Order Code RS22582
January 25, 2007
Polar Bears: Listing Under the
Endangered Species Act
Eugene H. Buck
Specialist in Natural Resources Policy
Resources, Science, and Industry Division
Polar bears depend on an Arctic sea ice habitat, which some believe is threatened
by climate warming causing an earlier thaw and later freeze of coastal sea ice. The Fish
and Wildlife Service has proposed listing polar bears as threatened species under the
Endangered Species Act, acknowledging the increasing threats to their existence.
Although this listing decision must be solely based on the best available scientific and
commercial information, some are concerned that an ESA listing might have extensive
economic impacts, since federal agencies are required under the ESA to ensure that
anything they authorize or fund that might affect polar bears would not jeopardize the
survival of these bears or their sea ice habitat.
The polar bear, Ursus maritimus, is one of the largest terrestrial carnivores,
inhabiting circumpolar Arctic regions wherever sea ice is present for a substantial part of
the year. Nineteen populations of polar bears have an estimated total abundance of
20,000 to 25,000 animals. Two of these populations occur within U.S. jurisdiction — the
Southern Beaufort Sea population (shared with Canada) is estimated at 1,800 animals,
while the Chukchi/Bering Seas population (shared with Russia) is estimated at 2,000
animals. Some believe that polar bear population abundance is declining worldwide.1
The polar bear is a carnivore, or meat eater, with the ringed seal as its primary prey.
Over most of their range, polar bears remain on the sea ice year-round or spend at most
only short periods on land. A polar bear may stalk a seal by waiting quietly for it to
emerge from its blow hole, an opening seals make in the ice allowing them to breathe or
Marine Mammal Commission, Annual Report to Congress, 2005 (Bethesda, MD: July 15,
2006), p. 50 (hereafter cited as “Marine Mammal Commission report”). Population status and
trends are not available for many of these populations. Two Canadian populations are known to
be increasing, recovering under conservative harvest limits after severe past reductions. Two
other populations in the Western Hudson Bay and the Southern Beaufort Sea are both declining.
climb out of the water to rest. In October and November, male polar bears head out onto
pack ice where they spend the winter. Pregnant females, however, seek sites on the
mainland or on sea ice to dig large dens in snow where they give birth and spend the
Because the primary habitat of the polar bear is sea ice and this species is
evolutionarily adapted to life on sea ice, it is usually considered to be a marine mammal.
In the United States, polar bears are protected and managed under the Marine Mammal
Protection Act (MMPA; 16 U.S.C. §§1361, et seq.), with the Fish and Wildlife Service
(FWS) as the federal management agency. The Alaska Nanuuq Commission, a Native
organization representing villages in northern and northwestern Alaska, provides input
on matters related to the conservation and sustainable use of polar bears. In addition, the
multilateral 1973 Agreement on the Conservation of Polar Bears3 and the 2000 bilateral
Agreement Between the Government of the United States of America and the
Government of the Russian Federation on the Conservation and Management of the
Alaska-Chukotka Polar Bear Population provide a basis for international cooperation on
polar bear management.
Human Activities Affecting This Species
Climate Change. A May 2002 report by an environmental organization raised
concerns that polar bears were threatened by climate change.4 An October 2003 article
in the journal Nature confirmed that, in recent decades, the extent of Arctic sea ice has
declined significantly as the result of climate warming: ice break-up in many areas is
occurring earlier and freeze-up later.5 In addition, others assert that Arctic sea ice is
experiencing a continual decline that cannot easily be reversed.6 Distribution patterns of
some polar bear populations have changed in recent years. Greater numbers of bears are
being found onshore near the Bering Sea,7 and in some parts of Canada, with Inuit hunters
reporting more bears present on land during summer and fall.8 There may be several
U.S. Dept. of the Interior, Fish and Wildlife Service, “Polar Bear Fact Sheet,” available at
[http://www.fws.gov/home/feature/2006/polarbear.pdf], and “Polar Bear Questions and
Answers,” available at [http://www.fws.gov/home/feature/2006/PolarbearFAQ.pdf].
Parties to this agreement are Canada, Denmark, Norway, the Russian Federation, and the United
Stefan Norris, Lynn Rosentrater, and Pal Martin Eid, Polar Bears at Risk, World Wildlife Fund,
May 2002, available at [http://www.ngo.grida.no/wwfap/polarbears/risk/PolarBearsAtRisk.pdf].
Seymour Laxon, Neil Peacock, and Doug Smith, “High Interannual Variability of Sea Ice
Thickness in the Arctic Region,” Nature, v. 425 (Oct. 30, 2003), pp. 947-950.
R. W. Lindsay and J. Zhang, “The Thinning of the Arctic Sea Ice, 1988-2003: Have We Passed
a Tipping Point?,” Journal of Climate, v. 18, no. 22 (2005), pp. 4879-4894.
S. L. Schliebe, T. Evans, S. Miller, and J. Wilder, “Fall Distribution of Polar Bears along
Northern Alaska Coastal Areas and Relationship to Pack Ice Position,” in Collection of Scientific
Papers from the 4th International Conference of Marine Mammals of the Holarctic, ed. V. M.
Belkovich (St. Petersberg, Russia: 2006), p. 559.
