Endangered and Threatened Wildlife and Plants; 12-Month Petition Finding and Proposed Rule To List the Polar Bear (Ursus maritimus) as Threatened Throughout Its Range

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DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 RIN 1018-AV19 Endangered and Threatened Wildlife and Plants; 12-Month Petition Finding and Proposed Rule To List the Polar Bear ( Ursus maritimus ) as Threatened Throughout Its Range AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule and notice of 12-month finding.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), announce a 12-month finding on a petition to list the polar bear ( Ursus maritimus ) as threatened with critical habitat under the Endangered Species Act of 1973, as amended (Act). After review of all available scientific and commercial information, we find that listing the polar bear as a threatened species under the Act is warranted. Accordingly, we herein propose to list the polar bear as threatened throughout its range pursuant to the Act. This proposed rule, if made final, would extend the Act's protections to this species. Critical habitat for the polar bear is not determinable at this time. The Service seeks data and comments from the public on this proposed listing rule.

DATES:

We will consider all comments on this proposed rule received by the close of business (5 p.m.) Alaska Local Time on April 9, 2007. Requests for a public hearing must be received by the Service on or before close of business (5 p.m.) Alaska Local Time on February 23, 2007.

ADDRESSES:

If you wish to comment, you may submit your comments and materials concerning this proposed rule by any one of several methods:

1. You may submit written comments to the Supervisor, U.S. Fish and Wildlife Service, Marine Mammals Management Office, 1011 East Tudor Road, Anchorage, Alaska 99503.

2. You may hand deliver written comments to the Marine Mammals Management Office at the above address.

3. You may send comments by electronic mail (e-mail)

materials concerning this proposed rule by any one of several methods:

1. You may submit written comments to the Supervisor, U.S. Fish and Wildlife Service, Marine Mammals Management Office, 1011 East Tudor Road, Anchorage, Alaska 99503.

2. You may hand deliver written comments to the Marine Mammals Management Office at the above address.

3. You may send comments by electronic mail (e-mail). You may send your comments by electronic mail (e-mail) directly to the Service at: Polar_Bear_Finding@fws.gov or to the Federal eRulemaking Portal at http://www.regulations.gov. See the Public Comments Solicited section below for file format for electronic filing and other information.

The complete file for this finding and proposed rule is available for inspection, by appointment, during normal business hours at the above address. These documents are also available on the Service's Marine Mammal Web site located at: http://alaska.fws.gov/fisheries/mmm/polarbear/issues.htm.

FOR FURTHER INFORMATION CONTACT:

Scott Schliebe, Marine Mammals Management Office (see ADDRESSES section) (telephone 907/786-3800). Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 1-800-877-8339, 24 hours a day, 7 days a week.

SUPPLEMENTARY INFORMATION:

Public Comments Solicited

We intend that any final action resulting from this proposed rule will be as accurate and as effective as possible. Therefore, we request comments or information from the public, other concerned governmental agencies, the scientific community, industry, or any other interested party concerning this proposed rule. We particularly seek comments concerning:

(1) Information on taxonomy, distribution, habitat selection (especially denning habitat), food habits, population density and trends, habitat trends, and effects of management on polar bears;

formation from the public, other concerned governmental agencies, the scientific community, industry, or any other interested party concerning this proposed rule. We particularly seek comments concerning:

(1) Information on taxonomy, distribution, habitat selection (especially denning habitat), food habits, population density and trends, habitat trends, and effects of management on polar bears;

(2) Information on the effects of sea ice change on the distribution and abundance of polar bears and their principal prey over the short and long term;

(3) Information on the effects of other potential listing factors, including oil and gas development, contaminants, ecotourism, hunting, poaching, on the distribution and abundance of polar bears and their principal prey over the short and long term;

(4) Information on regulatory mechanisms and management programs for polar bear conservation, including mitigation measures related to oil and gas exploration and development, hunting conservation programs, anti-poaching programs, and any other private, tribal, or governmental conservation programs which benefit polar bears;

(5) The specific physical and biological features to consider, and specific areas that may meet the definition of critical habitat and that should or should not be considered for a proposed critical habitat designation as provided by section 4 of the Act;

(6) Information relevant to whether any populations of the species may qualify as distinct population segments; and

ch benefit polar bears;

(6) Information relevant to whether any populations of the species may qualify as distinct population segments; and

(7) The data and studies refered to within this proposal.

If you wish to comment, you may submit your comments and materials concerning this proposed rule by any one of several methods, as listed above in the ADDRESSES section. If you submit comments by e-mail, please submit them in ASCII file format and avoid the use of special characters and encryption. Please include “Attn: Polar Bear Finding” and your name and return address in your e-mail message. Please note that the e-mail address will be closed at the termination of the public comment period.

Our practice is to make comments, including names and home addresses of respondents, available for public review during regular business hours. Individual respondents may request that we withhold their names and/or home addresses, etc., but if you wish us to consider withholding this information, you must state this prominently at the beginning of your comments. In addition, you must present rationale for withholding this information. This rationale must demonstrate that disclosure would constitute a clearly unwarranted invasion of privacy. Unsupported assertions will not meet this burden. In the absence of exceptional, documentable circumstances, this information will be released. We will always make submissions from organizations or businesses, and from individuals identifying themselves as representatives of or officials of organizations or businesses, available for public inspection in their entirety. Comments and materials received will be available for public inspection, by appointment, during normal business hours at the U.S

stances, this information will be released. We will always make submissions from organizations or businesses, and from individuals identifying themselves as representatives of or officials of organizations or businesses, available for public inspection in their entirety. Comments and materials received will be available for public inspection, by appointment, during normal business hours at the U.S. Fish and Wildlife Service Office at the address listed in ADDRESSES.

Background

Section 4(b)(3)(A) of the Act (16 U.S.C. 1531 et seq. requires that, for any petition to add a species to, remove a species from, or reclassify a species on one of the Lists of Endangered and Threatened Wildlife and Plants, we first make a determination whether the petition presents substantial scientific or commercial information indicating that the petitioned action may be warranted. To the maximum extent practicable, this determination is to be made within 90 days of receipt of the petition, and published promptly in the Federal Register .

If the petition is found to present substantial information, section Federal Register .

Species for which listing is warranted but precluded are considered to be “candidates” for listing. Section 4(b)(3)(C) of the Act requires that a petition for which the requested action is found to be warranted but precluded be treated as though resubmitted on the date of such finding, i.e., requiring a subsequent finding to be made within 12 months. Each subsequent 12-month finding is also to be in the Federal Register . We typically publish these findings in our Candidate Notice of Review (CNOR). Our most recent CNOR was published on September 12, 2006 (71 FR 53756).

Previous Federal Action

s in our Candidate Notice of Review (CNOR). Our most recent CNOR was published on September 12, 2006 (71 FR 53756).

Previous Federal Action

On February 17, 2005, we received a petition from the Center for Biological Diversity, dated February 16, 2005, requesting that we list the polar bear as threatened throughout its range, and that critical habitat be designated concurrently with the listing. The petition was clearly identified as such, and contained the name, authorized signature, and address of the requesting party. Included in the petition was supporting information regarding the species' taxonomy and ecology, historical and current distribution, present status, and actual and potential causes of decline. We acknowledged the receipt of the petition in a letter dated July 1, 2005. In that letter, we also advised the petitioners that, due to funding constraints in fiscal year (FY) 2005, and the need to comply with court orders and settlement agreements, we would not be able to begin processing the petition at that time.

In a letter dated July 5, 2005, the petitioner informed us that two additional parties were joining as petitioners: the Natural Resources Defense Council and Greenpeace, Inc. In the same letter, the petitioners informed us of two new scientific articles, Hansen et al. (2005) and Stroeve et al. (2005), that they wanted us to consider when conducting our evaluation of the petition to list the polar bear. In a letter we received on December 27, 2005, the petitioners submitted additional new information to be considered, along with the information in the initial petition, in making our 90-day finding.

rmation to be considered, along with the information in the initial petition, in making our 90-day finding.

On December 15, 2005, the petitioners filed a complaint for declaratory and injunctive relief in the United States District Court for the Northern District of California, challenging our failure to issue a 90-day finding in response to the petition as required by section 4(b)(3) of the Act. On February 7, 2006, we made our 90-day finding that the petition presented substantial scientific information indicating that listing the polar bear may be warranted; the finding and our initiation of a status review was published in the Federal Register on February 9, 2006 (71 FR 6745). In a stipulated settlement agreement approved by the Court on July 5, 2006, we agreed to submit a 12-month finding to the Federal Register by December 27, 2006. This notice constitutes our 12-month finding for the petition to list the polar bear as threatened, in fulfillment of the stipulated settlement agreement.

Status Assessment

Pursuant to section 4(b)(3)(A) of the Act, we conducted a status review of the polar bear. With this notice we announce the completion and availability of the Polar Bear Status Assessment (Status Assessment or Schliebe et al. (2006a)). The Status Assessment was compiled and edited by staff of the Service's Marine Mammals Management Office of Region 7 (Scott Schliebe; Thomas Evans; Kurt Johnson, Ph.D.; Michael Roy, Ph.D.; Susanne Miller; Charles Hamilton; Rosa Meehan, Ph.D.; and Sonja Jahrsdoerfer). Information contained in the original petition, as well as additional information provided by the petitioners, was considered during the development of the Status Assessment. In addition, all comments received from the public during the open public comment period were considered

Kurt Johnson, Ph.D.; Michael Roy, Ph.D.; Susanne Miller; Charles Hamilton; Rosa Meehan, Ph.D.; and Sonja Jahrsdoerfer). Information contained in the original petition, as well as additional information provided by the petitioners, was considered during the development of the Status Assessment. In addition, all comments received from the public during the open public comment period were considered. To ensure that the Status Assessment would be complete and based on the best available scientific and commercial information, we solicited information from the public on the status of the polar bear in two separate public comment periods announced in the Federal Register (February 9, 2006; 71 FR 6745) and (May 17, 2006; 71 FR 28653). In addition, all available scientific and commercial information on polar bears and threats to polar bears was reviewed and considered during development of the the Status Assessment and proposed rule.

In accordance with Service policies, peer review of the draft Status Assessment was sought from 12 independent experts in the fields of polar bear ecology, contaminants and physiology, climatic science and physics, and traditional ecological knowledge. Comments were received from 10 peer reviewers, and those comments were addressed in revisions to the draft Status Assessment. The Status Assessment, a list of peer reviewers, and comments received from peer reviewers are available upon request from the Marine Mammals Management Office as well as on the Service's Marine Mammal Web site located at: http://alaska.fws.gov/fisheries/mmm/polarbear/issues.htm. Literature cited in the Status Assessment serves as the basis for the 12-month finding and proposed rule.

Species Biology

Information presented in this section is summarized from the Status Assessment (Schliebe et al. 2006a). For more detailed information on the biology of the polar bear, please consult the Status Assessment

located at: http://alaska.fws.gov/fisheries/mmm/polarbear/issues.htm. Literature cited in the Status Assessment serves as the basis for the 12-month finding and proposed rule.

Species Biology

Taxonomy and Evolution

Throughout the Arctic, polar bears are known by a variety of common names, including nanook, nanuq, ice bear, sea bear, isbjørn, white bears, and eisbär. Phipps (1774) first proposed and described polar bear as a species distinct from other bears and provided a scientific name Ursus maritimus. A number of alternative names followed, but Harington (1966), Manning (1971, p. 9), and Wilson (1976) (all three references cited in Amstrup 2003, p. 587) subsequently promoted the name Ursus maritimus that has been used since. The polar bear is usually considered a marine mammal since its primary habitat is the sea ice (Amstrup 2003, p. 587), and it is evolutionarily adapted to life on sea ice (see further discussion under General Description section). The polar bear was included on the list of species covered under the U.S. Marine Mammal Protection Act of 1972 as amended (16 U.S.C. 1361 et seq.) (MMPA).

Genetic research has confirmed that polar bears evolved from grizzly (brown) bears ( Ursus arctos ) 250 to 300 thousand years ago (Cronin et al. 1991, p. 2990; Talbot and Shields 1996a, p. 574). Only in portions of northern Canada and northern Alaska do the ranges of polar bears and grizzly bears overlap. Cross-breeding of grizzly bears and polar bears in captivity has produced

General Description

northern Alaska do the ranges of polar bears and grizzly bears overlap. Cross-breeding of grizzly bears and polar bears in captivity has produced

General Description

Polar bears are the largest of the living bear species (DeMaster and Stirling 1981 p. 1; Stirling and Derocher 1990 p. 190). They are characterized by large body size, a stocky form, and fur color that varies from white to yellow. They are sexually dimorphic; females weigh 181 to 317 kilograms (kg) (400 to 700 pounds (lbs)) and males up to 654 kg (1,440 lbs). Polar bears have a longer neck and a proportionally smaller head than other members of the bear family (Ursidae), and are missing the distinct shoulder hump common to grizzly bears. The nose, lips, and skin of polar bears are black (Demaster and Stirling 1981 p. 1; Amstrup 2003 p. 588).

Polar bears are evolutionarily adapted to life on sea ice. Adaptations to this life include: (1) White pelage with water-repellent guard hairs and dense underfur; (2) a short furred snout; (3) small ears for reduced surface area; (4) teeth specialized for a carnivorous rather than an omnivorous diet; and (5) feet with tiny papillae and “suction cups” on the underside, for increased traction on ice (Stirling 1988, p. 24). Additional adaptations include large, paddle-like feet (Stirling 1988, p. 24), and claws that are shorter and more strongly curved than those of grizzly bears, and larger and heavier than those of black bears ( Ursus americanus ) (Amstrup 2003, p. 589).

Distribution and Movements

ier than those of black bears ( Ursus americanus ) (Amstrup 2003, p. 589).

Distribution and Movements

Polar bears evolved to utilize the Arctic sea ice niche and are distributed throughout most ice-covered seas of the Northern Hemisphere. They are generally limited to areas where the sea is ice-covered for much of the year; however, polar bears are not evenly distributed throughout their range. They are most abundant near the shore in shallow-water areas, and in other areas where currents and ocean upwelling increase marine productivity and serve to keep the ice cover from becoming too solidified in winter (Stirling and Smith 1975, p. 132; Stirling et al. 1981, p. 49; Amstrup and DeMaster 1988, p. 44; Stirling 1990, pp. 226-227; Stirling and Øritsland 1995, p. 2607; Amstrup et al. 2000b, p. 960). Over most of their range, polar bears remain on the sea ice year-round or spend only short periods on land. They occur throughout the East Siberian, Laptev, and Kara Seas of Russia; Fram Strait, Greenland Sea, and Barents Sea of northern Europe (Norway and Greenland (Denmark)); Baffin Bay, which separates Canada and Greenland, through most of the Canadian Arctic archipelago and the Canadian Beaufort Sea; and in the Chukchi and Beaufort Seas located west and north of Alaska.

The distribution of polar bears in most areas varies seasonally with the seasonal extent of sea ice cover and availability of prey. In Alaska in the winter, sea ice may extend 400 kilometers (km) (248 miles (mi)) south of the Bering Strait, and polar bears will extend their range to the southernmost proximity of the ice (Ray 1971, cited in Amstrup 2003, p. 587). Sea ice disappears from the Bering Sea and is greatly reduced in the Chukchi Sea in the summer, and polar bears occupying these areas move as much as 1,000 km (621 mi) to stay with the pack ice (Garner et al. 1990, p. 222; Garner at al. 1994b, pp. 407-408)

the Bering Strait, and polar bears will extend their range to the southernmost proximity of the ice (Ray 1971, cited in Amstrup 2003, p. 587). Sea ice disappears from the Bering Sea and is greatly reduced in the Chukchi Sea in the summer, and polar bears occupying these areas move as much as 1,000 km (621 mi) to stay with the pack ice (Garner et al. 1990, p. 222; Garner at al. 1994b, pp. 407-408). Throughout the polar basin during the summer, polar bears generally concentrate along the edge of or into the adjacent persistent pack ice. Significant northerly and southerly movements of polar bears appear to depend on seasonal melting and refreezing of ice (Amstrup et al. 2000, p. 142). In other areas, for example, when the sea ice melts in Hudson Bay, James Bay, Davis Strait, Baffin Bay, portions of the Canadian High Arctic, and some portions of the Barents Sea, polar bears remain on land for up to several months while they wait for winter and new ice to form (Jonkel et al. 1976; Schweinsburg 1979; Prevett and Kolenosky 1982; Schweinsburg and Lee 1982; Ferguson et al. 1997; Lunn et al. 1997 all cited in Amstrup 2003, p. 587; Mauritzen et al. 2001, p. 1710).

