Details:

Personal Author:
Waring, Gordon T.; DiGiovanni, Robert A., Jr; Josephson, Elizabeth; Wood, Stephanie; Gilbert, J. R. (James R.);
Waring, Gordon T.; DiGiovanni, Robert A., Jr; Josephson, Elizabeth; Wood, Stephanie; Gilbert, J. R. (James R.); Less -
Corporate Authors:
Northeast Fisheries Science Center (U.S.);
NOAA Program & Office:
NMFS (National Marine Fisheries Service); NEFSC (Northeast Fisheries Science Center);
NMFS (National Marine Fisheries Service); NEFSC (Northeast Fisheries Science Center); Less -
Description:
This survey was conducted to obtain an abundance estimate for the New England harbor seal (Phoca vitulina concolor) population, as the previous estimate (2001) was outdated for stock assessment purposes. Aerial photographic surveys and radio tracking of harbor seals on ledges along the Maine coast were conducted during the pupping period in late May 2012. Twenty-nine harbor seals (20 adults and 9 juveniles) were captured and radio-tagged prior to the aerial survey. Of these, 18 animals (6 adult males, 6 adult females, 2 juvenile males and 4 juvenile females) were available during the survey to develop a correction factor for the fraction of seals not observed. The estimate of harbor seal abundance in 2012 was 75,834 (11,625 standard deviation [sd]; 0.153 coefficient of variation [CV]). Nmin, the lower 20% confidence limit, was 66,884. The 2012 point estimate is 24% lower than the 99,340 reported for 2001. Possible reasons for the lower estimate include changes in survey design, differences in the age/sex ratio of radio-tagged seals available for obtaining a correction factor, differences in harbor seal distribution between 2001 and 2012, and/or that the population has actually declined. [doi:10.7289/V5ZC80VT (http://dx.doi.org/10.7289/V5ZC80VT)]
Content Notes:
Gordon T. Waring (retired), Robert A. DiGiovanni Jr., Elizabeth Josephson, Stephanie Wood, and James R. Gilbert (retired). "August 2015." "Web version posted September 3, 2015"--Document home page. doi:10.7289/V5ZC80VT (http://dx.doi.org/10.7289/V5ZC80VT) System requirements: Adobe Acrobat Reader. Includes bibliographical references (pages 8-9).
Keywords:
[+]
Aerial Photogrammetry
Harbor Seal
Monitoring
Radio Tracking
Research
Seal Populations

Series:
NOAA technical memorandum NMFS-NE ; 235;
DOI:
http://doi.org/10.7289/V5ZC80VT
Document Type:
Technical Memorandum;
Place as Subject:
New England;
Rights Information:
Public Domain
Compliance:
Library
Main Document Checksum:
[+]
urn:sha256:1ffe6651941870d96d4662542aec7bb1bbe522f6472944897f6fbf7b2170a73f
File Type:

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