Potential population-level effects of increased haulout-related mortality of Pacific walrus calves

Udevitz, Mark S.; Taylor, Rebecca L.; Garlich‐Miller, Joel L.; Quakenbush, Lori T.; Snyder, Jonathan A.

doi:10.1007/s00300-012-1259-3

Cited by 39 publications

(34 citation statements)

References 15 publications

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“…Finally, walruses ( Odobenus rosmarus ) offer an additional large prey in the CS (Rode et al., ) that is nearly absent from the BS. Although polar bears rarely kill adult walruses, recent large aggregations on terrestrial haul‐outs have led to juvenile mortality during disturbance‐related stampedes (Udevitz, Taylor, Garlich‐Miller, Quakenbush, & Snyder, ). With calves and juveniles weighing ≥60 kg (Fay, ), such carcasses can offer substantial resources for polar bears in the CS.…”

Section: Discussionmentioning

confidence: 99%

Increased Arctic sea ice drift alters adult female polar bear movements and energetics

Durner

Douglas

Albeke

et al. 2017

Global Change Biology

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Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice drift could significantly affect the movements and the energy balance of polar bears (Ursus maritimus) which forage, nearly exclusively, on this substrate. We used radio‐tracking and ice drift data to quantify the influence of increased drift on bear movements, and we modeled the consequences for energy demands of adult females in the Beaufort and Chukchi seas during two periods with different sea ice characteristics. Westward and northward drift of the sea ice used by polar bears in both regions increased between 1987–1998 and 1999–2013. To remain within their home ranges, polar bears responded to the higher westward ice drift with greater eastward movements, while their movements north in the spring and south in fall were frequently aided by ice motion. To compensate for more rapid westward ice drift in recent years, polar bears covered greater daily distances either by increasing their time spent active (7.6%–9.6%) or by increasing their travel speed (8.5%–8.9%). This increased their calculated annual energy expenditure by 1.8%–3.6% (depending on region and reproductive status), a cost that could be met by capturing an additional 1–3 seals/year. Polar bears selected similar habitats in both periods, indicating that faster drift did not alter habitat preferences. Compounding reduced foraging opportunities that result from habitat loss; changes in ice drift, and associated activity increases, likely exacerbate the physiological stress experienced by polar bears in a warming Arctic.

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Section: Discussionmentioning

confidence: 99%

Increased Arctic sea ice drift alters adult female polar bear movements and energetics

Durner

Douglas

Albeke

et al. 2017

Global Change Biology

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“…Other marine mammals are generally less well studied than polar bears, but impacts of changing ice conditions have also been documented in the past decades for various ice‐dependent pinnipeds. For example, Pacific walruses ( Odobenus rosmarus ) have shifted their summer distribution and haul‐out patterns markedly, coming ashore in vast herds on the coasts of Alaska and far eastern Siberia as the Bering Sea ice has retracted north of the shelf in recent years, increasing the risk of calf mortality [ Udevitz et al ., ]. Availability of suitable ice has become an issue for harp seals ( Pagophilus groenlandicus ) at their southernmost breeding area and breeding failure occurs more frequently now than a few decades ago [e.g., Bajzak et al ., ; Johnston et al ., ], and a recent dramatic reduction in pup production of this species has been documented in the White Sea population [ International Council for the Exploration of the Sea , ].…”

Section: Biological Impacts Of the Changing Sea Ice Covermentioning

confidence: 98%

Arctic sea ice in transformation: A review of recent observed changes and impacts on biology and human activity

et al. 2014

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Sea ice in the Arctic is one of the most rapidly changing components of the global climate system. Over the past few decades, summer areal extent has declined over 30%, and all months show statistically significant declining trends. New satellite missions and techniques have greatly expanded information on sea ice thickness, but many uncertainties remain in the satellite data and long-term records are sparse. However, thickness observations and other satellite-derived data indicate a 40% decline in thickness, due in large part to the loss of thicker, older ice cover. The changes in sea ice are happening faster than models have projected. With continued increasing temperatures, summer ice-free conditions are likely sometime in the coming decades, though there are substantial uncertainties in the exact timing and high interannual variability will remain as sea ice decreases. The changes in Arctic sea ice are already having an impact on flora and fauna in the Arctic. Some species will face increasing challenges in the future, while new habitat will open up for other species. The changes are also affecting people living and working in the Arctic. Native communities are facing challenges to their traditional ways of life, while new opportunities open for shipping, fishing, and natural resource extraction. Significant progress has been made in recent years in understanding of Arctic sea ice and its role in climate, the ecosystem, and human activities. However, significant challenges remain in furthering the knowledge of the processes, impacts, and future evolution of the system.

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“…In addition to increases in mortality (especially of calves) due to trampling, it is anticipated that increased use of land haul outs may result in increased energy expenditure during feeding bouts and reduced access to preferred feeding grounds. Specifi cally, projections indicated that an increase in mortality of walrus calves at land haul outs had a greater effect on the population than an equivalent increase in harvest-related mortality distributed among all age classes (Udevitz et al 2013 ). Specifi cally, projections indicated that an increase in mortality of walrus calves at land haul outs had a greater effect on the population than an equivalent increase in harvest-related mortality distributed among all age classes (Udevitz et al 2013 ).…”

Section: Changes In Life-history and Diet Of Walruses And Seals In Thmentioning

confidence: 99%

The Pacific Arctic Region

Grebmeier¹,

Maslowski²

2014

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Potential population-level effects of increased haulout-related mortality of Pacific walrus calves

Cited by 39 publications

References 15 publications

Increased Arctic sea ice drift alters adult female polar bear movements and energetics

Increased Arctic sea ice drift alters adult female polar bear movements and energetics

Arctic sea ice in transformation: A review of recent observed changes and impacts on biology and human activity

The Pacific Arctic Region

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