Puerto Rican Circus Bears
Chairman of the board, Robert J. Wilson, represented PBI at the 14th Biennial Conference on the Biology of Marine Mammals held last fall in Vancouver, B.C. The next conference is scheduled for Greensboro, North Carolina, in 2003.
"About 2,000 people attended," Wilson says. He enjoyed productive discussions with polar bear scientists from many parts of the world, including Ian Stirling and Nick Lunn of Canada; Scott Schliebe, Tom Evans, and Donald Hansen (Minerals Management Service) of the U.S.; and Andrew Derocher and Mette Mauritzen of Norway. Upon his return Wilson prepared this summary of the proceedings.
Abstracts of Papers Presented at the 14th Biennial Conference on the Biology of Marine Mammals
Vancouver B.C. Nov. 28-Dec. 3, 2001
Effects of Climate Warming on Polar Bears and Seals
by Stirling, Ian; Lunn, N.J. (Presented at the plenary session.)
From 1981 to 2001 the average condition of adult male and female polar bears declined significantly in western Hudson Bay, as did the proportion of independent cubs. A long-term warming trend during spring appears responsible for early ice breakup, which reduces the time the bears can hunt seals. On a global scale, climate warming has reduced the extent of arctic ice by 15% over the past 20 years. Unseasonable weather events have resulted in increased mortality of ringed seal pups and the collapse of polar bear dens, which have killed the mothers and pups inside. Increased forest fire activity is affecting polar bear maternity denning habitat in western Hudson Bay.
Scientific Uncertainty and Inuit Qaujimanituqangit (Traditional Knowledge):
Polar Bear Co-Management in the Canadian Land Claim Environment.
by Atkinson, Stephen; Taylor, Mitchell
This paper examines the co-management of polar bears in the M'Clintock Channel polar bear population. From 1974 to 2000 harvest quotas were based on mark and recapture methods and statistical models. During that time, the polar bear population was over-harvested and reduced from 750 bears to fewer than 367. Local hunters believe global warming has reduced numbers faster than statistics show and have recommended a hunting moratorium. During a two-year moratorium, scientific methods and Inuit qaujimanituqangit will be utilized in the hopes this can provide a stronger approach to management than either can offer alone.
Polar Bear Aerial Surveys in the Eastern Chukchi Sea.
by Schliebe, S; Fischbach, A.S., Evans, T.J.; Kaixdorff, S.B.; York, G.
The new Polar Bear Treaty between the U.S. and Russia will require better estimates of bears in the Bering and Chukchi seas. This paper describes the process used for doing the aerial surveys and the assumptions used for population estimates. Density estimates from the selected models ranged from .0093 to .0164 bears/km2. The paper discusses model problems and plans for survey of the Western Chukchi Sea.
Forward Looking Infrared (FLIR):
A New Method for Detecting Maternal Polar Bear Dens.
by Simac, K.; Amstrup, S.; York, G.; McDonald, Tl; Durner, G; Fischbach, A.
The study tested the ability of FLIR to detect known polar bear dens from a helicopter. The FLIR detected nine of the 17 subject dens and also discovered two dens not previously known. In analyzing the variables that cause "mistakes," the presenters recommend that FLIR surveys be done as early as possible in winter to minimize snow depths over the den, when clear and preferably cold air conditions have been preceded by at least 24 hours of stable temperatures, and when solar exposure is absent.
Relating Polar Bear Ecology to the Dynamics of Sea Ice.
by Mauritzen, Mette (and 10 others including Derocher, A and Belikov)
(Joint Norway/ Russia group)
The group analyzed radio tag data from 80 females (12 years of data) and den counts (six years), comparing them with sea ice movement data. They determined that polar bear movements are related more to prey selection than to ice movements. Many times, ice change seemed to act as a treadmill increasing the energetic cost of geographic displacement. The group concluded that the results have clear applications in assessing climate change impacts on polar bears.
Habitat Selection by Polar Bears.
by Hansen, D.J.
The paper describes the results of aerial surveys in the Beaufort and Chukchi seas from 1979 to 1999 by NOSC and MMS. The results [surprise] are that bears prefer 80% to 100% ice cover to lower ice coverages and to open water. Thus, 60% of sightings were seen in heavy ice cover but only 3.8% were seen in open water. 17% of sightings were seen on land, most of these associated with whale carcasses and bowhead whale subsistence harvest sites on Barter and Cross islands.
Predicting the Numbers of Polar Bears Impacted by Oilspills.
by Durner, G; Amstrup, S; McdDonald, T.; Smith, C.; Johnson, W.
The authors shared the development of a statistical model analyzing the possible effects of an oil spill from BP Alaska's proposed Liberty Oil Production Island in the central Beaufort Sea. They used predictions of polar bear densities and applied oil spill models. They found a greater effect in mixed ice (fall) than in open water (summer). Estimates ranged from 0 to 61 bears being involved. 75% of spill models resulted in 12 or fewer bears becoming oiled.
"Aberrant" Polar Bears in East Greenland.
by Born, E.W.; Dietz, R.; Hansen, C.S.; Sandell, H.; Sandell, B.
Discussions were held with natives and specimens were examined in East Greenland and at Svalbard where polar bears have extremely high POP (Persistent Organic Pollutants, e.g. PCB) concentrations. Since 1990, 10 cases of female polar bears with deformities in the external sex organs (pseudo-hermaphrodites) have been recorded in Svalbard. Discussions with natives revealed 13 additional cases of deformities, including extra nipples or claws, a partial melanism, missing limbs, and malformed newborn. Whether these cases are POP related is unknown.
Organochlorine Contaminants and Trace Elements in Adult Male Polar Bears from Western and Northern Alaska.
by Evans, Thomas J.
This paper presented a fairly comprehensive review of contaminants along with a comparison to findings in other populations. The PCB levels in Alaskan polar bears are relatively low compared to high levels from bears in eastern Hudson Bay and Svalbard. However, levels of HCH are the highest of any reported in the Arctic. [HCH is estrogenic and affects reproductive organs and offspring survival]. Many other compounds were compared.
Fatty Acid Composition of the Blubber of Polar Bears and of their Prey, Ringed Seals, Bearded Seals and Harp Seals.
by Derocher, O; Andersen, M.; Derocher, A.E.; Kovacs, K.M Lydersen, C.; Wiig, O.
The blubber composition of polar bears and their prey was compared. The authors determined that the fatty acid pattern of polar bear blubber is not a reflection of the patterns in the bear's diet, but is, instead, distinctly different from them. This indicates that polar bear blubber has a unique fatty acid composition which does not directly reflect the fatty acid composition of their prey. [This is a hot topic in marine mammal research recently, especially in analyzing whale blubber samples to see if it reflects what they are eating.]
Thyroid Hormone in Marine Mammal Evolution: Implications for Pinniped Health.
by Crockford, S.J.
A very new theory, not yet well studied or discussed. Crockford questions whether thyroid hormones can affect evolutionary behavior. Thyroid hormones respond to stress. Using polar bears as one example, she theorizes that brown bears on the ABC islands of Alaska were under stress. A handful of fearless bears (stress-tolerant individuals with a distinct thyroxine phenotype) go to ice areas and begin to eat seals. The descendants become a new species because fearfulness genes are left behind. Thyroxine also controls embryonic pigment cells and white spotting is common and can lead to all white animals. Hence, she asserts, thyroid hormones could provide a mechanism by which polar bears evolved from brown bears. It's an interesting theory, but hard to test.
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