April 13, 2024

Incidence of Odontocetes with Dorsal Fin Collapse in Maui Nui, Hawaii


Stephanie H. Stack, Jens J. Currie, Jessica A. McCordic, and Grace L. Olson


Abstract: We examined the incidence of bent or collapsed dorsal fins of eight species of odontocetes observed in the nearshore waters of Maui Nui, Hawaii. Between 1995 and 2017, 1,312 distinctive individual odontocetes were photographically documented. Our photo-identification catalogs include 583 spinner dolphins (Stenella longirostris longirostris), 164 bottlenose dolphins (Tursiops truncatus), 132 short-finned pilot whales (Globicephala macrorhynchus), 253 pantropical spotted dolphins (Stenella attenuata), 82 false killer whales (Pseudorca crassidens), 70 melon-headed whales (Peponocephala electra), 15 pygmy killer whales (Feresa attenuata), and 13 rough-toothed dolphins (Steno bredanensis). Of these, two false killer whales (2.44% of catalog), two spinner dolphins (0.34% of catalog), and three pantropical spotted dolphins (1.19% of catalog) displayed major dorsal fin disfigurements. Both spinner dolphins and two of the spotted dolphins had multiple resights spanning several years, with one spotted dolphin having a 16-year span between resights. The two false killer whales with bent dorsal fins did not have any resights and were only sighted once throughout the study period. We also present the first progression of dorsal fin collapse after a significant injury to the leading edge of a spinner dolphin. Results from this research expand our knowledge on injuries to marine mammals and the survivorship of wild dolphins with dorsal fin injuries and contribute to the management of odontocetes in Hawaii, where interactions with fishing gear are a significant conservation issue.
Key Words: odontocete, disfigurement, dorsal fin, deformity, injury
Document: Article
DOI: https://doi.org/10.1578/AM.45.3.2019.257
Page Numbers: 257-265

Info SKU: Vol__45__Iss__3_Stack Category: