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Blainville's Beaked whale dorsal fin 
													identification photo
Blainville's beaked whale.

Since our research began, we have documented over 2000 encounters with marine mammals in The Bahamas and have recorded twenty-four different species, including endangered species such as sperm whales (Physeter macrocephalus), humpback whales (Megaptera novaeangliae) and West Indian manatees (Trichechus manatus).

The majority of species found around the islands are deep-diving toothed whales and dolphins, many of which are unstudied elsewhere. Therefore, our dataset is facilitating the development of both nationwide and global conservation policies. This is most notable for Ziphiid beaked whales, which are rarely seen in other areas of the world but can be found regularly in the deep-water canyons that divide the islands of the Bahamas.

Since our study began in 1991, we have had over 200 encounters with beaked whales, involving three species: Blainville's beaked whales (Mesoplodon densirostris), Gervais' beaked whales (M. europaeus) and Cuvier's beaked whales (Ziphius cavirostris). The high frequency of encounters with Blainville's beaked whales has allowed us to conduct a detailed individual photo-identification study of this species that is the only one of its kind worldwide. We have identified 165 individuals from over 9,000 photographs over 11 years of study, with a re-sighting rate of 39%. These photo-identification data are being used to investigate patterns of distribution, residency and social structure, which are contributing to an assessment of the vulnerability of beaked whales to anthropogenic noise.

We also conduct a detailed study of the population ecology of Atlantic bottlenose dolphins (Tursiops truncatus) that inhabit the shallow water of Little Bahama Bank.

Rough-toothed dolphins
Documenting a pod of rough-toothed dolphins (Steno bredanensis).

We have obtained more than 67,000 identification photographs of dolphins at multiple study sites around this relatively pristine shallow bank habitat. Data on the re-sighting of individual dolphins at different study sites has been used to provide a population estimate of around 1080 (95% credibility intervals = 607-2561) non-calf dolphins in 2001, despite a high re-sighting rate of some dolphins at individual sites.

Our molecular genetic analysis has also provided evidence for genetic mixing between dolphins using the different study sites, although analysis of association patterns suggests that there is a high level of population structuring with dolphins grouping preferentially with relatives in some areas. We have found that the dolphins on Little Bahama Bank exhibit a relatively high level of genetic diversity, in contrast to more depleted populations of dolphins around the world, further indicating the healthy status of this population.

We anticipate that biological information on this population will therefore serve as a baseline for monitoring the status of bottlenose dolphin populations in less pristine environments around the world.


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