Tag Archives: Kane Basin

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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Experts’ vision of an ice-free summer is already wrong & benefitting polar bears

Polar bear populations in most of the Canadian Arctic Archipelago (CAA) must be booming, as they are elsewhere. That’s because the ‘experts’ were even more wrong in their predictions of future sea ice conditions than most people realize: they expected the CAA would remain choked with ice during a ‘nearly ice-free’ summer driven by human-caused global warming.

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Wang and Overland 2012 fig 3b marked

Map presented by Wang and Overland (2012: Fig 3) shows what these experts thought a ‘nearly ice-free’ summer would look like, which they expected to occur by 2030 or so.

Look at the map from Wang and Overland (2012) above, which is what they thought a ‘nearly ice-free’ summer would look like in the year 2030 or so.

Wang and Overland used the same models used by USGS biologists to predict the future survival of polar bears based on habitat loss (Amstrup et al. 2007; Atwood et al. 2016; Durner et al. 2007, 2009). Note the thick ice in the CAA — what USGS experts call the ‘Archipelago’ sea ice ecoregion (denoted by white in the map), indicating ice about 1 metre thick (2-3 feet) — expected to remain at the height of summer in 2030.

[Earlier renditions of sea ice projections (e.g. ACIA 2005) show something similar. The second update of the ACIA released just yesterday (AMAP 2017, described here by the CBC) has prudently included no such firm predictions in their Summary for Policy Makers, just dire warnings of future catastrophe. But see the 2012 update.]

 

The problem is that ice in this region has been largely absent most summers since 2006, even though overall ice extent has been much more extensive than expected for a ‘nearly ice-free’ summer, as I show below.

This is not another “worse than we thought” moment (Amstrup et al. 2007) — this is sea ice models so wrong as to be useless: failed models used to inform future polar bear survival models that got the bears declared ‘threatened’ with extinction in the US in 2008 (Crockford 2017).

It also means polar bears are almost certainly doing much better than recent population counts indicate, since only one subpopulation out of the six in the CAA has recently been assessed. But since polar bear specialists have consistently underestimated the adaptability of this species and the resilience of the Arctic ecosystem to respond to changing conditions, it’s hard to take any of their hyperbole about the future of polar bears seriously. Continue reading

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.

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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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