|Scientific Name:||Ursus maritimus|
|Species Authority:||Phipps, 1774|
Thalarctos maritimus (Phipps, 1774)
|Taxonomic Notes:||Phipps (1774) first described polar bears as a distinct species and named it Ursus maritimus. Other names were suggested including Thalassarctos, Thalarctos and Thalatarctos ultimately settling on Ursus (Thalarctos) maritimus Erdbrink (1953) and Thenius (1953) based on interbreeding between brown bears (Ursus arctos) and polar bears in zoos. Based on the fossil record and evolution Kurtén (1964) recommended the Phipps (1774) name Ursus maritimus, which was promoted by Harrington (1966), Manning (1971) and Wilson (1976) and is used today (see DeMaster and Stirling 1988, Wilson and Reeder 1993, Amstrup 2003 for review and references).|
|Red List Category & Criteria:||Vulnerable A3c ver 3.1|
|Assessor/s:||Schliebe, S., Wiig, Ø., Derocher, A. & Lunn, N. (IUCN SSC Polar Bear Specialist Group)|
|Reviewer/s:||Derocher, A.E. & Born, E.W. (Polar Bear Red List Authority)|
The assessment is based on a suspected population reduction of >30% within three generations (45 years) due to decline in area of occupancy (AOO), extent of occurrence (EOO) and habitat quality.
Polar bears rely almost entirely on the marine sea ice environment for their survival so that large scale changes in their habitat will impact the population (Derocher et al. 2004). Global climate change posses a substantial threat to the habitat of polar bears. Recent modeling of the trends for sea ice extent, thickness and timing of coverage predicts dramatic reductions in sea ice coverage over the next 50?100 years (Hassol 2004). Sea ice has declined considerably over the past half century. Additional declines of roughly 10?50% of annual sea ice are predicted by 2100. The summer sea ice is projected to decrease by 50?100% during the same period. In addition the quality of the remaining ice will decline. This change may also have a negative effect on the population size (Derocher et al. 2004). The effects of sea ice change are likely to show large differences and variability by geographic location and periods of time, although the long term trends clearly reveal substantial global reductions of the extent of ice coverage in the Arctic and the annual time frames when ice is present.
While all bear species have shown adaptability in coping with their surroundings and environment, polar bears are highly specialized for life in the Arctic marine environment. Polar bears exhibit low reproductive rates with long generational spans. These factors make facultative adaptation by polar bears to significantly reduced ice coverage scenarios unlikely. Polar bears did adapt to warmer climate periods of the past. Due to their long generation time and the current greater speed of global warming, it seems unlikely that polar bear will be able to adapt to the current warming trend in the Arctic. If climatic trends continue polar bears may become extirpated from most of their range within 100 years.
There is little doubt that polar bears will have a lesser AOO, EOO and habitat quality in the future. However, no direct relation exists between these measures and the abundance of polar bears. While some have speculated that polar bears might become extinct within 100 years from now, which would indicate a population decrease of >50% in 45 years based on a precautionary approach due to data uncertainty. A more realistic evaluation of the risk involved in the assessment makes it fair to suspect population reduction of >30%.
Other population stress factors that may also operate to impact recruitment or survival include toxic contaminants, shipping, recreational viewing, oil and gas exploration and development. In addition to this comes a potential risk of over-harvest due to increased quotas, excessive quotas or no quotas in Canada and Greenland and poaching in Russia.
This assessment was reviewed by all the participants at the 14th Working Meeting of the IUCN SSC Polar Bear Specialist Group held in Seattle, Washington, USA during June 20-24, 2005.
Polar bears live throughout the ice-covered waters of the circumpolar Arctic, and their range is limited by the southern extent of sea ice. Although some occur in the permanent multi-year pack ice of the central Arctic basin, they are most common in the annual ice over the continental shelf and inter-island archipelagos that surround the polar basin. Polar bears that have continuous access to sea ice are able to hunt throughout the year. However, in those areas where the sea ice melts completely each summer, polar bears are forced to spend several months on land fasting on stored fat reserves until freeze-up. Use of land by polar bears during the ice-free season appears to be increasing in certain locations.
