Bimini Dolphin Research

Report #9

A tropical wave caused much rain, lightning and wind from Tuesday through Sunday. Thunderstorms ceased on Friday morning but strong easterly winds remained. In general, wind direction was out of the East at 15-20 knots and the seas were 3-4 foot (3 or 4 on the Beaufort windscale). Three out of the nine survey trips scheduled for this week had to be cancelled due to poor weather conditions. During Monday morning's survey trip (seas mirror-like conditions), we sighted a large group of 30 spotted dolphins comprised of all age classes. The adults (class 4 and 5) in this large group would split into three groups (in tight formations) and show sexual/aggressive behavior; the groups would travel in different directions for a few minutes and then would coalesce again into one large group and travel slowly towards the west. Meanwhile, mother/calf pairs and juveniles were observed swimming between these tight groups spaced at 3-4 dolphin body lenghts from each other. Two attempts to swim with them were made but the dolphins did not show any interest in us and would continue their travel towards the west. During the afternoon's survey we sighted about 11 spotted dolphins which were showing sexual behavior when first sighted. Of this group, two adult (class 4) dolphins interacted closely with us for almost 30 minutes. Both survey trips on Tuesday were cancelled. Wednesday and Thursday morning trips did not have any sightings; 3-4 foot seas and frequent whitecaps decreased our sighting probability greatly. On Friday morning we sighted a pod of 3-4 bottlenose dolphins but these dived down immediately and showed no interest in us. On our last trip this week we encountered four spotters (class 3 and 4) which interacted very closely with us for almost 35 minutes. This group showed social/play behavior by dragging turtle grass with their pectoral fins and swimming closely and in tight circles around people. 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