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357 lines
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Plaintext
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THE STATE OF THE
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POLAR BEAR REPORT
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2023
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The Global Warming Policy Foundation
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Briefing 67
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Susan Crockford
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The State of the Polar Bear Report 2023
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Susan Crockford
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Briefing 67, The Global Warming Policy Foundation
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© Copyright 2024, The Global Warming Policy Foundation
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iii
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Contents
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About the author iii
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Foreword v
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Executive summary v
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1. Introduction 1
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2. Conservation status 1
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3. Population trends 5
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4. Habitat and primary productivity 6
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5. Human/bear interactions 11
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6. Discussion 14
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Bibliography 16
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Notes 24
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About the Global Warming Policy Foundation 26
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About the author
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Dr Susan Crockford is an evolutionary biologist and has been working for more than 40 years in
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archaeozoology, paleozoology and forensic zoology.1
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She is a former adjunct professor at the
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University of Victoria, British Columbia and works full time for a private consulting company she
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co-owns (Pacific Identifications Inc). She is the author of Eaten: A Novel (a science-based polar bear
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attack thriller), Polar Bear Facts and Myths (for ages seven and up, also available in French, German,
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Dutch, Portuguese, and Norwegian), Polar Bears Have Big Feet (for preschoolers), and several
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fully referenced books including, Polar Bear Evolution: A Model for the Origin of Species, Sir David
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Attenborough and the Walrus Deception, The Polar Bear Catastrophe That Never Happened, and Polar
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Bears: Outstanding Survivors of Climate Change,2 as well as a scientific paper on polar bear conservation status and a peer-reviewed paper on the distribution of ancient polar bear remains.3
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She has
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authored several earlier briefing papers, reports, and videos for GWPF, as well as opinion pieces for
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major news outlets, on polar bear and walrus ecology and conservation.4
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Susan Crockford blogs
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at www.polarbearscience.com.
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v
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Foreword
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This report is intended to provide
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a brief update on the habitat and
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conservation status of polar bears,
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with commentary regarding inconsistencies and sources of bias found
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in recent literature that won’t be
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found elsewhere. It is a summary
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of the most recent information
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on polar bears, relative to historical records, based on a review of
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2023 scientific literature and media
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reports, and, in places, reiterates or
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updates information provided in
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previous papers. This publication
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is intended for a wide audience,
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including scientists, teachers,
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students, decision-makers, and
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members of the general public
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interested in polar bears and the
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Arctic sea ice environment.
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Executive summary
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2023 marked 50 years of international cooperation to protect
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polar bears across the Arctic.
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Those efforts should be hailed as
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a conservation success story: from
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late-1960s population estimate by
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the US Fish and Wildlife Service of
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about 12,000 individuals, numbers
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have almost tripled, to just over
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32,000 in 2023 (with a wide range
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of potential error for both estimates).
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• There were no reports from
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the Arctic in 2023 indicating polar
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bears were being harmed due to
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lack of suitable habitat, in part
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because Arctic sea ice in summer
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has not declined since 2007.
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• Contrary to expectations, a
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study in Svalbard found a decrease
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in polar bears killed in defense of
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life or property over the last 40
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years, despite profound declines in
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sea ice over the last two decades.
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• A survey of Southern Hudson
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Bay polar bears in 2021 showed
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an astonishing 30% increase over
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five years, which adds another 223
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bears to the global total.
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• A concurrent survey of Western
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Hudson Bay polar bears in 2021
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showed that numbers had not
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declined since 2011, which also
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means they have not declined
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since 2004. Movement of polar
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bears across the boundaries with
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neighbouring subpopulations
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may account for the appearance
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of a decline, when none actually
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occurred.
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• The IUCN Polar Bear Specialist
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Group has ignored a 2016 recommendation that the boundaries
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of three Hudson Bay subpopulations (Western HB, Southern HB,
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and Foxe Basin) be adjusted to
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account for genetic distinctiveness
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of bears inhabiting the Hudson Bay
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region. A similar boundary issue
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in the western Arctic between the
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Chukchi Sea, and the Southern and
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Northern Beaufort subpopulations,
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based on known movements of
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bears between regions, has been
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acknowledged since 2014 but has
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not yet been resolved.
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• The US Fish and Wildlife Service
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and the IUCN Polar Bear Specialist
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Group, in their 2023 reports, failed
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to officially acknowledge the newfound South-East Greenland bears
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as the 20th subpopulation, despite
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undisputed evidence that this is a
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genetically distinct and geographically isolated group. Numbers are
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estimated at 234 individuals.
