Rough-toothed dolphin Sounds (Steno bredanensis)
Rough-toothed dolphin whistles and clicks
Whistles and echolocation clicks from Steno bredanensis (rough-toothed dolphins) recorded using a towed hydrophone array (average depth 6-8m). This was Sighting #245 (group size ~ 24 animals) from the HICEAS 2002 survey off the Hawaiian Islands chain [20.376, -160.037]. Sound credit: Shannon Rankin, SWFSC, NOAA Fisheries - goo.gl/8ZnA4N.
Rough-toothed dolphins (Steno bredanensis) are found primarily in deep waters throughout tropical and subtropical areas of the world, including Hawaii, the Gulf of Mexico, and the Mediterranean Sea. They are easily distinguished by their long, smooth head and narrow beak, and the lack of a bulbous melon. Their body color is dark, with white lips and throat. The belly (ventral) surface has irregular spots and blotches. In addition, white and yellowish scars are usually present on the body, a result of fighting with other rough-toothed dolphins or bites from squid and/or cookie cutter sharks.
Rough-toothed dolphins are named for vertical ridges that occur on their teeth, giving them a “roughened” appearance. Their diet consists of fish and cephalopods, although they are notorious for depredating baited fishing lines. Rough-toothed dolphins typically form close-knit groups of 10-20 individuals (groups up to 90 individuals have been observed). They also associate with other dolphin species such as short-finned pilot whales, common bottlenose dolphins, pantropical spotted dolphins, and spinner dolphins.
Although little is known about the species, whistles and broadband click sounds have been recorded from these dolphins. Rough-toothed dolphins produce short-duration (~ 0.5 s) whistles that range in frequency, on average, from 2.5 to 10 kHz. These whistles are simple in their structure, containing an average of 1.5 steps. The limited available data on Pacific rough-toothed dolphins suggest they produce broadband echolocation clicks from 10 to 90 kHz that can occur in a series or short bursts of 0.1-0.2 seconds.
- Kerem, D., O. Goffman, M. Elasar, N. Hadar, A. Scheinin, and T. Lewis. 2016. The rough-toothed dolphin, Steno bredanensis, in the Eastern Mediterranean Sea: a relict population? Chapter 8 in: Advances in Marine Biology, Volume 75. Pp 233-258.
- Oswald, J.N., J. Barlow, and T. F. Norris. 2003. Acoustic identification of nine delphinid species in the eastern tropical Pacific Ocean. Marine Mammal Science. 19(1): 20-37.
- Rankin, S. 2015. Vocalizations of the rough-toothed dolphin, Steno bredanensis, in the Pacific Ocean. Marine Mammal Science. 31(4): 1538-1548.
- Seabra de Lima, I.M., L. Guimaraes de Andrade, R. R. de Carvalho, J. Laislon-Brito Jr, and A. de Freitas Azevedo. 2012. Characteristics of whistles from rough-toothed dolphins (Steno bredanensis) in Rio de Janeiro coast, southeastern Brazil. Journal of the Acoustical Society of America. 131(5): 4173-4181.
- Guide to Marine Mammals of the World, National Audubon Society, pp 346-349