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- Valued Component Features
- Polar Bear research in ASTIS
Valued Component Features
Rationale for Selection
Polar bears are an integral component of the Arctic ecosystem in Nunavut as they are the top predator within the food web. Polar bears also have significant cultural and economic importance to the Inuit and are hunted by almost all communities (Priest and Usher 2004). Over a five year period from 1996 to 2001 the mean number of polar bears taken from hunting was approximately 1339 (Priest and Usher 2004). Hides are sold commercially as luxury items and may bring high prices in the fur market. Inuk guided hunting is also a source of income from the tourist industry and polar bear watching tours have also become popular (COSEWIC 2002).
Polar bears rely on sea ice habitat for survival as it provides them access to the seal species that make up the majority of their diet. For this reason, Polar bear habitat shows the same variability from year to year as the sea ice. When this variability is compounded with the uncertainty of the effects that climate change has on arctic ice patterns, it becomes very difficult to accurately identify the spatial boundaries of polar bear key habitat as they are changing from year to year and decade to decade. Key habitat for polar bears includes areas of active ice (leads, polynyas) in the spring and early summer when access to prey is most critical.
Polar bears prefer productive waters near shorelines, the edge of the pack ice and polynyas as these areas provide access to the seals that they prey on. Landfast ice also provides important foraging habitat for polar bears in the spring when seals and their pups are in their birth lairs. Polar bears tend to return to the same denning area year after year or an area of similar habitat quality (Lunn, et al. 2004; Stirling, et al. 2004). Denning areas in the high arctic study area are concentrated along the coastal regions of Melville Island, Bathurst Island, Ellesmere Island, and Alex Heiberg Island. In portions of the high arctic, polar bears are forced onto the land in the summer as the ice recedes and spend up to several months in summer retreat areas while they wait for the ice to return. These areas have been identified on Bathurst Island and northeastern Devon Island (Figure 4-1).
Limitations to polar bear populations include relatively low reproductive capacity, hunting, environmental contamination, offshore and land-based oil and gas exploration, industrial development and climate change.
Female polar bears have low reproductive rates, which makes them vulnerable to any threat that could impact health and population abundances (COSEWIC 2002).
Polar bears are vulnerable to pollutants directly and indirectly. They are the top predator in Arctic food webs and therefore are susceptible to bioaccumulationFootnote 1. within this ecosystem. These toxins can accumulate in polar bear tissues from the prey items consumed. Pollutants may interfere with hormone regulation, immune system function, and possibly reproduction (Stirling 1990).
Susceptibility to Oil and Gas Activities
Increased human activity, oil and gas exploration and coastal development in the Arctic may diminish important land based maternity denning habitat and possibly spring feeding habitats at the ice edge.
Marine based seismic exploration can only proceed in areas of open water. Although it is not uncommon to see polar bears swimming in open water, adverse interactions with polar bears would be unlikely and effects would be limited. The impact of land-based activities on maternal denning has not been studied.
The presence of stationary drill-ships and drill-sites has been shown to attract polar bears, possibly from seal utilization of rig-induced cracks (Stirling 1998). This may increase access to prey (Richardson, et al. 1995) but may also increase the threat of killing these bears in areas of higher human activities.
Polar bears do not seem to be deterred from noise associated with offshore oil activities (even when swimming in the water), construction, ice-breakers or vessel traffic (Richardson, et al. 1995).
Physiological studies on the effects of oil on polar bears show there is a high probability that a single major oil spill in a critical habitat area for polar bears may have a significant effect on the population (COSEWIC 2002). Polar bears have been shown to be extremely sensitive to the toxic effects of oil and quickly succumb to kidney failure and death when exposed to situations where their fur became oiled, and oil was ingested while grooming (Stirling 1998).
