CHANGES IN ABUNDANCE OF HARBOR SEALS IN MAINE, 1981–2001 |
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| Authors: | James R Gilbert Gordon T Waring Kate M Wynne Nikolina Guldager |
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| Institution: | Wildlife Ecology, University of Maine, Orono, Maine 04469, U.S.A. E-mail:;Northeast Fisheries Science Center, National Marine Fisheries Service, 166 Water Street, Woods Hole, Massachusetts 02543, U.S.A.;University of Alaska, Sea Grant, Marine Advisory Program, 118 Trident Way, Kodiak, Alaska 99615, U.S.A.;Wildlife Ecology, University of Maine, Orono, Maine 04469, U.S.A. |
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| Abstract: | Aerial counts of harbor seals ( Pboca vitulina concolor ) on ledges along the Maine coast were conducted during the pupping season in 1981, 1986, 1993, 1997, and 2001. Between 1981 and 2001, the uncorrected counts of seals increased from 10,543 to 38,014, an annual rate of 6.6 percent. In 2001 30 harbor seals were captured and radio-tagged prior to aerial counts. Of these, 19 harbor seals (six adult males, two adult females, seven juvenile males, and four juvenile females) were available during the survey to develop a correction factor for the fraction of seals not observed. The corrected 2001 abundance estimate was 99,340 harbor seals. Productivity in this population has increased since 1981 from 6.4% pups to 24.4% pups. The number of gray seals ( Halichoerus grypus ) counted during the harbor seal surveys increased from zero in both 1981 and 1986 to 1,731 animals in 2001. |
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| Keywords: | harbor seal Phoca vitulina population estimation distribution New England gray seal Halichoerus grypus |
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