The species is found in Canada (Manitoba, Newfoundland, Labrador, Nunavut, Northwest Territories, Quebec, Yukon Territory, Ontario), Greenland/Denmark, Norway (including Svalbard), Russian Federation (North European Russia, Siberia, Chukotka, Sakha (Yakutia), Krasnoyarsk), United States (Alaska). Also, vagrants occasionally reach Iceland.
Canada (Labrador, Manitoba, Newfoundland, Northwest Territories, Nunavut, Ontario, Québec, Yukon); Greenland; Norway; Russian Federation (Krasnoyarsk, North European Russia, West Siberia, Yakutiya); Svalbard and Jan Mayen; United States (Alaska)
|FAO Marine Fishing Areas:||
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||There are nineteen hypothesized subpopulations or stocks which number in total 20,000 to 25,000 bears. Considerable overlap of putative populations occurs and genetic differences among them are small.|
|Habitat and Ecology:||
Polar bears occur at low densities throughout their range and are most abundant in shallow water areas near shore or where currents or upwellings increase biological productivity near ice areas associated with open water, polynyas or lead systems. Polar bears are not as abundant in the high central arctic over deeper waters of the polar basin.
Seasonally, in the summer open water season in the Canadian arctic islands and Svalbard, and in recent years during the fall in northern Alaska and Russian Chukotka, polar bears may be found on land in higher densities.
Breeding occurs in March to May, implantation is delayed until autumn, and birth is generally thought to occur from late November to mid-January. Although some cubs are born in earth dens, most births occur in snow dens that may be occupied between 5?6 months during the maternal event. In Alaska the maternal dens are located on the offshore sea ice. Only pregnant female polar bears den for this protracted period of time, during which time they rely on fat stores for energy and sustenance. The average litter size is less than two. Cubs are dependent upon mothers until after the start of their third year of life. Age of first reproduction is normally 5?6 years for females. These factors contribute to the low reproductive potential for the species.
The Intergovernmental Panel on Climate Change and the Arctic Climate Impact Assessment have both predicted that the Arctic is extremely vulnerable to projected climate change. Polar bears will likely be shifted pole-ward if the sea ice retreats. According to new scenarios presented by the Nansen Environmental and Remote Sensing Centre and others, the polar ice cap will disappear almost entirely during summer in the next 100 years.
The increasing changes in the sea ice that affect access to prey will have a negative effect on the bears. With less food, polar bears will fail to reproduce more often and give birth to smaller young that have higher mortality rates.
Polar bears may be forced on shore for extended periods and rely on fat reserves deposited the previous spring for survival. In such a situation they will be increasingly vulnerable to hunting if not regulated. If these periods become excessively long, mortality will increase. Sea ice is also used for access to den areas and if ice patterns change, existing den areas may be unreachable. Warmer temperatures and higher winds may reduce ice thickness and increase ice drift. Because polar bears must walk against the moving ice (like walking the wrong way on an escalator) increased ice movements will increase energy use and reduce growth and reproduction.
Polar bears are the apex predator and are exposed to high levels of pollutants that are magnified with each step higher in the food web. A key characteristic of the pollutants is that they tend to persist in the environment and resist degradation. Many of the organochlorine pollutants are lipophilic or "fat loving" and bond tightly to fat molecules. Polar bears are particularly vulnerable to organochlorines because they eat a fat rich diet. Ringed, bearded, and harp seals comprise the main food of polar bears and the blubber layer is preferentially eaten by the bears and subsequently, the intake of pollutants is high.
