Tag Archives: ringed seals

W. Hudson Bay polar bear numbers declined then stabilized, says new paper

Posted on February 26, 2016 | Comments Off on W. Hudson Bay polar bear numbers declined then stabilized, says new paper
Polarbear_Parks Canada Wapusk in August

Western Hudson Bay bear, Wakusp National Park, August 2011.

In the just-published version of their Western Hudson Bay (WHB) population survey conducted in 2011, Nick Lunn and colleagues highlighted in the abstract:

“Our analysis suggested a long-term decline in the number of bears from 1,185 (993-1411) in 1987 to 806 (653-984) in 2011…” 

But they didn’t mention that the 806 estimate for 2011 was based on only a portion of the WHB region (Fig. 1) and has not been accepted by their peers as a valid estimate of the population size. They also failed to mention that the decline occurred due to thick spring ice and/or unsuitable snow conditions for ringed seals between 1989 and 1992 (Fig. 2), which resulted in reduced availability of polar bear prey (as I discussed in detail in Crockford 2015).

They know the “long-term” population decline is what the media will grab onto and run with – rather than the next sentence, which says “In the last 10 years of the study, the number of bears appeared stable due to temporary stability in sea ice conditions.”

In other words, their study shows there has been no decline in the population since 2004, which had been predicted to occur (see previous post, Prediction #1), and there has been no trend in either breakup or freeze-up dates between 2001 and 2010 (or since). See previous post on the government report on which this paper is based here.

The bottom line is this: no one is buying this population estimate of 806 bears for the Western Hudson Bay population – both the IUCN Polar Bear Specialist Group and Environment Canada are using Seth Stapleton and colleagues (2014) estimate from their aerial survey done the same year and that official population size number is 1030 bears. Continue reading →

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Same amount of sea ice for Hudson Bay polar bears as 2013, bears still on the ice

Posted on June 16, 2015 | Comments Off on Same amount of sea ice for Hudson Bay polar bears as 2013, bears still on the ice

Sea ice coverage for Hudson Bay on 14 June converged on levels recorded in 2013, when breakup was slightly later than the average of the last two decades.

r10_Hudson_Bay_ts

There is also more ice over Hudson Bay than there was in 2011, which was an early breakup year (charts for other Arctic regions here, originals here).

Andrew Derocher notes (via twitter) that rather than heading to shore, most of the Hudson Bay bears with satellite tracking collars (7/10) are out on the ice (Fig. 1 below). They appear to be hunting along the ice edge, where they are most likely to find seals.

Update 17 June 2015: Sea ice images for the week 18 June 2015 compared to other years added below, for Hudson Bay and the Beaufort Sea.

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Superb sea ice conditions for polar bears worldwide during their critical feeding period

Posted on April 3, 2015 | Comments Off on Superb sea ice conditions for polar bears worldwide during their critical feeding period

Prognosis, excellent. The sea ice hunting platform that polar bears require is everywhere and Davis Strait ice extent is the fourth-highest it’s ever been at this time of year.

Sea ice extent global 2015 April 2 NSIDC with anomaly WUWT

The spring feeding period is a messy, brutal business – many cute baby seals will die as polar bears consume 2/3rds of their yearly food supply over the next few months (April – June/early July), while sea ice is abundant.

Arctic marine mammals_Dec 31 2014_Polarbearscience

That leaves the remaining 1/3 of their energetic needs to be met over the following 9 months (most of it in late fall (late November/December) and hardly any during the summer months, regardless of whether the bears are on land or out on the sea ice) or over the winter. Continue reading

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Polar bear biologists try – again – to blame S. Beaufort thick spring ice on global warming

Posted on February 13, 2015 | Comments Off on Polar bear biologists try – again – to blame S. Beaufort thick spring ice on global warming

The trouble is, sea ice researchers and atmospheric scientists have not drawn that conclusion, despite what a new paper by Pilfold and colleagues imply. It shows just what lengths desperate IUCN Polar Bear Specialist Group  (PBSG) biologists will go to in order to link the recent decline of Southern Beaufort bear numbers to global warming while ignoring similar past declines.

Beaufort Sea pressure ridges_Spring 1949 wikipedia sm

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Faux polar bear figures – my editorial in the National Post

Posted on January 15, 2015 | Comments Off on Faux polar bear figures – my editorial in the National Post

Published in the Business section (Financial Post “Comments”) of the National Post this morning:

Paul J. Richards/AFP/Getty Images [NP story]

Paul J. Richards/AFP/Getty Images [from original NP essay]

“Faux polar bear figures” [not my choice of title, by the way]

In which I conclude:

“We admire polar bear biologists for their professional dedication to this iconic species, and rightly so. However, while it’s understandable that polar bear biologists are conservation-minded, the public and policy makers need them to be scientists first and advocates for polar bear protection second. Polar bears are currently doing well – data shenanigans to keep them classified as “threatened” undermine the whole point of doing science.”

