Rough-toothed Dolphin (Steno bredanensis)Species Description
Rough-toothed dolphins are small members of the dolphin group that reach a length of 8.5 feet (2.6 m) and weight of 350 pounds (160 kg).
They have a small head with a long beak with no crease at the melon. Their dorsal fin is relatively large and tall and is located at the mid-back and they have relatively long flippers (pectoral fins). Body color is dark with white lips and throat and a dark dorsal cape that is narrow between the blowhole and dorsal fin. The belly (ventral) surface has irregular spots and blotches.
Reproductive biology is poorly known in this species, but it is known that maturity occurs at 11 years of age and maximum longevity is 32 years.
Rough-toothed dolphins usually occur in tight-knit groups of 10 to 20. They often associate with other dolphins including short-finned pilot whales, bottlenose dolphins, pantropical spotted dolphins, and spinner dolphins. They apparently feed primarily on squids and fishes.
Rough-Toothed Dolphin Range Map
(click for larger view PDF)
Rough-toothed dolphins are found primarily in deep waters throughout tropical and warmer temperate areas of the world. There are two recognized stocks in the U.S.: Hawaii and Northern Gulf of Mexico.
Current population sizes for the different U.S. stocks are: Hawaii - 19,900 and Northern Gulf of Mexico - 2,220. There are not enough data to determine trends in these stocks. See below for links to the most recent stock assessments for the U.S. populations.
A few are "taken" in drive fisheries and there is some, probably small, bycatch in gillnet fisheries. There is no reported bycatch from U.S. fisheries, but they are known to take bait in commercial and recreational fisheries in the Main Hawaiian Islands. Strandings are moderately common; two in the Gulf region are thought to be related to fishery interactions. A mass stranding of 62 animals occurred off Marathon, Florida in March 2005.
Rough-toothed dolphins are considered Data Deficient in the IUCN Redlist . There are no known conservation efforts directed specifically at this species as they are poorly known and have few fishery interactions, and there are no other known threats.
|Stock Assessment Reports||n/a||various|
- Hawaii Odontocete Data Biases: Research Study [pdf]
- Public Debriefing from 2005 Florida Mass Stranding [pdf]
- NOAA's National Marine Sanctuaries
- Listen to Rough-toothed Dolphin Sounds
Updated: December 12, 2012