Certain areas of the Arctic, such as northeastern Greenland, the Barents Sea and the Kara Sea, have higher levels of pollutants. Based on studies in other species, it is reasonable to believe that the pollutant load of polar bears in some areas are negatively affecting the immune system, hormone regulation, growth patterns, reproduction, and survival rates of polar bears. Recent studies have suggested that the immune system is weaker in polar bears with higher levels of PCBs. A major concern with polar bears pertains to their reproductive system. There are suggestions that species with delayed implantation are more vulnerable to the effects of pollution through endocrine (hormone) disruption. Further, female polar bears are food deprived during gestation their pollution loads increase because as they use their fat stores, where pollutants are stored, for energy. Because the cubs are nursed on fat rich milk, the cubs are exposed to very high pollution loads from their mother.
Oil development in the Arctic poses a wide range of threats to polar bears ranging from oil spills to increased human-bear interactions. It is probable that an oil spill in sea ice habitat would result in oil being concentrated in leads and between ice floes resulting in both polar bears and their main prey (ringed and bearded seals) being directly exposed to oil. Another concern is that seals covered in oil may be a major source of oil to polar bears. Other studies suggest that polar bears are sensitive to disturbance at maternity den sites. Disturbance could occur both when a pregnant female is selecting a den site and during the winter-spring after the cubs are born. If exploration or development occurred sufficiently close to a den, the mother may abandon the den prematurely or abandon her offspring.
Over-harvest is an ongoing concern for some polar bear populations: particularly in areas where there is no information on population size (e.g., Québec, east Greenland, and the Chukchi Sea) and no quotas. It is important that population estimates and projections are based on substantiated scientific data. An additional concern is that population inventory programs occur relatively infrequently in some areas so if the harvest rate is above the sustainable level, the population may be reduced before the next inventory is made. Recent development of co-management agreements and greater involvement of local people and hunters is improving the management of polar bears in some areas.
The principle use of polar bears in the circumpolar arctic is for subsistence purposes. These include consumption of meat; use of hides in the construction of clothing such as mittens, boots (mukluks), fur ruffs for parkas, and fur pants; and small scale creation of items of handicraft. The US (Alaska), Canada and Greenland manage a subsistence harvest. Norway and Russia prohibit harvest of polar bears. In Russia during the early 1990s an unsanctioned harvest of polar bears began following dissolution of the Soviet Union. Levels of harvest are not quantified.
In Canada a portion of the annual harvest is by sports hunters employing native guides utilizing traditional harvest methods such as dog-teams. The harvest levels are regulated and based on principles of sustainable resource management. Greenland introduced a quota system which came into force on January 1, 2006 and plans to start sport hunting in the near future.
A small number of orphaned cubs are placed in zoos and public display facilities.
Research activities: live capture and release of polar bears.
Public viewing and photography are another form of utilization and occur locally at Churchill, Canada, and other remote areas, at specific locals in Svalbard, Norway, and to a limited extent in location on the north coast of Alaska.
Conservation actions vary by jurisdiction. The International Agreement on the Conservation of Polar Bears provides guidance, and Article II of the Agreement states that each contracting party "shall manage polar bear populations in accordance with sound conservation practices based on the best available scientific information," and according to Article VII, "The Contracting Parties shall conduct national research programs on polar bears" and "..consult with each other on the management of migrating polar bear populations". These articles have been important for stimulating governments to support applied research to answer management questions regarding polar bears throughout their range. This work is coordinated through the IUCN SSC Polar Bear Specialist Group (PBSG). Resolutions from the PBSG are developed and directed toward ensuring that the terms and intentions of the Agreement are being met.
Coordinated research is ongoing, management actions reviewed for consistency, and legislation to effect bilateral management for internationally shared populations such as between the US-Russia is being pursued. Additional cooperative management agreements between Canada and Greenland are desirable and currently being developed.
Additional details of the Global Status and Management of Polar Bears are contained in the IUCN "Status Survey and Conservation Action Plan: Bears" (Servheen et al. 1999).
It is listed on CITES Appendix II.
|Citation:||Schliebe, S., Wiig, Ø., Derocher, A. & Lunn, N. 2008. Ursus maritimus. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 16 June 2012.|
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