Polar Bear

I. Background
I. BACKGROUND
Polar bears occur in 19 subpopulations throughout
the seasonally and permanently ice-covered marine
waters of the northern hemisphere (Arctic and
Subarctic), in Canada, Denmark (Greenland),
Norway, Russia, and the United States (Fig. 1). The
United States contains portions of two subpopulations:
the Chukchi Sea and the Southern Beaufort
Sea. These 2 subpopulations have also been identified
as “stocks” under the MMPA.
Polar bear subpopulations have been further
classified as occurring in one of four ecoregions (Fig.
2, Amstrup et al. 2008) based on the spatial and
temporal dynamics of sea ice in the subpopulation’s
range. Subpopulations classified as occurring in the
Seasonal Ice Ecoregion share the characteristic that
the sea ice in their range fully melts in the summer,
during which time bears are forced on shore for
extended periods of time until the sea ice reforms.
Subpopulations occurring in the Archipelago
Ecoregion are characterized as having heavy
annual and multi-year sea ice that fills the channels
between the Canadian Arctic Islands. Bears in this
ecoregion remain on the sea ice throughout the
year. The Polar Basin Divergent Ecoregion, which
includes the two United States subpopulations, is
characterized by the formation of annual sea ice
that is swept away from the shore as sea ice melts
during the summer. The Polar Basin Convergent
Ecoregion is characterized by annual sea ice that
converges towards shoreline, allowing bears access
to nearshore ice year-round. Although information
is limited, the global genetic structure of polar bears
appears to reflect the four ecoregions (Paetkau et al.
1999, Peacock et al. 2015).
The most recent circumpolar population estimate
by the IUCN Red List Assessment was 26,000 (95%
Confidence Interval of 22,000 to 31,000) polar bears
(Wiig et al. 2015).
Figure 1. Map of the polar bear subpopulations (source: Polar Bear Specialist
Group). The subpopulations include: Southern Beaufort Sea (SB), Chukchi Sea,
Laptev Sea, Kara Sea, Barents Sea, East Greenland, Northern Beaufort (NB), Kane
Basin (KB), Norwegian Bay (NW), Lancaster Sound (LS), Gulf of Boothia (GB),
M’Clintock Channel (MC), Viscount Melville Sound (VM), Baffin Bay, Davis Strait,
Foxe Basin, Western Hudson Bay (WH), Southern Hudson Bay and the Arctic Basin
(AB).
Polar Bear Conservation Management Plan 9