Tag Archives: mark-recapture

S Beaufort polar bears largely recovered from known 2004-2006 decline, says new study

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.

Polar bear with collar and tag_USGS_labeled

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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Polar bear biologists doing mark-recapture work in Hudson Bay may have misled the world

What exactly are Western Hudson Bay (WHB) polar bear researchers hiding? Since 2004, research on the body condition and cub production of Western Hudson Bay (WHB) polar bears has been carried out but none of the results of these mark-recapture studies have been made public.

U Alberta student Mislan bio photos_PolarBearScience

The researchers all claim that WHB polar bears are struggling to survive because of recent sea ice changes but won’t release the 10 years worth of updated information they possess on the bears or the sea ice.

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Inuit resist government requests to tag and collar polar bears in MClintock Channel

Inuit residents of Cambridge Bay in the Central Canadian Arctic are resisting requests by the Nunavut Government to tranquilize, collar and tag polar bears to assist in their population survey.

“A female polar bear and her two cubs dash across the ice near Gjoa Haven, where the polar bear hunt has been limited for nearly 15 years. (PHOTO BY JANE GEORGE)” Story here, also by Jane George.

“A female polar bear and her two cubs dash across the ice near Gjoa Haven, where the polar bear hunt has been limited for nearly 15 years. (PHOTO BY JANE GEORGE)” Story here, also by Jane George.

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W Hudson Bay mark-recapture studies of polar bears were invalid, says peer-reviewed study

“Our results suggest that mark–recapture estimates may have been negatively biased due to limited spatial sampling. We observed large numbers of bears summering in southeastern WH, an area not regularly sampled by mark–recapture.” Stapleton et al. 2014.

Polar bear at Wapusk National Park (just south of Churchill) in August 2011. Courtesy Parks Canada.

Polar bear at Wapusk National Park in August 2011. Courtesy Parks Canada.

We’ve seen the results of this 2011 study before, in government report format. But now it’s been revamped, peer-reviewed and published in a respected scientific journal – it actually came out in February, without fanfare, but I’ve only just come across it.

Some excerpts below, with conclusions that should raise some eyebrows.

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Guest Post: Invasive Research is Alive and Well in Canada

This is a guest post by Kelsey Eliasson, who blogs at Polarbearalley, with his thoughts on the issue of the invasive research involved in polar bear mark-recapture studies around Churchill, Manitoba — which, as you’ll see, is a far different situation than I described for Nunavut (previous posts here, here, and here on this topic. Map below to get you oriented).

Kelsey is a writer, artist and polar bear guide who has spent 14 bear seasons watching the polar bears of Churchill. For five years, he ran Churchill’s monthly newspaper published occasionally, the Hudson Bay Post. Currently, he divides his year between the Yukon, Churchill and, occasionally, Riverton, home of Manitoba’s largest moose statue.

Churchill is in the Western Hudson Bay polar bear subpopulation, governed by the Province of Manitoba, while the community of Arviat, also in 'Western Hudson Bay' is overseen by the Government of Nunavut.

Churchill lies in the Western Hudson Bay (WHB) polar bear subpopulation, governed by the Province of Manitoba, while the community of Arviat, also in the Western Hudson Bay subpopulation, is overseen by the Government of Nunavut – different governments, different rules – as Kelsey points out below.

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Invasive Research is Alive and Well in Canada, by Kelsey Eliasson

The recent post about Foxe Basin was of particular interest to me, as I have been following the growing gap between the north and science for some time now. The stance taken by the Inuit is viewed as an inspiration by the guides over here in Churchill. For many years, we have tried to voice our deep concerns over the levels of handling and drugging that our bears (the Western Hudson Bay population) are subjected to on an annual basis.

This time last year, I tried to raise the topic for discussion after Andrew Derocher announced that ‘everything was on the table’ including feeding bears. At that time, the top polar bear researchers had sat down to discuss options for saving bears – except reducing handling and research – i.e. chasing bears down by helicopter and then shooting them with tranquilizers. Continue reading

Foxe Basin aerial survey a watershed moment for polar bear research, Part 2

As I outlined earlier this week, Canadian Inuit objected so strenuously to routine mark-recapture methods used by polar bear biologists during the early days of a Foxe Basin population study in 2008 that the work was abandoned and an aerial survey done instead.

In this post, I’ll examine how the polar bear biologists involved reacted to that crisis, which they called a “control of research” issue.

In a published version of a conference paper, co-authored by two of the original investigators of the Foxe Basin mark-recapture study, Lily Peacock and Andrew Derocher (Peacock et al. 2011:374), had this to say:

Control of research is a developing source of conflict. In recent years, some permits for management-oriented research on polar bears were denied by the Government of Nunavut, local hunting and trapping organizations in the Northwest Territories, and by Makivik Corporation in Quebec. Furthermore, in a 2009 resolution, Inuit Tapiriit Kanatami opposed the capture of polar bears throughout Canada (available by request from http://www.itk.ca), even though the application of physical marks is one of the most effective methods of population estimation. Co-management is particularly difficult in Nunavut because of the large number of subpopulations (12), which makes it difficult to fund and conduct research.” [my bold]

They raised an interesting point – since the Government of Nunavut has the power to insist biologists do more than reiterate that their way of counting bears is the only acceptable way, and because the government can deny permits to projects that don’t measure up, it can lock out traditional polar bear research for virtually all of Canada (the vast majority of Canada’s 13 subpopulations are in Nunavut, see Fig. 1), especially since aboriginal organizations in the Northwest Territories and Quebec have followed Nunavut’s lead.