The distribution patterns of some polar bear populations during the open water and early fall seasons have changed in recent years. In the Beaufort Sea, for example, greater numbers of polar bears are being found on shore during this period than recorded at any previous time (Schliebe et al. 2006b, p. 559). In Baffin Bay, Davis Strait, western Hudson Bay and other areas of Canada, Inuit hunters are reporting an increase in the numbers of bears present on land during summer and fall (Dowsley and Taylor 2005, p. 2; Dowsley 2005, p. 2). The exact reasons for changes may involve a number of factors, including changes in sea ice (Stirling and Parkinson 2006, p. 272)

s time (Schliebe et al. 2006b, p. 559). In Baffin Bay, Davis Strait, western Hudson Bay and other areas of Canada, Inuit hunters are reporting an increase in the numbers of bears present on land during summer and fall (Dowsley and Taylor 2005, p. 2; Dowsley 2005, p. 2). The exact reasons for changes may involve a number of factors, including changes in sea ice (Stirling and Parkinson 2006, p. 272).

Data from telemetry studies of adult female polar bears show that they do not wander aimlessly on the ice, nor are they carried passively with the ocean currents as previously thought (Pedersen 1945 cited in Amstrup 2003, p. 587). Results show strong fidelity to activity areas that are used over multiple years. Some polar bear populations are closely associated with pack ice. In the Chukchi and Beaufort Sea areas of Alaska and northwestern Canada, less than 10 percent of the polar bear locations obtained were on land (Amstrup 2000, p. 137; Amstrup, USGS, unpublished data); the majority of the land locations were locations with bears occupying maternal dens during the winter. A similar pattern was found in East Greenland (Wiig et al. 2003, p. 511). In the absence of ice during the summer season, some populations of polar bears in eastern Canada, Hudson Bay, and the Barents Sea are remaining on land for protracted periods of time until ice again forms and provides a platform for them to move to sea ice.

Food Habits

Polar bears are carnivorous and an upper level predator of the Arctic marine ecosystem. Polar bears prey heavily throughout their range on ringed seals ( Phoca hispida ) and, to a lesser extent, bearded seals ( Erignathus barbatus ) and in some locales, other seal species. On average, an adult polar bear needs approximately 2 kg (4.4 lbs) of seal fat per day to survive (Best 1985, p. 1035). Sufficient nutrition is critical and may be obtained and stored as fat when prey is abundant

. Polar bears prey heavily throughout their range on ringed seals ( Phoca hispida ) and, to a lesser extent, bearded seals ( Erignathus barbatus ) and in some locales, other seal species. On average, an adult polar bear needs approximately 2 kg (4.4 lbs) of seal fat per day to survive (Best 1985, p. 1035). Sufficient nutrition is critical and may be obtained and stored as fat when prey is abundant.

Although seals are their primary prey, polar bears also have been known to kill much larger animals such as walruses ( Odobenus rosmarus ), narwhal ( Monodon monoceros ), and belugas ( Delphinapterus leucas ) (Kiliaan et al. 1978; Smith 1980, p. 2206; Smith 1985; Lowry et al. 1987, p. 141; Calvert and Stirling 1990, p. 352; Smith and Sjare 1990, p. 99). In some areas and under some conditions, prey and carrion other than seals may be quite important to polar bear sustenance. Stirling and Øritsland (1995, p. 2609) suggested that in areas where ringed seal populations were reduced, other prey species were being substituted. Like other ursids, polar bears will eat human garbage (Lunn and Stirling 1985, p. 2295), and when confined to land for long periods they will consume coastal marine and terrestrial plants and other terrestrial foods (Russell 1975, p. 122; Derocher et al. 1993, p. 252), but the significance of other terrestrial foods to polar bears may be limited (Lunn and Stirling 1985, p. 2296; Ramsay and Hobson 1991, p. 600; Derocher et al. 2004, p. 169).

Reproduction

Polar bears are characterized by a late age at sexual maturity, small litter sizes, and extended parental investment in raising young, factors that combine to contribute to a very low reproductive

Females generally mature and breed for the first time at 4 or 5 years and give birth at 5 or 6 years of age. Litters of two cubs are most common, but litters of three cubs are seen sporadically across the Arctic. When foraging conditions are difficult, polar bears may “defer” reproduction in favor of survival (Derocher et al. 1992, p. 564)

rs that combine to contribute to a very low reproductive

Polar bears enter a prolonged estrus between March and June, when breeding occurs. Ovulation is thought to be induced by mating (Wimsatt 1963; Ramsay and Dunbrack 1986; Derocher and Stirling 1992; all cited in Amstrup 2003, p. 599), and implantation is delayed until autumn. The total gestation period is 195 to 265 days (Uspenski 1977 cited in Amstrup 2003, p. 599), although active development of the fetus is suspended during most of this period. The timing of implantation, and therefore the timing of birth, is likely dependent on body condition of the female, which depends on a variety of environmental factors.

Newborn polar bears are helpless, have hair, but are blind and weigh only 0.6 kg (1.3 lb) (Blix and Lentfer 1979, p. 68). Cubs grow rapidly, and may weigh 10 to 12 kg (22 to 26 lbs) by the time they emerge from the den in the spring. Young bears will stay with their mothers until weaning, which occurs most commonly in early spring when the cubs are 2.3 years of age. Female polar bears are available to breed again after their cubs are weaned, so the reproductive interval for polar bears is 3 years.

Polar bears are long-lived mammals not generally susceptable to disease, parasites, or injury. The oldest known female in the wild was 32 years of age and the oldest known male was 28, though few polar bears in the wild live to be older than 20 (Stirling 1988, p. 139; Stirling 1990, p. 225). Due to extremely low reproductive rates, polar bears require a high rate of survival to maintain population levels

ears are long-lived mammals not generally susceptable to disease, parasites, or injury. The oldest known female in the wild was 32 years of age and the oldest known male was 28, though few polar bears in the wild live to be older than 20 (Stirling 1988, p. 139; Stirling 1990, p. 225). Due to extremely low reproductive rates, polar bears require a high rate of survival to maintain population levels. Survival rates increase up to a certain age, with cubs-of-the-year having the lowest rates and prime age adults (between 5 and 20 years of age) having survival rates that can exceed 90 percent.

Polar Bear—Sea Ice Habitat Relationships

Polar bears are distributed throughout the ice-covered waters of the circumpolar Arctic (Stirling 1988, p. 61), and are reliant on the sea ice as their primary habitat (Amstrup 2003, p. 587). Polar bears depend on sea ice for a number of purposes, including as a platform from which to hunt and feed upon seals; as habitat on which to seek mates and breed; as a platform to move to terrestrial maternity denning areas, and sometimes for maternity denning; and as a substrate on which to make long-distance movements (Stirling and Derocher 1993, p. 241). Mauritzen et al. (2003, p. 123) indicated that habitat use by polar bears during certain seasons may involve a trade-off between selecting habitats with abundant prey availability versus the use of safer retreat habitats with less prey. Their findings indicate that polar bear distribution may not be solely a reflection of prey availability, but other factors such as energetic costs or risk may be involved.

Stirling et al. (1993, p. 15) defined seven types of sea ice habitat and classified polar bear use of these ice types based on the presence of bears or tracks in order to determine habitat preferences. The seven types of sea ice were: stable fast ice with drifts; stable fast ice without drifts; floe edge ice; moving ice; continuous stable pressure ridges; coastal low level pressure ridges; and fiords and bays

al. (1993, p. 15) defined seven types of sea ice habitat and classified polar bear use of these ice types based on the presence of bears or tracks in order to determine habitat preferences. The seven types of sea ice were: stable fast ice with drifts; stable fast ice without drifts; floe edge ice; moving ice; continuous stable pressure ridges; coastal low level pressure ridges; and fiords and bays. Polar bears were not evenly distributed over these sea ice habitats, but concentrated on the floe ice edge, on stable fast ice with drifts, and on areas of moving ice (Stirling 1990 p. 226; Stirling et al. 1993, p. 18). In another assessment, categories of ice types included: pack ice; shore-fast ice; transition zone ice; and polynyas ( i.e. , open water areas within the ice); and leads (USFWS 1995, p. 9). Pack ice, which consists of annual and multi-year ice in constant motion due to winds and currents, is the primary summer habitat for Alaskan polar bears. Shore-fast ice is used for feeding on seal pups, movements, and occasionally for maternity denning. Open water at leads and polynyas attracts seals and other marine mammals and provides preferred hunting habitats during winter and spring.

Polar bears must move throughout the year to adjust to the changing distribution of sea ice and seals (Stirling 1988, p. 63; USFWS 1995, p. 4). In some areas, such as Hudson Bay and James Bay, polar bears remain on land when the sea ice retreats in the spring and they fast for several months (up to 8 months for pregnant females) before fall freeze-up (Stirling 1988, p. 63; Derocher et al. 2004, p. 163). Some populations unconstrained by land masses, such as those in the Barents, Chukchi and Beaufort Seas, spend each summer on the multiyear ice of the polar basin (Derocher et al. 2004, p. 163). In intermediate areas such as the Canadian Arctic, Svalbard, and Franz Josef Land archipelagos, bears stay with the ice most of the time, but in some years they may spend up to a few months on land (Mauritizen et al. 2001, p. 1710)

ained by land masses, such as those in the Barents, Chukchi and Beaufort Seas, spend each summer on the multiyear ice of the polar basin (Derocher et al. 2004, p. 163). In intermediate areas such as the Canadian Arctic, Svalbard, and Franz Josef Land archipelagos, bears stay with the ice most of the time, but in some years they may spend up to a few months on land (Mauritizen et al. 2001, p. 1710). Most populations use terrestrial habitat partially or exclusively for maternity denning; therefore, females must adjust their movements in order to access land at the appropriate time (Stirling 1988, p. 64; Derocher et al. 2004, p. 166).

Sea ice changes between years in response to environmental factors may have consequences to the distribution and productivity of polar bears as well as their prey. In the southern Beaufort Sea, anomalous heavy ice conditions in the mid-1970s and mid-1980s (thought to be roughly in phase with a similar variation in runoff from the MacKenzie River) caused significant declines in productivity of ringed seals (Stirling 2002, p. 68). Each event lasted approximately three years and caused similar declines in the natality of polar bears and survival of subadults, after which reproductive success and survival of both species increased again.

Maternal Denning Habitat

Throughout the species' range, most pregnant female polar bears excavate dens in snow located on land in the fall-early winter period (Harington 1968, p. 6; Lentfer and Hensel 1980, p. 102; Ramsay and Stirling 1990, p. 233; Amstrup and Gardner 1994, p. 5). The only known exceptions are in Western and Southern Hudson Bay, where polar bears first excavate earthen dens and later reposition into adjacent snow drifts (Jonkel et al 1972, p. 146; Ramsey and Stirling 1990, p. 233), and in the southern Beaufort Sea, where a portion of the population dens in snow caves located on pack and shorefast ice. Successful denning by polar bears requires accumulation of sufficient snow for den construction and maintenance

udson Bay, where polar bears first excavate earthen dens and later reposition into adjacent snow drifts (Jonkel et al 1972, p. 146; Ramsey and Stirling 1990, p. 233), and in the southern Beaufort Sea, where a portion of the population dens in snow caves located on pack and shorefast ice. Successful denning by polar bears requires accumulation of sufficient snow for den construction and maintenance. Adequate and timely snowfall combined with winds that cause snow accumulation leeward of topographic features create denning habitat (Harington 1968, p.12).

A great amount of polar bear denning occurs in core areas (Harington 1968, pp. 7-8) which show high use over time. In some portions of the species' range, polar bears den in a more diffuse pattern, with dens scattered over larger areas at lower density (Lentfer and Hensel 1980, p. 102; Stirling and Andriashek 1992, p. 363; Amstrup 1993, p. 247; Amstrup and Gardner 1994, p. 5; Messier et al. 1994, p. 425; Born 1995, p. 81; Ferguson et al. 2000a, p. 1125; Durner et al. 2001, p. 117; Durner et al. 2003, p. 57).

Habitat characteristics of denning areas vary substantially from the rugged

Polar bears are largely food deprived while on land in the ice-free period; during this time they survive on stored fat reserves. Pregnant females that spend the late summer on land prior to denning may not feed for 8 months (Watts and Stirling 1988, p. 627). This may be the longest period of food deprivation of any mammal, and it occurs at a time when the female gives birth to and then nourishes new cubs.

Current Population Status and Trend

y mammal, and it occurs at a time when the female gives birth to and then nourishes new cubs.

Current Population Status and Trend

The total number of polar bears worldwide is estimated to be 20,000-25,000. Polar bears are not evenly distributed throughout the Arctic, nor do they comprise a single nomadic cosmopolitan population, but rather occur in 19 relatively discrete populations (Figure 1). The boundaries of these populations are based on behavioral and ecological factors and were developed from decades of intensive scientific studies as well as traditional knowledge (Lunn et al. 2002, p. 41). Although there is overlap in areas occupied by members of the populations, with the exception of the Arctic Basin population, these boundaries are sufficiently discrete to manage the populations independently. Correspondence between genetic data and movement data reinforces current population designations (Paetkau et al. 1999, p. 1571; Amstrup 2003, p. 590).

BILLING CODE 4310-55-P EP09JA07.000

Population size estimates and qualitative categories of the current trend and status data for each polar bear population are discussed below. This discussion was derived from information presented at the World Conservation Union—International Union for Conservation of Nature and Natural Resources, Species Survival Commission (IUCN/SSC) Polar Bear Specialist Group (PBSG) meeting held in Seattle, Washington, in June 2005, and updated with results that became available as of October 2006 (PBSG 2006). The information on each

The East Greenland population number is unknown since no population surveys have been conducted in the past. The status and trend have not been determined due to the absence of abundance data. The Barents Sea population was estimated to comprise 3,000 animals based on the only population survey conducted in this vast area during 2004. Because only one abundance estimate is available, the status and trend cannot yet be determined

mber is unknown since no population surveys have been conducted in the past. The status and trend have not been determined due to the absence of abundance data. The Barents Sea population was estimated to comprise 3,000 animals based on the only population survey conducted in this vast area during 2004. Because only one abundance estimate is available, the status and trend cannot yet be determined. The Kara Sea population number is unknown because population surveys have not been conducted; thus status and trend of this population cannot yet be determined. The Laptev Sea population is estimated to comprise 800 to 1,200 animals, based on an extrapolation of historical aerial den survey data. Status and trend cannot yet be determined for this population. The Chukchi Sea population is estimated to comprise 2,000 animals based on extrapolation of aerial den surveys. Status and trend cannot yet be determined for this population. The Southern Beaufort Sea population is comprised of 1,500 animals based on conclusion of a recent population inventory. The predicted trend is declining and the status is designated as reduced. The Northern Beaufort Sea population is comprised of 1,200 animals. The trend is designated as stable and status is determined to be not reduced, although a new abundance estimate will be developed in the near future. The Viscount-Melville population is estimated to comprise 215 animals. The trend is increasing although the status is designated as severely reduced from prior excessive harvest. The Norwegian Bay population number is 190 animals and the trend is noted as declining while the status is listed as not reduced. The Lancaster Sound population is estimated to be 2,541 animals and the trend is stable and status is not reduced. The M'Clintock Channel population is estimated at 284 animals and the trend is increasing although the status is severely reduced from excessive harvest

t. The Norwegian Bay population number is 190 animals and the trend is noted as declining while the status is listed as not reduced. The Lancaster Sound population is estimated to be 2,541 animals and the trend is stable and status is not reduced. The M'Clintock Channel population is estimated at 284 animals and the trend is increasing although the status is severely reduced from excessive harvest. The Gulf of Boothia population abundance estimate is 1,523 animals and the trend is stable and status is designated as not reduced. The Foxe Basin population comprises 2,197 animals and the population trend is stable and the status is not reduced. The Western Hudson Bay population estimate is 935 animals and the trend is declining and the status is reduced. The Southern Hudson Bay population estimate is 1,000 animals and the trend is stable and status is not reduced. The Kane Basin population is comprised of 164 animals and its trend is declining and status is reduced. The Baffin Bay population is estimated to be 2,074 animals and the trend is declining and status is reduced. The Davis Strait population is estimated at 1,650 animals based on traditional ecological knowledge (TEK) and data are unavailable to assess trends or status. The Arctic Basin population estimate, trend, and status are unknown.

