Apparently, some biologists think that outputs from complex computer models will convince native Arctic residents that invasive mark-recapture work has no long-term effect on the health and well-being of polar bears.
Photo by Jake Steven Arnatsiaq. Original here.
Comments Off on Polar bear biologists miss the mark in new study on invasive mark-recapture effects
Posted in Uncategorized
Tagged Amstrup, Bromaghin, Government of Nunavut, handling, Inuit, invasive research, mark-recapture, models, observations, Peacock, polar bear, Rode, satellite collars, tranquilizer drugs
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.
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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Comments Off on Recent S. Beaufort polar bear count was a cherry-picked result – new evidence
Posted in Advocacy, Conservation Status, Population
Tagged abundance, aerial survey, Amstrup, Beaufort Sea, Bromaghin, cherry-picking, IUCN, mark-recapture, models, PBSG, polar bear, population estimate, population recovery, Red list, Rode, satellite collars, sea ice, Southern Beaufort, USFWS, withholding data
The largest conservation organization in the world says that predictive models developed by polar bear biologist Steven Amstrup are utterly unsuitable for scientifically estimating future populations. Earlier this year, mathematical modeling experts at the International Union for the Conservation of Nature, who maintain the Red List of Threatened Species, made it clear that Amstrup’s models (used in 2008 to convince the US Fish and Wildlife Service to list polar bears as ‘threatened’ due to predicted global warming) do not meet IUCN standards.
I’d say this makes Amstrup’s polar bear projections (Amstrup et al. 2008, 2010) no more scientifically useful than a crystal ball prophesy, but you wouldn’t know it by his recent actions — or the silence of his fellows.
Comments Off on Amstrup knows his polar bear predictions are flawed – but continues to promote them
Posted in Advocacy, Conservation Status, Sea ice habitat
Tagged Amstrup, Bayesian models, conservation, crystal ball, data deficient, ESA, extinction, IPCC, IUCN, models, PBSG, polar bear, Polar Bear Specialist Group, predictions, Red list, Resit Akçakaya, sea ice, threatened, vulnerable
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.
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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Comments Off on Polar bear researchers knew S Beaufort population continued to increase up to 2012
Posted in Advocacy, Conservation Status, Population
Tagged abundance, aerial survey, Beaufort Sea, Bromaghin, cherry-picking, IUCN, mark-recapture, models, PBSG, polar bear, population estimate, population recovery, Regehr, satellite collars, sea ice, Southern Beaufort, thick spring ice, USFWS, withholding data
A bit more good news about polar bear populations, this time from an abundance study in the Southern Beaufort Sea. A paper released yesterday showed a 25-50% decline in population size took place between 2004 and 2006 (larger than previously calculated). However, by 2010 the population had rebounded substantially (although not to previous levels).
All the media headlines (e.g. The Guardian) have followed the press release lead and focused on the extent of the decline. However, it’s the recovery portion of the study that’s the real news, as it’s based on new data. Such a recovery is similar to one documented in the late 1970s after a significant decline occurred in 1974-1976 that was caused by thick spring ice conditions.
The title of the new paper by Jeffery Bromaghin and a string of polar bear biologists and modeling specialists (including all the big guns: Stirling, Derocher, Regehr, and Amstrup) is “Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline.” However, the study did not find any correlation of population decline with ice conditions. They did not find any correlation with ice conditions because they did not include spring ice thickness in their models – they only considered summer ice conditions.
I find this very odd, since previous instances of this phenomenon, which have occurred every 10 years or so since the 1960s, have all been associated with thick spring ice conditions (the 1974-76 and 2004-2006 events were the worst). [Another incident may have occurred this spring (April 2014) but has not been confirmed].
Whoever wrote the press release for this paper tried hard to suggest the cause of the 2004-2006 event might have been “thin” winter ice caused by global warming that was later deformed into thick spring ice, an absurd excuse that has been tried before (discussed here). If so, what caused the 1974-1976 event?
It seems rather unscientific as well as implausible to even try to blame this recent phenomenon on global warming. However, neither the authors of the paper or the press release writers seemed to want to admit that 2-3 years of thick ice development in the Southern Beaufort could have been the cause of the population decline in 2004 (as for all of the previous events). No, that wouldn’t do, not in the age of global warming.
So, we are left with this equally absurd conclusion from the author:
“The low survival may have been caused by a combination of factors that could be difficult to unravel,” said Bromaghin, “and why survival improved at the end of the study is unknown.”
I’ve summarized the paper to the best of my understanding (there was a lot of model-speak to wade through), leaving out the prophesies of extinction, which in my opinion don’t add anything.
UPDATE November 19, 2014: Don’t miss my follow-up post, with some startling new information, “Polar bear researchers knew S. Beaufort population continued to increase up to 2012“
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Comments Off on S Beaufort polar bears largely recovered from known 2004-2006 decline, says new study
Posted in Population, Sea ice habitat
Tagged abundance, Amstrup, Beaufort Sea, Bromaghin, Derocher, low survival, mark-recapture, models, polar bear, population estimate, population recovery, Regehr, satellite collars, sea ice, Southern Beaufort, Stirling, summer ice minimum, thick spring ice
Polar bear activist Steven Amstrup made an astonishing statement in an interview earlier this week — he insisted that the current rate of warming in the Arctic is greater than anything polar bears have lived through before. He also said that optimistic comments on the future of polar bears made by geneticist Matt Cronin a few weeks ago were “incautious” and “misleading.”
Previously, I described how a new paper by Cronin and colleagues confirmed that genetic evidence indicates polar bears have been around long enough to have survived several past Interglacial periods that were warmer than today (and therefore, would have had virtually no summer ice). Cronin, not unreasonably, had some critical things to say about computer modeled predictions that polar bears could not survive in an Arctic without summer sea ice.
On Monday, the Anchorage Daily News gave Amstrup a forum to rebuke Cronin for his comments. A similar story was also carried by the Washington Post. [In the same ADN article, geneticist Charlotte Lindqvist, offered an outdated argument against future polar bear survival that I’ll deal with later]
Today, I’ll address Amstrup’s ridiculous assertion that the current rate of warming, attributed by him primarily to human activities rather than natural variation, is something polar bears have never experienced in their evolutionary history (a period of more than 400,000 years!).
Let’s start with the offending portion of the news item (published March 31, 2014):
Comments Off on Amstrup grasps at straws to defend his polar-bears-are-doomed computer model
Posted in Advocacy, Evolution, History
Tagged Amstrup, Anchorage Daily News, Cronin, Eemian, future, global warming, Holocene, interglacial, Lindqvist, misleading, models, past warming trends, polar bear, polar bear resilience, rate of warming
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