Differential Response by Manatees to Playbacks of Sounds Simulating Approaching Vessels

TitleDifferential Response by Manatees to Playbacks of Sounds Simulating Approaching Vessels
Publication TypeJournal Abstract
AuthorsMiksis-Olds, J, Miller, JH, Tyack, PL, Reynolds, JE, Donaghay, PL
JournalJournal of the Acoustical Society of America
KeywordsApproaching Vessels, Mantatees, Responses, Sounds

One of the most pressing concerns associated with the endangered Florida manatee is mortality due to collisions with watercraft. Watercraft collisions are the leading identified cause of adult mortality, resulting in greater than 30% of manatee deaths each year. Reducing adult mortalities is critical to the recovery of the manatee population, as population trends are more sensitive to adult deaths than to those of other age groups. Acoustic playback experiments were conducted to assess the behavioral responses of manatees to watercraft approaches. Playback stimuli were constructed to simulate a vessel approach to approximately 10 m in seagrass habitats. Stimulus categories were (1) silent control; (2) idle outboard approach; (3) planing outboard approach; and (4) fast personal watercraft approach. These results are the first to document responses of wild manatees to playback stimuli. Analyses of swim speed, changes in behavioral state, and respiration rate indicate that the animals respond differentially to the playback categories. The most pronounced responses, relative to the controls, were elicited by the personal watercraft. Quantitative documentation of response during playbacks will provide data that may be used as the basis for future models to predict the impact of specific human activities on manatee and other marine mammal populations.

Refereed DesignationUnknown