For populations with long-term data we can establish trends, but cannot do so for populations with short-term or lack of data. Of the populations for which data are available to assess status and trend, two are noted to be increasing (Viscount Melville and M'Clintock Channel). Both of these populations were severely reduced in the past and are recovering under conservative harvest limits. The two populations with the most extensive time series of data, Western Hudson Bay and Southern Beaufort Sea, are both declining. However, based on environmental factors and observed patterns of population trends for some populations it is likely that most populations will exhibit declines in the future

ations were severely reduced in the past and are recovering under conservative harvest limits. The two populations with the most extensive time series of data, Western Hudson Bay and Southern Beaufort Sea, are both declining. However, based on environmental factors and observed patterns of population trends for some populations it is likely that most populations will exhibit declines in the future.

Summary of Factors Affecting the Polar Bear

Section 4 of the Act (16 U.S.C. 1533), and implementing regulations at 50 CFR part 424, set forth procedures for adding species to the Federal List of Endangered and Threatened Species. Under section 4(a) of the Act, we may list a species on the basis of any of five factors, as follows: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence. In making this finding, information regarding the status and trends of the polar bear is considered in relation to the five factors provided in section 4(a)(1) of the Act.

In the context of the Act, the term “threatened species” means any species or subspecies or, for vertebrates, Distinct Population Segment (DPS) that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The term “endangered species” means any species that is in danger of extinction throughout all or a significant portion of its range. The Act does not define the term “foreseeable future.” The PBSG, when they reassessed the status of polar bears globally in June 2005, used the criteria described in the IUCN/SSC Red List process (IUCN 2004) to determine which Red List category the polar bear should be assigned

dangered species” means any species that is in danger of extinction throughout all or a significant portion of its range. The Act does not define the term “foreseeable future.” The PBSG, when they reassessed the status of polar bears globally in June 2005, used the criteria described in the IUCN/SSC Red List process (IUCN 2004) to determine which Red List category the polar bear should be assigned. The criteria, used for all species that IUCN assesses in the Red List process, use observed, estimated, inferred or suspected population size reductions of a certain percentage over the last 10 years or three generations, whichever is the longer to categorize species. A generation, as defined by IUCN, is calculated as the age of sexual maturity (5 years) plus 50 percent of the length of the lifetime reproductive period (20 years). Based on these calculations, the projected length of 1 generation for a polar bear was calculated at 15 years, and the projected period for 3 generations was calculated as 45 years.

For another species evaluated for listing as threatened, the Yellowstone cutthroat trout ( Oncorhynchus clarki bouvieri ), the status assessment report (May et al. 2003 p. 10) considered the “foreseeable future” to be 2-3 decades (4 to 10 generations), depending on the productivity of the environment. For the greater sage grouse ( Centrocercus urophasianus ) the status reviewers agreed that given all of the uncertainties, a reasonable timeframe for “foreseeable future” for the threatened definition was approximately 30 to 100 years [approximately 10 greater sage-grouse generations or 2 sagebrush habitat regeneration cycles (70 FR 2244)]

ations), depending on the productivity of the environment. For the greater sage grouse ( Centrocercus urophasianus ) the status reviewers agreed that given all of the uncertainties, a reasonable timeframe for “foreseeable future” for the threatened definition was approximately 30 to 100 years [approximately 10 greater sage-grouse generations or 2 sagebrush habitat regeneration cycles (70 FR 2244)].

Given the IUCN criteria, the life-history and population dynamics of polar bears, documented changes to date in both multi-year and annual sea ice, and the direction of projected rates of change of sea ice in future decades, we consider the three generation timespan used in the IUCN Red List criteria to be a reasonable projection of foreseeable future and provides a time frame for analysis of whether polar bears are likely to become endangered. Therefore,

We considered all relevant, available information under each of the listing factors in the context of present-day polar bear distribution. Our evaluation of the five factors with respect to polar bear populations is presented below. While the polar bear can be delineated into 19 populations, and population-specific interaction of various listing factors may affect these populations at different levels or rates, in this 12-month finding and proposed rule we evaluated the status of the species throughout its entire range because we find that the entire species meets the definition of a threatened species under the Act. Accordingly, we have not considered the petitioners' alternative of assessing whether listing of particular distinct population segments is warranted.

A. Present or Threatened Destruction, Modification, or Curtailment of the Species' Habitat or Range

s is warranted.

A. Present or Threatened Destruction, Modification, or Curtailment of the Species' Habitat or Range

Polar bears are believed to be completely dependent upon Arctic sea ice for survival (Moore and Huntington, in press; Laidre et al. in prep.). They need sea ice as a platform for hunting, for seasonal movements, for travel to terrestrial denning areas, for resting, and for mating. Some polar bears use terrestrial habitats seasonally, such as pregnant females for denning and some bears, all sex and age classes, for resting during open water periods. While open water may not be an essential habitat for polar bears because life functions such as feeding, reproduction or resting do not occur in open water, open water is a fundamental part of the marine system that supports seal species, the principal prey of polar bears, and seasonally returns to ice in the form needed by the bears. Further, the open water interface with sea ice is an important habitat in that it is used to a great extent by polar bears. The extent of open water is important because vast areas of open water may limit a bear's ability to access sea ice or land. Snow cover is also an important component of polar bear habitat in that it provides insulation and cover for young polar bears and ringed seals in snow dens or lairs.

Overview of Arctic Sea Ice Change

Initial syntheses of climate models and environmental change data have identified potentially significant changes to the landscapes and biota in Arctic regions as a consequence of climate change (ACIA 2005, p. 1017; IPCC 2001a, p. 920). Climate trends are not occurring evenly or in a linear fashion throughout the world; Arctic regions are being disproportionately affected by higher levels of warming (Overpeck 2006, p. 1749). Observations of Arctic changes, including diminishing sea ice, shrinking glaciers, thawing permafrost, and Arctic greening, validate earlier findings (Morison et al. 2000, p. 360; Sturm et al. 2003, pp. 63-65; Comiso and Parkinson 2004, pp

g evenly or in a linear fashion throughout the world; Arctic regions are being disproportionately affected by higher levels of warming (Overpeck 2006, p. 1749). Observations of Arctic changes, including diminishing sea ice, shrinking glaciers, thawing permafrost, and Arctic greening, validate earlier findings (Morison et al. 2000, p. 360; Sturm et al. 2003, pp. 63-65; Comiso and Parkinson 2004, pp. 38-43; Parkinson in press).

Additional studies indicate that previous projections regarding the rate and extent of climate change underestimated the temperature trend, reductions to annual sea ice during the summer and winter periods, reductions to multi-year pack ice, and reductions in thickness (Rothrock et al. 2003, p. 3471; Stroeve et al. 2005, p. 2). Overpeck et al. (2005, p. 309) indicated that the Arctic is moving toward a new “super interglacial” state that falls outside of natural glacial-interglacial periods that have characterized the past 800,000 years. These changes appear to be driven largely by the albedo effect (see explanation in following paragraph), and there are few, if any, processes that are capable of altering this trajectory. There is no paleoclimatic evidence for a seasonally ice-free Arctic during the past 800,000 years (Overpeck et al. 2005, p. 309).

The National Snow and Ice Data Center (NSIDC is part of the University of Colorado Cooperative Institute for Research in Environmental Sciences, and is affiliated with the National Oceanic and Atmospheric Administration National Geophysical Data Center through a cooperative agreement) reported that the amount of sea ice in 2006 was the second lowest on record (since satellites began recording sea ice extent measurements via passive microwave imagery in 1978), and the pace of melting was accelerating. The latest sea ice measurements are thought to indicate that ice melt is accelerating due to a positive feedback loop

ional Geophysical Data Center through a cooperative agreement) reported that the amount of sea ice in 2006 was the second lowest on record (since satellites began recording sea ice extent measurements via passive microwave imagery in 1978), and the pace of melting was accelerating. The latest sea ice measurements are thought to indicate that ice melt is accelerating due to a positive feedback loop. The albedo effect involves reduction of the extent of lighter-colored sea ice or snow, which reflects solar energy back into the atmosphere, and a corresponding increase in the extent of darker-colored water or land that absorbs more of the sun's energy. This greater absorption of energy causes faster melting, which in turn causes more warming, and thus creates a self-reinforcing cycle that becomes amplified and accelerates with time. Lindsay and Zhang (2005, p. 4892) suggest that feedback mechanisms caused a tipping point in Arctic sea ice thinning in the late 1980s, sustaining a continual decline in sea ice cover that cannot easily be reversed. Results of a new study by a team of scientists from the National Center for Atmospheric Research and two universities, using projections from a state-of-the-art community climate system model, suggest that abrupt reductions in the extent of summer ice are likely to occur over the next few decades, and that near ice-free September conditions may be reached as early as 2040 (Holland et al, 2006).

Observed and Projected Changes in Arctic Sea Ice

(Holland et al, 2006).

Observed and Projected Changes in Arctic Sea Ice

Sea ice is the defining characteristic of the marine Arctic and has a strong seasonal cycle (ACIA 2005, p. 30). It is typically at its maximum extent in March and minimum extent in September (Parkinson et al. 1999, p. 20, 840). There is considerable inter-annual variability both in the maximum and minimum extent of sea ice. In addition, there are decadal and inter-decadal fluctuations to sea ice extent due to changes in atmospheric pressure patterns and their associated winds, continental discharge, and influx of Atlantic and Pacific waters (Gloersen 1995, p. 505; Mysak and Manak 1989, p. 402; Kwok 2000, p. 776; Parkinson 2000b, p. 10; Polyakov et al. 2003, p. 2080; Rigor et al. 2002, p. 2660; Zakharov 1994, p. 42).

Observations have shown a decline in late summer Arctic sea ice extent of 7.7 percent per decade and in the perennial sea ice area of up to 9.8 percent per decade since 1978 (Stroeve et al. 2005, p.1; Comiso 2006, p. 75). A lesser decline of 2.7 percent per decade has been observed in yearly averaged sea ice extents (Parkinson and Cavalieri 2002, p. 441). The rate of decrease appears to be accelerating, with record low minimum extents in the sea ice cover recorded during 2002 through 2005 (Stroeve et al. in press; Comiso 2006, p. 75). Average air temperatures across most of the Arctic Ocean from January to August 2006 were about 2 to 7 degrees Fahrenheit (°F) warmer than the long-term average across the region during the preceding 50 years, indicating that ice melt is accelerating due to a positive feedback loop that enhances warming through the albedo effect. Observations have likewise shown a thinning of the Arctic sea ice of 32 percent or more from the 1960s and 1970s to the 1990s in some local areas (Rothrock et al. 1999, p. 3471; Yu et al. 2004, p. 11). The length of the melt period affects sea ice cover and ice thickness (Hakkinen and Mellor 1990; Laxon et al

lerating due to a positive feedback loop that enhances warming through the albedo effect. Observations have likewise shown a thinning of the Arctic sea ice of 32 percent or more from the 1960s and 1970s to the 1990s in some local areas (Rothrock et al. 1999, p. 3471; Yu et al. 2004, p. 11). The length of the melt period affects sea ice cover and ice thickness (Hakkinen and Mellor 1990; Laxon et al. 2003, cited in Comiso 2005,

Projected Changes in Sea Ice Cover

A number of climate models have been developed that project future conditions in the Arctic, as well as globally (ACIA 2005, p. 99; IPCC 2001b, p. 471). All models predict continued Arctic warming and continued decreases in the Arctic sea ice cover in the 21st century (Johannessen 2004, p. 328) due to increasing global temperatures, although the level of increase varies between models. Comiso (2005, p. 43) found that for each 1°Centigrade (C) (1.6 °F) increase in surface temperature (global average) there is a corresponding decrease in perennial sea ice cover of about 1.48 million km 2 (.57 million mi 2 ). Further, due to increased warming in the Arctic region, accepted models project almost no sea ice cover during summer in the Arctic Ocean by the end of the 21st century (Johannessen et al. 2004, p. 335). More recently, the NSIDC cautioned that the Arctic will be ice-free by 2060 if current warming trends continue (Serreze 2006, p. 2).

The winter maximum sea ice extent in 2005 and 2006 were both about 6 percent lower than average values, indicating significant decline in the winter sea ice cover. In both cases, the observed surface temperatures were also significantly warmer and the onset of freeze-up was later than normal. In both years, onset of melt also happened early (Comiso in press). A continued decline would mean an advance to the north of the 0 °C (32 °F) isotherm temperature gradient, and a warmer ocean in the peripheral seas of the Arctic Ocean. This in turn may result in a further decline in winter ice cover

face temperatures were also significantly warmer and the onset of freeze-up was later than normal. In both years, onset of melt also happened early (Comiso in press). A continued decline would mean an advance to the north of the 0 °C (32 °F) isotherm temperature gradient, and a warmer ocean in the peripheral seas of the Arctic Ocean. This in turn may result in a further decline in winter ice cover.

Predicted Arctic atmospheric and oceanographic changes for time periods through the year 2080 include increased air temperatures, increased precipitation and run-off, and reduced sea ice extent and duration (ACIA 2005, tables on pp. 470 and 476).

Effects of Sea Ice Habitat Change on Polar Bears

Observed and predicted changes in sea ice cover, characteristics, and timing have profound effects on polar bears. Sea ice is a highly dynamic habitat with different types, forms, stages, and distributions of ice that all operate as a complex matrix in determining biological productivity and use by marine organisms, including polar bears and their primary prey base—ice seal species. Polar bear use of sea ice is not uniform. Their preferred habitat is the annual ice located over continental shelf and inter-island archipelagos that circle the Arctic basin. Ice seals demonstrate a similar preference to these ice habitats.

Hudson Bay in Canada typifies change in the Arctic due to its southern location and occurrence on a divide between a warming and a cooling region (AMAP 2003, p. 22). It is therefore an ideal area to study the impacts of climate change. In addition, Hudson Bay has the most significant long-term time series of data on the ecology of polar bears and is the site of the first documented evidence of major and ongoing impacts to polar bears from sea ice changes. Many researchers over the past 40 years have predicted an array of impacts to polar bears from climatic change that include adverse effects on denning, food chain disruption, and prey availability (Budyko 1966; Vibe 1967, cited in Derocher et al

s of data on the ecology of polar bears and is the site of the first documented evidence of major and ongoing impacts to polar bears from sea ice changes. Many researchers over the past 40 years have predicted an array of impacts to polar bears from climatic change that include adverse effects on denning, food chain disruption, and prey availability (Budyko 1966; Vibe 1967, cited in Derocher et al. 2004, p. 164; Lentfer 1972, p. 169; Tynan and DeMaster 1997, p. 315; Stirling and Derocher 1993, pp. 241-244). Stirling and Derocher (1993, p. 240) first noted changes in polar bears in Western Hudson Bay such as declining body condition, lowered reproductive rates, and reduced cub survival; they attributed these changes to a changing ice environment. Subsequently, Stirling et al. (1999, p. 303) established a statistically significant link between climate warming in Western Hudson Bay, reduced ice presence, and observed declines in polar bear physical and reproductive parameters, including body condition (weight) and natality.

