Polar bear  (Ursus maritimus)

Polar bears are not endangered, though if hunting was not regulated they would be, due to their slow rates of population growth. They do face threats however, that must be constantly monitored (4). The Polar Bear Specialist Group reported in their 2005 meeting that the greatest challenge to the conservation of polar bears may be large-scale ecological change resulting from climatic warming, if the trend documented in recent years continues (5). Other threats to this species include pollution, poaching, and disturbances from industrial activities (4) (5).

While the effects of climate change are not certain, it is recognised that even minor climate changes can have profound effects on polar bears and their sea-ice habitat (4). For example, if climate change results in increased snow in the Arctic, polar bears may be less able to hunt prey by entering seal birth lairs, which will affect the survival of both polar bear adults and cubs. On the other hand, if there is reduced snow and increased seasonal rain, seal productivity may be reduced as the lairs may not be thick enough to protect the pups as they develop, or lairs may collapse and kill the seals. In turn this would reduce prey for the polar bears. Unusual warm weather could also impact the polar bear's denning activity (6).

Persistent Organic Pollutants (POP) also pose a threat to polar bears. Studies on the accumulation of organochlorines (caused by pollutants) through food chains have shown that polar bears, as top predators, are at risk of accumulating elevated levels of these compounds. These levels are associated with a range of effects, including neurological, reproductive and immunological changes, which may, for example, reduce ability to fight diseases and reproduce (6).

In the 1960s and 1970s, extensive hunting of polar bears had pushed them to the brink of extinction. This threat had a considerable impact on polar bear populations, and, though hunting is now controlled, populations are still recovering (4).

Following the drastic population losses of polar bears in the 1960s and 1970s, an international accord was reached between the five nations with polar bears (Canada, Norway, US, the former USSR and Denmark, which governed Greenland at that time) (4). These nations signed the ‘International Agreement on the Conservation of Polar Bears', and agreed to prohibit unregulated hunting and to outlaw the hunting of the bears from aircrafts and icebreakers (4). The agreement also obliged each nation to protect polar bear denning sites and migration routes, as well as undertake and share information on polar bear research (4). This was one of the first and most successful international conservation measures of the 21st century and was responsible for the recovery of the polar bear (4). The threats caused by climate change are now the main concern, especially as the rate at which environmental changes could occur may be faster than the rate at which many species can adapt. More than ever, the complexity of these issues and their global nature will demand international cooperation if this species and other wildlife is to survive (4).