BMMRO research associates, Dr. John Durban (National Marine Fisheries Service, U.S.) and doctoral student Holly Fearnbach (University of Aberdeen, U.K. and National Marine Fisheries Service U.S.) have just completed the fifth consecutive annual October survey to monitor bottlenose dolphins in the Sea of Abaco, with support from Friends of the Environment. The aim of this study is to continue BMMRO's 20-year long time series of individual dolphin photo-identification, to monitor population dynamics and health, and compare survey results to similar monitoring efforts in the late 1990's.

Photograph of a curious calf (less than one year old) on Tilloo Bank	Photograph of a sub-adult dolphin leaping during social interactions	Photograph of a juvenile dolphin with a fresh and severe shark-bite wound on its flank

Almost 1100 miles of boat-based survey effort were conducted in the waters between the Pelican Cays Land and Sea Park in the south and Green Turtle Cay in the north (see map), between Great Abaco Island and the barrier islands /reefs. Seventeen (17) dolphin groups were encountered over 21 survey days. Unfortunately, this represents a significant decrease in sighting frequency compared to previous years, with a dolphin group only being seen every 64 miles of survey effort, on average. This contrasts sharply with the high sighting frequency (a group every 15 miles) in the late 1990s, notably before hurricane Floyd. A relatively high proportion of the dolphins photographed this year displayed fresh shark-bite wounds, possibly acquired around the time of hurricane Irene's passage over Abaco in late August. We do not yet fully understand why this happens, but it may be that the dolphins seek slightly deeper water during intense storms, exposing them to larger predatory sharks (see recent paper by Holly Fearnbach and co-authors). This finding is consistent with our observations immediately following previous hurricanes, and suggests that, in addition to the dolphins that survived shark attacks, some individuals may also have died as a result. Continued monitoring of the presence and absence of individual dolphins during future surveys will allow us to quantify mortality rates, and to understand the impact of hurricanes and other factors on the status of this population.

Map of survey tracks and locations of encounters with dolphins