Increased Polar Bear Movements

Polar bears are inefficient moving on land; they expend approximately twice the average energy use of other mammals when walking (Best 1982, p. 63; Hurst et al. 1982, p. 273). Sea ice circulation in the Arctic is clockwise, and polar bears tend to walk against this movement to maintain a position near preferred habitat within large geographical home ranges (Mauritzen et al. 2003a, p. 111). Currently, ice thickness is diminishing and there is increased transport of multi-year ice from the polar region. This increased rate and extent of ice movements requires additional efforts and energy expenditure for polar bears to maintain their position near preferred habitats (Derocher et al. 2004, p.167). Ferguson et al. (2001, p. 51) found that polar bears inhabiting areas of highly dynamic ice had much larger activity areas and movement rates compared to those bears inhabiting more stable, persistent ice habitat

eased rate and extent of ice movements requires additional efforts and energy expenditure for polar bears to maintain their position near preferred habitats (Derocher et al. 2004, p.167). Ferguson et al. (2001, p. 51) found that polar bears inhabiting areas of highly dynamic ice had much larger activity areas and movement rates compared to those bears inhabiting more stable, persistent ice habitat. Although polar bears are capable of living in areas of highly dynamic ice movement, they show inter-annual fidelity to the general location of preferred habitat (Mauritzen et al. 2003b, p. 122).

As sea ice moves more quickly or becomes more fragmented, polar bears would likely use more energy to maintain contact with consolidated ice, because moving through highly fragmented sea ice is difficult and likely more energy-intensive than walking over consolidated sea ice (Derocher et al. 2004, p. 167). During summer periods the remaining ice in much of the central Arctic is now positioned away from more productive continental shelf waters and over much deeper, less productive waters, such as in the Beaufort and Chukchi Seas of Alaska. If the width of leads or extent of open water increases, the transit time for bears and the need to swim or to travel will increase (Derocher et al. 2004, p. 167). Derocher et al. (2004, p. 167) suggests that as habitat patch sizes decrease, available food resources are likely to decline, resulting in reduced residency time and thus increased movement rates. The consequences of increased energetic costs to polar bears are reduced weight and condition and corresponding reduction in survival and recruitment rates (Derocher et al. 2004, p. 167)

. 2004, p. 167). Derocher et al. (2004, p. 167) suggests that as habitat patch sizes decrease, available food resources are likely to decline, resulting in reduced residency time and thus increased movement rates. The consequences of increased energetic costs to polar bears are reduced weight and condition and corresponding reduction in survival and recruitment rates (Derocher et al. 2004, p. 167).

Additionally, as movement of sea ice increases and areas of unconsolidated ice increase, some bears will lose contact with the main body of ice and drift into unsuitable habitat from which

Polar Bear Distribution Changes

Recent studies indicate that polar bear distributions are changing and that these changes are strongly correlated to similar changes in sea ice and the ocean-ice system. Specifically, in Western Hudson Bay, breakup of the annual sea ice now occurs approximately 2.5 weeks earlier than it did 30 years ago (Stirling et al. 1999, p. 299). The earlier spring breakup was highly correlated with dates that female polar bears came ashore (Stirling et al. 1999, p. 299). Declining reproductive rates, subadult survival, and body mass (weights) have resulted from longer periods of fasting on land as a result of the progressively earlier breakup of the sea ice caused by an increase in spring temperatures (Stirling et al. 1999, p. 304; Derocher et al. 2004, p. 165).

Stirling et al. (1999, p. 304) reported a significant decline in the condition (weights) of both male and female adult polar bears since the 1980s in Western Hudson Bay, as well as lower natality rates. A positive relationship between body mass of females with cubs and survival of cubs was also established; survival of cubs of mothers in better condition (heavier) was greater than survival of cubs from lighter mothers (Derocher and Stirling 1996, p. 1248).

Stirling et al. (1999, p

) of both male and female adult polar bears since the 1980s in Western Hudson Bay, as well as lower natality rates. A positive relationship between body mass of females with cubs and survival of cubs was also established; survival of cubs of mothers in better condition (heavier) was greater than survival of cubs from lighter mothers (Derocher and Stirling 1996, p. 1248).

Stirling et al. (1999, p. 304) cautioned that although downward trends in the size of the Western Hudson Bay population had not been detected, if trends in life history parameters continued downward “they will eventually have a detrimental effect on the ability of the population to sustain itself.” Population declines have now been determined based on a recent analysis of an ongoing mark-recapture population study, and the earlier predictions of Stirling et al. (1999; p. 304) have been proven. Between 1987 and 2004, the number of polar bears in the Western Hudson Bay population declined from 1,194 to 935, a reduction of about 22 percent (Regehr et al. in prep.). Progressive declines in the condition and survival of cubs, subadults, and bears 20 years of age and older, likely initiated the decline in the size of the Westen Hudson Bay population; these declines appear to have been initiated by progressively earlier sea ice breakup. Once the population began to decline, existing harvest rates of this population contributed to the reduction in the size of the population (Regehr et al. in prep.).

Starting in the 1990s, Schliebe (unpublished data) has observed a trend of increasing use of coastal areas by polar bears during the fall open water period in the Southern Beaufort Sea. High numbers of bears were found to be using coastal areas during some years, where previously observations of polar bears on the coast were rare. The study period included record minimal ice conditions for the month of September in four of the six survey years

ta) has observed a trend of increasing use of coastal areas by polar bears during the fall open water period in the Southern Beaufort Sea. High numbers of bears were found to be using coastal areas during some years, where previously observations of polar bears on the coast were rare. The study period included record minimal ice conditions for the month of September in four of the six survey years. There was a significant relationship between the mean distance from the coast to the edge of pack ice and the numbers of bears observed on the coast. As the distance to the edge of the ice increased, the number of bears near shore increased. Conversely, as ice advanced toward shore, the number of bears near shore decreased. These results suggest that environmental factors, possibly similar to those observed in Western Hudson Bay, are influencing the distribution of polar bears in the southern Beaufort Sea. They also suggest that increased polar bear use of coastal areas may continue if the summer retreat of the sea ice continues to receed in the future as predicted (Serreze et al. 2000, p. 159; Serreze and Barry 2005).

Gleason et al. (2006, p. 1) also found a shift in polar bear distributions in the southern Beaufort Sea. Their study evaluated polar bear distribution during three periods (1979 to 1986, 1987 to 1996, and 1997 to 2005), and found that the September distribution of polar bears was primarily associated with offshore sea ice during the earlier two periods, but land and open water during the later period. These findings coincide with the lack of pack ice (concentrations of greater than 50 percent) caused by a retraction of ice in the study area during the latter period (Stroeve et al. 2005, p. 2; Comiso 2002 in Comiso 2005, p. 46; Comiso 2003, p. 3509; Comiso 2005, p. 52).

The findings of Gleason et al. (2006 p. 1) are consistent with those reported by Schliebe et al. (2006b, p

the later period. These findings coincide with the lack of pack ice (concentrations of greater than 50 percent) caused by a retraction of ice in the study area during the latter period (Stroeve et al. 2005, p. 2; Comiso 2002 in Comiso 2005, p. 46; Comiso 2003, p. 3509; Comiso 2005, p. 52).

The findings of Gleason et al. (2006 p. 1) are consistent with those reported by Schliebe et al. (2006b, p. 559), and confirm an increasing trend in use of coastal areas by polar bears in the southern Beaufort Sea in recent years and a decline in ice habitat near shore. The proximate causes for changes in polar bear distribution are thought to be (1) retraction of pack ice far to the north for greater periods of time in the fall and (2) later freeze-up of coastal waters.

Other polar bear populations exhibiting distribution changes with larger numbers of bears onshore include the Chukchi Sea (Kochnev 2006, p. 162), Baffin Bay, Davis Strait, Foxe Basin, and Hudson Bay populations (Stirling and Parkinson 2006). Stirling and Parkinson (2006, p. 261-275) provide an analysis of pack ice and distribution changes for the Baffin Bay, Davis Strait, Foxe Basin, and Hudson Bay populations. They indicate that earlier sea ice breakup will likely result in longer periods of fasting for polar bears during the extended open-water season and this is why more polar bears have been observed near communities and hunting camps in recent years. Distribution changes of polar bears have been noted during a similar period of time for the northern coast of Chukotka (Kochnev 2006, p. 162) and on Wrangel Island, Russia (Kochnev 2006, p. 162; N. Ovsyanikov, pers. comm.). The relationship between the maximum number of polar bears, the number of dead walruses, quantity of accessible food, and the distance of the ice-edge from Wrangel Island was evaluated. The regression analysis revealed that the strongest correlation was between bear numbers and distance to the ice-edge (Kochnev 2006, p. 162)

rangel Island, Russia (Kochnev 2006, p. 162; N. Ovsyanikov, pers. comm.). The relationship between the maximum number of polar bears, the number of dead walruses, quantity of accessible food, and the distance of the ice-edge from Wrangel Island was evaluated. The regression analysis revealed that the strongest correlation was between bear numbers and distance to the ice-edge (Kochnev 2006, p. 162).

In Baffin Bay, traditional Inuit knowledge studies and anecdotal reports indicate in many areas that greater numbers of bears are being encountered on land during the summer and fall open-water seasons. Interviews with elders and senior hunters in three communities in Nunavut, Canada, revealed that most respondents (83 percent) believed that the population of polar bears had increased. The increase was attributed to more bears seen near communities, cabins, and camps, and hunters encountering bear sign in areas not previously used by bears. Some people interviewed noted that these observations could reflect a change in bear behavior rather than an increase in population.

Stirling and Parkinson (2006, p. 263) evaluated sea ice conditions and distribution of polar bears in five populations in eastern Canada: Western Hudson Bay, Eastern Hudson Bay, Baffin Bay, Foxe Basin, and Davis Strait. Their analysis of satellite imagery beginning in the 1970s indicates that the sea ice is breaking up at progressively earlier dates, so that bears must fast for longer periods of time during the open water season. Stirling and Parkinson (2006, pp. 271-272) point out that long-term data on population size and body condition of bears from the Western Hudson Bay, and population and harvest data from the Baffin Bay population indicate that these populations are declining or likely to be declining. The authors indicate that as

Seasonal polar bear distribution changes noted above and the negative effect of prolonged use of terrestrial habitat are a concern for populations

-term data on population size and body condition of bears from the Western Hudson Bay, and population and harvest data from the Baffin Bay population indicate that these populations are declining or likely to be declining. The authors indicate that as

Seasonal polar bear distribution changes noted above and the negative effect of prolonged use of terrestrial habitat are a concern for populations. Although polar bears have been observed using terrestrial food items such as blueberries, snow geese ( Anser caerulescens ), and reindeer ( Rangifer tarandus ), these alternate foods are not believed to represent significant sources of energy (Derocher et al. 2004, p. 169). Also, the inefficiency of polar bear locomotion noted above likely explains why polar bears are not known to hunt musk oxen ( Ovibos moschatus ) or snow geese, potential prey species that co-occur with the polar bear in many areas (Lunn and Stirling 1985, p. 2295). The energy needed to catch such species would almost certainly exceed the amount of energy a kill would provide (Lunn and Stirling 1985, p. 2295). Consequently, adaptive behaviors of using terrestrial habitat instead of sea ice will not offset energy losses from decreased seal consumption, and nutritional stress will result.

Effects of Sea Ice Habitat Changes on Polar Bear Prey

Reduced Seal Productivity

Ringed seals in many areas prefer stable, shore-fast ice for construction of birth lairs. Pups are born between mid-March and mid-April, nursed for about 6 weeks, and weaned prior to spring breakup in June (Smith 1980, p. 2201; Stirling 2002, p. 67). During this time period, both ringed seal pups and adults are hunted by polar bears (Smith 1980, p. 2201). Ferguson et al. (2005, pp. 130-131) demonstrated that decreased snow depth in April and May, possibly influenced by the timing of spring breakup, may have a detrimental effect on ringed seal recruitment in Western Hudson Bay

spring breakup in June (Smith 1980, p. 2201; Stirling 2002, p. 67). During this time period, both ringed seal pups and adults are hunted by polar bears (Smith 1980, p. 2201). Ferguson et al. (2005, pp. 130-131) demonstrated that decreased snow depth in April and May, possibly influenced by the timing of spring breakup, may have a detrimental effect on ringed seal recruitment in Western Hudson Bay. Reduced snowfall results in less snow drift accumulation to the leeward side of pressure ridges; pups in lairs with thin snow roofs are more vulnerable to predation than pups in lairs with thick roofs (Ferguson et al 2005, p. 131). Access to birth lairs for thermoregulation is considered crucial to the survival of nursing pups when air temperatures fall below 0 °C (32 °F) (Stirling and Smith 2004, p. 65). Warming temperatures that melt snow-covered birth lairs contributed to pups being exposed to ambient conditions and suffering from hypothermia (Stirling and Smith 2004, p. 63). Ferguson et al. (2005, p. 121) concluded that “earlier spring breakup of sea ice together with snow trends suggest continued low pup survival in western Hudson Bay.”

Harwood et al. (2000, pp. 11-12) reported that an early spring breakup negatively impacted the growth, condition, and probably the survival of unweaned ringed seal pups. Early breakup was believed to have interrupted lactation in adult females, which in turn, negatively affected the condition and growth of pups. Earlier ice breakups similar to those documented by Harwood et al. (2000, p. 11) and Ferguson et al. (2005, p. 131) are predicted to occur more frequently, and as a result a decrease in productivity and abundance of ringed seals is predicted (Ferguson et al. 2005, p. 131)

s believed to have interrupted lactation in adult females, which in turn, negatively affected the condition and growth of pups. Earlier ice breakups similar to those documented by Harwood et al. (2000, p. 11) and Ferguson et al. (2005, p. 131) are predicted to occur more frequently, and as a result a decrease in productivity and abundance of ringed seals is predicted (Ferguson et al. 2005, p. 131). Similar to earlier spring breakup or reduced snow cover, increased rain on snow events during the late winter also negatively impact ringed seal recruitment by damaging or eliminating snow-covered pupping lairs, increasing exposure and the risk of hypothermia, and facilitating predation by polar bears and Arctic foxes ( Alopex lagopus ) (Stirling and Smith 2004, p. 65). Stirling and Smith (2004, p. 64) document the collapse of the snow roofs of ringed seal birth lairs near southeastern Baffin Island and the resultant exposure of adult seals and pups to hypothermia. Predation of pups by polar bears was observed and the researchers suspect that most of the pups in these areas were eventually killed by polar bears (Stirling and Archibald 1977, p. 1127), Arctic foxes (Smith 1976 cited in Stirling and Smith 2004, p. 65) or possibly gulls (Lydersen and Smith 1989 cited in Stirling and Smith 2004, p. 66). Stirling and Smith (2004, p. 66) postulated that should early season rain become regular and widespread in the future, mortality of ringed seal pups will increase, especially in more southerly parts of their range, and local populations may be significantly reduced. Any significant decline in ringed seal numbers, especially in the production of young, could affect reproduction and survival of polar bears (Stirling and Smith 2004, p. 66)

ted that should early season rain become regular and widespread in the future, mortality of ringed seal pups will increase, especially in more southerly parts of their range, and local populations may be significantly reduced. Any significant decline in ringed seal numbers, especially in the production of young, could affect reproduction and survival of polar bears (Stirling and Smith 2004, p. 66).

Reduced Prey and Availability

Ringed seals are the primary prey of the polar bear in most areas, though bearded seals, walrus, harbor seals ( Phoca vitulina ), harp seals ( Phoca greenlandica ), hooded seals ( Crystophora cristata ), and beluga whales are sometimes taken and may be locally important to some populations (Stirling and Archibald 1977, p. 1129; Smith 1980, p. 2206; Smith and Sjare 1990, p. 100; Iverson et al. 2006, p. 114). Ice-associated seals, including the ringed seal, are vulnerable to habitat loss from changes in the extent or concentration of Arctic ice because they depend on pack-ice habitat for pupping, foraging, molting, and resting (Tynan and DeMaster 1997, p. 312; Derocher et al. 2004, p. 168).

