Bimini Dolphin Research

Report # 13

The weather was not pleasant at the beginning of the week since we had much rain and wind speeds up to 25 knots from the southwest (waves 5-7 feet). Due to this, the trip on Monday was cancelled. A total of six afternoon survey trips were conducted this week. The weather on Tuesday improved with a shift in wind direction to the East; wind speed was still at 15 knots and wave height at 3-4 feet but the wind direction allowed us to survey an area on the leeside (west side protected from easterly winds) of the island of North Bimini, where the sea state was better. This area is not included in our survey area but has resulted in many sightings over the last month; in fact, most of the sightings this week and last week occurred near or in this area. Tuesday's survey resulted in a sighting of four spotted dolphins (2 calves and 2 adults); four attempts to swim with them were made which resulted in brief interactions (all less than five minutes). Weather conditions for Wednesday and the rest of the week improved with wind out of the East at less than 10 knots. On Wednesday we had a late sighting of 15-20 spotted dolphins at 7:38 p.m. on our way to the harbour. This large group was comprised of all age groups and did not seem to be travelling in any specific direction; sexual and social behavior were observed between adults and juveniles. One encounter of 15 to 20 minutes was possible before lighting conditions forced us to return to the harbour (not all 15 dolphins interacted with people for the duration of the encounter). Survey trips on Friday, Saturday and Sunday afternoon resulted in many sightings of spotted dolphins; the sizes of the groups varied greatly during surface observation and in-water encounters, ranging from 3-20 individual dolphins. Most groups were comprised of adults and juveniles which were travelling towards the south or southwest while showing bouts of feeding or social/sexual behavior. On each of these days, we had in-water encounters lasting more than 30 minutes. Friday's 40-minute encounter was the most spectacular. The encounter began with three juveniles interacting with people and showing play behavior (picking up seaweed with flukes and fins) for 20 minutes; then, six more juvenile spotted dolphins joined and we were able to observe aggressive behavior within this group for 10 minutes until a group of 10 adult spotted dolphins also joined and the behavioral state changed to sexual/aggressive. 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