FORENSIC METHODS FOR CHARACTERIZING WATERCRAFT FROM WATERCRAFT-INDUCED WOUNDS ON THE FLORIDA MANATEE (TRICHECHUS MANATUS LATIROSTRIS)

Authors

  • Sentiel A. Rommel,

    1. Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Marine Mammal Pathobiology Lab, 3700 54th Ave. South, St. Petersburg, Florida 33711, U.S.A. E-mail: rommels@uncw.edu
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    • 1

      Current address: Biology and Marine Biology, UNCW, 601 S. College Rd., Wilmington, North Carolina 28403, U.S.A.

  • Alexander M. Costidis,

    1. Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Marine Mammal Pathobiology Lab, 3700 54th Ave. South, St. Petersburg, Florida 33711, U.S.A. E-mail: rommels@uncw.edu
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  • Thomas D. Pitchford,

    1. Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Marine Mammal Pathobiology Lab, 3700 54th Ave. South, St. Petersburg, Florida 33711, U.S.A. E-mail: rommels@uncw.edu
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    • 2

      Current address: FWRI Jacksonville Field Laboratory, Jacksonville, Florida 32221, U.S.A.

  • Jessica D. Lightsey,

    1. Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Marine Mammal Pathobiology Lab, 3700 54th Ave. South, St. Petersburg, Florida 33711, U.S.A. and University of Florida, College of Veterinary Medicine, Marine Mammal Health Program, Gainesville, Florida, U.S.A.
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    • 3

      Current address: Lightsey Veterinary Relief Services, 239 Granite Street, Pacific Grove, California 93950, U.S.A.

  • Richard H. Snyder,

    1. PE, Recreational Boating Consulting LLC, 5326 Fond du Lac Rd, Oshkosh, Wisconsin 54902–7554, U.S.A.
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  • Elsa M. Haubold

    1. Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, 100 Eighth Ave. SE, St. Petersburg, Florida 33701, U.S.A.
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    • 4

      Current address: Florida Fish and Wildlife Conservation Commission, 620 South Meridian Street, Mail Station 10, Tallahassee, Florida 32399, U.S.A.


Abstract

Watercraft-related mortality represents 1,253 (24.9%) of 5,033 Florida manatee (Trichechus manatus latirostris) deaths recorded between 1 January 1979 and 31 December 2004. Wound patterns generated by collisions with watercraft are diagnostic. Sets of cuts and scrapes that are roughly equidistant and perpendicular to the direction of vessel travel are consistent with lacerations made by propeller blades. From these lesions, estimates of propeller diameter, pitch, rotation, and direction of travel may be obtained. Considerable overlap of propeller sizes and pitches on different size vessels, common use of counter rotation propellers, and numerous other complicating factors may confound efforts to accurately predict vessel size and type from propeller wounds. Of the more than one million watercraft registered in Florida, 98% are ≤12.2 m (40 ft), yet watercraft 5.3–36.6 m (17.5–120 ft) are known to have killed manatees. Analysis of a 5-yr subset of mortality data suggests that a disproportionate number of propeller-caused watercraft-related mortalities could be attributed to propeller diameters ≥43.2 cm (17 in.), inferring that these were caused by watercraft ≥12.2 m (40 ft).

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