Figure 1. Territory covered by the Government of Nunavut (top, Wikipedia) and the 13 polar bear subpopulations in Canada (bottom, Environment Canada).

Figure 1. Territory covered by the Government of Nunavut (top, Wikipedia) and the 13 polar bear subpopulations in Canada (bottom, Environment Canada).

That means if polar bear researchers can’t find a way to make their research mesh with Inuit concerns, they’ll be out of work in Canada. Let’s take a look at their approach and see how well it worked for them — explaining in part the new prominence of aerial surveys for population assessments. Continue reading

Foxe Basin aerial survey – a watershed moment for polar bear research, Part 1

While researching the population status of Foxe Basin polar bears I came across an issue that seems to have garnered relatively little attention outside the polar bear community – Inuit objections to the handling of polar bears during mark-recapture surveys and the effect of this on polar bear research in Canada.

 Figure 1. US Fish and Wildlife biologists handling a polar bear in the southern Beaufort during a fall survey, October 24, 2001. Steve Amstrup photo.


Figure 1. US Fish and Wildlife biologists handling a polar bear in the southern Beaufort during a fall survey, October 24, 2001. Steve Amstrup photo.

Foxe Basin is a large polar bear subpopulation region that encompasses the northern portion Hudson Bay into the area west of Baffin Island, see map below (courtesy IUCN Polar Bear Specialist Group).

FoxeBasin_PBSG website_Oct 2013Mark-recapture research methods routinely used by polar bear biologists became especially contentious in Foxe Basin during a population study initiated in 2007/2008, with Inuit residents voicing objections and biologists defending its practice. The following year, the mark-recapture effort was halted and an aerial survey took its place.

The aerial survey has been completed and a report on it was released in 2012 (Stapleton et al. 2012; see previous post for results) but we’ve heard very little about what happened to that mark-recapture study and why the Government of Nunavut pulled the plug on it. I plan to change that with the next couple of posts.

I’m not claiming to understand the nuances of the story because I’m only going by available documents. However, I think it’s important to shine some light on this issue since it has clearly changed the shape of polar bear research in Canada.
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Foxe Basin polar bear status – another stable population

Foxe Basin_PBSG

Figure 1. Polar bear subpopulation regions defined by the Polar Bear Specialist Group, Foxe Basin marked.

Foxe Basin is a large subpopulation region (Fig. 1), with a total area of 1.18 million square km (Vongraven and Peacock 2011). It comprises Northern Hudson Bay and western Hudson Strait, and the area between western Baffin Island and eastern Melville Peninsula, with a large island (Southampton Island) in the middle (Figs. 2 and 3).

Figure 1. Foxe Basin polar bears subpopulation region, courtesy IUCN PBSG

Figure 1. Foxe Basin polar bears subpopulation region, courtesy IUCN PBSG

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Guest post: How ‘science’ counts bears

This essay by Dr. Jim Steele, professor emeritus, San Francisco State University, is reblogged from a July 3 2013 post at WUWT post, with Dr. Steele’s permission. I am not a field biologist and have never done a mark-recapture study but Dr. Steele has. His perspective on the way polar bear biologists count bears and estimate survival in the Southern Beaufort is a perfect companion to yesterday’s post, a related post that I’ll put up later this week, and this one from December, among others. I’ve added links to the references cited in this essay where they are available, as is my custom. See the original post for Jim’s responses to comments and questions.

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Guest post by Jim Steele   “How ‘science’ counts bears”

The Inuit claim “it is the time of the most polar bears.” By synthesizing their community’s observations they have demonstrated a greater accuracy counting Bowhead whales and polar bears than the models of credentialed scientists. To estimate correctly, it takes a village. In contrast the “mark and recapture” study, which claimed the polar bears along South Beaufort Sea were victims of catastrophic global warming and threatened with extinction, relied on the subjective decisions of a handful of modelers.

In mark and recapture studies, the estimate of population abundance is skewed by the estimate of survival. For example, acknowledging the great uncertainty in his calculations of survival, in his earlier studies polar beat expert Steven Amstrup reported three different population estimates for bears along the South Beaufort Sea. If he assumed the adult bears had an 82% chance of surviving into the next year, the models calculated there were 1301 bears. If survivorship was 88%, the abundance climbed to 1776 bears. If he estimated survivorship at a more robust 94%, then polar bear abundance climbed to 2490.1 Thus depending on estimated survival rates, a mark-and-recapture study may conclude that the population has doubled, or that it has suddenly crashed.

Here are the simplified basics of estimating survival.

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