Polar bear populations are known to fluctuate based on prey availability (Stirling and Lunn 1997, p. 177). For example, declines in ringed and bearded seal numbers and productivity have resulted in marked declines in polar bear populations (Stirling 1980, p. 309; Stirling and Øslashritsland 1995, p. 2609; Stirling 2002, p. 68). Ringed seal young-of-the-year represented the majority of the polar bear diet, and fluctuations in the productivity of ringed seal pups will likely be reflected immediately in polar bear reproduction and cub survival (Stirling and Lunn 1997, p. 177). For polar bears, the most critical factor which affects reproductive success, subsequent condition, and survival is the availability of ringed seal pups from about mid-April to ice break up sometime in July (Stirling and Lunn 1997, p. 176)

tions in the productivity of ringed seal pups will likely be reflected immediately in polar bear reproduction and cub survival (Stirling and Lunn 1997, p. 177). For polar bears, the most critical factor which affects reproductive success, subsequent condition, and survival is the availability of ringed seal pups from about mid-April to ice break up sometime in July (Stirling and Lunn 1997, p. 176).

Thus, major declines in sea ice habitat as projected will likely result in a decline in polar bear abundance over time due to reduced prey availability (Derocher et al. 2004, p. 167). The effects of declining ice habitat on seals will vary depending on the location, timing and extent of reductions, based on the information presented by Derocher et al. (2004). While it is possible that reduced ice cover along with increased open and warmer water will enhance primary productivity of seal prey items, and thus seal productivity, ultimately such a regime will negatively impact polar bears. An increased area and duration of open water will result in polar bears having reduced access to prey during critical periods of the year and physical condition of bears will decline. Further, reductions in sea ice cover will result in diminished productivity and distribution changes of ringed seals over time because seals depend on sea ice for pupping and resting. Thus a reduction in sea ice is likely to result in a net reduction in abundance of ringed seals (ACIA 2005, p. 520).

Grebmeier et al. (2006, p. 1461) found that a major ecosystem shift is occurring in the Northern Bering Sea indicated by a decrease in benthic (bottom-dwelling) prey populations, which could affect Pacific walrus and bearded seal Boreogadus saida ), one of the primary prey species of ringed seals, is strongly associated with sea ice throughout its range and uses the underside of the ice to escape from predators (Craig et al. 1982 and Sekerak 1982 cited in Gaston et al. 2003, p. 230)

Northern Bering Sea indicated by a decrease in benthic (bottom-dwelling) prey populations, which could affect Pacific walrus and bearded seal Boreogadus saida ), one of the primary prey species of ringed seals, is strongly associated with sea ice throughout its range and uses the underside of the ice to escape from predators (Craig et al. 1982 and Sekerak 1982 cited in Gaston et al. 2003, p. 230). It is therefore likely that a decrease in seasonal ice cover could have adverse effects on Arctic cod (Tynan and DeMaster 1997, p. 314; Gaston et al. 2003, p. 231). Sea ice regime changes in the Arctic have been implicated in distribution changes of other species as well. Cooper et al. (2006, p. 98) observed orphaned Pacific walrus in waters as deep as 3,000 m (9,843 ft) in the Canada Basin of the Arctic Ocean. These observations indicate that the Pacific walrus population may be ill-adapted to rapid seasonal sea ice retreat off Arctic continental shelves.

Several species of seals that currently occur at the southern edge of the range of polar bears could also expand their range northward. In the north Pacific, this could include harbor seals ( Phoca vitulina ), spotted seals ( Phoca largha ), and ribbon seals ( Phoca fasciata ). In the north Atlantic, harp and hooded seals could expand northward and become available as prey, particularly if their pupping (natal) grounds located on heavy, thicker ice are only available in more northern latitudes (Derocher et al. 2004, p. 168). A study of seals preyed upon by polar bears in three major regions of the Canadian Arctic, Davis Strait, western Hudson Bay, and the Beaufort Sea, revealed that diets differed among the regions, and within the region for Davis Strait. These differences were thought to be based on different rates of availability of the different seal species, as determined by their abundance.

The absence of ice in southerly pupping areas or the relocation of pupping areas to more northerly areas could affect seal production

Hudson Bay, and the Beaufort Sea, revealed that diets differed among the regions, and within the region for Davis Strait. These differences were thought to be based on different rates of availability of the different seal species, as determined by their abundance.

The absence of ice in southerly pupping areas or the relocation of pupping areas to more northerly areas could affect seal production. Repeated years of little or no ice in the Gulf of St. Lawrence resulted in almost zero production of harp seal pups, compared to hundreds of thousands in good ice years (ACIA 2005, p. 510). Marginal ice conditions and early ice breakup during harp seal whelping are believed to have resulted in increased juvenile mortality from starvation and cold stress and an overall reduction in this age class (Johnston et al. 2005, pp. 215-216). Northerly shifts of whelping areas for hooded seals were reported to occur during periods of warmer climate and diminished ice (Burns 2002 p. 42). In recent years, the position of the hooded seal whelping patch near Jan Mayen has changed position, likely in response to decreased sea ice in East Greenland; the number of seal also decreased (T. Haug, pers. comm. 2005). Marginal sea ice cover may have significant effects on harp and hooded seals since the amount and quality of ice suitable for whelping may be greatly reduced, resulting in higher density whelping areas (Johnston et al. 2005, p. 218). Crowding in whelping areas may increase the risks of disease transmissions and epizootics (Fay 1974, p. 394), but the effects of crowding at the harp and hooded seal whelping patches are largely unknown (Johnston et al. 2005, p. 218). Born (2005a) indicated that early ice breakup in years with “light” ice conditions may influence seals other than ringed seals. Other ice breeding seals, ribbon and spotted seals, may also be similarly affected by marginal ice conditions and early breakup (Born 2005a)

394), but the effects of crowding at the harp and hooded seal whelping patches are largely unknown (Johnston et al. 2005, p. 218). Born (2005a) indicated that early ice breakup in years with “light” ice conditions may influence seals other than ringed seals. Other ice breeding seals, ribbon and spotted seals, may also be similarly affected by marginal ice conditions and early breakup (Born 2005a). It is unlikely that increased take of other species such as bearded seals, walrus, or harbor seals, even where they are available, could compensate for reduced availability of ringed seals (Derocher et al. 2004, pp. 168-169).

Changes in prey availability may have especially large impacts on immature bears. Polar bears feed preferentially on blubber, and adult bears often leave much of a kill behind. Younger bears, which are not as efficient at taking seals, are known to utilize these kills to supplement their diet (Derocher et al. 2004, p. 168). Younger bears may be disproportionately impacted if there are fewer kills or greater consumption of kills by adults, resulting in less prey to scavenge (Derocher et al. 2004, pp. 167-168). Altered prey distribution would also likely lead to increased competition for prey between dominant and subordinate bears, resulting in subordinate or sub-adult bears having reduced access to prey (Derocher et al. 2004, p. 167). Thus, a decrease in ringed seal abundance and availability would result in a concomitant decline in polar bear populations.

Demographic Effects on Polar Bears

The potential effects of sea ice changes on population size are difficult to quantify, especially for a long-lived and widely dispersed species like the polar bear. The key demographic factors for polar bears are physical condition, reproduction, and survival. Alteration of these characteristics has been associated with elevated risks of extinction for other species (McKinney 1997; Beissinger 2000; Owens and Bennett 2000 all cited in Derocher et al. 2004, p. 170)

ficult to quantify, especially for a long-lived and widely dispersed species like the polar bear. The key demographic factors for polar bears are physical condition, reproduction, and survival. Alteration of these characteristics has been associated with elevated risks of extinction for other species (McKinney 1997; Beissinger 2000; Owens and Bennett 2000 all cited in Derocher et al. 2004, p. 170).

Physical condition of polar bears has been shown to determine the welfare of individuals, and ultimately, through their reproduction and survival, the welfare of populations (Stirling et al. 1999, p. 304; Regehr et al. in prep). Declines in fat reserves during critical times in the polar bear life cycle are likely to lead to an array of impacts including a delay in the age of first reproduction, decrease in the proportion of females with adequate fat stores to complete successful denning, decline in litter sizes with more single cub litters and fewer cubs overall, as well as lower cub body weights and lower survival rates (Derocher et al. 2004, p. 170). Derocher and Stirling (1998, pp. 255-256) demonstrated that body mass of adult females is correlated with cub mass at den emergence, with heavier females producing heavier cubs and lighter females producing lighter cubs. Heavier cubs have a higher rate of survival (Derocher and Stirling 1996, p. 1249). Females in poor condition will result in a higher proportion that do not initiate denning or are likely to abandon their den and cub(s) mid-winter (Derocher et al. 2004, p. 170). Females with insufficient fat stores or in poor hunting condition in the early spring after den emergence could lead to increased cub mortality (Derocher et al. 2004, p. 170). In the southern Beaufort Sea, Regehr et al. (2006, p. 20) recently found that survival rates for cubs were significantly lower than estimates from earlier studies

eir den and cub(s) mid-winter (Derocher et al. 2004, p. 170). Females with insufficient fat stores or in poor hunting condition in the early spring after den emergence could lead to increased cub mortality (Derocher et al. 2004, p. 170). In the southern Beaufort Sea, Regehr et al. (2006, p. 20) recently found that survival rates for cubs were significantly lower than estimates from earlier studies. The lower survival rate of cubs coincided with warming temperatures and altered atmospheric circulation starting in the winter of 1989-1990 that caused an abrupt change in sea ice conditions in the Arctic basin. In addition, sea ice conditions that include broken or more fragmented ice may require young cubs to enter water more frequently and for more prolonged periods of time, thus increasing mortality from hypothermia. Blix and Lenter (1979, p. 72) and Larsen (1985, p. 325) indicate that cubs are unable to survive immersion in icy water for more than approximately 10 minutes. This is due to cubs having little insulating fat, their fur losing its insulating ability when wet (though the fur of adults sheds water and recovers its insulating properties quickly), and the core body temperature dropping rapidly when they are immersed in icy water (Blix and Lenter 1979, p. 72).

Reductions in sea ice, as discussed above, will alter ringed seal distribution, abundance, and availability for polar bears. Such reductions will, in turn, decrease polar bear body condition (Derocher et al. 2004, p. 165). Derocher et al. (2004, p. 165) projected that most females in the Western Hudson Bay

n Hudson Bay

Furthermore, with the extent of winter sea ice projected to be reduced in the future, opportunities for increased feeding to recover fat stores during this season may be limited. Mortality of polar bears is thought to be the highest in winter when fat stores are low and energetic demands are greatest. Pregnant females are in dens during this period using fat reserves and not feeding. Polar bears hunt seals at their breathing holes, however, increased open water or fragmented ice will provide seals alternatives to establishing breathing holes, likely reducing their availability to polar bears and decreasing bear hunting success (Derocher et al. 2004, p. 167).

In general, Derocher et al. (2004, p. 170) predict demographic impacts will adversely affect female reproductive rates and juvenile survival first while adult female survival rates would be affected under severe conditions. Regehr et al. (2005, p. 233) showed that while the Western Hudson Bay population has declined 22 percent since 1987, this decline was not uniform across all age classes of bears. Survival of prime-adult polar bears (age 5 to 19 years) was stable over the course of the study; however, survival of juvenile, subadult, and past prime age polar bears declined as a function of earlier spring sea ice breakup date.

The Southern Beaufort Sea population has also been subject to dramatic changes in the sea ice environment beginning in the winter of 1989 to 1990 (Regehr et al. 2006, p. 2). These changes were linked initially through direct observation of distribution changes during the fall open water period. With the exception of the Western Hudson Bay population, the Southern Beaufort Sea population has the most complete and extensive time series of life history data, dating back to the late 1960s. A 5-year coordinated capture-recapture study of this population to evaluate changes in the health and status of polar bears and life history parameters such as reproduction, survival, and abundance was completed in 2006

tion of the Western Hudson Bay population, the Southern Beaufort Sea population has the most complete and extensive time series of life history data, dating back to the late 1960s. A 5-year coordinated capture-recapture study of this population to evaluate changes in the health and status of polar bears and life history parameters such as reproduction, survival, and abundance was completed in 2006. Results of this study indicate that the estimated population size has gone from 1,800 bears (Amstrup et al. 1986, p. 244; Amstup 2000, p. 146) to 1,526 polar bears in 2006 (Regehr et al. 2006, p. 16). The precision of the earlier estimate of 1,800 polars was low, and consequently the 2006 estimate of 1,526 is not statistically significantly different. Amstrup et al. (2001, p. 230) provides an additional population estimate of as many as 2,500 bears for this population in the late 1980s, although the statistical variance could not be calculated and thus precludes comparative value of the estimate. Survival rates, weights, and skull sizes were compared for 2 periods of time, 1967 to 1989 and 1990 to 2006. In the later period, estimates of total survival for cubs declined significantly from .65 (Amstrup and Durner 1995, p. 1316) to .43. Cub weights also decreased slightly. The authors believed that poor survival of new cubs may have been related to declining physical condition of females entering dens and consequently of the cubs born during recent years as reflected by smaller skull measurements. Also, between years during the 5-year study, a general decline in survival rates for cubs, females older than cubs, and males older than cubs was noted. In addition, body weights for adult males decreased significantly and skull measurements were reduced since 1990. Since male polar bears continue to grow into their teen years (Derocher et al. 2005, p. 898), if nutritional intake was similar since 1990, the size of males should have increased (Regehr et al. 2006, p. 18)

rates for cubs, females older than cubs, and males older than cubs was noted. In addition, body weights for adult males decreased significantly and skull measurements were reduced since 1990. Since male polar bears continue to grow into their teen years (Derocher et al. 2005, p. 898), if nutritional intake was similar since 1990, the size of males should have increased (Regehr et al. 2006, p. 18). The observed changes reflect a trend toward smaller size adult male bears. Although a number of the indices of population status were not independently significant, nearly all of the indices illustrated a declining trend. In the case of Western Hudson Bay, declines in cub survival and physical stature were recorded for a number of years (Stirling et al. 1999, p. 300; Derocher et al. 2004, p. 165) before a statistically significant decline in the population size was confirmed (Regehr et al. in prep.). Amstrup (pers. comm. 2006) indicates that if the trends in loss of sea ice continue as predicted, then, similar to the conditions for the Western Hudson Bay population, the ultimate effect will be a significant decline in the population trend for the Southern Beaufort Sea population. This declining trend will occur within the 45-year period determined to be the foreseeable future.

In further support of the interaction of environmental factors, nutritional stress and their effect on polar bears, several unusual mortality events have been documented in the southern Beaufort Sea. During the winter and early spring of 2004, three observations of polar bear cannibalism were recorded (Amstrup et al. 2006, p. 1). Similar observations had not been recorded in that region despite studies extending back for decades. In the fall of 2004, four polar bears were observed to have drowned while attempting to swim between shore and distant pack ice in the Beaufort Sea. Despite offshore surveys extending back to 1987, similar observations had not previously been recorded (Monnett and Gleason 2006, p. 3)

2006, p. 1). Similar observations had not been recorded in that region despite studies extending back for decades. In the fall of 2004, four polar bears were observed to have drowned while attempting to swim between shore and distant pack ice in the Beaufort Sea. Despite offshore surveys extending back to 1987, similar observations had not previously been recorded (Monnett and Gleason 2006, p. 3). In spring of 2006, three adult female polar bears and one yearling were found dead. Two of these females and the yearling had no fat stores and apparently starved to death, while the third adult female was too heavily scavenged to determine a cause of death. This mortality is suspicious because prime age females have had very high survival rates in the past (Amstrup and Durner 1995, p. 1315). Similarly, the yearling that was found starved was the offspring of another radio-collared prime age female whose collar had failed prior to her yearling being found dead. Annual survival of yearlings, given survival of their mother, was previously estimated to be 0.86 (Amstrup and Durner 1995, p. 1316). The probability, therefore, that this yearling died while its mother was still alive was only approximately 14 percent. Regehr et al. (2006, p. 27) indicate that these anecdotal observations, in combination with changes in survival of young and declines in size and weights reported above suggest mechanisms by which a changing sea ice environment can affect polar bear demographics and population status.

