Tag Archives: baffin bay

Breakup of sea ice on track in Canada as critical feeding period for polar bears ends

Relative to recent years and potential impacts on polar bear health and survival in Canada, there is nothing alarming in the pattern or speed of sea ice breakup for 2017, either over Hudson Bay, the southern Beaufort, or the eastern high Arctic.

Sea ice Canada 2017 June 8

Last year at this time (see map below), there was more open water in Hudson Bay and in the Southern Beaufort yet the polar bears came ashore in fine shape that summer and there was no hue-and-cry of dying bears anywhere. Breakup this year is on track to be about 3 weeks earlier than it was in the 1980s, as it has been since at least 2001, a conclusion reached by polar bear specialists (Castro de la Guardia et al. 2017; Lunn et al. 2016), who examined sea ice breakup to 2015.

Sea ice extent Canada 2016 June 8 CIS

Here are critical words to remember (more details here) from biologist Martin Obbard and colleagues (2016:29) on the relationship between body condition and sea ice for Southern Hudson Bay (SH) polar bears, which apply equally well to bears in other regions:

Date of freeze-up had a stronger influence on subsequent body condition than date of break-up in our study. Though models with date of freeze-up were supported over models with other ice covariates, we acknowledge that lower variability in freeze-up dates than in ice duration or break-up dates could have influenced the model selection process. Nevertheless, we suggest that a stronger effect of date of freeze-up may be because even though break-up has advanced by up to 3-4 weeks in portions of Hudson Bay it still occurs no earlier than late June or early July so does not yet interfere with opportunities to feed on neonate ringed seal pups that are born in March-April in eastern Hudson Bay (Chambellant 2010). Therefore, losing days or weeks of hunting opportunities during June and July deprives polar bears of the opportunity to feed on adult seals, but does not deprive them of the critical spring period (Watts and Hansen 1987) when they are truly hyperphagic. No doubt, the loss of hunting opportunities to kill adult seals has a negative effect on body condition, but it appears that for bears in SH a forced extension of the fast in late fall has a greater negative effect on subsequent body condition.” [my bold]

In other words, by mid-June at least (maybe earlier), polar bears have largely finished their intensive feeding that’s so critical to their survival over the rest of the year.

That’s why the latest count of SH polar bears (Obbard et al. 2015) showed a stable population (and see this recent post on WHB polar population estimates). But freeze-up was late last year and that’s what will make the difference to polar bears over the coming year.

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Baffin Bay and Kane Basin polar bears not ‘declining’ concludes new report

The 2016 Scientific Working Group report on Baffin Bay and Kane Basin polar bears was released online without fanfare last week, confirming what local Inuit have been saying for years: contrary to the assertions of Polar Bear Specialist Group scientists, Baffin Bay and Kane Basin subpopulations have not been declining but are stable.

polar-bear-feeding_shutterstock_sm

Until recently, the Baffin Bay (BB) and Kane Basin (KB) polar bear subpopulations, that live between NW Greenland, and Baffin and Ellesmere Islands, were assessed with confidence by the IUCN Polar Bear Specialist Group (PBSG) to be declining due to suspected over-hunting (see 2016 Report, Ch. 1, pg. 4).

It turns out they were wrong.

map-baffinbay

New (2016) polar bear subpopulation estimates for BB and KB:

Baffin Bay 2,826 (95% CI = 2,059-3,593) at 2013

                  [vs. 1546 (95% CI = 690-2,402) expected 2004]

                  vs. 2,074 (95% CI = 1,553-2,595) in 1997

  Kane Basin357 (95% CI: 221 – 493) at 2013

                    vs. 164 (95% CI: 94 – 234) in 1997

[1997 figures from 2015 IUCN Red List estimates, from Supplement, pg. 8); 2004 “expected” figure for Baffin Bay from 2016 SWG report, Ch. 1, pg. 4]

In 2014, Environment Canada’s assessments were ‘data deficient’ for Kane Basin and ‘likely declining’ for Baffin Bay (see map below):
ec_polarbearstatus_and-trends-lg_2010-2014-mapscanada_oct-26-2014

However, the results of this new study (conducted 2011-2013) would likely make KB in the map above dark blue (‘stable’), and BB light blue (‘likely stable’), depending on how the new information is interpreted (given differences in methodology between the 1991-1997 and 2011-2013 counts). Note that a recent paper by Jordan York, Mitch Taylor and others (York et al. 2016) suggested this outcome for Baffin Bay was likely (i.e. ‘stable’) but thought that the status of Kane Basin would remain ‘declining.’

This new information leaves only the Southern Beaufort subpopulation (SB) in a ‘likely declining’ condition, but since that decline was due to thick spring ice conditions in 2004-2006 (Crockford 2017), it does not reflect a response to recent loss of summer sea ice. The new population estimates for Baffin Bay and Kane Basin also suggests that a revision needs to be made to the 2015 IUCN Red List assessment with respect to the global population estimate because polar bears are clearly more abundant in Baffin Bay and Kane Basin than previously thought.

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Narwhal and beluga ice entrapment is natural – not caused by global warming

A part-time Arctic researcher eager for media attention suggested earlier today that the ice entrapment of narwhals in 2008 and again in 2015 at Pond Inlet (that made headlines around the world) was the result of “sudden changes in temperature” caused by climate change. This grossly misleading claim ignores the facts: ice entrapment of narwhals is an entirely natural feature of the Arctic that has been known about for hundreds of years.

