Shark Attacks on Dolphins in Bahamas

Evidence of shark attacks on Atlantic spotted dolphins (Stenella frontalis) off Bimini, The Bahamas

Kelly Melillo-Sweeting and Stephen D. Turnbull

ABSTRACT:

The rate of shark predation on small cetaceans is poorly understood, but information is increasing as more long-term cetacean and shark studies are conducted. Resident Atlantic spotted dolphins (Stenella frontalis), off the coast of Bimini, The Bahamas, have been the subject of ongoing photo-ID and behavioral studies since 2001. Sharks in this area have also been systematically documented for decades. Despite these efforts, an actual shark attack on a dolphin has not been observed in Bimini and such an observation is rare anywhere in the world. Because of this, photo-ID records will be analyzed for evidence of shark-induced injuries, often in the form of a crescent-shaped injury or scar.  Approximately 15% of cataloged individuals within the Bimini dolphin population exhibit evidence of a shark attack. Patterns in the location on the body of the attack and trends related to age and sex will be calculated. Although the level of healing will prevent most scars from being linked to a specific shark species, we suspect bull (Carcharhinus leucas), tiger (Galeocerdo cuvieri), shortfin make (Isurus oxyrinchus) and dusky sharks (Carcharhinus obscures) to be possible predators of dolphins near Bimini. We also expect to see few injuries to the ventral portion of the body, where most attacks would likely be fatal. This study does not estimate the rate of attacks on dolphins; here, we estimate the rate of unsuccessful attacks.

Presentation at 19th Biennial Conference on the Biology of Marine Mammals
Tampa Florida, 27. Nov – 2nd Dec 2011

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