Open Water Habitat

As indicated earlier, open water is not considered essential habitat to polar bear life functions because activities such as feeding, reproduction, or resting do not occur on the open water and are limited when only open water is available. However, the extent of open water is important in that vast areas of open water present a barrier or hazard under certain circumstances for polar bears to access sea ice or land

er, open water is not considered essential habitat to polar bear life functions because activities such as feeding, reproduction, or resting do not occur on the open water and are limited when only open water is available. However, the extent of open water is important in that vast areas of open water present a barrier or hazard under certain circumstances for polar bears to access sea ice or land. Diminished sea ice cover will also increase the energetic cost to polar bears for travel, pose potential for drowning that may occur during long distance swimming or swimming under unfavorable sea wave conditions, and may result in hypothermia for young cubs as previously discussed. Under diminishing sea ice scenarios (IPCC 2001, p. 489; ACIA 2005, p. 192; Serreze 2006), ice-dependent seals, the principal prey of polar bears will also be affected through distribution changes and reductions in productivity, ultimately translating into reductions in population size.

Reduced Feeding Opportunities

Polar bears are capable of swimming great distances, but exhibit a strong preference for sea ice (Mauritzen et al.

Overall, a reduction in sea ice and corresponding increase in open water is likely to result in a net reduction in ringed and bearded seals, and Pacific walrus abundance (ACIA 2005, p. 510) as well as a reduction in ribbon and spotted seals (Born 2005a). While harp and hooded seals may change their distribution and potentially serve as a prey for polar bears, it appears unlikely that these species can successfully redistribute in a rapidly changing environment and reproduce and survive at former levels. Loss of southern pupping areas due to inadequate or highly variable ice conditions may also serve to reduce these species as a potential polar bear prey (Derocher et al. 2004, p. 168)

e their distribution and potentially serve as a prey for polar bears, it appears unlikely that these species can successfully redistribute in a rapidly changing environment and reproduce and survive at former levels. Loss of southern pupping areas due to inadequate or highly variable ice conditions may also serve to reduce these species as a potential polar bear prey (Derocher et al. 2004, p. 168). It is also unlikely that increased take of other species such as bearded seals, walrus, harbor seals, or harp and hooded seals regionally if they are available, could compensate for reduced availability of ringed seals (Derocher et al. 2004, p. 168).

Open Water Swimming

Open water is considered to present a potential hazard to polar bears required to make long distance transits of that open water seeking sea ice or land habitat. As indicated previously, four polar bears drowned in open water while attempting to swim between shore and distant ice in 2004 (Monnett and Gleason 2006, p. 5). Because the survey area covered 11 percent of the study area, an extrapolation of the survey data to the entire study area indicates that up to 36 bears may have been swimming and 27 of these may have drowned during this event. Seas during this period were rough and extensive areas of open water persisted between pack ice and land. Mortalities due to offshore swimming during late-ice (or mild ice) years may also be an important and unaccounted source of natural mortality given energetic demands placed on individual bears engaged in long-distance swimming (Monnett and Gleason 2006, p. 6). This evidence suggests that drowning-related deaths of polar bears may increase in the future if the observed trend of regression of pack ice and/or longer open water periods continues.

hat drowning-related deaths of polar bears may increase in the future if the observed trend of regression of pack ice and/or longer open water periods continues.

Wave height (sea state) increases as a function of the amount of open water surface area. Thus ice reduction not only increases areas of open water across which polar bears must swim, but may have an influence on the size of wave action. Considered together these may result in over-all increases in bear mortality associated with swimming when there is little sea ice to buffer wave action (Monnett and Gleason 2006, p. 5). Evidence of such mortality has also been reported by Julian Dowdeswell, Head of the Scott Polar Research Institute of England, who observed one exhausted and one apparently dead polar bear apparently stranded at sea east of Svalbard in 2006.

Terrestrial Habitat

Although sea ice is the polar bear's principal habitat, terrestrial habitat serves a vital function seasonally for denning. In addition, use of terrestrial habitat is seasonally important for resting and feeding in the absence of suitable sea ice. This habitat may take on a more prominent role in maintaining the health and condition of polar bears in future years. The following section describes the effects or potential effects of climate change and other factors on polar bear use of terrestrial habitat. It focuses on access to or changes in the quality of denning habitat, and on distribution changes and corresponding increases in polar bear-human interactions in coastal areas. Also discussed are the potential consequences of and potential concerns for development, primarily oil and gas exploration and production that occurs in polar bear habitat (marine and terrestrial).

Access to and Alteration of Denning Areas

Many female polar bears repeatedly return to specific denning areas on land (Harrington 1968, p. 11; Schweinsburg et al. 1984, p. 169; Garner et al. 1994b, p. 401; Ramsay and Stirling 1990, p. 233)

nces of and potential concerns for development, primarily oil and gas exploration and production that occurs in polar bear habitat (marine and terrestrial).

Access to and Alteration of Denning Areas

Many female polar bears repeatedly return to specific denning areas on land (Harrington 1968, p. 11; Schweinsburg et al. 1984, p. 169; Garner et al. 1994b, p. 401; Ramsay and Stirling 1990, p. 233). To access preferred denning areas, pack ice must drift close enough or must freeze sufficiently early in the fall to allow pregnant females to walk or swim to the area by late October or early November (Derocher et al. 2004, p. 166). Under likely climate change scenarios, the distance between the edge of the pack ice and land will increase (ACIA 2005, pp. 456-459). As distance increases between the southern edge of the pack ice and coastal denning areas, it will become increasingly difficult for females to access preferred denning locations. Most high-density denning areas are located at more southerly latitudes (Figure 2). For populations that den at high latitudes in the Canadian archipelago islands, the effects may be less or may become evident later in time than for more southerly populations.

The most recent study based on updated modeling suggests that near ice-free September conditions may be reached as early as 2040 (Holland et al., 2006). Derocher et al. (2004, p. 166) predicted that under these climate change scenarios, pregnant female polar bears will likely be unable to reach many of the most important denning areas in the Svalbard Archipelago, Franz Josef Land, Novaya Zemlya, Wrangel Island, Hudson Bay, and the Arctic National Wildlife Refuge and north coast of the Beaufort Sea (Figure 2).

BILLING CODE 4310-55-P EP09JA07.001

BILLING CODE 4310-55-C Increased drift rates of ice floes that may serve as a platform for denning are of concern (Derocher et al. 2004, p. 166)

y of the most important denning areas in the Svalbard Archipelago, Franz Josef Land, Novaya Zemlya, Wrangel Island, Hudson Bay, and the Arctic National Wildlife Refuge and north coast of the Beaufort Sea (Figure 2).

BILLING CODE 4310-55-P EP09JA07.001

BILLING CODE 4310-55-C Increased drift rates of ice floes that may serve as a platform for denning are of concern (Derocher et al. 2004, p. 166). In northern Alaska, polar bear maternity

In some locations, bears may adopt the denning strategy used by the Western Hudson Bay population, where pregnant females leave the ice in the spring at breakup and summer in locations near where they ultimately den (Derocher et al. 2004, p. 166). Under such a scenario females must accumulate sufficient fat stores to fast for 8, or more, months before they can return to sea ice to resume feeding on seals (Derocher et al. 2004, p. 166). While this strategy may be used more frequently in the future, its usefulness in maintaining populations is questionable. The results of Regehr et al. (in press) indicate that the Western Hudson Bay population has been in decline over the past 19 years, with the physical condition of bears declining due to greater periods of fasting on land caused by earlier spring breakup (Stirling et al. 1999, p. 300).

Climate change also impacts the quality of snow for denning (Derocher et al. 2004, p. 166). Insufficient snow limits den construction (Derocher et al. 2004, p. 166). Changes in the amount and timing of snowfall also impact the thermal properties of the dens (Derocher et al. 2004, p. 166). Because polar bear cubs are born helpless and nurse up to 3 months before emerging from the den; major changes in the thermal properties of dens could negatively impact cub survival (Derocher et al. 2004, p. 167). For example two cubs born to a captive held female without a den and exposed to temperatures of approximately −43 °C (−45 °F), both died within 2 days (Blix and Lentfer 1979, p. 67)

66). Because polar bear cubs are born helpless and nurse up to 3 months before emerging from the den; major changes in the thermal properties of dens could negatively impact cub survival (Derocher et al. 2004, p. 167). For example two cubs born to a captive held female without a den and exposed to temperatures of approximately −43 °C (−45 °F), both died within 2 days (Blix and Lentfer 1979, p. 67).

Finally, the occurrences of rain events are projected to increase throughout the Arctic in winter (ACIA 2005, p. 993). Increased rain in late winter and early spring can result in both polar bear natal den collapses as well as ringed seal den collapses (Stirling and Smith 2004, p. 64). Polar bear den collapse following a warming period in the Beaufort Sea resulted in the death of a mother and her two young cubs (Clarkson and Irish 1991, p. 83). In another instance, unseasonable rain south of Churchill, Manitoba, caused large snow banks along creeks and rivers used for denning to collapse from the weight of the wet snow (Stirling and Derocher 1993, p. 244).

Oil and Gas Exploration, Development, and Production

Each of the Parties to the 1973 Polar Bear Agreement (see International Agreements and Oversight section below), have developed detailed regulations pertaining to the extraction of oil and gas within their countries. The greatest level of oil and gas activity within polar bear habitat is currently occurring in the United States (Alaska). Exploration and production activities are also actively underway in Russia, Canada, Norway, and Denmark (Greenland). In the United States, all such leasing and production activities are required to comply with the National Environmental Policy Act (42 U.S.C. 4321 et seq. (NEPA), and numerous other statutes, which guide exploration, development and production so as to minimize possible environmental impacts. In Alaska, the majority of oil and gas development is on land, however, some offshore production sites have been developed, and others are planned

nd production activities are required to comply with the National Environmental Policy Act (42 U.S.C. 4321 et seq. (NEPA), and numerous other statutes, which guide exploration, development and production so as to minimize possible environmental impacts. In Alaska, the majority of oil and gas development is on land, however, some offshore production sites have been developed, and others are planned.

Historically, oil and gas activities have resulted in little direct mortality to polar bears, and that mortality which has occurred, has been associated with human bear interactions as opposed to a spill event. However, oil and gas activities are increasing as development continues to expand throughout the United States Arctic and internationally, including in polar bear terrestrial and marine habitats. The greatest concern for future oil and gas development is the effect of an oil spill or discharges in the marine environment impacting polar bears or their habitat. Much of the north slope of Alaska contains habitat suitable for polar bear denning (Durner et al. 2001, p. 119). Further, in northern Alaska and elsewhere, distribution of polar bears appears to be changing to use of land areas during the open water season. Some of these areas coincide with areas that have been developed for oil and gas production. This increases the potential for interactions with humans (Durner et al. 2001, p. 115; National Research Council (NRC) 2003, p. 168).

The National Research Council (2003, p. 169) evaluated the cumulative effects of oil and gas development in Alaska and concluded the following relates to polar bears and ringed seals:

• “Industrial activity in the marine waters of the Beaufort Sea has been limited and sporadic and likely has not caused serious cumulative effects to ringed seals or polar bears.

• Careful mitigation can help to reduce the effects of oil and gas development and their accumulation, especially if there is no major oil spill

ska and concluded the following relates to polar bears and ringed seals:

• “Industrial activity in the marine waters of the Beaufort Sea has been limited and sporadic and likely has not caused serious cumulative effects to ringed seals or polar bears.

• Careful mitigation can help to reduce the effects of oil and gas development and their accumulation, especially if there is no major oil spill. However, the effects of full-scale industrial development of waters off the North Slope would accumulate through the displacement of polar bears and ringed seals from their habitats, increased mortality, and decreased reproductive success.

• A major Beaufort Sea oil spill would have major effects on polar bears and ringed seals.

• Climatic warming at predicted rates in the Beaufort Sea region is likely to have serious consequences for ringed seals and polar bears, and those effects will accumulate with the effects of oil and gas activities in the region.

• Unless studies to address the potential accumulation of effects on North Slope polar bears or ringed seals are designed, funded, and conducted over long periods of time, it will be impossible to verify whether such effects occur, to measure them, or to explain their causes.”

There is the potential for alteration of polar bear habitat from oil and gas development, exploration (seismic) or other activities in denning areas, and potential oil spills in the marine environment. Any such impacts would be additive to other factors already or potentially affecting polar bears and their habitat.

ould be additive to other factors already or potentially affecting polar bears and their habitat.

Documented impacts on polar bears by the oil and gas industry during the past 30 years are minimal. Polar bears spend a limited amount of time on land, coming ashore to feed, den, or move to other areas. At times, fall storms deposit bears along the coastline where bears remain until the ice returns. For this reason, polar bears have mainly been encountered at or near most coastal and offshore production facilities, or along the roads and causways that link these facilities to the mainland. During those periods, the likelihood of interactions between polar bears and industry activities increases. We have found that the polar bears interaction planning and training requirements set forth in these regulations and required through the letters of authorization (LOA) process have increased polar bear awareness and minimized these encounters. LOA requirements have also increased our knowledge of polar bear activity in the developed areas.

No lethal take associated with industry has occurred during the period covered by incidental take regulations. Prior to issuance of regulations, lethal takes by industry were rare. Since 1968, there have been two documented cases of lethal take of polar bears associated with oil and gas activities. In both instances, the lethal take was reported to be in defense of human life. In the winter of 1968-1969, an industry employee shot and killed a polar bear. In 1990, a female polar bear was killed at a drill site on the west side of Camden Bay. In contrast, 33 polar bears were killed in the Canadian Northwest Territories from 1976 to 1986 due to encounters with industry. Since the beginning of the incidental take program, which includes measures that minimize impacts to the species, no polar bears have been killed due to encounters associated with the current industry activities on the North Slope of Alaska

n the west side of Camden Bay. In contrast, 33 polar bears were killed in the Canadian Northwest Territories from 1976 to 1986 due to encounters with industry. Since the beginning of the incidental take program, which includes measures that minimize impacts to the species, no polar bears have been killed due to encounters associated with the current industry activities on the North Slope of Alaska.

However, based on mitigation measures in place now and likely to be used in the future, historical information on the level of oil and gas development activities occurring within polar bear habitat within the Arctic, the lack of direct quantifiable impacts to polar bear habitat from these activities noted to date, and because of the localized nature of the development activities, or possible events such as oil spills, they do not threaten the species throughout all or a significant portion of its range.

Conclusion for Factor A

Polar bears have evolved in a sea ice environment and sea ice serves as an essential platform from which they meet life functions. Polar bear populations throughout the Arctic are being affected by changes in their sea ice habitat. Increased temperatures, earlier onset of and longer melting periods, increased rain-on-snow events, and positive feedback systems which amplify these phenomena will all operate to decrease the extent of sea ice during all seasons. This will result in fragmentation of habitat, increase the extent of open water areas in all seasons, reduce the amount of heavier and more stable multi-year ice, and affect the quality of shore fast ice. In turn, these factors will negatively impact polar bears by increasing the energetic demands of movement in seeking prey, redistributing substantial portions of populations seasonally into terrestrial habitats with marginal values for feeding, and increasing levels of negative bear-human interactions

e the amount of heavier and more stable multi-year ice, and affect the quality of shore fast ice. In turn, these factors will negatively impact polar bears by increasing the energetic demands of movement in seeking prey, redistributing substantial portions of populations seasonally into terrestrial habitats with marginal values for feeding, and increasing levels of negative bear-human interactions. As the sea ice edge retracts to deeper, less productive polar basin waters, polar bears will face increased intraspecific competition for limited food resources and increased open water swimming. We expect similar reductions in productivity for most ice seal species (decreasing availability or timing of availability for polar bears as food), composition changes of seal species in some areas, and eventually decreased levels of seal abundance. Prey species, such as ringed seals, will likely remain distributed in shallower, more productive southerly areas characterized by vast expanses of open water. These factors will, in turn, result in the reduced physical condition of polar bears, which leads to population-level demographic declines through reduction of survival and recruitment rates. The ultimate effect of these inter-related events, factors, and effects (Table 1) will be that polar bear populations will decline or continue to decline. Not all populations will be affected evenly in the level, rate, and timing of impact, but within the foreseeable future, it is predicted that all populations will be either directly or indirectly impacted.

