Habitat:  Oceanic

Rough-toothed dolphins are seen most commonly in groups of 10-20, although herds of over 100 have been reported. They may appear lethargic and rarely bowride. At other times, they move at high speed with the chin and head above the surface, in a distinctive skimming behavior described as "surfing." In the eastern tropical Pacific, they tend to associate with floating objects and sometimes with other cetaceans.

Sexual maturity is reached at approximately 10 years for females and approximately 14 years for males. The rough-toothed dolphin is thought to live up to 32 years.

Feeding mode:  Seizing

Rough-toothed dolphins feed on cephalopods and fish, including such large fish as mahi mahi (also called dorado or dolphinfish). Recently, it has been suggested that these dolphins may be adapted to be specialist feeders on mahi mahi.

Known prey species:

Invertebrates:  Teuthowenia sp., Tremoctopus violaceus

Fish:  Pranesus insularum, Cololabis adocetus, Tylosurus crocodilus, Coryphaena hippurus

Main threats:

Harvest

Fisheries bycatch

Conservation status:

The IUCN lists the rough toothed dolphin as “data deficient”, as too little is known about the species to assess its conservation status.  This species is not listed as threatened or endangered by the U.S. government.  No fisheries are known to specialize on this species, but rough-toothed dolphins are one of several species killed in direct fisheries in Japan, Sri Lanka, Indonesia, the Caribbean, Papua New Guinea, the Solomon Islands, and West Africa.  They are sometimes taken as by-catch in purse seine fisheries for tuna in the eastern tropical Pacific, and in gillnet fisheries in Sri Lanka, Brazil, and the offshore North Pacific.  Their offshore distribution in most areas should reduce their potential problems of habitat loss and alteration.

NMFS has estimated the population of two stocks in U.S. waters.  The northern Gulf of Mexico population is estimated at 852 (CV=0.31) based on data from 1991-1995 surveys, and the Hawaiian stock is estimated to be 123 (CV=0.63) based on surveys conducted in 1993, 1995, and 1998.

For current information on the conservation status of this species, please consult the following websites.

CITES web-page

Convention on Migratory Species (Appendix II)

International Whaling Commission

U.S. NMFS Stock Assessment Reports

Genetics Genbank

Images Google Images

Museum Collections Smithsonian Institution

Acoustics Cornell/Macaulay Library

Jefferson, T.A. 2002. Rough-toothed dolphin Steno bredanensis. Pp. 1055-1059 in W.F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.

Lodi, L., and B. Hetzel. 1999. Rough-toothed dolphin, Steno bredanensis, feeding behaviors in Ilha Grande Bay, Brazil. Biociencias 7:29-42.

Miyazaki, N., and W.F. Perrin. 1994. Rough-toothed dolphin Steno bredanensis (Lesson, 1828). Pp. 1-21 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Volume 5 The first book of dolphins. Academic Press.

Pitman, R.L., and C. Stinchcomb. 2002. Rough-toothed dolphins (Steno bredanensis) as predators of mahimahi (Coryphaena hippurus). Pacific Science 56:447-450.

Watkins, W.A., P. Tyack, K.E. Moore, and G. Notarbartolo di Sciara. 1987. Steno bredanensis in the Mediterranean Sea. Marine Mammal Science 3:78-82.