Rough-toothed Dolphin -- Cetacean Info at Whale Songs

SCIENTIFIC NAME: Steno bredanensis

DISCOVERED: Lesson, 1828

COMMON NAME: Rough-Toothed Dolphin, Slopehead


* Distribution is poorly known
* Widespread in warm waters around the world- where sea temperature is above 77 degrees F (25 degrees C)
* Avoids cold surface waters and cold currents
* Sightings around Hawaii and off the coast of Brazil
* Permanent population in the Mediterranean


* Tall, falcate fin
* Conical head
* Beak continuous with forehead
* Dark, narrow cape- may have purplish hue
* Pinkish white blotches
* Long, narrow beak
* White "lips"
* White or pinkish white below
* Body robust in front of dorsal fin
* Long, narrow beak
* Broad flukes
* Keels below and above tail stock
* Some animals may be highly scarred
* Dark patch around large eyes



* Deep tropical, subtropical, and warm temperate waters around the world


* Mainly pelagic- pelagic octopus, squid and the remains of several species of pelagic fish have been found in stomachs


* Longest mature male was 2.65m and the longest female was 2.55m
* Average length of sexually mature animals in the western North Atlantic was 2.32 m for males and 2.31 m for females
* Longest reported foetus was 0.87m
* Average ages of sexually mature animals in the Western North Pacific was 14 years for males and 10 years for females
* Maximum ages of 32 and 30 years


* Difficult to observe
* May be submerged as long as 15 minutes
* Fast swimmer- sometimes porpoising with low, arc-shaped leaps
* Swims with dorsal fin and small part of back clearly visible
* Sometimes bow-rides- especially in front of fast-moving vessels
* May associate with Bottlenose Dolphins and pilot whales- less frequently with spinner dolphins and spotted dolphins- occasionally with shoals of yellowfish tuna
* May be seen logging
* 10-20 (1-50) - sometimes in groups of several hundred


* Not thought to be particularly numerous in any specific area- observations of herds of several hundred animals have been made
* May sometimes be confused with bottlenose dolphins
* Observers have not yet located areas of high relative abundance


* Direct general fishery for small cetaceans in the West Indies
* Very small numbers involved in the West Indies
* Also small direct fisheries in the Soloman Islands, Papua New Guinea and Japan
* Meat is used for human consumption
* Accidental captures and stranded specimens have also been used for human consumption in West Africa
* Small numbers taken in the Pacific tuna fishery
* Small gillnet fisheries in Sri Lanka and probably elsewhere in the Indian Ocean
* Incidental take in pelagic driftnet fisheries within the range