Table 1.—Likely Impacts to the Polar Bear From Recession of the Sea Ice—Adapted and Modified From Derocher et al. (2004, p. 171) Characteristic Time frame 1 Projected change Body weight/condition Short Decline, increased variation. Movement patterns Short Increased, alteration of existing patterns. Cub survival Short Decline, increased variation. Reproductive rates Short Variable, increased variation. Bear-human interactions Variable Increase

Recession of the Sea Ice—Adapted and Modified From Derocher et al. (2004, p. 171) Characteristic Time frame 1 Projected change Body weight/condition Short Decline, increased variation. Movement patterns Short Increased, alteration of existing patterns. Cub survival Short Decline, increased variation. Reproductive rates Short Variable, increased variation. Bear-human interactions Variable Increase. Den areas Medium Reduced access, modification of areas used. Growth rates Medium Variable, downward trend. Prey composition Medium Change in species, utilization, age of prey. Population boundaries Medium Mixing of adjacent populations. Population size Medium Variable downward trend. Intraspecific aggression Variable Increased. Cannibalism Variable Possible increase. Adult survival Medium-Long Decline, Increased variation. 1 Short = <10 years, Medium = 10-20 years, Long = >20 years. Time frame of impact will vary between populations and is dependent upon rate of change in a given population. The southerly populations of Western Hudson Bay, Southern Hudson Bay, Foxe Basin, Davis Strait, and Baffin Bay, where bears already experience stress from seasonal ice retreat fasting, will be affected earliest (Stirling and Parkinson 2006). Earlier melt periods and increased open water periods will result in lengthened seasonal use of land and increased period of fasting, resulting in decreased physical condition for bears in these populations. Other populations including the Chukchi Sea, Barents Sea, Southern Beaufort Sea and possibly the Kara Sea and Laptev Sea (these are characterized as open Arctic Basin populations) will, or are currently, experiencing initial effects of changes in sea ice. These populations are vulnerable to large-scale dramatic seasonal fluctuations in ice movements, decreased abundance and access to prey, and increased energetic costs of hunting. We expect that the polar bear populations inhabiting the central island archipelago of Canada will be affected later

en Arctic Basin populations) will, or are currently, experiencing initial effects of changes in sea ice. These populations are vulnerable to large-scale dramatic seasonal fluctuations in ice movements, decreased abundance and access to prey, and increased energetic costs of hunting. We expect that the polar bear populations inhabiting the central island archipelago of Canada will be affected later. These more northerly populations are expected to be affected last due to the buffering effects of the island archipelago complex, which lessens effects of oceanic currents and seasonal retractions of ice and retains a higher proportion of heavy, more stable multi-year sea ice. These populations include Norwegian Bay, Lancaster Sound, M'Clintock Channel, Viscount-Melville, Kane Basin, and the Gulf of Boothia.

For polar bears, current and anticipated changes to the sea ice habitat are expected to threaten the species (Aars et al. 2006). This

Some scientists conclude that the “future persistence of polar bears is tenuous” (Derocher et al. 2004, p. 172), reinforcing their earlier warnings that “[u]ltimately, if sea ice disappeared altogether, polar bears would become extinct” (Stirling and Derocher 1993, p. 243). Changes in the timing of sea ice formation and break-up and the loss of the polar bear's sea ice habitat will pose increasing risk to polar bears as the climate continues to warm (Derocher et al. 2004, p. 164), and ultimately all polar bear populations will suffer. Rosentrater (2005, p. 3) notes “if current trends continue, polar bears and other species that require a stable ice platform for survival could become extinct by the end of the century.”

extinct by the end of the century.”

This opinion is not universally shared. Other polar bear biologists have indicated that it is possible, even with the total loss of summer sea ice, that a small number of polar bears would survive semi-indefinitely and not go extinct provided there is still some ice cover during the winter and marine mammals continued to be available for capture or scavenging. As a species, polar bears have survived at least two warming periods, the Eem Interglacial period (140,000-115,000 years Before Present (BP)), and the Holocene “climate optimum” (ca 8000-4000 BP) (Dansgaard et al. 1993, p. 218; Dahl-Jensen et al. 1998, p. 268). Greenland ice cores revealed that the climate was much more variable in the past and some of the historical shifts between the warm and cold periods were rapid, suggesting that the recent relative climate stability seen during the Holocene may be an exception (Dansgaard et al. 1993, p. 218). The precise impacts of these warming periods on polar bears and the Arctic sea ice habitat are unknown.

A recent study of the Bering Sea, one of the most productive marine ecosystems on the planet, concluded “[a] change from arctic to subarctic conditions is underway in the northern Bering Sea” (Grebmeier et al. 2006, p. 1461). This is being caused by warmer air and water temperatures, and less sea ice. “These observations support a continued trend toward more subarctic ecosystem conditions in the northern Bering Sea, which may have profound impacts on Arctic marine mammal and diving seabird populations as well as commercial and subsistence fisheries” (Grebmeier et al. 2006, p. 1463).

rctic marine mammal and diving seabird populations as well as commercial and subsistence fisheries” (Grebmeier et al. 2006, p. 1463).

As the changes in marine ecosystems continue, polar bear populations are expected to experience impacts comparable to those already observed in the Western Hudson Bay (Stirling et al. 1999, p. 304) as well as in the Southern Beaufort Sea (Regehr et al. 2006, p.14). Changes in the timing of sea ice formation and break up will pose increasing risk to polar bears as the climate continues to warm (Derocher et al. 2004, p. 173), and ultimately affect all polar bear populations and threaten the species throughout all or a significant portion of its range in the foreseeable future.

We find that polar bear populations throughout their distribution in the circumpolar Arctic are threatened by ongoing and projected changes in their sea ice habitat.

B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes

Use of polar bears for commercial, recreational, scientific, and education purposes is generally low, with the exception of harvest. Use for non-lethal scientific purposes is highly regulated and does not pose a threat to populations. Similarly, the regulated, low-level of use for educational purpose through placement of cubs or orphaned animals into zoos or public display facilities or through public viewing is not a threat to populations. Sport harvest of polar bears in Canada is discussed in the harvest section below. For purposes of population assessment, no distinction is made between harvest uses for sport or subsistence purposes. Take associated with defense of life, scientific research, illegal take, and other forms of take are generally included in harvest management statistics so this section also addresses all forms of take including bear-human interactions.

Overview of Harvest

Polar bears historically have been and continue to be an important renewable resource for coastal communities throughout the Arctic (Lentfer 1976, p

ciated with defense of life, scientific research, illegal take, and other forms of take are generally included in harvest management statistics so this section also addresses all forms of take including bear-human interactions.

Overview of Harvest

Polar bears historically have been and continue to be an important renewable resource for coastal communities throughout the Arctic (Lentfer 1976, p. 209: Amstrup and DeMaster 1988, p. 41; and IUCN 1999, p. 257 Table 14.1). Polar bears and polar bear hunting remain an important part of indigenous peoples' myths and legends and polar bear hunting is a source of pride, prestige, and accomplishment. Polar bears provide a source of meat and raw materials for handicrafts, including functional clothing such as mittens, boots (mukluks), parka ruffs, and pants (Nageak et al. 1988, p.6; Marine Mammal Commission 1995, p. 18).

Prior to the 1950s, most hunting was by indigenous people for subsistence purposes. Increased sport hunting in the 1950s and 1960s, however, resulted in population declines (Prestrud and Stirling 1994). International concern about the overall status of polar bears resulted in biologists from the five polar bear range nations forming the Polar Bear Specialist Group (PBSG) within the IUCN Species Survival Commission (SSC) structure (IUCN 1999, p. 262). The PBSG was largely responsible for the development and ratification of the 1973 International Agreement on the Conservation of Polar Bears (1973 Agreement) (Prestrud and Stirling 1994, p. 114) (see Section D—Adequacy of existing regulatory mechanisms below for details)

forming the Polar Bear Specialist Group (PBSG) within the IUCN Species Survival Commission (SSC) structure (IUCN 1999, p. 262). The PBSG was largely responsible for the development and ratification of the 1973 International Agreement on the Conservation of Polar Bears (1973 Agreement) (Prestrud and Stirling 1994, p. 114) (see Section D—Adequacy of existing regulatory mechanisms below for details).

Harvest Management by Nation

Canada

Canada manages or shares management responsibility for 13 of the world's 19 polar bear populations (Kane Basin, Baffin Bay, Davis Strait, Foxe Basin, Western Hudson Bay, Southern Hudson Bay, Gulf of Boothia, Lancaster Sound, Norwegian Bay, M'Clintock Channel, Viscount Melville Sound, Northern Beaufort Sea, and Southern Beaufort Sea) Wildlife management is a shared responsibility of the Provincial and Territorial governments. The Federal government (Canadian Wildlife Service) has an ongoing research program and is involved in management of wildlife populations shared with other jurisdictions, especially ones with other nations (e.g., where a polar bear stock ranges across an international boundary). To facilitate and coordinate management of polar bears, Canada has formed the Federal Provincial Technical Committee for Polar Bear Research and Management (PBTC) and the Federal Provincial Administrative Committee for Polar Bear Research and Management (PBAC). These committees include Provincial, Territorial, and Federal representatives who meet annually to review research and management activities.

Polar bears are harvested in Canada. All human-caused mortality (i.e., hunting, defense of life, and incidental kills) are included in a total allowable harvest. Inuit people from communities in Nunavut, Northwest Territories (NWT), Manitoba, Labrador, Newfoundland, and Quebec conduct hunting. In Ontario, the Cree as well as the Inuit can harvest polar bears

hunt polar bears. Licenses are issued annually for a small fee contingent upon reporting harvest during the prior 12 months. Until 2006, no quotas were in place but harvest statistics were collected through Piniarneq, a local reporting program (Born and Sonne 2005 in PBSG 2006, p. 137). In January 2006, a new harvest monitoring and quota system was implemented (Lønstrup 2005 in PBSG 2006, p. 133). Annual quotas are determined in consideration of international agreements, biological advice, user knowledge, and consultation with the Hunting Council. Part of the quota may be used for sport hunting (Lønstrup 2005 in PBSG 2006, p. 133).

Norway

Norway and Russia share jurisdiction over the Barents Sea population of polar bears. Management in Norway is the responsibility of the Ministry of the Environment (Wiig 1995, p.110). The commercial, subsistence or sport hunting of polar bears in Norway is prohibited (Wiig 1995, p.110). Bears may only be killed in self-defense, protection of property, and “mercy” kills and kills must be reported and recorded (Gjertz and Scheie 1998, p. 337).

Russia

The commercial, subsistence or sport hunting of polar bears in Russia is prohibited. Some bears are killed in defense of life, and a small number of cubs are taken annually for zoos. Despite the 1956 ban on hunting polar bears in Russia, illegal harvest is occurring in the Chukchi Sea region and elsewhere where there is limited monitoring or enforcement of this prohibition (PBSG 1995, p. 9; Belikov et al. 2005 in PBSG 2006, p. 153). There is also a significant interest in re-opening a subsistence hunt by indigenous people in Russia. The combined ongoing illegal hunting in Russia and legal subsistence harvest in Alaska is a concern for the Chukchi Sea polar bear population, which may be in decline (USFWS 2003, p.1)

imited monitoring or enforcement of this prohibition (PBSG 1995, p. 9; Belikov et al. 2005 in PBSG 2006, p. 153). There is also a significant interest in re-opening a subsistence hunt by indigenous people in Russia. The combined ongoing illegal hunting in Russia and legal subsistence harvest in Alaska is a concern for the Chukchi Sea polar bear population, which may be in decline (USFWS 2003, p.1). Full implementation of the Agreement between the United States of America and the Russian Federation on the Conservation and Management of the Alaska-Chukotka Polar Bear Population (Bilateral Agreement) is attended to rectify this situation, but such implementation has not yet occurred (Schliebe et al. 2005 in PBSG 2006, p. 75). Accordingly, we have not relied on implementation of the Bilateral Agreement in our assessment of the threat of overutilization to polar bears. (see International Agreements and Oversight section below).

United States

Polar bear subsistence hunting has been done by Alaska Natives for centuries (Lentfer 1976, p. 209). Polar bear hunting and the commercial sale of skins took on increasing economic importance to Alaskan Natives when whaling began in the 1850s (Lentfer 1976, p. 209) Trophy hunting using aircraft began in the late 1940s. In the 1960s, State of Alaska hunting regulations became more restrictive, and in 1972 aircraft-assisted hunting was stopped altogether (Lentfer 1976, p. 209). Between 1954 and 1972, an average of 222 polar bears was harvested per year, resulting in a decline in polar bear populations in Alaska (Amstrup et al.1986, p. 246).

r year, resulting in a decline in polar bear populations in Alaska (Amstrup et al.1986, p. 246).

Passage of the Marine Mammal Protection Act (MMPA) in 1972 established a prohibition on the sport or commercial hunting of polar bears in Alaska. However, within the MMPA a provision allows for continued harvest of polar bears by coastal dwelling Alaska Natives for subsistence and handicraft purposes. The MMPA also prohibits the commercial sale of any marine mammal parts or products except those that have been significantly altered into handicrafts or clothing by Alaska Natives. Currently, the subsistence harvest of polar bears by Alaska Natives, provided it is conducted in a non-wasteful manner, cannot be restricted unless a population is designated as depleted (i.e., below the optimum sustainable population level). The ability to avoid depletion through cooperative management agreements between Alaska Native Organizations and the Service to regulate subsistence take is an amendment to the MMPA that has been proposed, yet remains to be adopted. The Service cooperates with the Alaska Nanuuq Commission, a non-profit organization that represents interests of Alaska Native polar bear users, to address polar bear subsistence harvest issues. In addition, for the Southern Beaufort Sea population, hunting is regulated voluntarily and effectively through an agreement between the Inuvialuit of Canada and the Inupiat of Alaska (Brower et al 2002) (see International Agreements and Oversight section below). The harvest is monitored by the Service's marking and tagging program. Illegal take or trade is monitored by the Service's law enforcement program.

The MMPA was amended in 1994 to provide for the import into the United States of sport-hunted polar bear trophies legally taken by the importer in Canada

nupiat of Alaska (Brower et al 2002) (see International Agreements and Oversight section below). The harvest is monitored by the Service's marking and tagging program. Illegal take or trade is monitored by the Service's law enforcement program.

The MMPA was amended in 1994 to provide for the import into the United States of sport-hunted polar bear trophies legally taken by the importer in Canada. Prior to approving a polar bear population for import of such trophies, the Service must find that Canada has a monitored and enforced sport-hunting program consistent with the 1973 Agreement on the Conservation of Polar Bears (1973 Polar Bear Agreement) and that the program is based on scientifically sound quotas ensuring the maintenance of the population at a sustainable level. Currently, six populations are approved for import of polar bears trophies (62 FR 7302, February 18, 1997; 64 FR 1529, January 11, 1999; 66 FR 50843, October 5, 2001).

Harvest Summary

A thorough review and evaluation of past and current harvest, including other forms of removal, for all populations has been described in the Polar Bear Status Assessment (Schliebe et al. 2006a). The Status Assessment is available on the Service's Marine http://alaska.fws.gov/fisheries/mmm/polarbear/issues.htm. Table 2 provides a summary of harvest statistics from the populations and is included herein as a reference. The total harvest and other forms of removal were considered in the summary analysis.

Five populations (including four that are hunted) have no estimate of potential risk from overharvest, since adequate demographic information necessary to conduct a population viability analysis and risk assessment are not available (Table 1). For one of the populations, Chukchi Sea, severe overharvest was suspected to have occurred during the past 10-15 years, and anecdotal information was that the trend of population size was believed to be in decline (Aars et al. 2006, pp. 34-35)

om overharvest, since adequate demographic information necessary to conduct a population viability analysis and risk assessment are not available (Table 1). For one of the populations, Chukchi Sea, severe overharvest was suspected to have occurred during the past 10-15 years, and anecdotal information was that the trend of population size was believed to be in decline (Aars et al. 2006, pp. 34-35). The Chukchi Sea, Baffin Bay, Kane Basin and Western Hudson Bay populations may be being overharvested (Aars et al. 2006, pp. 40, 44-46). In other populations, including East Greenland and Davis Strait, substantial harvest occurs annually in the absence of scientifically-derived population estimates (Aars et al. 2006, pp. 39, 46). Considerable debate has occurred regarding the recent changes in population estimates based on indigenous or local knowledge (Aars et al. 2006, p. 57) and subsequent quota increases for some populations in Nunavut (Lunn et al. 2005, p. 20). Increased polar bear observations along the coast may be attributed to changes in bear distribution due to lack of suitable ice habitat rather than to increased population size (Stirling and Parkinson 2006). Additional inventories are needed to reconcile these differing interpretations.

