between Arctic nations about management and harvests. But management and hunting quotas would only be a national or possibly bilateral issue for discrete populations.

Studies of polar bear population discreteness were prioritized in the years that followed. There are now thought to be between 20,000 and 25,000 bears in the world, which occur in 19 relatively discrete sub-populations5,6

. I

Threats The polar bear is identified as Vulnerable by the IUCN Red List based on a suspected population reduction due to loss of sea ice habitat caused by climate warming7

. Other population

stress factors include over-harvest, toxic contaminants, shipping, recreational viewing, oil and gas exploration, and development7

.

Retreating and thinning sea ice may affect polar bears in many ways8

II . Less sea ice makes it difficult for the bears to

hunt seals, or may even reduce seal numbers. When waters around traditional polar bear denning areas are ice-free, pregnant females may have difficulties in getting ashore to dig maternity dens. Pregnant females that are stranded on shore, may have less access to food when the sea ice disappears in spring and summer so that their overall condition is reduced when they give birth in late autumn9,10

. Lack of fat reserves

may limit their ability to nurse cubs for three to four months and cub mortality may increase. There are several factors that have consequences for population growth and sustainability11

.

Some populations are already showing signs of stress and IUCN’s International Polar Bear Specialists Group fears that poor ice conditions will have significant negative impacts on polar bear populations in the near future. The world’s polar bear population could be reduced by two-thirds by the year 2050 if climatologists are correct about the extent that sea ice will change in the coming decades1

. Also, less sea ice is

increasing human-polar bear interactions (by forcing polar bears to stay on land for longer periods) which may have negative impacts on both polar bears and people in these regions in coming years12

. 74 PROTECTING ARCTIC BIODIVERSITY

Many parts of the Arctic are affected by air and seaborne transboundary pollutants that may have far-reaching negative effects upon Arctic ecosystems. Topping the food chain in the Arctic, the polar bear is exposed to high levels of pollutants that are magnified with each step higher in the food web (a process known as biomagnification). Recent studies have suggested that the immune system may be weaker in polar bears with higher levels of toxic contaminants (e.g., Polychlorinated Biphenyls or PCBs)2

. There is also

evidence that the hormone system of polar bears is affected by pollution, something that may interfere with reproduction and growth2

. Climate change could also indirectly affect Arctic animals topping the food chain, such as the polar bear, through the secondary release of toxic contaminants have long been trapped in snow, ice and permafrost that is now melting13,14

. Regulating POPs and marine pollution

The Nunavut government decided, in the beginning of March 2010, to reduce the hunting quotas of the Baffin Bay polar bear population from 105 to 65 animals by 2013. This is a region where polar bear numbers have been disputed by scientists and Inuit. Inuit in Baffin Bay have demanded compensation for hunters who have long relied on polar bears as part of their livelihoods. The bears create an important income source through the sales of hides and sport-hunting packages.

At the time, the Nunavut government also hoped that slashing the hunting quota in Baffin Bay would help Canada sway international opinion away from a U.S. proposal to ban the commercial trade of polar bear products, by reclassifying the polar bear as a species at risk of extinction under the Convention on the International Trade in Endangered Species (CITES)20

. The U.S. proposal to CITES

was subsequently rejected by a majority of governments in late March 201016

.