Beaufort Sea Census
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Dr. Ian Stirling of the Canadian Wildlife Service removes a satellite collar from a female bear. Click the image to enlarge.
The Southern Beaufort Sea population is hunted by native people in both countries, the Inupiat of northern Alaska and the Inuvialuit of northwestern Canada. The annual harvest is kept below a presumed sustainable yield due to a unique and precedent-setting user's agreement between the two groups. Hunters in both nations would like to see their harvests increase. They recognize, however, that this can only be done if the population can sustain it. Thus, they have been among the study's strongest supporters.
"Local native people rely on polar bears as an important source of income and sustenance," Amstrup explains. "At the same time, these bears are exposed to oil and gas exploration and other human encroachments, not to mention the major concern of global warming and the worldwide spread of pollutants."
Due to all these potential threats, accurate population estimates are needed, he says, so scientists can develop sustainable management plans and prevent the over-harvests that occurred in the past.
Improved Methods
Amstrup notes that scientists have conducted mark and recapture studies and radio collaring efforts in the Southern Beaufort Sea for more than 30 years, but estimates of population size and trend have remained elusive. This is partly because scientists in Alaska and Canada collected data independently before learning that the population was shared. A new method of analyzing radiotelemetry data from both Alaska and Canada, however, has allowed quantification of the boundaries of the Southern Beaufort Sea population and the degree to which it overlaps with adjacent populations.
Now Amstrup and his Ph.D. student, Eric Regehr of the University of Wyoming at Laramie, are developing analysis techniques that show promise of greatly improving their ability to estimate the number of bears in a given population. Captures of new bears during this study will allow Amstrup and Regehr to further refine those techniques. Better estimates of numbers combined with recent improvements in the understanding of bear movements can help assure wise stewardship of polar bears in the future.
"Local native people rely on polar bears as an important source of income and sustenance," Amstrup explains. "At the same time, these bears are exposed to oil and gas exploration and other human encroachments, not to mention the major concern of global warming and the worldwide spread of pollutants."
Due to all these potential threats, accurate population estimates are needed, he says, so scientists can develop sustainable management plans and prevent the over-harvests that occurred in the past.
Improved Methods
Amstrup notes that scientists have conducted mark and recapture studies and radio collaring efforts in the Southern Beaufort Sea for more than 30 years, but estimates of population size and trend have remained elusive. This is partly because scientists in Alaska and Canada collected data independently before learning that the population was shared. A new method of analyzing radiotelemetry data from both Alaska and Canada, however, has allowed quantification of the boundaries of the Southern Beaufort Sea population and the degree to which it overlaps with adjacent populations.
Now Amstrup and his Ph.D. student, Eric Regehr of the University of Wyoming at Laramie, are developing analysis techniques that show promise of greatly improving their ability to estimate the number of bears in a given population. Captures of new bears during this study will allow Amstrup and Regehr to further refine those techniques. Better estimates of numbers combined with recent improvements in the understanding of bear movements can help assure wise stewardship of polar bears in the future.