Apr 272012
 

Polar Bears International says recent media reports about increasing polar bear numbers in Western Hudson Bay present a highly misleading picture of the actual situation.

The stories “stem[] from a press release on a preliminary study of the Western Hudson Bay population that relied on a different methodology (aerial vs. capture-recapture) and larger geographic survey area than previous studies,” PBI said.

The aerial survey was conducted for the government of Nunavut in Canada. The Inuit population in Nunavut is concerned that the hunting quota in Western Hudson Bay will be lowered.

An article in the Toronto Globe & Mail said the survey “shows the bear population in a key part of northern Canada is far larger than many scientists thought, and might be growing.”

“The bear population is not in crisis as people believed,” Drikus Gissing, Nunavut’s director of wildlife management, told the Globe & Mail. “There is no doom and gloom.”

The Globe & Mail story, by reporter Paul Waldie, provided context.

There’s much at stake in the debate. Population figures are used to calculate quotas for hunting, a lucrative industry for many northern communities. Hunting polar bears is highly regulated but Inuit communities can sell their quota to sport hunters, who must hunt with Inuit guides. A polar-bear hunting trip can cost up to $50,000. Demand for polar-bear fur is also soaring in places like China and Russia and prices for some pelts have doubled in the past couple of years, reaching as high as $15,000.

The Nunavut hunting quota in the western Hudson Bay area fell to 8 from 56 after the 2004 report from Environment Canada. The Nunavut government increased it slightly last year but faced a storm of protest. Over all, about 450 polar bears are killed annually across Nunavut. Mr. Gissing said a new quota is expected to be announced in June.

The article also quoted longtime polar bear scientist Andrew Derocher, who questioned the validity of the survey’s conclusions.

Instead of the survey’s estimate that 1,013 bears are living in the area, PBI chief scientist Steven Amstrup said the more important piece of information is the number of yearlings seen from the air — 22, or 3 percent of the 701 bears “actually counted.”

“By comparison, in Alaska during the good ice years of the 1980s, about 15 percent of the animals observed were yearlings,” PBI said in an email sent out April 26. (See below for the text.)

The brief (eight-page) report from Nunavut notes the paucity of young bears. “Relatively few cubs of the year (50) and yearlings (22) were observed in [Western Hudson Bay] in comparison to the recent polar bear surveys in Foxe Basin in 2009 and 2010. Additionally, average litter sizes were the lowest recorded in recent years amongst the 3 Hudson Bay sub-populations suggesting that reproductive output in WH was poor in 2011.”

MediaMatters, a nonprofit watchdog group (yes, it’s a “liberal” watchdog group) took a look at the story on earlier in April, citing Amstrup’s criticisms.

More links

Here’s the reprint from the PBI email:

The Truth About Polar Bear Numbers April 2012      
Nearing BearYou may have seen recent headlines stating that the Western Hudson Bay polar bear population–widely considered the most endangered–is, in fact, “healthy and abundant.”Sadly, that’s not the case. So what’s going on? The media flurry stems from a press release on a preliminary study of the Western Hudson Bay population that relied on a different methodology (aerial vs. capture-recapture) and larger geographic survey area than previous studies. Dr. Steven C. Amstrup, PBI’s chief scientist, says that media reports have made the serious mistake of comparing the aerial survey–with a point estimate of 1,013 polar bears–to a capture-recapture study from 2004 showing 934 bears. “It’s not a meaningful comparison,” he says. “It’s reasonable to expect there would be more polar bears in a larger geographic area than a smaller one. But even if the new aerial survey focused on exactly the same geographic area, it wouldn’t be surprising to derive a slightly different population estimate when using a different survey method.” He adds that from the standpoint of population welfare, it’s the trend in numbers that is critical, not a single survey from one point in time–so the aerial count will become meaningful only after several years of data are available. “A single point estimate of population size says nothing about whether the trend is up, down, or stable. Trend can only be addressed by multiple point estimates collected over time.”Dr. Amstrup says the new aerial survey does, however, include a piece of information relevant to trend: Of the 701 polar bears actually counted during the survey, only 22 (or about 3%) were yearlings–a very low percentage. By comparison, in Alaska during the good ice years of the 1980s, about 15% of the animals observed were yearlings.”If that 3% figure is even close to the number of surviving yearlings out there now, it’s not at all clear to me how the Hudson Bay population could be sustaining itself,” he says. “This observation is very much in line with the previously published indications that survival–especially of young–is declining.”Mom and cub on backThe release in question was issued by a Nunavut group interested in increasing polar bear hunting quotas.Scientists who study polar bears emphasize that their concern about polar bears is focused on the future. Because polar bears rely on the sea ice to reach their prey, sea ice losses from a warming Arctic threaten their survival.

“The available data from Hudson Bay indicate declining condition and survival,” says Amstrup. “But in the bigger picture, whether any one population is currently declining, stable, or increasing is beside the point. Ultimately, all polar bears will disappear from their current ranges if we do not mitigate the rise in greenhouse gases.”


Photo Credits:

Bear Photos by Daniel J. Cox/NaturalExposures.com;

Survey Photo by BJ Kirschhoffer