The Chukchi Sea finally has a polar bear population estimate! According to survey results from 2016 only recently made public, about 2937 bears (1522-5944) currently inhabit the region, making this the largest subpopulation in the Arctic. This is exciting news — and a huge accomplishment — but the US Fish and Wildlife Service responsible for the work has been oddly mum on the topic.
Not only that, but an extrapolation of that estimate calculated by USFWS researchers for Chukchi plus Alaska (the US portion of the Southern Beaufort Sea subpopulation) was estimated at 4437 (2283-9527), although with “significant uncertainty.” Nevertheless, it means the 2016 estimate for Alaska could be roughly three times what it was in 2010: a whopping 1500 or so, up from about 450 (or about 225-650) for the same area estimated during the last survey (Bromaghin et al. 2015: Fig. 5a).
Even if the real number for Alaska is only twice as large (~1000), that’s still a huge improvement. It would eliminate the Southern Beaufort as the only polar bear subpopulation in the Arctic to have shown a significant decline blamed on human-caused global warming (Crockford 2018). If the recovery is real, it means the 2004-2006 decline was a temporary fluctuation after all, just like previous declines in the region. I expect, however, that it will take a dedicated SB population survey for officials to concede that point.
There is not yet a detailed report to cite (Regehr et al. in prep), but the numbers were announced at the 10th meeting of the Russian-American Commission on Polar Bears held at the end of July this year (AC SWG 2018) by Eric Regehr (formerly of the US Fish & Wildlife Service, as of 2017 at the University of Washington). [h/t to G.H.] This was the same report that raised the quota for subsistence hunting in the Chukchi from 58 to 85, based on these new figures, as I discussed last week.
From “Military bases to open on Wrangel Island and Chukotka” 22 October 2015.
Regehr was quoted as saying:
“Chukchi bears remain larger and fatter and have not seen downward trends in cub production and survival, according to new preliminary information on the health and numbers of bears.”
Posted in Conservation Status, Population
Tagged Alaska, body condition, Chukchi Sea, cub survival, fat bears, guesstimate, healthy, increase, polar bear, population, Regehr, sea ice, Southern Beaufort, thriving, triplets
Four bears were photographed outside of Red Bay, Southern Labrador on Thursday 8 March and a bear was spotted ashore in NE Newfoundland overnight on Wednesday.
Posted in Polar bear attacks, Sea ice habitat
Tagged condition, cubs, Davis Strait, Labrador, Newfoundland, onshore, polar bear, sea ice, sightings, Strait of Belle Isle, triplets
A statement yesterday from Yegor Vereshchagin, wildlife conservation manager from Chukotka, Russia (Polar Bears Adjust to Climate Change, 20 February 2018) confirms that Chukchi Sea polar bears are currently doing extremely well.
Contrary to previous reports and predictions (e.g. Amstrup 2011; Amstrup et al. 2007, 2008; Durner et al. 2009), there appears to be no threats due to recent declines in summer sea ice (Rode and Regehr 2010; Rode et al. 2013, 2014, 2018) or from poaching.
Posted in Conservation Status, Population, Sea ice habitat
Tagged Chukchi Sea, Chukotka, climate change, poaching, polar bear, population size, Russia, sea ice, triplets
Back in October, I wrote about US Fish & Wildlife biologist Eric Regehr comments about a recent survey of Chukchi Sea polar bears, the results of which are still not published. Since then, I’ve been able to track down a bit of information.
This project appears to have run for five years, from 2008 to 2011. The work was confined to the eastern (US) portion of the Chukchi, see maps below (Polar Bear News 2010; Rode and Regehr 2010). Researchers were doing mark-recapture work with helicopters, putting radio collars on some females and radio ear tags on a few males. They worked primarily in March and April (mating season for polar bears), operating entirely on the offshore sea ice – working, I might add, on bears that technically speaking do not exist, since the official population estimate for this region is “zero” (they are not included in the global estimate of 20,000-25,000, see pdf here,, discussed here).
