Evidence of a shark attack on a West Indian manatee (Trichechus manatus) in Puerto Rico

West Indian manatees ( Trichechus manatus) are generally considered to have no natural predators. Based on overlaps in habitat use, the likelihood exists of opportunistic attack by large predators. On 19 May 2001, an adult manatee was recovered from Loíza, in northeastern Puerto Rico with signs of injuries, respiratory distress and diving difficulties. The animal died during the rescue attempt, and a necropsy revealed two healed scars in the animal’s peduncle. One crescent-shaped, healed, depigmented, and depressed, and the other, a small dark gray, semi-arched mark, opposite to the first. Based on this, we attributed these scars to a shark attack. External and internal gross examination demonstrated that the difficulty in diving and distressed breathing were the result of severe gas distention and impaction in the distal colon. It is plausible that the attack may have resulted from a preexisting condition, which prevented the manatee from evading the shark attack. Manatees in Puerto Rico share coastal habitat with 12 species of sharks. Of these, possible culprits for the shark attack on this manatee could be the tiger shark ( Galeocerdo cuvier), and the bull shark ( Carcharhinus leucas). Sharks are confirmed predators of the dugong ( Dugong dugon), but evidence of shark predation on the West African manatee ( Trichechus senegalensis) and Amazonian manatees ( Trichechus inunguis) is inconclusive. No evidence suggesting antemortem attacks of sharks have been recorded for manatees either in Florida or the Caribbean. Thus, this is the first confirmed record of an ante-mortem shark attack on a West Indian manatee.