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Rough-toothed Dolphin (Steno bredanensis)

Status | Taxonomy | Species Description | Habitat | Distribution |
Population Trends | Threats | Conservation Efforts | Regulatory Overview |
Key Documents | More Info

  rought-toothed dolphin. (c) alison roberts.
Rough-toothed Dolphin
(Steno bredanensis)
Photo: © Alison Roberts, Pacific Whale Foundation



MMPA - Rough-toothed dolphins, like all marine mammals, are protected under the MMPA.
CITES Appendix II - throughout its range

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus: Steno
Species: 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 dolphins prefer deeper areas of tropical and warmer temperate waters where their prey are concentrated.

rough-toothed dolphin range map
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.

Population Trends
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.

Conservation Efforts
Rough-toothed dolphins are considered Data Deficient in the IUCN Redlist This link is an external site.. 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.

Regulatory Overview
This species is protected under the Marine Mammal Protection Act of 1972 as amended.

Key Documents
(All documents are in PDF format.)

Title Federal Register Date
Stock Assessment Reports n/a various

More Information

Updated: December 12, 2012

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