Effects of Boat Noise on Dolphin Behavior and Distribution
By Christine Shepard, PhD Student, University of California at Santa Cruz

Previous research conducted by SDRP has demonstrated short-term behavioral and acoustical responses of bottlenose dolphins to vessel traffic.  High levels of boat traffic can lead to injuries or disturbance, as manifested by changes in behavior and use of acoustic signaling.  Additionally, yearly increases in Sarasota Bay vessel activity have created an underwater acoustic environment that is significantly different from the acoustic environment even thirty years ago. The purpose of this project is to understand how underwater noise generated by increased vessel activity affects behavior and distribution of resident dolphins in Sarasota Bay.

Temporal and spatial variation in boat noise may produce differences in habitat use, habitat selection, and behavioral patterns of resident dolphins. To evaluate the potential effects of increased vessel activity, I propose to examine the quantitative relationships between levels of boat traffic and resultant noise.  Geographic Information Systems (GIS) will be used to examine historical patterns of habitat use by Sarasota Bay dolphins over a 5 year period relative to the distributions and activities of vessels during the same period, as collected by Sue Hofmann and her Earthwatch volunteer teams.   I will also use focal follows and line transect surveys to evaluate the effects of short term increases in vessel activity, such as peaks that occur on weekends or holidays.

 Through the methods outlined above, I hope to develop a clear understanding of how increased vessel activity affects the Sarasota Bay resident dolphins.  Results from this project will aid conservation efforts directed towards coastal cetaceans in other regions of increased anthropogenic noise due to vessel activity. This work will form the basis of my graduate research as a Ph.D. student at the University of California, Santa Cruz.  Support for this project has come from Earthwatch Institute, NOAA Fisheries, and the UCSC Ocean Sciences Department.