Determining a correction factor for aerial surveys of harbor seals in California

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Harvey, J. T., & Goley, D. (2011). Determining a correction factor for aerial surveys of harbor seals in California. Marine Mammal Science, 27(4), 719-735. doi:10.1111/j.1748-7692.2010.00446.x
Metadata
TitleDetermining a correction factor for aerial surveys of harbor seals in California
AuthorsT. Harvey, D. Goley
AbstractCounts of pinnipeds provide a minimal estimate of population size because some unknown proportion of individuals is in the water during surveys. We determined a correction factor (CF) for Pacific harbor seals (Phoca vitulina richardii) by estimating the proportion ashore of 180 seals tagged with flipper-mounted radio tags throughout California. The mean proportions of tagged individuals ashore during four complete surveys in 2004 were not different between central and northern California (F= 1.85, P= 0.18) or between sexes (F= 0.57, P= 0.45), but a lesser proportion of weaners was ashore than subadults or adults (F= 7.97, P= 0.001), especially in northern California. The CF calculated for the statewide census of harbor seals was 1.65, using transmitters operating during the survey (n= 114). Using a mark-recapture estimator for tag survival (phi) and the four telemetry surveys the mean CF for central and northern California was 1.54 ± 0.38 (95% CI). A CF for southern California of 2.86 was based on a single survey. Using the mean CF of 1.54 and a statewide count in 2009 we estimated 30,196 (95% CI = 22,745-37,647) harbor seals in California.
JournalMarine Mammal Science
Date2011
Volume27
Issue4
Start page719
End page735
ISSN08240469
Subjectsaerial survey, census, mark-recapture method, movement, pinniped, population estimation, population size, survival, tagging, telemetry, California, United States, Phoca, Phoca vitulina richardii, Pinnipedia
NoteCited By (since 1996):3, CODEN: MMSCE

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