I have written extensively about the Southern Beaufort issue — below are links to some of these, which have links to the rest. References are included in these individual posts. Contact me if there is a reference you cannot find: Continue reading

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Current ice conditions don’t bode well for Beaufort Sea polar bears

Posted on April 18, 2014 | Comments Off on Current ice conditions don’t bode well for Beaufort Sea polar bears

Thick spring ice along the shore of the Eastern and Southern Beaufort is bad news for polar bears, especially females emerging from their dens with new cubs. Are those conditions developing now?

Beaufort Sea pressure ridges_Spring 1949 wikipedia sm

Every 10 years or so, since at least the 1960s, nearshore ice gets too thick for ringed seals to maintain their breathing holes and many breeding seals depart the area. This leaves a lot of polar bears without the baby seals they need to consume to get them through the rest of the year (that’s if they don’t (or can’t) leave themselves).

I’ve discussed various aspects of this phenomenon before, with references – see the list at the end of this post.

Sadly, we are on schedule for such conditions to recur – could be this year, could be next. The last time of heavy spring ice was 2004 and previous heavy ice conditions occurred the springs of 1964, 1974 (the worst), 1984, 1992 and 2004. The 2004-2006 event was reportedly almost as bad as the 1974-1976 event.

So, prompted by reports of the heaviest sea ice conditions on the East Coast “in decades” and news that ice on the Great Lakes is, for mid-April, the worst it’s been since records began, I took a close look at ice thickness charts for the Arctic. I’m not suggesting these conditions are necessarily related to Beaufort ice, just that they got me thinking.

Here’s a screencap of the US Navy ice thickness animation chart for yesterday [from WUWT Sea Ice Page]

Figure 1. Arctic Sea Ice Thickness (NRL), for April 18, 2014. Look at thick ice (yellow, 3.5-4.0 meters thick) spreading along the north coast of Alaska. See the 30 day animation here.

Figure 1. Arctic Sea Ice Thickness (NRL), for April 18, 2014. Look at thick ice (yellow, 3.5-4.0 meters thick) spreading along the north coast of Alaska. See the 30 day animation here.

Below is a similar image from about the same time last year, with the Southeast Beaufort Sea marked.

Figure 2. Arctic Sea Ice Thickness (NRL), for April 13, 2013. Southeastern Beaufort marked.

Figure 2. Arctic Sea Ice Thickness (NRL), for April 13, 2013. Southeastern Beaufort marked.

I don’t think this bodes well for Beaufort bears but we’ll have to wait and see if there are any reports of starving bears bit later this spring and summer. Sea ice charts aren’t a guarantee that this heavy spring ice phenomenon is developing in the Beaufort, but they could be a warning.

Below are archived ice age charts from the US National Snow and Ice Data Center (NSIDC) for some previous years when Beaufort bears had trouble, especially 2004-2006, with which I compare this year’s conditions. [h/t Steve Goddard for alerting me to this resource]

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Polar bear cannibalism and sea ice, the spring of 1976

Posted on October 30, 2013 | Comments Off on Polar bear cannibalism and sea ice, the spring of 1976

Remember Ian Stirling’s claim that late freeze up in Western Hudson Bay in 2009 was forcing polar bears to resort to cannibalism (here and here), with gut-wrenching images and video provided for the media? Or Steve Amstrup’s claim for a similar phenomenon in the Southern Beaufort in 2004?

I pointed out that Stirling’s claim was way overblown and that Amstrup’s incidents were almost certainly the result of heavy ice in the spring (not low ice in summer), similar to the heavy ice conditions and polar bear starvation documented in the same region back in 1974-1976.

It turns out that the heavy ice conditions documented in the Eastern Beaufort in the mid-1970s had much broader effects on polar bears and ringed seals than has been appreciated.
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Kaktovik polar bears could be back on the ice this weekend

Posted on October 4, 2013 | Comments Off on Kaktovik polar bears could be back on the ice this weekend

This is a quick follow up on my last post (here) on Kaktovik polar bears of the Southern Beaufort Sea subpopulation.

Kaktovik is the bright pink dot on the ice map below (October 3, 2013: click to enlarge), from the Canadian Ice Service – if the ice doesn’t get to the polar bears waiting on shore this weekend, it will be within swimming distance.

Note that this map doesn’t show the shorefast ice that is already forming along the beaches, bridging the gap between land and the offshore ice.

Shorefast ice provides the fall’s first ice platform for polar bears to hunt seals. It doesn’t need to be extensive for the bears to get out there — researchers working in Western Hudson Bay found that an ice concentration of only 10% marked the point when polar bears left the shore.

