Polar Bear numbers

Inel drags me into the polar bear wars again by quoting the Heartland Institute: "Real-world evidence shows polar bear numbers are increasing rapidly throughout the Arctic". She offers no evidence against this, which is fair enough as they offer no evidence for it past the bare (geddit?) assertion.

So wot is happening to PB numbers? As in, now, not as in, wot might happen in the future.

The top google hit for polar bear numbers is
Nude Scientist (under myth: Climate myths: Polar bear numbers are increasing). They say "There are thought to be between 20,000 and 25,000 polar bears in 19 population groups around the Arctic. While polar bear numbers are increasing in two of these populations, two others are definitely in decline. We don't really know how the rest of the populations are faring, so the truth is that no one can say for sure how overall numbers are changing." That doesn't support Heartland, but nor does it support panic.

But NS points to the alaskan fisheries folk, which looks vaguely authoritative, at least from the outside :-). Aside: they sez: "The effects of the Eemian or Sangamon interglacial period (warming period) around 131,000BP on the Arctic marine ecosystem and polar bears are unknown." And thats it. Sounds like a good research project.

Sadly that doc lacks the vital "table 1" with the pop estimates in it, so I looked and found the PBSG version which looks good. It doesn't exactly match the NS quote: they have 2 inc, 1 stable, 5 declining and the rest of the 19 are "data insufficient".

If anyone can find better or more authoritative numbers, please let me know. But the result of this little trawl is a best-guess that an overall current best-guess assessment for change in numbers would be "don't know".

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The problem is that people then go and conclude its GW that's the cause of any change.

What it looks like is that the major cause of deaths is lead poisoning, from bullets.

Out of a tag set of polar bears, most deaths were from being shot.

Its mankind, but its not GW.

It's interesting to see that the 2 populations whose "observed or predicted trend" says "increasing" have a status labeled "severely reduced", while their "estimated risk of future decline" is "very low". I.e., exactly the two most threatened populations in the past are expected to grow in the future (or have recently been observed growing). I don't know what to make of that - probably nothing, but I just noticed and thought it's strange.

This page fleshes out some of the numbers: http://pbsg.npolar.no/new-status.htm

All the below is from reading the table and the notes linked above, and no prior knowledge:

It's worth noting that the two areas of increasing numbers both had hunting moratoriums a few years ago. These were introduced as a result of the low estimates (revised down from earlier, higher estimates). Both have now re-introduced hunting quotas. I skim-read the page but those were the only two areas with the word moratorium (found using the search tool). They are also two areas that share a border.

Southern Beaufort was counted at 2006 (unpublished when the table was compiled 2005) and declining. Foxe Basin was declining before 2004 when a reduced hunting quota was introduced. In 2004 the population was reported to have recovered and the quota has since been raised, it was marked as stable. Baffin Bay 2004 showed decline through "over-harvesting" and Davis Strait & Barents Sea (both 2004) are "data deficient". All the other areas' data is from 2000 or earlier - some even before 1995.

As 1995 was the previous record low for ice, and the general average has been decreasing since then, and one or two year hunting quota/moratorium changes can have a noticeable affect, much of the data seems out of date.

From reading the notes on the declining areas, ice loss is one (of a few) factor. Whether and when it becomes factor elsehwhere will (I guess) depend on whether ice loss picks up in those other areas. It seems that as the ice loss is not uniform across the Arctic, some subpopulations will be more affected earlier than others.

I would guess that the bay areas may be most stable as the ice lasts longer in bays?

The Alaska FWS report shows a more complicated relationship between polar bears and ice than I had thought.
(p.27) "In the Viscount Melville Sound area...ringed seals occurred at lower densities than in most other areas of polar bear habitation, possibly because there is a greater proportion of multi-year ice in this area, which is less preferable by ringed seals."
(p.29) "In the Southern Beaufort Sea heavy ice conditions in the mid-1970s and mid-1980s caused significant declines in productivity of ringed seals...Each event lasted approximately three years and caused similar declines in the natality of polar bears and survival of subadults."
(p.47 Norwegian Bay) "The preponderance of heavy multi-year ice through most of the central and western areas has resulted in low densities of ringed seals and consequently, low densities of polar bears."
(p.48 Lancaster Sound) "The western third of this region is dominated by heavy multi-year ice and apparently low biological productivity, as evidenced by low densities of ringed seals."
My overall impression is that a Goldilocks principle applies:
Too little ice: bad for polar bears
Too much ice, especially multi-year ice: bad for polar bears
Stable fast ice with drifts, floe edge and polynyas: good for polar bears.

The USGS recently completed reviews of polar bear population in all habitats of N. America - their prospects are very poor. Links to studies -

http://www.usgs.gov/newsroom/special/polar_bears/

A news article discusses the findings. "Most polar bears could die out by 2050"
http://www.msnbc.msn.com/id/20645362

I thought the Bush Administration's announcement to consider adding the bears to the endangered species list was either a) good science accidently slipping by them or b) a preemptive strike to minimize bad publicity. As the article explains on the 2nd page, it was neither. An environmental lawsuit forced them to address the issue.

My 'name link' quotes Dr. Mitch Taylor, a Canadian polar bear biologist whose studies are sometimes quoted to claim there is no problem. Dr. Taylor takes Australian writer Tim Flannery to task for misleading statements and cherry-picking.

Such is the thinness of people in the far north that the guys who should be studying and saving or trying to save the bears and work, more or less, for the govt. also work for the hunters. So you find one of the top writers, in the field of studies about the bears is also the guy most avidly spreading the line that the whole bear story about drowning bears is BS and the bears are flourishing. He goes on and on about how important the bears are, how much a hunter-guide makes off a few kills for tourist hunters and how the economy of the North depends on the hunt, and throws out a few lines on how hateful and ignorant all the eco-freaks are. With defenders like that, the bears have no chance and might as well go on a mass drowning. Are the bears swimming out too far looking for the ice, at times, sure they are. Are the populations declining as a result? Well, they are not increasing as a result.The only population that seems to be increasing is Americans who want to kill Polar Bears, and Canadian experts who are busy, busy, busy, helping out with truckloads of propaganda and riding shotgun with the hunters to take out any approaching eco-freaks.