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1
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1. Introduction
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Fifty years ago, on 15 November 1973, the five Arctic nations of
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Canada, Russia, the USA, Norway and Greenland signed an international treaty to protect polar bears against the rampant overhunting
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that had taken place in the first half of the 20th century, and which
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had decimated many subpopulations. The treaty was effective, and
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by the late 1990s, polar bear populations that could be studied had at
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least doubled, making it a huge conservation success story. However,
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in 2009, the wording of the treaty was amended to protect the bears
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against on-going and future loss of sea ice habitat , which was
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assumed to be caused by human-generated greenhouse gas emissions. This was in line with similar declarations by the International
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Union for the Conservation of Nature (IUCN) and the US Endangered
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Species Act (USESA). These pessimistic conservation assessments,
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based on computer-modelled future declines rather than observed
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conditions, have been upheld ever since, even as the predicted relationship between polar bear survival and sea-ice loss has failed to
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emerge in the observational data.5
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The current population of polar bears is large, and their historical range has not diminished due to habitat loss since 1979. Indeed,
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previously inhabited areas have been recolonised as numbers have
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recovered: recent data suggest that territory in Davis Strait used before
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1970 during the summer ice-free period – by all ages and by pregnant
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females for maternity denning – is now being used once again.6.
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2. Conservation status
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The IUCN, in their 2015 Red List assessment, provided by the Polar
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Bear Specialist Group (PBSG), again listed polar bears as ‘vulnerable’
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to extinction, just as it did in 2006. Similarly, in 2023 the US Fish and
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Wildlife Service (USFWS) upheld its 2008 conclusion that polar bears
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were ‘threatened’ with extinction. In both instances, conservation
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status assessments have been based on computer-modelled predictions of future sea-ice conditions and assumed resultant population
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declines rather than current conditions.7
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In Canada, the 2018 COSEWIC report assigned a status of ‘special
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concern’ to the species. This assessment had not changed by 2023.8
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3. Population size at 2023
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Global
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The latest official estimate for the global population, from 17 October
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2023, is the PBSG estimate of 26,000 (range 22,000–31,000), arrived
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at in 2015 and unadjusted since then. In their 2023 assessment, the
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PBSG has failed to increase this estimate, even to account for undisputed, statistically-significant increases in two subpopulations and
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the addition of a newly-discovered subpopulation, which should reasonably boost their very conservative mid-point estimate to about
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26,600: Kane Basin is up by 133, Southern Hudson Bay is up by 223,
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and newly-discovered SE Greenland adds another 234.9
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2
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However, survey results postdating preparation of the 2015
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assessment, including those made public after July 2021 (for
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Davis Strait, Chukchi Sea, SE Greenland, Western Hudson Bay, and
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Southern Hudson Bay), plausibly brought the mid-point total to
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just over 32,000 (Figure 1).10
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A plan to survey all Russian polar bear subpopulations between
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2021 and 2023 seems to have been put on hold. In addition, an
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abundance estimate for the Viscount Melville subpopulation in the
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western Canadian Arctic has still not been released, even though
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a three-year survey completed in 2014 has produced other published data.11 Surveys of Lancaster Sound and East Greenland
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were completed in spring 2023, and these results, when released,
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may put the global population mid-point estimate well above
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32,000.12 While there is a wide margin of potential error attached
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to this number, it is nowhere near the figure of 7,493 (6,660–8,325),
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implicit in the prediction that two thirds of the global population
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of polar bears would be gone by now, given the sea ice conditions
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prevailing since 2007.13
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Note that the 2023 USFWS Status Report did not include the
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Kara Sea estimate of 3,200 bears, the Laptev Sea estimate of 1,000
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bears, or the East Greenland estimate of 2,000 bears, figures that
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were used for the 2015 IUCN assessment. It also used the lowest
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of three available 2016 estimates for the Chukchi Sea, as discussed
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in the State of the Polar Bear Report 2021.
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14 Although the USFWS
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report was published in August 2023, it also did not include results
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of the 2021 assessments of the Western and Southern Hudson
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Bay subpopulations that were published in November 2022, or
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the newly-discovered subpopulation of South East Greenland
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reported in June 2022.15.
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Figure1: Estimates of the
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global polar bear population, 1960 to date.
