Prevalence and Impacts of Motorized Vessels on Bottlenose Dolphins (Tursiops truncatus) in the Indian River Lagoon, Florida

摘要

Vessel-based anthropogenic impacts on bottlenose dolphins (Tursiops truncatus) in the Indian River Lagoon (IRL), Florida, were investigated by quantifying visible physical injuries to dorsal fins from photo-identification data collected from 1996 to 2006. Forty-three dolphins, 6.0% of the distinctly marked population, had injuries related to vessel impact. Impact was determined from previously published vessel-related wound definitions and the elimination of other possible wound sources. Spatial distribution was determined by dividing the IRL into six segments based on hydrodynamics and geographic features. Dolphins were assigned to a segment(s) and corresponding county according to ranging patterns. Segment 4, consisting of St. Lucie and Martin Counties, had the highest prevalence (9.9/100 distinct dolphins) of boat-injured dolphins and had the highest number of registered boaters per km super(2) of habitat. These preliminary data suggest that vessel impacts on dolphins occur disproportionally in the IRL and should be considered a high-priority management issue for local governments. Behavioral data collected during photo-identification surveys support the possibility of a low tolerance and sensitization to vessel interactions. Recommendations to reduce direct and indirect impacts from vessels on dolphins are discussed.