Bimini Dolphin Research

Report # 17

The weather was excellent again this past week with wave heights not greater than one foot and winds below 3 knots. Showers and thunderstorms were present from Monday through Wednesday making the sky overcast during the survey hours. This week, the air temperature and humidity have been the highest for this summer season. Seven survey trips were conducted this week (one each day) during afternoon hours. We had sightings on all survey trips except for Monday´s trip. We had sixteen sightings of spotted dolphins, most of which occurred outside the survey area and over deep reefs (40 to 80 feet deep) which are 2 to 3 miles west of North Bimini. Group sizes of spotted dolphins fluctuated greatly between 2 to 11 dolphins this week as they would spread out to feed and then coalesce again for short periods of time. Only the sightings on Friday´s survey trip occurred within the survey area. Most of the sightings of spotters happened after 6:30 p.m. when spotters were observed porpoising after needlefish or flying fish in the distance. Even though the spotters were mostly spread out during their feeding bouts, succesful encounters (with close interaction between dolphins and humans) of up to 20 minutes were possible. Four sightings of bottlenose dolphins with group sizes ranging between 3-6 were also made. One of these sightings occurred over a shoal south of South Bimini (Bimini is actually comprised of two islands, North and South Bimini; the survey area is north of North Bimini) during our stop at a snorkel site. A second sighting of bottlenose dolphins was a mixed group of 8 spotters and 3 bottlenose dolphins. Except for the mixed group, during which aggressive/sexual behavior was observed, bottlenose dolphins were observed displaying feeding behavior, i.e. short surface intervals and steep dives to the bottom in the same location. As a reminder, we are working with Bill and Nowdla Keefe's Bimini Undersea (their dive boats and dolphin trips) for our research vessels. We are based on Bimini and go out about five miles or so from the island to search for dolphins. Until next week, Xenia