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Polar bears in the Beaufort Sea: A 30-year mark-recapture case history

Journal of Agricultural, Biological, and Environmental Statistics

By:
, , and
https://doi.org/10.1198/108571101750524562

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Abstract

Knowledge of population size and trend is necessary to manage anthropogenic risks to polar bears (Ursus maritimus). Despite capturing over 1,025 females between 1967 and 1998, previously calculated estimates of the size of the southern Beaufort Sea (SBS) population have been unreliable. We improved estimates of numbers of polar bears by modeling heterogeneity in capture probability with covariates. Important covariates referred to the year of the study, age of the bear, capture effort, and geographic location. Our choice of best approximating model was based on the inverse relationship between variance in parameter estimates and likelihood of the fit and suggested a growth from ≈ 500 to over 1,000 females during this study. The mean coefficient of variation on estimates for the last decade of the study was 0.16—the smallest yet derived. A similar model selection approach is recommended for other projects where a best model is not identified by likelihood criteria alone.

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Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Polar bears in the Beaufort Sea: A 30-year mark-recapture case history
Series title:
Journal of Agricultural, Biological, and Environmental Statistics
DOI:
10.1198/108571101750524562
Volume:
6
Issue:
2
Year Published:
2001
Language:
English
Publisher:
The International Biometric Society
Contributing office(s):
Alaska Biological Science Center, Alaska Science Center
Description:
14 p.
First page:
221
Last page:
234
Country:
Canada, Russia, United States
Other Geospatial:
Beaufort Sea