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Detection of sea otters in boat-based surveys of Prince William Sound, Alaska

Marine Mammal Science
By: , , and 
https://doi.org/10.1111/j.1748-7692.1995.tb00274.x

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Abstract

Boat-based surveys have been commonly used to monitor sea otter populations, but there has been little quantitative work to evaluate detection biases that may affect these surveys. We used ground-based observers to investigate sea otter detection probabilities in a boat-based survey of Prince William Sound, Alaska. We estimated that 30% of the otters present on surveyed transects were not detected by boat crews. Approximately half (53%) of the undetected otters were missed because the otters left the transects, apparently in response to the approaching boat. Unbiased estimates of detection probabilities will be required for obtaining unbiased population estimates from boat-based surveys of sea otters. Therefore, boat-based surveys should include methods to estimate sea otter detection probabilities under the conditions specific to each survey. Unbiased estimation of detection probabilities with ground-based observers requires either that the ground crews detect all of the otters in observed subunits, or that there are no errors in determining which crews saw each detected otter. Ground-based observer methods may be appropriate in areas where nearly all of the sea otter habitat is potentially visible from ground-based vantage points.

Publication type Article
Publication Subtype Journal Article
Title Detection of sea otters in boat-based surveys of Prince William Sound, Alaska
Series title Marine Mammal Science
DOI 10.1111/j.1748-7692.1995.tb00274.x
Volume 11
Issue 1
Year Published 1995
Language English
Publisher Wiley
Contributing office(s) Alaska Science Center, Alaska Science Center Biology MFEB
Description 13 p.
First page 59
Last page 71
Country United States
State Alaska
Other Geospatial Prince William Sound
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