Unpublished reports in 2005 by M. Dowsley and M. Taylor, as cited in the FWS polar bear
reasons for these changes, including changes in sea ice. The projected loss of sea ice may
affect the polar bear in survival and reproduction by:
shortening the season during which ice is available as a platform for
increasing the distance between the ice edge and land, thereby making
it more difficult for female bears to reach preferred denning areas;
requiring bears to travel through fragmented sea ice and open water,
which uses more energy than walking across stable ice formations;
reducing the availability of ice-dependent prey, such as ringed seals; and
requiring bears to spend more time on land, thereby increasing the
potential for adverse human-polar bear interactions.9
Contaminants. Three main groups of contaminants are thought to present the
greatest potential threat to polar bears — petroleum hydrocarbons, persistent organic
pollutants (polychlorinated biphenyls, chlordanes, DDT and its metabolites, toxaphene,
dieldrin, hexachlorobenzene, hexachlorocyclohexanes, and chlorobenzenes), and heavy
metals. Polar bears are particularly vulnerable to oil spills, due to the damage of oil to
polar bear fur (decreasing the bears’ ability to thermoregulate) and to ingestion of oil
(poisoning) from grooming and/or eating contaminated prey.10 Although elevated
concentrations of some persistent organic pollutants have been discovered in polar bears,
it has been difficult to determine what biological effects these chemicals might have on
polar bears. Mercury is the heavy metal of greatest concern because of its toxicity at low
concentration, and its magnification and accumulation through the food chain. However,
polar bears appear able to demethylate mercury and accumulate elevated levels of
mercury without detrimental effects.11
Subsistence and Sport Harvest. The United States only allows limited
subsistence harvest of polar bears by Alaska Natives.12 In addition to subsistence harvest,
Canada permits limited sport harvest of polar bears. Under 1994 amendments to the
MMPA, U.S. citizens may obtain permits to import sport-harvested polar bear trophies
from Canada.13 There is greater concern for the Chukchi/Bering Seas population due to
status report (see footnote 18).
Marine Mammal Commission report, p. 52.
D.J. St. Aubin, “Physiologic and Toxic Effects on Polar Bears,” in Sea Mammals and Oil:
Confronting the Risks, J.R. Geraci and D.J. St. Aubin, eds. (New York, NY: Academic Press,
Inc., 1990), p. 235-239.
Arctic Monitoring and Assessment Programme, AMAP Assessment 2002: Persistent Organic
Pollutants in the Arctic (Oslo, Norway: 2005), p. 123.
In the year from July 1, 2004 through June 30, 2005, Alaska Natives harvested 27 bears from
the Southern Beaufort Sea population and 33 bears from the Chukchi/Bering Sea population.
Sections 4 and 5 of P.L. 103-238.
anecdotal evidence that unregulated harvest by Russian Natives on the Chukotka
Peninsula may be reaching unsustainable levels.14
On February 17, 2005, FWS received a petition from the Center for Biological
Diversity requesting that FWS list the polar bear as threatened throughout its range and
that it designate critical habitat for this species.15 The Natural Resources Defense Council
and Greenpeace, Inc., joined as petitioners on July 5, 2005. On December 15, 2005, the
petitioners filed a complaint, challenging FWS’s failure to issue a 90-day finding on the
petition.16 On February 7, 2006, FWS announced a finding that the petition presented
substantial scientific information indicating that listing the polar bear might be warranted,
and subsequently announced the initiation of a formal status review.17
On January 9, 2007, FWS announced its 12-month finding on the petition —
concluding that, after a review of scientific and commercial information,18 listing the
polar bear as a threatened species under the ESA was warranted — and formally proposed
such listing.19 This proposed rule does not designate critical habitat for the polar bear.
A 90-day period (through April 9, 2007) was announced to receive data and comments,
with requests for a public hearing accepted for 45 days (through February 23, 2007).
Internationally, polar bears are listed on Appendix II of the Convention on
International Trade in Endangered Species of Fauna and Flora (CITES), which contains
species not necessarily threatened with extinction but requiring controlled trade to prevent
The Secretary of the Interior must decide whether to list polar bears under the ESA
based only on the best available scientific and commercial information, after an extensive
series of procedural steps to ensure public participation and the collection of relevant
information. At this point, the Secretary may not consider the economic effects that
Marine Mammal Commission report, p. 50-51.
For additional background on the Endangered Species Act as well as regulatory procedures
under this act, see CRS Report RL31654, The Endangered Species Act: A Primer, by M. Lynne
Corn, Eugene H. Buck, and Pamela Baldwin.
In a settlement agreement, approved on July 5, 2006, FWS agreed to submit a 12-month finding
on the petition by December 27, 2006.
71 Fed. Reg. 6745, Feb. 9, 2006. Information on the status of the polar bear was solicited from
the public in this notice and again in 71 Fed. Reg. 28653, May 17, 2006.
The polar bear status assessment document is available at [http://alaska.fws.gov/fisheries/
72 Fed. Reg. 1064-1099, Jan. 9, 2007.
For additional background on CITES, see CRS Report RL32751, The Convention on
International Trade in Endangered Species of Wild Fauna and Flora (CITES): Background and
Issues, by Pervaze A. Sheikh and M. Lynne Corn.
listing may have on the area where the species occurs. This is the only place in the ESA
where economic considerations are expressly forbidden; such considerations may enter
in later stages. Economic factors cannot be taken into account at this stage, because
Congress directed that listing be fundamentally a scientific question: is the continued
existence of the species threatened?
Although economic considerations play no role in the ESA listing decision itself, the
potential economic effect of an ESA listing of polar bears is an issue. Some are
concerned that a decision to list polar bears under the ESA might have extremely broad
and severe economic impacts, since federal agencies are required under the ESA to ensure
that anything they authorize or fund that might affect polar bears would not jeopardize
the survival of these bears or the sea ice where they live (their habitat). Affected
industries and activities could include oil and gas exploration, commercial shipping,
releases of toxic contaminants, and emissions of climate-affecting pollution.