Table 2.—Polar Bear Harvest Statistics, Adapted From the PBTC Status Table Population Aerial survey/M-R Number (year of estimate) ±2 SE 5 yr mean kill Actual removals Likelihood of decline (next 10 years) a 3 yr mean kill Actual removals Likelihood of decline (next 10 years) a 1 yr mean kill Actual removals Likelihood of decline (next 10 years) a Identified permitted harvest b Estimated maximum sustainable yield c Observed or predicted trend d Status e Southern Beaufort Sea 1500 (2006) 1000-2000 57.8 No Estimate 59.3 No Estimate 44 No Estimate 81 84 Decline Reduced. Northern Beaufort Sea 1200 (1986) 133-2097 36.2 No Estimate 38 No Estimate 36 No Estimate 65 56 Stable Not reduced. Viscount Melville 161 (1992) 121-201 4.4 5.6% 4.7 6.5% 5 6.8% 7 10 Increase Severely reduced

stimated maximum sustainable yield c Observed or predicted trend d Status e Southern Beaufort Sea 1500 (2006) 1000-2000 57.8 No Estimate 59.3 No Estimate 44 No Estimate 81 84 Decline Reduced. Northern Beaufort Sea 1200 (1986) 133-2097 36.2 No Estimate 38 No Estimate 36 No Estimate 65 56 Stable Not reduced. Viscount Melville 161 (1992) 121-201 4.4 5.6% 4.7 6.5% 5 6.8% 7 10 Increase Severely reduced. Norwegian Bay 190 (1998) 102-278 2.6 70.5% 2.7 73.1% 4 84.4% 4 9 Decline Not reduced. Lancaster Sound 2541 (1998) 1759-3323 74 67.0% 79 74.0% 87 80.6% 85 119 Stable Not reduced. M’Clintock Channel 284 (2000) 166-402 3 2.5% 1 1.0% 2 1.8% 3 13 Increase Severely reduced. Gulf of Boothia 1528 (2000) 953-2093 45.8 3.3% 48.3 4.3% 66 12.9% 74 72 Increase Not reduced. Foxe Basin 2197 (1994) 1677-2717 97.2 14.0% 96 12.1% 97 13.1% 106 + Quebec 108 Stable Not reduced. Western Hudson Bay 935 (2004) 791-1079 44.8 99.9% 46.3 99.9% 43 99.9% 62 44 Decline Reduced. Southern Hudson Bay 1000 (1988) 784-1216 36.6 0.1% 36.7 0.1% 27 0.1% 25 + Ontario, Quebec 47 Increase? Not reduced. Kane Basin 164 (1998) 94-234 10.8 99.9% 10.3 99.9% 11 99.9% 5 + Greenland 8 Decline Reduced. Baffin Bay 2074 (1988) 1544-2604 216.8 99.9% 251.7 99.9% 252 99.9% 105 + Greenland 72 Decline Reduced. Davis Strait 64.8 12.9% 67.3 17.1% 70 18.9% 46 + Greenland, Quebec, Labrador 77 Stable Not reduced. East Greenland Unknown 70 No Estimate 50 No Estimate Data Deficient Data Deficient. Barents Sea 3000 (2004) Data Deficient Data Deficient. Kara Sea Data Deficient Data Deficient. Laptev Sea 800-1200 (1993) Data Deficient Data Deficient. Chukchi Sea 2000 (1993) 43-AK. Unk # in Chukotka No Estimate Unknown No Estimate 43++ No Estimate Unknown Unknown. Data Deficient Data Deficient. a Presented is the proportion of simulation runs using the RISKMAN model and vital rates presented in natural survival and recruitment tables resulting in any decline after 10 years of simulation, assuming minimum 2M:1F in the harvest

ent Data Deficient. Chukchi Sea 2000 (1993) 43-AK. Unk # in Chukotka No Estimate Unknown No Estimate 43++ No Estimate Unknown Unknown. Data Deficient Data Deficient. a Presented is the proportion of simulation runs using the RISKMAN model and vital rates presented in natural survival and recruitment tables resulting in any decline after 10 years of simulation, assuming minimum 2M:1F in the harvest. One-minus this value represents the proportion of simulations resulting in population increase. b The identified permitted harvest includes the maximum harvest that is presently allowed by jurisdictions with an identified quota. c The estimated maximum sustainable yield (MSY) is based on a meta-analysis of the 1990s that assumed mean reproduction and survival for polar bears across their range in Canada (given information available at the time). MSY = N * 0.0156/Pr[F], where N = total population number, 0.0156 is a constant derived from a meta-analysis to estimate survival and recruitment rates for Canadian polar bears, and Pr[F] = proportion of the harvest that is female (assumed to be 0.333, i.e., 2M:1F sex-selective harvest). d Observed or predicted status as suggested by PVA results and, where vital rates are not sufficient for analysis, anectodatal information. e Current status relative to probable historic numbers. Bear-Human Interactions

Polar bears come into conflict with humans when they scavenge for food at sites of human habitation, and also because they occasionally prey or attempt to prey upon humans (Stirling 1988, p.182). “Problem bears” are most often sub-adults, because they are inexperienced hunters and because their feeding habits include more scavenging than adult bears (Stirling 1988, p. 182). Following sub-adults, females with cubs are most likely to interact with humans, because females with cubs are likely to be thinner and hungrier than single adult bears, and starving bears are more likely to interact with humans in their pursuit of food (Stirling 1988, p. 182)

e inexperienced hunters and because their feeding habits include more scavenging than adult bears (Stirling 1988, p. 182). Following sub-adults, females with cubs are most likely to interact with humans, because females with cubs are likely to be thinner and hungrier than single adult bears, and starving bears are more likely to interact with humans in their pursuit of food (Stirling 1988, p. 182). For example, in Churchill, Manitoba, Canada, an area of high polar bear use generally, the occurrence of females with cubs feeding at the town's garbage dump in the fall increased during years when bears came ashore in poorer condition (Stirling 1988, p. 182). Other factors that may influence bear-human encounters include increased land use activities, increased human populations in areas of high polar bear activity, increased polar bear population size, and earlier polar bear departure from ice habitat to terrestrial habitats.

Increased interactions and defense kills may occur under predicted climate change scenarios (Derocher et al. 2004, p.169). Direct interactions between people and bears in Alaska have increased markedly in recent years and this trend is expected to continue (Amstrup 2000, p. 153). Since the late 1990s, the timing of complete ice formation in the fall has occurred later in November or early December than it formerly did (which was in September and October), resulting in an increased amount of time polar bears spend on land, which consequently increases the probability of bear-human interactions occurring in coastal villages. Adaptive management programs focusing on the development of community or ecotourism based polar bear-human interaction plans that include polar bear patrols, deterrent and hazing programs, efforts to manage and minimize sources of attraction, and programs to educate residents of polar bear behavior and ecology are needed and should be developed in the future.

Conclusion for Factor B

Polar bears are harvested in Canada, Alaska, Greenland, and Russia

of community or ecotourism based polar bear-human interaction plans that include polar bear patrols, deterrent and hazing programs, efforts to manage and minimize sources of attraction, and programs to educate residents of polar bear behavior and ecology are needed and should be developed in the future.

Conclusion for Factor B

Polar bears are harvested in Canada, Alaska, Greenland, and Russia. Active harvest management programs are in place for populations in Canada, Greenland, and Alaska. Principles of sustainable yield are instituted through harvest quotas or guidelines; other forms of removal, such as for defense of life, are considered through management actions by the responsible jurisdictions. Hunting or killing polar bears is illegal in Russia although an unknown level of harvest occurs. While overharvest occurs for some populations, laws and regulations for most management programs have been instituted to ensure harvests result in healthy and sustainable populations. These actions are largely viewed as having been successful in reversing wide spread overharvests by many jurisdictions that resulted in population depletion during the period prior to signing of the multi-lateral 1973 Agreement on the Conservation of Polar Bears (Prestrud and Stirling 1994) (Discussed further in Factor D). For the internationally-shared populations in the Chukchi Sea, Baffin Bay, Kane Basin, and Davis Strait, conservation agreements have been developed (United States-Russia) or are in development (Canada-Greenland). These agreements have not yet been implemented and therefore are not being relied upon in our evaluation of Factor B.

not being relied upon in our evaluation of Factor B.

We conclude that harvest, increased bear-human interaction levels, defense of life take, illegal take, and take associated with scientific research programs are occurring regionally for some populations. However, we find that overutilization as a singular factor does not threaten the species throughout all or a significant portion of its range. Continued harvest and increased mortality from bear-human encounters or other forms of mortality, however, may become a more significant threat factor in the future for polar bear populations experiencing nutritional stress or declining population numbers as a consequence of habitat change. The PBSG 2006 (Aars et al. 2006) through resolution urged that a precautionary approach be instituted when setting harvest limits in a warming Arctic. Continued efforts are necessary to ensure that harvest or other forms of removal do not exceed sustainable levels and thus do not threaten the species in the foreseeable future.

C. Disease and Predation

Disease

Except for the presence of trichinella larvae, the occurrence of diseases and parasites in polar bears is rare compared to other bears. Trichinella has been documented in polar bears throughout their range and although infestations can be quite high they are normally not fatal (Rausch 1970, p. 360; Dick and Belosevic 1978, p. 1143; Larsen and Kjos-Hanssen 1983, p. 95; Taylor et al. 1985, p. 303; Forbes 2000, p. 321). Although rabies is commonly found in Arctic foxes, there has been only one confirmed instance of rabies in polar bears (Taylor et al. 1991, p. 337). Morbillivirus has been documented in polar bears from Alaska and Russia (Garner et al. 2000, p. 477; C. Kirk, University of Alaska, Fairbanks, pers. comm. 2006). Antibodies to the protozoan parasite, Toxoplasma gondii , were found in Alaskan polar bears; however, it is not known if this is a health concern for polar bears (C. Kirk, University of Alaska, Fairbanks, pers. comm. 2006)

1991, p. 337). Morbillivirus has been documented in polar bears from Alaska and Russia (Garner et al. 2000, p. 477; C. Kirk, University of Alaska, Fairbanks, pers. comm. 2006). Antibodies to the protozoan parasite, Toxoplasma gondii , were found in Alaskan polar bears; however, it is not known if this is a health concern for polar bears (C. Kirk, University of Alaska, Fairbanks, pers. comm. 2006).

It is unknown whether polar bears are more susceptible to new pathogens due to their lack of previous exposure to disease and parasites. Many different pathogens and viruses have been found in seal species that are polar bear prey (Duignan et al. 1997, p. 7; Measures and Olson 1999, p. 779; Dubey et al. 2003, p. 278; Hughes-Hanks et al. 2005, p. 1226), so the potential exists for transmission of these diseases to bears. As polar bears become more stressed, they may eat more of the intestines and internal organs than they do presently, thus increasing their potential exposure to parasites and viruses (Derocher et al. 2004, p. 170; Amstrup et al. 2006b, p. 3). In addition, pathogens may expand their range northward from more southerly areas under projected climate change scenarios (Harvell et al. 2002, p. 60).

Intraspecific Predation

Intraspecific killing has been reported among all North American bear species (Derocher and Wiig 1999, p. 307; Amstrup et al. 2006, p. 1). Reasons for intraspecific predation in bear species is poorly understood but thought to include population regulation, nutrition, and enhanced breeding opportunities in the case of predation of cubs. Although infanticide by male polar bears has been well documented (Hansson and Thomassen 1983, p. 248; Larsen 1985, p. 325; Taylor et al. 1985, p. 304; Derocher and Wiig 1999, p. 307), it is thought that this activity accounts for a small percentage of the cub mortality.

Cannibalism has also been documented in polar bears (Derocher and Wiig 1999, p. 307; Amstrup et al. 2006b, p. 1). Amstrup et al. (2006b, p

anticide by male polar bears has been well documented (Hansson and Thomassen 1983, p. 248; Larsen 1985, p. 325; Taylor et al. 1985, p. 304; Derocher and Wiig 1999, p. 307), it is thought that this activity accounts for a small percentage of the cub mortality.

Cannibalism has also been documented in polar bears (Derocher and Wiig 1999, p. 307; Amstrup et al. 2006b, p. 1). Amstrup et al. (2006b, p. 1) observed three instances of cannibalism in the southern Beaufort Sea during the spring of 2004 involving two adult females—one an unusual mortality of a female in a den and another a yearling. This is notable because, throughout a combined 58

The potential importance of cannibalism and infanticide for polar bear population regulation is unknown. However, given our current knowledge of disease and predation, we do not believe that these factors are currently having population level effects.

Conclusion for Factor C

Although disease pathogen titers are present in polar bears, no epizootic outbreaks have been detected. Although there are limited indications that intraspecific stress through cannibalism may be increasing, population level effects are not believed to have resulted. We find that disease and predation (including intraspecific predation) do not threaten the species throughout all or a significant portion of its range. Potential for disease outbreaks or increased mortality from cannibalism warrants continued monitoring and may become a more significant threat factor in the future for polar bear populations experiencing nutritional stress or declining population numbers.

D. Inadequacy of Existing Regulatory Mechanisms

Regulatory mechanisms directed specifically at managing threats to polar bears exist in all of the range states where the species occurs, as well as between (bilateral and multilateral) range states. There are no known regulatory mechanisms effectively addressing reductions in sea ice habitat at this time

l stress or declining population numbers.

D. Inadequacy of Existing Regulatory Mechanisms

International Agreements

International Agreement on the Conservation of Polar Bears

Canada, Denmark (on behalf of Greenland), Norway, the Russian Federation, and the United States are parties to the Agreement on the Conservation of Polar Bears (1973 Polar Bear Agreement) singed in 1973; by 1978 the Agreement was ratified by all parties. The 1973 Polar Bear Agreement requires the parties to take appropriate action to protect the ecosystem of which polar bears are a part, with special attention to habitat components such as denning and feeding sites and migration patterns, and to manage polar bear populations in accordance with sound conservation practices based on the best available scientific data. The 1973 Polar Bear Agreement relies on the efforts of each party to implement conservation programs and does not preclude a party from establishing additional controls (Lentfer 1974, p.1).

The 1973 Polar Bear Agreement is viewed as a success in that polar bear populations recovered from excessive harvests and severe population reductions in many areas (Prestrud and Stirling 1994). At the same time, implementation of the terms of the 1973 Polar Bear Agreement vary across the member parties. Efforts are needed to improve current harvest management practices, such as restricting harvest of females and cubs, establishing sustainable harvest limits, and controlling illegal harvests (PBSG 1998, pp. 47-48). In addition, a lack of protection of key habitats by member parties, with few notable exceptions for some denning areas, is a weakness (Prestrud and Stirling 1994, p. 118)

mber parties. Efforts are needed to improve current harvest management practices, such as restricting harvest of females and cubs, establishing sustainable harvest limits, and controlling illegal harvests (PBSG 1998, pp. 47-48). In addition, a lack of protection of key habitats by member parties, with few notable exceptions for some denning areas, is a weakness (Prestrud and Stirling 1994, p. 118).

IUCN/SSC Polar Bear Specialist Group

As previously mentioned, the Polar Bear Specialist Group (PBSG) operates under the IUCN Species Survival Commission (SSC). The PBSG was formed in 1968 and contributed to the negotiation and development of the 1973 Polar Bear Agreement. The PBSG meets periodically at 3-to 5-year intervals in compliance with Article VII of the 1973 Polar Bear Agreement; said article instructs member parties to conduct national research programs on polar bears, particularly research relating to the conservation and management of the species and, as appropriate, coordinate such research with the research carried out by other parties, consult with

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