Steno bredanensis 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Cetartiodactyla Delphinidae

Scientific Name: Steno bredanensis (G. Cuvier in Lesson, 1828)
Regional Assessments:
Common Name(s):
English Rough-toothed Dolphin
French Sténo
Spanish Delfín de Pico Largo

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2008-07-01
Assessor(s): Hammond, P.S., Bearzi, G., Bjørge, A., Forney, K.A., Karkzmarski, L., Kasuya, T., Perrin, W.F., Scott, M.D., Wang, J.Y. , Wells, R.S. & Wilson, B.
Reviewer(s): Rojas-Bracho, L. & Smith, B.D.
The species is widespread and abundant (with current population estimates around 150,000) and there have been no reported population declines or major threats identified.
Previously published Red List assessments:

Geographic Range [top]

Range Description:The Rough-toothed Dolphin is a tropical to subtropical species, which generally inhabits deep, oceanic waters of all three major oceans, rarely ranging north of 40°N or south of 35°S (Jefferson 2002). However, in some areas (such as off the coast of Brazil and West Africa), rough-toothed dolphins may occur in more shallow coastal waters. They are found in many semi-enclosed bodies of water (such as the Gulf of Thailand, Red Sea, Gulf of Mexico, Caribbean Sea, and Gulf of California), but they are regarded as visitors in the Mediterranean Sea (Watkins et al. 1987, Miyazaki and Perrin 1994, Reeves and Notarbartolo di Sciara 2006).

The map shows where the species may occur based on oceanography. The species has not been recorded for all the states within the hypothetical range as shown on the map. States for which confirmed records of the species exist are included in the list of native range states. States within the hypothetical range but for which no confirmed records exist are included in the Presence Uncertain list.
Countries occurrence:
Algeria; American Samoa; Angola; Anguilla; Antigua and Barbuda; Aruba; Australia; Bahamas; Bangladesh; Barbados; Belize; Benin; Bonaire, Sint Eustatius and Saba (Saba, Sint Eustatius); Brazil; British Indian Ocean Territory; Brunei Darussalam; Cambodia; Cameroon; Cape Verde; Cayman Islands; Chile; China; Cocos (Keeling) Islands; Colombia; Comoros; Congo; Congo, The Democratic Republic of the; Cook Islands; Costa Rica; Côte d'Ivoire; Cuba; Curaçao; Djibouti; Dominica; Dominican Republic; Ecuador; El Salvador; Equatorial Guinea; Fiji; France (Corsica); French Guiana; French Polynesia; Gabon; Gambia; Ghana; Gibraltar; Greece (Kriti); Grenada; Guadeloupe; Guam; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras; Hong Kong; India; Indonesia; Iran, Islamic Republic of; Israel; Italy (Sardegna, Sicilia); Jamaica; Japan; Kenya; Kiribati; Kuwait; Liberia; Libya; Madagascar; Malaysia; Maldives; Marshall Islands; Martinique; Mauritania; Mexico; Micronesia, Federated States of ; Morocco; Mozambique; Myanmar; Namibia; Nauru; New Caledonia; Nicaragua; Nigeria; Niue; Northern Mariana Islands; Oman; Pakistan; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Portugal; Puerto Rico; Qatar; Saint Helena, Ascension and Tristan da Cunha; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Vincent and the Grenadines; Samoa; Sao Tomé and Principe; Senegal; Seychelles; Sierra Leone; Singapore; Sint Maarten (Dutch part); Solomon Islands; Somalia; South Africa; Spain (Baleares, Canary Is.); Sri Lanka; Suriname; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Timor-Leste; Togo; Tonga; Trinidad and Tobago; Turks and Caicos Islands; United Arab Emirates; United States; Venezuela, Bolivarian Republic of; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Wallis and Futuna; Western Sahara; Yemen
FAO Marine Fishing Areas:
Atlantic – western central; Atlantic – eastern central; Atlantic – northeast; Atlantic – southeast; Atlantic – southwest; Indian Ocean – western; Indian Ocean – eastern; Mediterranean and Black Sea; Pacific – southwest; Pacific – western central; Pacific – northeast; Pacific – eastern central; Pacific – northwest; Pacific – southeast
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:There are few estimates of abundance for this species. An estimated 145,900 (CV=32%) Rough-toothed Dolphins inhabit the eastern tropical Pacific (Wade and Gerrodette 1993), and about 2,746 (CV=36%) occur in the northern Gulf of Mexico (Waring et al. 2008), including an estimated 1,238 (CV=65%) on the continental shelf (Fulling et al. 2003). The US NMFS has estimated the regional population around Hawaii to be 19,904 (CV=52%), based on recent vessel surveys (Carretta et al. 2006).
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Most often, Steno bredanensis is found in deep water far offshore, usually beyond the continental shelf (Maigret 1994), but may be seen close inshore in areas of steep bottom relief (Ritter 2002). In the eastern tropical Pacific, they tend to associate with other cetaceans (especially pilot whales and Fraser’s dolphins) (Miyazaki and Perrin 1994). Rough-toothed Dolphins feed on cephalopods and fish, including large fish such as Coryphaena hippurus (Pitman and Stinchcomb 2002).

Use and Trade [top]

Use and Trade: It is harvested in small numbers in a few places.

Threats [top]

Major Threat(s): No fisheries are known to specifically target this species, but small numbers are taken in drive fisheries at Okinawa in the Ryukyus and other islands of Japan, the Solomon Islands and Papua New Guinea, by harpoon in Japan, St. Vincent in the Lesser Antilles, and in West Africa. They were possibly formerly were taken at St. Helena in the South Atlantic. However, only 23 Rough-toothed Dolphins were captured in Japan (Okinawa) during the period 1976-81 (Miyazaki and Perrin 1994). Recent information suggests catches in Taiwan (J. