Characterization And Differentiation Of Bottlenose Dolphin Populations (genus Tursiops) In The Southeastern Us Based On Mortality Patterns And Morphometrics (united States)

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)


Marine Biology and Fisheries


Data on sex, age class, year and season of stranding were collected from 170 Tursiops from the Indian/Banana River system on the east coast of Florida from Jan 1976 to Dec 1983. In addition, measurements were collected from 297 skulls and 177 intact carcasses of Tursiops from the southeastern U.S.The mean yearly number of beached carcasses in the Indian/Banana River system was 19.5 producing mortality estimates of about 7 to 9 percent. Mortality appears seasonally uniform except under unusual circumstances. Mortality does not appear to differ between the sexes, but is significantly higher in newborn animals relative to other age classes. Calving appears to occur year-round except perhaps in fall or late summer. Males appear to attain sexual maturity at about age 10.Sexual dimorphism in skull and body measurements of southeastern U.S. Tursiops is minimal. Offshore Tursiops are larger with a proportionately shorter snout and proportionately smaller pectoral flippers than coastal animals. Morphological variation among groups of coastal dolphins is evident but less consistent and not as great as that between coastal and offshore bottlenose dolphins. Approximately 74% of adult length is attained in the first year of life and physical maturity appears to occur at about 10 to 12 yrs of age.In certain situations carcass salvage may provide information on mortality, reproduction, growth and stock discreteness. Morphometric analyses indicate the existence of 2 morphological types of Tursiops in the southeastern U.S.


Biology, Oceanography; Agriculture, Fisheries and Aquaculture

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