Kaktovik on CIS chart Oct 3 2013

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Record sea ice loss in 2007 had no effect on polar bears, Chukchi study confirms

Posted on September 15, 2013 | Comments Off on Record sea ice loss in 2007 had no effect on polar bears, Chukchi study confirms

One aspect of the recently published study on Chukchi Sea polar bears (Rode et al.2014 [now in print] 2013; see here and here) has not been stressed enough: their finding that the differences in overall condition between bears in the Chukchi and Southern Beaufort Seas came down to disparities in spring feeding opportunities and therefore, the condition of spring sea ice.

The fact that spring — not summer — is the most critical period for polar bears is something I’ve pointed out before (see here and here, for example) but it’s worth repeating at this time of year, when all eyes are on the annual ice minimum. It is often treated as a given that the decline in extent of summer sea ice in the Arctic since 1979 has been detrimental to polar bears. However, this is an assumption that we can now say is not supported by scientific evidence (see summary of that evidence here).

The results published by Rode et al. (2014 2013) not only add further support to the conclusion that declines in summer sea ice have not harmed polar bears, but should put the matter to rest – unless new evidence to the contrary is produced.

Chukchi bears, the report tells us, had more food available in the spring than Southern Beaufort bears (see map below) and this was the primary reason that bears were doing very well in the Chukchi and not quite as well in the Southern Beaufort. And because the polar bears for this study were captured and measured in mid-March to early May, from 2008 to 2011, they reflect spring-time conditions for 2008-2011 as well as year-round conditions from 2007 through 2010.

This means that the annual low ice extent for 2007 (record-breaking at the time), in the fall before this study began, had no discernible negative effect on either Chukchi or Southern Beaufort polar bears – and neither did similarly low annual minimums in two of the three remaining years of the study (Fig 1).

Figure 1. Sea ice extent at August 27, 2007 – the lowest extent that year (downloaded September 15, 2013 from IARC-JAXA, Arctic Sea-ice Monitor). At the time, it was the lowest extent recorded since 1979 (2012 broke that record). This (2007) was the fall before the Rode & Regehr study on Chukchi/Southern Beaufort polar bears began (2008-2011). The ice was almost as low in September 2008 and 2010, while 2009 was more like 2013.

Figure 1. Sea ice extent at August 27, 2007 – the lowest extent that year (downloaded September 15, 2013 from IARC-JAXA, Arctic Sea-ice Monitor). At the time, it was the lowest extent recorded since 1979 (2012 broke that record). This (2007) was the fall before the Rode & Regehr study on Chukchi/Southern Beaufort polar bears began (2008-2011). The ice was almost as low in 2008 and 2010, while 2009 was more like 2013.

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Polar bears have not been harmed by sea ice declines in summer – the evidence

Posted on August 18, 2013 | Comments Off on Polar bears have not been harmed by sea ice declines in summer – the evidence

PB logo colouredThe polar bear biologists and professional activists of the IUCN Polar Bear Specialist Group (PBSG) continue to insist that since 1979 increasingly smaller amounts of Arctic sea ice left at the end of summer (the September ice minimum) have already caused harm to polar bears. They contend that global warming due to CO2 from fossil fuels (“climate warming” in their lexicon) is the cause of this decline in summer ice.

In a recent (2012) paper published in the journal Global Change Biology (“Effects of climate warming on polar bears: a review of the evidence”), long-time Canadian PBSG  members Ian Stirling and Andrew Derocher (both of University of Alberta) summarized their position this way:

“Climate warming is causing unidirectional changes to annual patterns of sea ice distribution, structure, and freeze-up. We summarize evidence that documents how loss of sea ice, the primary habitat of polar bears (Ursus maritimus), negatively affects their long-term survival”

I’ve spent the last year examining their evidence of on-going harm, but in addition, I’ve looked at the evidence (much of it not mentioned in the Stirling and Derocher paper1) that polar bears have either not been harmed by less sea ice in summer or have thrived in spite of it.

This is a summary of my findings. I’ve provided links to my original essays on individual topics, which are fully referenced and illustrated. You are encouraged to consult them for complete details. This synopsis (pdf with links preserved, updated; pdf with links as footnotes, updated) complements and updates a previous summary, “Ten good reasons not to worry about polar bears” (pdf with links preserved; pdf with a foreword by Dr. Matt Ridley, with links as footnotes).

Update 8 September 2013: to include links to my post on the recently published Chukchi population report; updated pdfs have been added above.

Update 22 January 2014: added figure comparing March vs. September sea ice extent using the same scale, from NOAA’s “2014 Arctic Report Card,” discussed here.
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