Narwhals_at risk from climate change_CBC 13 Aug 2016 headline

Narwhals: the ‘giant unicorn of the sea’ at risk from climate change” (CBC, 13 August 2016), a print version of a CBC Radio interview with Clint Wright that aired 8 August 2016. Wright is the general manager at the Vancouver Aquarium and apparently has “joined a team of researchers to tag and study” narwhals for several years – but does not seem to know much about the history or circumstances of natural ice entrapment.

Ice entrapment of small whales is nothing new. The first formally documented incident – in English – occurred in 1915 (Porsild 1918) and the phenomenon has probably occurred as long as there has been ice in the Arctic (millions of years).

Animals routinely become trapped in a few specific areas due to local geography: when ice that forms in the north moves south quickly, it blocks the entrances to inlets or coastal bays that still have open water. The presence of the pack ice causes nearby  temperatures to drop quickly. Rapid development of ice on the bay proceeds from the mouth toward the head of the bay. Any whales present cannot escape to open water and will eventually die or be eaten.

Pond Inlet at the north end of Baffin Island is one such place but Disko Bay in western Greenland is another. In fact, Pond Inlet and Disko Bay are almost identical in geographic layout even though they lie on opposite sides of Baffin Bay, so it’s not surprising that both are locations of repeated entrapment events.

Three highly informative journal articles on the phenomenon of ice entrapment of narwhals and beluga are open access documents that reveal some fascinating details of such incidents, including polar bear predation on trapped whales. h/t T. Nelson Continue reading

Cannibalism video shot in 2015 did not involve a starving polar bear

National Geographic has just posted an exclusive video shot mid-summer of 2015 of a male polar bear killing and eating a young cub.

National Geographic 2015 cruise Cannibalism video screencap_Feb 23 2016

It’s worth watching (23 February 2016; Polar bear cannialzies cub) [update: Youtube version posted below]. It was filmed in 2015 in Baffin Bay at mid-summer (during either their July 28-Aug 9 or Aug 7- 19 cruise; pdf of itinerary, dates and prices – oh my god, the prices! here). [Summer is 1 July-30 September]

You’ll soon realize the male bear was not thin or starving (as was true of a much-publicized 2011 event captured on film off Svalbard).

It is also obvious based on the dates listed above that this incident debunks the explanation that cannibalism by adult males is driven primarily by their desire to mate with the mother of the consumed cub: this incident occurred sometime between August 7 and August 19 (as I was informed via email, by a reader on one of those two cruises), which is well past the breeding season for polar bears. A male bear would not still have viable sperm by August and a female could not be forced into estrus. [added 26 February 2016]

National Geographic is already hyping this incident as more evidence of climate change harming polar bears, as the article accompanying the video suggests. However, this is just the typical oversell that accompanies much to do with polar bear these days.

The bear was not “driven to desperation” : he simply took advantage of a rare chance to eat during the summer:

“Without the ability to hunt seals, polar bears may be driven to ever more extreme cannibalism, if they’re not already.”

It’s clear to me that this was an opportunistic kill made at a time of year when few seals are available, as even Stirling admits. It reiterates the point I’ve made many times before, that polar bears on the sea ice in summer have few feeding opportunities.

Incidents of cannibalism cannot be said to be increasing because there is no scientific baseline for which recent occurrences can be compared. Scattered anecdotal reports of any behaviour cannot be touted as evidence for a trend even though they may be of interest and worth recording.

UPDATE 23 February 2016: Video now posted on Youtube, see it copied below:

Winter returns to the Arctic – freeze-up 2015 at October 20 expands polar bear habitat

Fall is the season when polar bears that have spent the summer fasting can return to the refreezing sea ice to resume successful hunting. For polar bears, fall is the second-most important time of year for hunting, after spring.

masie_all_zoom_4km_2015 Oct 20

The date when freeze-up occurs across the Arctic varies from place to place and year to year, but the process is well underway this year. The US National Snow and Ice Data Center’s MASIE map for 20 October 2015 (above) shows 7.7 mkm2 of sea ice, up from the annual low of 4.41 mkm2 almost 6 weeks ago.

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2nd highest ice coverage for Hudson Bay since 1971 at mid-August – only 1992 higher

Since 1971, there has been no year when there was as much ice left on Hudson Bay as there is this year at August 13th, except 1992 – the year when Mt. Pinatubo seemingly affected Hudson Bay ice levels but not any other region in Eastern Canada or the Beaufort Sea. Odd, that – see the graphs below.

Hudson Bay same week 13 Aug 1971-2015

Doesn’t mean that much to polar bears, since they will mostly be fasting whether they are onshore for the summer or riding the ice – they primarily live off their fat this time of year. Still, the relative ice levels are interesting because it could impact freeze-up dates later this fall, which will influence the bears’ ability to hunt before the winter fast sets in.

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Sea ice breakup update: high ice coverage just about everywhere, even Hudson Bay

There is still a lot of sea ice in Hudson Bay, Foxe Basin, Davis Strait and Baffin Bay this week – more than average for this date – with slightly less than average in the Beaufort Sea. Past behaviour of Western and Southern Hudson Bay polar bears suggests the mean date that bears come ashore for the summer this year will be later than average due to the plentiful ice available, regardless of when polar bear biologists decide that “breakup” has occurred.

Hudson Bay breakup July 8 2015_CIS

Hudson Bay, with almost 50% of the bay still covered in ice, has the third highest coverage this week since 1992 (after 2009 and 2004); Davis Strait has the highest coverage since 1992; and Foxe Basin and Baffin Bay have the highest coverage since 1998. For this week, the Beaufort Sea has the second highest coverage since 2006 (after 2013), and more ice than was present in 1971, 1982, 1987, 1988 and 1998 – among others.

Published data shows that most polar bears of Western Hudson Bay traditionally come ashore in July, but this year it might be late July or even August. Have a look at the charts below.
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