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60
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40
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20
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0
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1960
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000s
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1980 2000 2020
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3
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Subpopulation survey results published in 2022
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For detailed discussions of the changing status and abundance
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issues over time for all 19 subpopulations, see the State of the Polar
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Bear Report 2018.
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16
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Western Hudson Bay (WH)
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An aerial survey conducted in September 2021 generated a new
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subpopulation estimate of 618 (range 385–852), an apparent
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decline of 27% since the 2016 estimate of 842 (range 562–1121)
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and about a 40% decline from a 2011 estimate of 949 (range 618–
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1280) that used similar survey methods. However, the WH 2021
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report authors stated categorically that this apparent decline since
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2011 was not statistically significant, in part due to evidence that
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some bears moved into neighbouring subpopulations combined
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with the large margins of error. While it seems inconceivable that
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a decline of 40% over 10 years could be statistically insignificant,
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recall that a similar conclusion was reached in 2015 regarding the
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42% increase in abundance of Svalbard bears. Since the estimate
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calculated in 2004 was 935 (range 794–1076), it seems the abundance of WH polar bears has not changed since 2004.17 Note that
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a more comprehensive survey was conducted in 2011, generating
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an estimate of 1030 (range 754–1406). This became the official WH
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estimate used by the PBSG.18
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Given the conclusions of the 2021 survey that the 2016 and 2021
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estimates were not statistically different from the 2011 estimate, it
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appears that the 2021 comprehensive estimate of 1030 may still
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be the most valid figure for WH.
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The 2021 WH survey authors also made it clear that the most
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recent population estimate was not associated with poor ice conditions, since sea-ice levels had been as good as the 1980s in four
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out of the five years between 2017 and 2021. Confoundingly, they
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could not explain why adult females and subadults were underrepresented in the population.
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No evidence was provided for lack of prey, and although
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emigration to neighbouring Southern Hudson Bay was largely
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dismissed as an explanation, the possibility of a movement north
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into Foxe Basin was not explored.
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This is odd, since a 2016 genetic study suggested that the
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northern boundary for WH polar bears should be moved to the
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north of Southampton Island (a major denning area currently
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included in FB) and the SH boundary to the north of Akimiski
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Island in James Bay, adding the entire southern Hudson Bay coast
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in Ontario, as well as the Belcher Islands, to WH (currently included
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in SH), leaving only James Bay to represent SH.19
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In 2023, the PBSG indicated the WH subpopulation was ‘likely
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decreasing’, based on the 2021 estimate of 618 bears. However,
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they did not include the caveat from the survey report that this
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apparent decline was not statistically significant, and also did not
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incorporate the conclusion of the 2022 Canadian Polar Bear Technical
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Committee (PBTC) that indigenous knowledge (IK) assessed this
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subpopulation as ‘increased’. Similarly, the 2023 assessment by the
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4
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USFWS listed WH as ‘likely decreased’, based on the 2016 survey
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only (2021 survey results were not included). It acknowledged
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that in 2022 IK considered this subpopulation to have ‘increased’.20
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Southern Hudson Bay (SH)
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An aerial survey conducted in September 2021 generated a new
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subpopulation estimate of 1119 (range 860–1454), which represented a 30% increase over five years. The result was considered
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robust, and reflective of the true size of the population. However,
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another estimate, of 1003 (range 773–1302), was generated based
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on the same data. This was considered more comparable to the
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2016 estimate of 780 (range 590–1029). While the authors did not
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explicitly address the issue of statistical significance, they concluded
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that a natural increase in numbers, via increased cub production
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and survival, must have taken place in conjunction with good sea
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ice conditions from 2017 to 2020, perhaps in addition to immigration from another unidentified subpopulation.21.
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In their 2023 assessment, the IUCN PBSG discussed the apparent
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increased abundance of SH bears, but did not unequivocally state
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that the subpopulation had increased, instead only implying that
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an increase may have been possible (‘years of relatively good ice
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conditions, combined with comparatively reduced harvest from
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2016–2021 may have buffered the population against further
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decline or allowed for recovery’). They also did not include the 2022
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assessment by the PBTC that IK considered the SH subpopulation
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was ‘stable/likely increased’ (i.e. stable in the James Bay portion,
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likely increased in southeastern Hudson Bay).22.
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The 2023 assessment by the USFWS listed SH as ‘likely decreased’,
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based only on 2016 survey results (2021 survey results were not
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included), but did acknowledge that in 2022, IK considered this
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subpopulation to be ‘stable/likely increased.’23.
