulout events. Wintering young animals did not show strong site selection. Some popular sites were used for all haulouts by all age and sex groups, and apparently have all the requirements of a good site for terrestrial haulout by southern elephant seals. Site selection becomes more apparent with age, suggesting the role of haulout experience in site selection.

RESTING HEART AND RESPIRATORY RATE IN WILD ADULT MALE WALRUSES (ODOBENUS ROSMARUS ROSMARUS)

Little is known about physiological parameters of free-ranging walruses (Odobenus rosmarus). The heart rate has been measured electronically during anesthesia (e.g., Born and Knutsen 1990a, Lanthier et al. 1999), but to allow interpretation of such results, and for meaningful monitoring of anesthesia, baseline heart and respiratory rates are essential. Furthermore, such data may contribute to estimation of energy consumption (e.g., McPhee et al. 2003). The heart rate in unrestrained walruses has been estimated based on inspection of movement of the thoracic region as part of pre-anaesthetic assessments (Born and Knutsen 1990a, Griffiths et al. 1993), but to the authors’ knowledge no exact data have been published. In this paper we describe a method for recording resting heart rate in unrestrained wild walruses and present data on respiratory rate and electronically recorded heart rate. The experiment was conducted during 12–16 August 2004 on the terrestrial haulout Sandoen in Young Sound in Northeast Greenland (74◦18′N, 20◦15′W). During summer, this haul-out is used by a group of approximately 60 Atlantic walruses, predominantly adult males (Born et al. 1995, Acquarone 2004). The feeding grounds are accessible from the ice break up in July until the formation of new fast-ice in October (Born et al. 1995, Rysgaard et al. 2003). Ten adult males (estimated body weight >1,000 kg) that had been out of the water for at least 1 h, and were resting at the perimeter of the hauled-out group were studied. Photo-identification was employed to avoid repeated measurements of the same individual. During the experiments, air temperature ranged between 3◦C and 12◦C and wind speed was between 3 m/s and 10 m/s. A battery-operated portable electrocardiograph (Cardiovit AT-4 vet, Schiller AG, Baar CH-6341, Switzerland) was equipped with two custom made cords for unipolar recording. These cords were made from 10 m screened cables ending in an insulated

Homing Behaviour in an Atlantic Walrus (&lt;I&gt;Odobenus rosmarus rosmarus&lt;/I&gt;)

An adult Atlantic walrus (Odobenus rosmarus rosmarus) male (31 years old in 2001) tracked by use of satellite telemetry in NE Greenland during four seasons (1989, 1990/1991, 2000/2001, 2001) revealed a remarkably high perennial tendency of homing and consistency of migration pattern. During all four inshore summering periods (August to September), the animal used only one terrestrial haul-out from which it made excursions to the same general shallow water area (i.e., likely clam beds) in western Dove Bay (ca. 76o to 77o N). In different years, the size of the inshore foraging area varied between 48 and 86 km 2 in August, and between 136 and 385 km 2 in September. The inshore foraging period lasted ca. 69 days in 1989 and 1990, but ca. 86 days in 2000 (no data for 2001). During fall 1989, 1990/1991 and 2000/2001, the walrus followed the same migration route in the Greenland Sea north to the wintering grounds in the Northeast Water polynya (ca. 79o to 81o N). Apparently, this movement pattern was relatively independent of annual variations in ice and temperature regimes. Offshore in the Greenland Sea–Fram Strait area, the walrus occurred mainly in areas with dense ice cover (> 90%). During both the inshore summer and offshore winter, the animal dived to at least 250 m (maximum depth limit of the transmitter). The tracking of this walrus, whose activity pattern was typical of male walruses in the region, shows that this stenophagous species is a creature of habit with a highly stereotypic movement pattern which apparently is influenced by the location of predictable feeding, wintering, and mating areas.

Historical and present distribution, abundance and exploitation of Atlantic walruses (Odobenus rosmarus rosmarus L.) in eastern Greenland

The status of the Atlantic walrus (Odobenus rosmarus rosmarus L in eastern Greenland is reviewed on the basis of several historical and recent sources of information on distribution, numbers and catch. Walruses occur in small groups along the east coast of Greenland from approximately 63° N to approximately 81° N. Their largest abundance is, however, north of approximately 73° 30' N. The sexes are generally segregated during summer: During August and September, about 50 males are found at each of two terrestrial haulouts Sandøen (74° 15' N) and Lille Snenæs (76° 52' N).&#x0D; Movement of walruses that could be identified from natural marks indicates that there is a connection between the two groups. During summer, the majority of mature females and subadults of both sexes are distributed further north, between about 80° N and about 81° N. Walruses winter in the Northeast Water Polynya, in leads and cracks in the offshore pack ice in the Fram Strait and Greenland Sea between about 78° N and about 81° N, further south in smaller recurring polynyas, and in the shear zone between fast ice and the pack ice along the east coast of Greenland. Although a connection between walruses in eastern Greenland and Svalbard has been demonstrated, the extent to which the eastern Greenland population is geographically isolated from groups further east has not been determined.&#x0D; A total kill of about I 680 walruses (including walruses killed-but-lost) by European sealers and hunters between 1889 and 1955 severely reduced the walrus population in eastern Greenland. Back-calculations based on estimates of the present population size of between 500 and 1000 walruses indicate that this population numbered between 700 and 1900 individuals in 1889, and most likely about 900 individuals.&#x0D; It is estimated that Greenlanders removed 20 to 30 walruses (primarily males) annually during the 198Os and 199Os (23% killed-but lost animals included). This appears to be a sustainable catch.

The Atlantic walrus (Odobenus rosmarus rosmarus) in West Greenland

In the early part of the 20th century Atlantic walruses (Odobenus rosmarus rosmarus) occurred abundantly between approximately 66°N and 70°45'N in Central West Greenland from September until mid June. Between September and December several hundred walruses hauled out on small islands and promontories between the entrance to Nassuttooq (Nordre Strømfjord, approx. 67°30'N) and approximately 67°45'N, south of the settlement of Attu. From 1911, the hunt for walruses at terrestrial haul out sites was intensified, and by the late 1930s the walruses had abandoned the terrestrial haul outs in this area.&#x0D; Between 1911 and the early 1940s, the catches of walruses in western Greenland (excluding the Avanersuaq/Thule area) increased rapidly, reaching a maximum of more than 600 animals reported for 1938 and 1940. Mainly reproductive females were caught and the proportion of unretrieved kills was high. Between the early 1940s and the mid 1960s catches decreased rapidly, apparently reflecting a decrease in the stock of walruses wintering off Central West Greenland. Between 1965 and 1987, the recorded annual catch in western Greenland south of 76°N averaged 56 walruses (SD = 19.7; range 19- 101 animals). It is estimated that during this period the total number of walruses removed by hunting was about 100 per year.&#x0D; Comparisons of the results of systematic aerial surveys conducted in early spring of 1981, 1982, 1984, 1990 and 1991 over the walrus wintering grounds at Central West Greenland revealed no trend in abundance. The line transect methods used in the 1990 and 1991 surveys gave higher and more robust estimates of abundance than the strip censuses used in the previous surveys, and resulted in estimates of abundance of about 500 walruses (not corrected for submerged animals).&#x0D; The stock structure of the total walrus population in the Baffin Bay and Davis Strait regions is obscure. However, this study has shown that the numbers of walruses in Central West Greenland are much lower than historical levels, and that walruses in this area are vulnerable.