Tag Archives: withholding data

Recent S. Beaufort polar bear count was a cherry-picked result – new evidence

New evidence has come to light that mark-recapture field work used to calculate a new population estimate for Southern Beaufort polar bears did not conclude in 2010 as implied in a widely-publicized paper last month but continued until 2013.

Amstrup w triplet_Prudhoe Bay 2005_USGS_sm

Steve Amstrup in S. Beaufort, 2005 (USGS photo), co-author of Rode et al. paper.

As I discussed previously, last month’s widely-hyped paper (Bromaghin et al. 2015 in press) – which reported a decline of ~40% between 2004 and 2010 (based on spring mark-recapture work) – was contradicted by fall survey counts that suggested strongly a population rebound would have been apparent if the mark-recapture work had continued another two years.

A new paper by Karyn Rode and colleagues (which includes Bromaghin and others (e.g. Amstrup) from the previous paper), summarized in a USGS press release issued on Monday and published online Tuesday, utilized comprehensive data collected during mark-recapture work carried out in spring from 1982 to 2013 in the Southern Beaufort Sea.

This new paper used the same kind of comprehensive data as Bromaghin and colleagues – from the same season, in the same region – to assess potentially negative effects of the mark-recapture research method itself, up to 2012 and beyond.

More on the Rode et al. conclusions later1 – for the moment, what is important is that the work described in the paper confirms that spring mark-recapture work on polar bears in the Southern Beaufort continued beyond 2010. Bromaghin and colleagues didn’t end their mark-recapture work prematurely — they actually left data collected in 2011 and 2012 out of their population estimate analysis when they had to have known the population had not finished rebounding from the 2004-2006 decline.
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W Hudson Bay polar bear mark-recapture study report 2013 – at last

I have finally secured a copy of the 2013 Western Hudson Bay mark-recapture study produced by Environment Canada.

The pertinent figure is below: as you can see, there was no declining trend in Western Hudson Bay polar bears between 2000 and 2011. Click to enlarge.

WH EC Polar Bear Demography report Lunn 26 Nov 2013 Final _Fig 8

I have relatives visiting so I don’t have time to do an in-depth summary but the report’s opening “Summary” is copied below and a pdf provided. More later when I have had time to look at it more closely. Background on the issue here.

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Public misled about W Hudson Bay bears since November 2013

Leading polar bear biologists knew by November 2013 that mark-recapture studies showed the Western Hudson Bay subpopulation had not changed appreciably since 2004 but none said so. This includes Steven Amstrup and Ian Stirling at Polar Bears International, Andrew Derocher (University of Alberta), and Nick Lunn (Canadian Wildlife Service), all of whom are (or have been) extensively involved in Western Hudson Bay polar bear research and have made recent statements to the media on this topic.

Polar_Bear_2004-11-15_Wapusk Nat Park_Wikipedia

More details have emerged about the status of Western Hudson Bay (WHB) polar bears (reported a few days ago here), reported this morning in NunatsiaqOnline, excerpts below.

The story reveals that there are two Canadian Wildlife Service (Environment Canada) reports containing population estimates of Western Hudson Bay polar bears – one produced in 2011 and another in November 2013 (reversing the 2011 conclusion) – that have not been made public.

[In contrast, Nunavut Government reports on their 2011 population estimate, based on aerial surveys, were made public in both draft and final report formats (and have since been peer-reviewed and published)]

The conclusion of the 2013 report, quoted in this mornings article, suggests that some of our most vocal polar bear specialists have been misleading the public about the status of the Western Hudson Bay population for the last year.
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Polar bear researchers knew S Beaufort population continued to increase up to 2012

Why did the Southern Beaufort polar bear population survey stop in 2010? It’s clear that the recently-published and widely-hyped new study stopped before the population rebound from a known decline was complete.

USFWS 2013-2014 PB News_cover_PolarBearScience

The researchers of the recently-published paper knew before starting their mark-recapture study in 2007 that the population decline had taken place. They also knew why the numbers dropped and that previous declines, caused by similar conditions, had been followed by a full recovery.

Did they really think a full recovery in population numbers was possible in only three four years, when cubs born in 2007 would not yet have been old enough to reproduce?

In fact, a US Fish and Wildlife Service (USFWS) fall survey of Southern Beaufort polar bears in 2012 found numbers were higher than they had been in a decade.
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