Population

Polar bear population facts are somewhat sketchy since much of the areas that Polar bears live in is inhospitable and sparsely populated. They largely live on the ice flows upon which they depend for food, reproduction and child rearing. This makes tracking them for scientific research complicated.

They are native to Canada, Greenland, Alaska and parts of eastern Russia being widely scattered in Canada, from the northerly Arctic islands and south to the Hudson Bay.  There have been sightings of Polar bear tracks as far north as the North Pole, however scientists believe that very few bears travel beyond 82 degrees North latitude. The northern Arctic Ocean has insufficient food available to support them.

No completely accurate census exists on which to base a global population approximation, but wildlife scientists use a working estimate of around 20,000 to 25,000 bears with about 60% of those dwelling in Canada's far North.

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In more populated regions where long-term analyses are obtainable, populations are bearing witness to signs of strain due to contracting sea ice. Canada's Western Hudson Bay population has deteriorated 22% since the early 1980s. The declines have been directly associated to an earlier ice break-up on Hudson Bay. A long-term study of the Southern Beaufort Sea population, which traverses the northerly seashore of Alaska and western Canada, has unveiled a decline in cub survival rates and in the weight and skull size of adult males. Such declines were noted in Western Hudson Bay bears preceding the population drop-off there. Another population listed as slumping is Baffin Bay. According to the latest report from the Polar Bear Specialist Group, the harvest levels from Nunavut when aggregated with those from Greenland (which were believed to be much lower than they really are) has resulted in this shared population to be in a non-sustainable harvest position, signifying that the population is in heavy danger of a severe decline. The Polar bear harvest is thought to be many times above what is sustainable.

The available data strongly suggests that Polar bear populations are in steep decline. Global climate change which is breaking up Polar ice packs is a chief suspect in the decline. However, research is not conclusive and further study is required.

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Name and Taxonomy

Kingdom:
ANIMALIA

Phylum:
CHORDATA

Class:
MAMMALIA

Order:
CARNIVORA

Family:
URSIDAE

Common Name/s:
POLAR BEAR (English)
OURS BLANC (French)
OURS POLAIRE (French)
OSO POLAR (Spanish)

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Species Authority:
Phipps, 1774

Synonym/s:

Thalarctos maritimus (Phipps, 1774)

Taxonomic Notes:
Phipps (1774) first identified polar bears as a distinct and separate species and titled it "Ursus maritimus" meaning "Sea Bear". Additional names were suggested including "Thalassarctos", "Thalarctos" and "Thalatarctos" at last settling on "Ursus (Thalarctos) maritimus" Erdbrink (1953) and Thenius (1953) based on crossbreeding between brown bears (Urus arctos) and polar bears in zoos. As a result of the fossil record and evolution Kurtén (1964) suggested the Phipps (1774) name "Ursus maritimus", which was advanced 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).

Other Names:

Ice Bear, Nanook

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Pollution

 Polar bear facts about pollution have not been written about as widely these days as the effects of global climate change. However, added together they represent a potentially fatal blow to the Polar bear population.

Most of the pollution in the Arctic is transported Northward by the large rivers draining into the Arctic and on wind and ocean currents that bring pollutants from southern latitudes. Polar bears feed on other Arctic marine animals such as seals which easily store fat in their blubber. As a result, a Polar bear carries a concentration of pollutants many times greater than that in the rest of the Arctic Ocean.

PBDEs (Polybrominated diphenyl ethers), a flame retardant found in hard plastic and polyurethane foam, have been detected in every Arctic species tested including fish, seals, Polar bears, beluga whales, pilot whales and birds. Many of these species are on the menu of Polar bears which are at the top of the Arctic food chain.

From water to algae to shrimp to cod to ringed seals to Polar bears — at each step up in the food chain, PBDEs increase five- to tenfold in a process called bio-magnification.

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Based on studies in other species, it is reasonable to believe that the concentration of pollutants in Polar bears in some areas are negatively affecting the immune system, hormone regulation, growth patterns, reproduction, and survival rates of Polar bears. Because cubs are being nursed on the fat rich milk of their mothers, they  are being exposed to very high pollution levels.

Recent studies in Norway and Canada show that Polar bears' immune cells and antibodies, needed to fight off disease, have been suppressed, and that their levels of testosterone, progesterone, vitamin A and thyroid hormones are altered by PBDEs. The most polluted Polar bears live in NE Greenland, the Barents Sea and the Kara Sea.

A mother Polar bear stores chemicals from a lifetime of exposure in her fat cells. The bodies of Polar bears are very efficient at metabolizing (breaking down) some pollutants but the problem is that many of these metabolites (by products of the break down process) are very active in their bodies before they are excreted. Furthermore, because female Polar bears fast during gestation the amount of pollution that is active in their bodies increases because they are using their fat stores for energy. This is where the pollutants they ingest from other marine animals is naturally stored. Because Polar bear cubs are nursed on fat rich milk, the cubs are exposed to very high pollution levels from their mothers and this is what makes the future of Polar bears questionable. That's borne out by the fact that most Polar bears die before their first birthday. This can be due to natural causes of course but pollution has increased their mortality rate significantly.

Another major concern with Polar bears as a result of pollution pertains to their reproductive and immune systems. There is evidence that suggests that the hormone system of Polar bears is affected by pollution and this may interfere with reproduction and growth and a weakened immune system may mean that these Polar bears are more susceptible to succumbing to disease or parasites.

Given that no Polar bear in the world is free from pollution, there is a great cause for concern.  Although some pollutants such as PCBs have had their levels dramatically reduced, there is still a lot of work to be done by governments to totally erase the negative impact that human pollution has on Polar bears.

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