Figure 1. Chukchi Sea – getting you oriented. Note the location of Kotzebue Sound, northeast of the Bering Strait. Map from Wikipedia.
In 2012, US Fish & Wildlife biologist Eric Regehr told reporter Jill Burke at Alaska Dispatch that they found the bears were “reproducing well and maintaining good body condition.” I’ve finally found some details regarding what he meant by that statement (although no final reports or peer-reviewed papers are out, see footnote below).
Did you know there used to be resident polar bears on two small islands in the Bering Sea? Given how much we don’t know about the polar bears of the Bering Sea, the bears that used to den and spend their summers on the St. Matthew Islands are a bright spot. These islands lay at the southern-most limit of the modern “Chukchi Sea” subpopulation (see Fig. 1) and were uninhabited by people when they were discovered in the 1760s – but they were a haven for polar bears.
We have details of the polar bears that gave birth and summered there because a US government biologist (Henry Wood Elliott) and a US navy Lieutenant (Washburn Maynard) surveyed the islands in 1874. Elliott wrote both an official report and a popular magazine article (for Harper’s Weekly Journal of Civilization) in 1875 describing the polar bears they saw; Maynard wrote a separate report in 1876. By 1899, there were none left, victims of the relentless slaughter of polar bears everywhere in the Arctic in that era (see previous discussion here).
Figure 1. St. Matthew Island is in the Bering Sea off the west coast of Alaska at about 60°N latitude. Compare this to the southern end of James Bay, Canada (which has a stable population of polar bears) at about 53 0N and Churchill, Manitoba (the so-called “polar bear capital of the world) at 58 046’N. Maps from Wikipedia.
Figure 2. A drawing of polar bears on St. Matthew Island that accompanied the May 1, 1875 Harper’s Weekly Journal of Civilization article written by Henry Elliot. See here.
[UPDATE: Jan. 27, 2013: a follow-up to this post is here.]
Posted in Life History, Sea ice habitat
Tagged Bering Sea, Chukchi, commercial harvest, Elliott, Hudson Bay, Klein, onshore, Rozell, sea ice extent, St. Matthew Island, triplets
In Part 1 of the Western Hudson Bay (WHB) polar bear story, I promised to explore the idea that rather than declining due to the effects of global warming, WHB polar bear populations may simply be returning to ‘normal’ after the rapid population increase that followed the intense over-harvests that occurred between 1890 and 1930 and again from 1945 to 1970.
Derocher and Stirling (1995:1664) had this to say about the life history features (like incidence of triplets and age of weaning) that made the polar bears of WHB unique:
“The results of our analyses suggest that the unique reproductive characteristics of polar bears in western Hudson Bay in the 1960s and 1970s were either a function of a population increasing from a depleted state and feeding on a relatively abundant prey base, or density-independent fluctuations in prey population size, or availability due to sea ice variation.“
In my last post, I discussed some of the evidence for how polar bear reproductive characteristics had changed since 1985. But how different were WHB polar bears, before and after 1985, from the other populations that had been dramatically reduced between 1890 and 1970, such as those in Svalbard/Barents Sea and Davis Strait?
There are two factors to consider in this recovery from over-harvest: population size changes and reproductive characteristics. Turns out, we don’t know much about the Davis Strait subpopulation but we do know a bit about Svalbard/Barents Sea bears since the 70s. And the Svalbard/Barents Sea vs. WHB comparison is a bit of an eye-opener.
A review paper, purporting to list the “effects of climate warming on polar bears” (Stirling and Derocher 2012:2697), has this to say about the state of research in western Hudson Bay:
“The most comprehensive long-term research on polar bear demography, body condition, subpopulation size, abundance, and reproductive success has been conducted on the Western Hudson Bay subpopulation.”
This means that compared to all of the 19 subpopulations of polar bears (see fig. 1), the very best information we have is for Western Hudson Bay (WHB) bears (fig. 2).
But are western Hudson Bay polar bears biologically typical of all polar bears? In this post, I’ll begin to examine that question.