Bermuda bottlenose dolphin tracking project update
Leigh Klatsky, MSc, Dolphin Quest

Beginning in 2003, the Bermuda Dolphin Tracking Project has focused on developing a better understanding of the habitat use and dive behavior of offshore bottlenose dolphins residing near Bermuda in the northwest Atlantic Ocean. A second successful field season occurred May 2005 with the capture, sampling and outfitting of three dolphins with satellite-linked and VHF transmitters before their release. The dolphins were tracked for 12, 14 and 46 days with two of the dolphins traveling over water depths of 5,000 m to Muir Seamount, located over 200 km to the northeast of Bermuda, before their tags ceased transmitting. The third dolphin remained within 60 km of Bermuda and made similar movements to those observed for the three dolphins tracked in 2003 for 45 days. This dolphin, and the three dolphins tagged in 2003, preferred to stay in close proximity to the Bermuda Pedestal and in water depths ranging between 1,000 -1,400 m. These movement patterns, along with year-round dolphin sightings, suggest there may be a resident population of dolphins around Bermuda. Further investigation is necessary to determine if Bermuda waters may also be a stop-over site of a larger range, as recently witnessed by the longer-ranging movements by the two dolphins.

The dive data collected from the time depth recorders located on the satellite tags revealed that although a majority of the total dives made by the three dolphins during the tracking period did not exceed five minutes in duration, several dives were recorded between 10 – 11 minutes. In addition, all three dolphins made dives beyond 600 m including the occasional dives made by the one female dolphin to depths between 800 - 900 m. These are the deepest recorded dive depths and durations for wild bottlenose dolphins to date.

This project has provided the opportunity to observe, examine and sample offshore dolphins found in the deep waters of the northwest Atlantic Ocean, as well as for comparison with the nearshore dolphins found in Sarasota Bay. Samples collected have been provided to many ongoing investigations, including blubber for contaminant analysis. Future research plans include a genetic study of these dolphins, as well as a photo-id study, to help determine if these animals should be managed as a local population and/or part of a larger oceanic population. This project has been funded by Dolphin Quest Inc. / Quest Global Management, with additional support from the Bermuda Zoological Society and the Chicago Zoological Society.