| Summary | A top predator which relies heavily on the marine environment used in this case as a proxy for ecosystem health |
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| Project | SESMAD |
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| Subtype | Natural Resource Unit |
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| Sector | Marine protected areas |
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| Biotic | Yes |
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| Explanation | |
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| Commons Aggregation | |
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| Explanation | The polar bears in the Nature Reserves in Svalbard represent a sub-set of the larger polar bear community across the Arctic. |
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| Commons Boundaries | Somewhat unclear boundaries (2) |
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| Explanation | The spatial extent of polar bears on & around Svalbard varies seasonally and between years depending on sea-ice extent. Female bears commonly show fidelity to den areas, but not to specific den sites (Garner et al 2004, Zeyl et al 2010).
The bears of Svalbard are considered reasonably distinct, but part of a larger community of bears across northern Russia. By studying the movements of bears using telemetry, Mauritzen et al (2002) conclude that somewhat discrete populations exist, but that there is spatial overlap between bears within these subpopulations. Paetkai et al (1999) found that there was no substantial genetic difference between bears on Svalbard and north of Russia (and very little difference with East Greenland) suggesting the interbreeding of bears within this range.
In the future, decreasing sea ice may restrict polar bear movement, and decrease the movement between regions. |
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| Commons Indicator | ["Ecosystem health and/or biodiversity"] |
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| Explanation | At the top of the food chain, the polar bear depends on a healthy seal population, which in turn relies on the abundance of various fish species. Therefore, monitoring body condition in polar bears is likely to be a good reflection of prey availability (Polar Institute 2014).
Although not directly related to the Nature Reserves, the polar bear is often used as a flagship species for climate change, since it is sensitive to the changing sea-ice conditions.
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| Commons Unit Size | Large (4) |
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| Explanation | Adult polar bears are typically 400-700kg and 2-3m long. |
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| Environmental Medium | Oceanic |
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| Explanation | The polar bear uses both terrestrial and marine environments. It primarily uses sea ice to hunt ringed and bearded seals (Derocher et al 2002). Svalbard bears use land ice/snow for hibernating and rearing young, and sometimes prey on foxes and reindeer (Derocher et al 2011). |
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| Inter Annual Predictability | High (3) |
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| Explanation | There are several regions within the East Svalbard Nature Reserves which are known to be important for polar bears (e.g. Kong Karls land), however polar bear density by region may vary slightly from year to year depending on sea-ice extent. As a relatively long-lived species with slow reproduction, polar bear populations do not fluctuate extensively from year to year (as compared with a species such as capelin). |
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| Intra Annual Predictability | High (3) |
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| Explanation | The seasonal patterns of the polar bear are reasonably predictable, although may vary according to the weather and sea-ice conditions. Bears hibernate during the polar winter and emerge in the spring. Lønø (1970) observes that females generally enter their dens in November/December, and emerge in April. |
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| Commons Renewability | Renewable (1) |
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| Explanation | |
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| Productivity | |
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| Explanation | The growth of the polar bear populations is relatively slow. On average, female bears in Svalbard do not usually have their first litter until at least 6 years of age, have 1.72 cubs/litter (Derocher 2005), and stay with their cubs for at least a full year (Lono 1970). Cub mortality is estimated at 0.48, which is higher than other polar bear populations (Larsen 1985). There are no reliable population estimates, but Derocher (2005) suggests that changes in age structure, reproductive rates, and body length may be indicators that the population is still recovering from polar bear hunting prior to 1973. |
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| Commons Accessibility | Somewhat accessible (2) |
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| Explanation | When venturing outside settlements of Svalbard, persons are required to carry a rifle in case they encounter a bear, thus indicating that encounters with polar bears are reasonably common. However, navigating from the settlements to view bears specifically within the East Svalbard Nature Reserves presents challenges, and accessibility depends on sea-ice extent. |
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| Commons Heterogeneity | Moderate (2) |
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| Explanation | Moderate
Polar bears are found throughout the polar regions near land with seasonal sea-ice (Mauritzen et al 2002), but are found on some islands in much higher density (e.g. Kong Karls Land).
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| Commons Mobility | Medium (2) |
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| Explanation | The home range of individual polar bears can vary widely from 200km2 to upwards of 400,000km2. The ranges can overlap with other bears, and as a whole, the general population is found in reasonably consistent regions throughout the year. Female bears show fidelity to den areas, but necessarily to specific den sites (Zeyl et al 2010). |
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| Commons Spatial Extent | 15000000 |
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| Explanation | Polar bears are found throughout the Arctic in regions with seasonal sea-ice. |
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| Technical Substitute | No |
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| Explanation | Polar bear viewing is often a highlight for tourists. There is no technical substitute for that kind of interaction. |
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