With masses of very thick, multiyear ice off Alaska this spring, the developing polynyas (open water) at either end of the Beaufort Sea are providing essential polar bear hunting habitat.
Patches of open water in the Beaufort Sea are naturally recurring phenomena. This year we have two excellent examples, shown by the yellow arrows in the sea ice thickness map above (from the Naval Research Laboratory).
The eastern-most polynya forms in the Canadian portion of the Beaufort most years in the spring. This open water feature is so common it has a name – the Cape Bathurst polynya. Last year, there wasn’t an obvious polynya there until sometime in June, but in 1975, a patch of open water almost as large (or larger) as this year’s had developed by the end of May (Fig. 1).
Figure 1. Cape Bathurst polynya at 28 May 1975 (Smith and Rigby 1981:Fig. 14h) and the polynya this year at 14 May (Canadian Ice Service). See discussion in the text below about the relative sizes. Click to enlarge.
According to the experts that study them, the timing and extent of the polynya formation depends on wind (Dunbar 1981:29), not temperature. This means that this spring’s polynya formation in the eastern Beaufort isn’t a symptom of global warming, it isn’t “missing polar bear habitat,” and it isn’t a sign of early sea ice breakup.
In fact, the Cape Bathurst polynya is a critical place for ringed seals and bearded seals to congregate in spring. Therefore, this is where many Southern Beaufort polar bears go to hunt. The presence of the polynya is especially crucial in years like this one, when very thick sea ice covers most of the Beaufort Sea. Continue reading
Posted in Life History, Sea ice habitat
Tagged Alaska, Arctic, bearded seal, Beaufort Sea, Cape Bathurst, Cleator, ice thickness, open water, Point Barrow, polynya, ringed seal, sea ice, spring, Stirling
Recent research (Crawford and Quakenbush 203; Rode et al. 2014) has shown that sea ice declines in the Chukchi and Beaufort Seas have made life better for ringed seals, not worse (as predicted) – ringed seals are in better condition and reproducing better than they were in the 1970s. Why? Ringed seals do most of their feeding in the open-water period (Young and Ferguson 2013), so a longer open-water season means fatter, healthier seals and more fat pups for polar bears to hunt the following spring.
However, Arctic ringed seals (as well as bearded seals) were designated as ‘threatened’ by the USA in 2012 under the Endangered Species Act, based on predicted ice and snow declines due to prophesied global warming. These listings are all about future threats, with no pretense of on-going harm.
Virtually no other Arctic nation has taken this step for Arctic seals — see previous discussion here. There are lots of ringed seals — an estimated 3-4 million world-wide and about 1.7 million within the critical habitat proposed by NOAA (see below).
As weak as the case for listing polar bears as ‘threatened’ has proven to be, the case for listing ringed and bearded seals is even more feeble (a judge has already sent the bearded seal listing back to the drawing board).
Posted in Conservation Status, Sea ice habitat
Tagged bearded seal, Beaufort Sea, Bering Sea, Chukchi Sea, conservation, critical habitat, endangered species, future threats, global warming, IUCN, models, NOAA, polar bear, predictions, public hearings, ringed seal, sea ice, threatened
A cross-Arctic comparison shows that the US has been the most aggressive in designating polar bears and their main prey species as ‘threatened with extinction’ due to the predicted effects of human-caused (“anthropogenic”) global warming (AGW), even though the US has the least amount of sea ice habit of all circumpolar nations.
I’ve made a chart listing the conservation status of these species across all Arctic nations (Canada, Russia, Norway, Denmark (for Greenland) and the USA), as well as the one international body that considers the conservation status of all species (International Union for Conservation of Nature, IUCN).
Oddly, the IUCN considers the polar bear vulnerable due to future threats from predicted sea ice losses but not ringed seals or bearded seals. This situation highlights the capricious nature of the use of “future threats” (almost exclusively based on predictions of AGW) as a valid criteria for evaluating the conservation status of Arctic marine mammals. It also suggests why the IUCN has tightened considerably its rules regarding this practice.
Posted in Conservation Status, Summary
Tagged AGW, Arctic nations, arctic seals, bearded seal, conservation, global warming, IUCN, North Pole, polar bear, Polar Bear Specialist Group, ringed seal, threatened with extinction, walrus
Here’s a significant turn of events involving a story I reported on earlier: a US District Court judge ruled on Friday 25 July 2014 that the Bering/Chukchi Sea population of bearded seal (Erignatha barbatus) was improperly given ‘threatened’ species status in 2012. Judge Beistline ordered the National Marine Fisheries Service (NMFS) “to correct deficiencies in its study of the population.“
Bearded seals are important secondary prey species for polar bears in some regions of the Arctic (Thiemann et al. 2008), after ringed seals (which were also listed as ‘threatened’ in 2012).
Among other points made in his written decision, the judge is quoted as saying (reported here):
“A listing under the ESA based upon speculation, that provides no additional action intended to preserve the continued existence of the listed species, is inherently arbitrary and capricious.” [my emphasis]
“Arbitrary and capricious” — now that’s a slap-down. He also reportedly called the ESA listing “an abuse of discretion.”
The question is, how often have other ESA listings – not challenged in court – been based on similarly arbitrary and capricious decisions that also involved an abuse of discretion?
More quotes from Judge Beistline’s decision, and reaction to it, below.
Posted in Conservation Status, Life History, Sea ice habitat
Tagged Alaska District Court judge, arbitrary, bearded seal, conservation status, declining sea ice, ESA, Judge Beistline, National Marine Fisheries Service, NMFS, polar bear prey, predictions, threat to survival, threatened with extinction
As I discussed in my last post, the Gulf of Boothia subpopulation in the central Canadian Arctic has the highest density of polar bears anywhere in the world. The question is, why?
For example, is the sea ice in the Gulf of Boothia region so markedly different from its nearest subpopulation-neighbor, M’Clintock Channel (Fig. 1), that it accounts for the wide disparity in polar bear densities between the two? The differences, remember, are dramatic: Gulf of Boothia, 18.3 bears per 1000 km2 vs. M’Clintock Channel, 1.9. And while M’Clintock Channel may be low in part due to recent over-harvests (see footnote 1), even the density before over-harvests occurred in M’Clintock Channel were only 4.7, compared to 10.4 bears per 1000 km2 in Gulf of Boothia (see Table 1 in previous post).
Today, I’ll take a look at sea ice and ringed seal habitat in the Gulf of Boothia and M’Clintock Channel, as well as information from a study on polar bear diets, which together shine some light on why the Gulf of Boothia is such a great place for polar bears.
Figure 1. Map showing the side-by-side relationship of M’Clintock Channel and the Gulf of Boothia. From Barber and Iacozza (2004: Fig. 1).
Posted in Life History, Population, Sea ice habitat
Tagged Barber and Iacozza, bearded seal, beluga whales, Gulf of Boothia, local Inuit knowledge, M'Clintock Channel, multiyear ice, narwhal, polar bear population density, ringed seal, sea ice habitat, Thiemann