Results and evaluation of a survey to estimate Pacific walrus population size, 2006

Suzann G. Speckman; Vladimir I. Chernook; Douglas M. Burn; Mark S. Udevitz; Anatoly A. Kochnev; Alexander Vasilev; Chadwick V. Jay; Alexander Lisovsky; Anthony S. Fischbach; R. Bradley Benter

doi:10.1111/j.1748-7692.2010.00419.x

Results and evaluation of a survey to estimate Pacific walrus population size, 2006

Marine Mammal Science

By: Suzann G. Speckman, Vladimir I. Chernook, Douglas M. Burn, Mark S. Udevitz, Anatoly A. Kochnev, Alexander Vasilev, Chadwick V. Jay, Alexander Lisovsky, Anthony S. Fischbach, and R. Bradley Benter

https://doi.org/10.1111/j.1748-7692.2010.00419.x

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Abstract

In spring 2006, we conducted a collaborative U.S.-Russia survey to estimate abundance of the Pacific walrus (Odobenus rosmarus divergens). The Bering Sea was partitioned into survey blocks, and a systematic random sample of transects within a subset of the blocks was surveyed with airborne thermal scanners using standard strip-transect methodology. Counts of walruses in photographed groups were used to model the relation between thermal signatures and the number of walruses in groups, which was used to estimate the number of walruses in groups that were detected by the scanner but not photographed. We also modeled the probability of thermally detecting various-sized walrus groups to estimate the number of walruses in groups undetected by the scanner. We used data from radio-tagged walruses to adjust on-ice estimates to account for walruses in the water during the survey. The estimated area of available habitat averaged 668,000 km² and the area of surveyed blocks was 318,204 km². The number of Pacific walruses within the surveyed area was estimated at 129,000 with 95% confidence limits of 55,000 to 507,000 individuals. This value can be used by managers as a minimum estimate of the total population size.

Additional publication details
Publication type	Article
Publication Subtype	Journal Article
Title	Results and evaluation of a survey to estimate Pacific walrus population size, 2006
Series title	Marine Mammal Science
DOI	10.1111/j.1748-7692.2010.00419.x
Volume	27
Issue	3
Year Published	2011
Language	English
Publisher	Society for Marine Mammalogy
Contributing office(s)	Alaska Science Center Biology MFEB
Description	40 p.
First page	514
Last page	553
Country	Russia, United States
Other Geospatial	Bering Sea
Google Analytic Metrics	Metrics page