Aquatic Mammals 2009, 35(3), 367-377, DOI 10.1578/AM.35.3.2009.367
Prevalence and Impacts of Motorized Vessels on Bottlenose
Dolphins (Tursiops truncatus) in the Indian River Lagoon, Florida
Sarah E. Bechdel,1 Marilyn S. Mazzoil,1 M. Elizabeth Murdoch,1
Elisabeth M. Howells,1 John S. Reif,2 Stephen D. McCulloch,1
Adam M. Schaefer,1 and Gregory D. Bossart1
1
Harbor Branch Oceanographic Institute at Florida Atlantic University, Center for Coastal Research – Marine Mammal
Research and Conservation, 5600 U.S. 1 North, Ft. Pierce, FL 34946, USA; E-mail: sbechdel@hboi.fau.edu
2
Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA
Abstract Plan (CCMP) to protect the living resources of the
Indian River Lagoon (IRL), Florida, from anthro-
Vessel-based anthropogenic impacts on bottlenose pogenic activities negatively affecting the estuary.
dolphins (Tursiops truncatus) in the Indian River Action Items were created to (1) measure boating
Lagoon (IRL), Florida, were investigated by quan- impacts on wildlife such as manatees (Trichechus
tifying visible physical injuries to dorsal fins from manatus latirostris), sea turtles (Caretta caretta,
photo-identification data collected from 1996 to Chelonia mydas myda), and dolphins; (2) establish
2006. Forty-three dolphins, 6.0% of the distinctly resource protection zones; and (3) raise environ-
marked population, had injuries related to vessel mental awareness through education of boat and
impact. Impact was determined from previously personal watercraft operators. In 2004, Florida
published vessel-related wound definitions and became the nation’s leader in the number of reg-
the elimination of other possible wound sources. istered boats (U.S. Coast Guard [USCG], 2002-
Spatial distribution was determined by dividing 2005), in addition to being the foremost in boating
the IRL into six segments based on hydrodynamics fatalities (Florida Fish and Wildlife Conservation
and geographic features. Dolphins were assigned Commission [FWC], 2008a). Despite increasing
to a segment(s) and corresponding county accord- awareness of human injuries and deaths attribut-
ing to ranging patterns. Segment 4, consisting of able to boating and the establishment of manatee
St. Lucie and Martin Counties, had the highest resource protection zones, current levels of boat
prevalence (9.9/100 distinct dolphins) of boat- traffic within the IRL continue to directly and indi-
injured dolphins and had the highest number rectly cause marine animal disturbance, injuries,
of registered boaters per km2 of habitat. These and mortality.
preliminary data suggest that vessel impacts on Vessel collisions have been confirmed for
dolphins occur disproportionally in the IRL and over 18 species of small cetaceans worldwide
should be considered a high-priority management (Van Waerebeek et al., 2007). Direct impacts are
issue for local governments. Behavioral data col- instantaneous involving body to boat contact with
lected during photo-identification surveys support propellers, skegs, and hulls (Wright et al.