Polar bear numbers dwindling as their hunting ground melts away

Polar bears have been the poster child for climate change, with multiple studies suggesting their overall numbers have been declining in recent years as Arctic sea ice continues to melt.

Adding to the concern is a new round of research coming out this week in the journal Ecological Applications that has found various polar bear populations in the southern Beaufort Sea, situated north of Alaska and Canada, have drastically dropped by 40 per cent since the start of this century.

The same study also found the juvenile survival rates were particularly worrisome, with only 2 of 80 cubs tracked in the project known to have survived.

This apparent crash in young cub survival rates comes on the heals of another study out last May that found plummeting number of births in Norway’s Arctic islands of Svalbard. The Barents Sea population of polar bears are thought to be one of the biggest, numbering a few thousand, but here too, suggestions are that the sea ice, which is the animals’s hunting ground, is rapidly dwindling.

While the overall population in the Beaufort Sea seemed to have an uptick near the end of the study, the authors suspect the low survival rates may have been caused by the increasingly thinner and more mobile ice during winters that makes it harder for the bears to hunt seals, their traditional prey.

However the polar bear’s suspected plight is not without controversy. While the International Union for the Conservation of Nature lists the species overall as vulnerable to extinction, we have to keep in mind that there are 19 distinct sub-populations scattered across the top of the world, from Canada, Russia, Norway and Denmark and nearly half of them have hardly been studied. The species can be particularly tricky to count because they can move across international borders, cross ice packs and open waters that span hundreds of kilometers.And let’s face it: These white furry guys can easily blend in amongst the expansive snow fields, virtually remaining undetectable.

While some of the populations are counted more often than others, sometimes biologists end up using different survey methods from one time to the next. Adding to the confusion are the population statistics, where some numbers coming out indicate a significant downward spiral, while others show healthy, stable numbers.

In the western Hudson Bay area, for instance, where the polar bear population is one of the most studied in the world, the number of polar bears has increased since the 1970s.

Scientists say that much is unknown about polar bear numbers because so much is still undocumented. But just because polar bear numbers may appear stable in some regions, it may be giving false hope.

Polar bear biologist Steven Amstrup, who studies the species in Hudson Bay, told NPR in an interview last year that the sea ice in the region is frozen a whole month less annually than it was three decades ago. This has meant that the polar bears don’t get to go out on the bay to hunt as much as they used to and as a result they are getting skinner and are in poorer condition.

"They’re 60 pounds lighter now than they might have been at this time of year 30 years ago," said Amstrup, a professor at the University of Wyoming.

"It’s really, really clear we have a problem. And yet we see very little action on either the national or even the international scale."