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Southeast Greenland (SG)
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As part of a multiyear project on the status of SG polar bears that
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began in 2011, surveys were conducted during mid-March and
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mid-April of 2015–2017 for bears that lived below 64°N latitude.
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The results were compared with data from bears living in EG further
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north, which had been collected up to 2021. This southern region
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of Greenland had not previously been surveyed, or even visited by
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polar bear scientists, and there are no permanent human inhabitants. Few Inuit hunters even venture into the region.24
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Based on capture-recapture data, a population estimate of
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234 (range 111–462) was generated for SG. Weight (indicating
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body condition or fatness) of almost two dozen females captured
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in SG averaged 186 kg, which was similar to females in Svalbard
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in the western Barents Sea (185 kg) in the 1990–2000 period and
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in EG in recent years (186 kg).
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Most surprisingly, there was strong evidence that these SG
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polar bears are the most genetically distinct subpopulation in
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the Arctic, indicating a lack of interbreeding with bears in EG for
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at least 200 years.25.
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5
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Much emphasis was given by study authors Kirstin Laidre
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and colleagues to their interpretation that bears in these SG fjords
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frequently used glacier ice to hunt seals during the summer; in
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other locations bears only do so occasionally. Seals feed in such
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‘glacier-front’ habitats in summer because primary productivity
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is high: melting glaciers in the fjords attract fish because their
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food – marine plankton – is plentiful. However, the only evidence
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provided of seal-hunting behaviour by polar bears in summer in
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SG is one photo, taken by an unidentified photographer, of a bear
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on glacier ice beside a seal kill taken in September 2016. As noted
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above, the SG polar bear surveys were conducted in March and
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April and therefore, frequent summer hunting of seals could not
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have been observed by the authors, but was simply assumed to
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have happened.
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In addition, although the authors imply that glacier-front habitat
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is rare, it is in fact rather common across the Arctic and widely
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used by polar bears year-round because the sea ice covering such
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fjords in late winter and spring (including those in SG) are used by
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ringed seals as a birthing platform. Moreover, newborn seals are
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the preferred prey of polar bears, making up roughly two thirds of
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their diet. Fjords with glacier ice are present all along both coasts
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of Greenland, in Svalbard, Novaya Zemlya and Franz Josef Land in
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Russia, and in Baffin and Ellesmere Islands in the Canadian Arctic.26
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The authors concluded their report with a recommendation
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that SG be officially recognized by the IUCN PBSG as a polar bear
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subpopulation distinct from EG for management and conservation
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purposes. However, despite the fact that Dr Laidre is currently the
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co-chair of the PBSG, and that in March 2023 the government of
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Greenland declared SG a protected ‘new and separate management unit’, the PBSG declined to add it as a distinct subpopulation.
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The 2023 USFWS assessment cited the 2022 Laidre report and its
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abundance estimate for SG, but regarding a change in boundaries
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for EG, it stated only that, ‘ecoregion and subpopulation status will
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likely be re-evaluated by PBSG in 2023’.27
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4. Population trends
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In Canada, where roughly two thirds of the world’s polar bear population live, a 2022 update from the PBTC for the first time included
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assessments based on Inuit IK for each of the 13 subpopulations for
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which Canada has sole or joint management responsibility. While
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the ‘scientific’ assessments for trends in abundance for these subpopulations are simply the widely varying ones provided by the
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PBSG in 2021, those based on IK were either ‘increased’ or ‘stable’.28
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Later in 2022, the Government of Canada published updated
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global polar bear population trend maps based on 2021 PBSG
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‘scientific’ data: no provision was made for the conflicting information from IK discussed above, calling into question whether IK
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assessments are actually given any weight in assessing current
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conditions.29 And while the 2023 USFWS assessment included the
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2022 Canadian IK trend information in their status table, it gave
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6
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priority to 2021 PBSG scientific data.30
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Figure 2 shows a more realistic representation of current
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polar bear population trends based on all available information
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(scientific survey results, IK, and studies on health and survival
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status published up to 31 December 2023, extrapolated to regions
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lacking recent survey data). This gives the following subpopulation classifications at 2023, including the new subpopulation of
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SE Greenland (SG):
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• seven ‘increasing’ or ‘likely increasing’ [KB, DS, MC, GB, CS, BS, SH].
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• four ‘stable’ or ‘likely stable’ [BB, SB, WH, SG].
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• nine ‘presumed stable or increasing’ [EG, LS, LP, KS, VM, NB, GB,
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FB, NW].
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