Potential Effects of Climate Change
Climate change poses a significant threat to polar bears because they rely on the ice for traveling, feeding habitat, and denning. Polar bears rely directly on sea ice as a mechanism to travel around the Arctic and indirectly as habitat for their prey (ringed and bearded seals) (Stirling and Øritsland 1995). They have local site fidelity and fixed home ranges which makes them particularly susceptible to changes in their habitat (Derocher, et al. 2004). Changes in the timing, duration, extent and quality of ice thickness due to climate change and its effect on polar bear health, abundance and range has received notable attention from several researchers (Derocher, et al. 2004; Stirling and Parkinson 2006; Stirling and Derocher 2007; Stirling, et al. In press). The main threat consistently identified is habitat loss of sea ice as a result of climate change (Stirling and Derocher 2007).
With changing ice conditions, polar bears may be forced to coastal land areas earlier on in the summer season (Stirling and Parkinson 2006). This may alter the amount of time they spend foraging on seals and would require a longer time spent not feeding and more time relying on stored body fat (Stirling and Parkinson 2006). Changes in the timing and duration of sea ice may also affect polar bears indirectly by changing the distribution of ringed seals forcing them to search for alternative food sources (Stirling and Parkinson 2006). Polar bears may be forced onto coastal land-based areas with higher human activities. Inuit hunters in Nunavut have reported that they see more polar bears near settlement areas during the open water season in recent years (Stirling and Parkinson 2006). All of these changes would increase the difficulty of survival in an already harsh environment (Derocher, et al. 2004).
Winter and Summer sensitivity ranking for Polar bear habitat in the high arctic study area is summarized in Figure 4-2.
High Sensitivity (5)
Habitat defined as highly sensitive for polar bears includes critical habitat as identified under SARA to protect areas that are essential to the survival of species that are listed as threatened or endangered under federal legislations. Critical habitat for polar bears in the high Arctic study area has not yet been identified or protected. Habitat that is legally protected as a park or conservation area is also considered highly sensitive.
Moderate/High Sensitivity (4)
Areas with seasonally dynamic ice, landfast ice, polynyas, and leads provide important feeding areas for polar bears during critical times of the year. These areas are rated as moderate to high sensitivity given that a proportion of the population may be concentrated in the areas at certain times of the year. As sea ice conditions are highly variable from year to year, these areas are rated as moderate/high sensitivity in the summer and winter seasons to indicate that this habitat is important to the polar bear population for periods throughout the year.
Polar bears show high fidelity to denning sites and these areas are essential to the survival of the species. Denning sites are used by polar bears during the open water season for conserving energy while seal hunting is not practical or in the winter for maternity dens.
Areas identified as important polar bear habitat under the Government of Nunavut‘s Wildlife Areas of Special Interest, or under the international Biological Program are also given a rating of moderate/high sensitivity for the summer and winter seasons. There is only one IBP site that falls within the high Arctic Study area.
Moderate Sensitivity (3)
Habitat rated as moderate sensitivity includes areas of dense annual pack ice which provides foraging habitat during non-critical times of the year. This includes the offshore regions of the polar bear core range that are covered in sea ice for most of the winter season.
Low/Moderate Sensitivity (2)
Marine and sea ice habitat outside of the core polar bear range may provide limited denning or foraging use for a lower density of the polar bear population.
Low Sensitivity (1)
Low sensitivity areas include terrestrial habitat and areas outside of the polar bear range.
Polar bears are often curious about development activities and are rarely deterred by the presence of ships, icebreakers, or land-based or ice based facilities, therefore mitigation programs often focus on the prevention of increased interactions between bears and oil and gas activities. As distribution and movement patterns can be variable and dependent on annual ice conditions, monitoring programs are used to ensure that oil and gas activities cause minimal disturbance to bears, and to identify habitat usage in the development area on an ongoing basis. Close communication with local communities and Hunter and trapper organizations, and the use of wildlife monitors onsite during development activities ensure that interactions with bears are minimized and activities do not interfere with critical aspects of habitat use and foraging opportunities.
ReferencesSee references used for polar bear information.
- Footnote 1
Bioaccumulation is the process of accumulationof a substance leading to progressively higher concentrations of a contaminant up through a food chain, via predators ingesting prey that have previously accumulated contaminants in their body tissue
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