Asphyxiation in a Bottlenose Dolphin (Tursiops truncatus) from Puerto Rico Due to Choking on a Black Margate (Anisotremus surinamensis)

Abstract: Bottlenose dolphins (Tursiops truncatus) are found in the coastal and offshore waters of Puerto Rico. However, little is known about causes of their mortal¬ity in the Caribbean. On 18 February 2002, a female bottlenose dolphin was found dead in Bahía de San Juan, Puerto Rico. Remarkably, a black margate (Anisotremus surinamensis) was firmly lodged in the dolphin’s oral cavity and the pharynx. The throat of the dolphin was markedly swollen; the larynx was dislocated; and signs of agonal death were evident. Grossly, the cause of death was determined to be asphyxiation due to choking. Fifty strandings of bottlenose dolphins have been reported between 1937 and 2006 in Puerto Rico and the Virgin Islands. In those for which a cause of death was determined, four were human related and 11 died of natural causes (including this case). The present case study fits the definitions of “choking” and “asphyxiation.” The evolved respiratory anatomy of cetaceans in which the larynx is inserted into the nasal passages leading to the blowhole makes asphyxiation due to choking unlikely in odontocetes. However, if the larynx is irreversibly dislodged from its normal position during swallowing, this may cause the dolphin to stop breathing or even drown. Thus, respiratory blockage from a natural prey item represents an uncommon mortality factor associated with piscivo¬rous cetaceans and is the first record of such marine mammal mortality in the Caribbean.

Key Words: asphyxia, choking, mortality, Caribbean, bottlenose dolphin, Tursiops truncatus, black margate, Anisotremus surinamensis

Document Type: Research article

DOI: 10.1578/AM.35.1.2009.48

Page Numbers: 48-54

$12.00Add to cart