Notable Stingray Spine-Associated Strandings Involving Two Female Bottlenose Dolphins in Florida and Massachusetts, USA, in the Context of Literature and Database Reviews

Trauma from stingray spines (caudal barbs) has been intermittently documented as a cause of mild to fatal illness in odontocetes, particularly bottlenose dolphins (Tursiops truncatus), as well as in pinnipeds, sirenians, the loggerhead sea turtle, great white shark, and cobia. Although stingray spines have been noted to cause serious injury to various organ systems, their potential involvement in cetacean reproductive tract pathology has not been previously described. In North America, published descriptions of wild cetacean strandings associated with stingray spines have all involved bottlenose dolphins in the southeastern United States, plus a bottlenose dolphin and a common dolphin (Delphinus delphis) in Mexico. In 2018, uterine rupture was observed in a gravid bottlenose dolphin found deceased in Florida with stingray spine penetration into the abdominal cavity. Gross necropsy and histopathology findings were compatible with the stingray spine being involved with the rupture. To provide fuller insight into the case, a scientific literature review was conducted, and results of an unpublished 1998 necropsy involving a coastal female bottlenose dolphin that stranded in the northeastern state of Massachusetts with stingray spine presence was reviewed. Additionally, a query of the nationwide U.S. marine mammal stranding database was conducted for stingray spine-associated cetacean strandings from 1995 to 2019. Of 61 cetacean strandings revealed in the query to involve stingray spine presence, 59 were bottlenose dolphins from the southeastern U.S. states, plus Puerto Rico and Virginia; a bottlenose dolphin in southern California and a short finned pilot whale (Globicephala macrorhynchus) were also noted. Query results did not support a bottlenose dolphin sex predilection for stingray spine-associated strandings; most such strandings involved adults. Behavioral, environmental, anthropogenic, and climatic events may influence marine mammal-stingray interactions. Continued vigilance for stingray spine-associated pathologic changes is warranted during marine mammal stranding investigations at diverse geographic sites.