Abstract: Mark-recapture estimate of Tursiops in Hawaii (fwd)

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Date: Tue Aug 28 2001 - 13:07:20 EDT

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    Baird, R.W., A.M. Gorgone, A.D. Ligon and S.K. Hooker. 2001.
    Mark-recapture abundance estimate of bottlenose dolphins (Tursiops
    truncatus) around Maui and Lana'i, Hawai'i, during the winter of
    2000/2001. Report prepared under Contract # 40JGNF0-00262 to the Southwest
    Fisheries Science Center, National Marine Fisheries Service, La Jolla, CA.


    Bottlenose dolphins were photo-identified in the area between the islands
    of Maui, Lana'i, Moloka'i and Kaho'olawe, Hawai'i (an area of
    approximately 3,000 km2) between November 2000 and March 2001. A total of
    328 hours were spent on the water during 49 days, and bottlenose dolphins
    were encountered on 32 occasions on 22 days. Fifty-nine individual
    dolphins had long-term recognizable markings (dorsal fin or back notches),
    and an additional 12 individuals (including 4 calves) were also documented
    based on body scars, dorsal fin shape or pigmentation patterns; thus,
    approximately 82% of individuals are thought to be recognizable in the
    long-term. Identification data were combined with a catalog of 63
    individuals that had been documented in the same study area in 1999 and
    during the spring of 2000. During this entire period each "marked"
    individual was documented an average of 3.6 times (range 1-16), though
    individuals were not re-sighted randomly; some were seen more often and
    some less often than expected by chance. A mark-recapture analysis of the
    population using identifications from 1999 and from November 2000-March
    2001, taking into account the proportion of marked individuals, produced
    an estimate of 134 dolphins (95% CI = 107-179). Using modeled rates of
    discovery the population was estimated at 122 individuals. Given the size
    of the study area and the presumed transitory nature of bottlenose
    dolphins around oceanic islands, the population in this area is
    surprisingly small.

    PDF copies can be obtained by writing to Robin Baird at rwbaird@is.dal.ca

    Robin W. Baird, Ph.D.
    Post-doctoral Fellow, Biology Department, Dalhousie University
    Cetacean and Sea Turtle Team, NMFS, NOAA Beaufort Lab
    101 Pivers Island Road, Beaufort, NC 28516 USA
    Phone: 252-728-8762
    Fax: 252-728-8784
    e-mail: robin.baird@noaa.gov or rwbaird@is.dal.ca

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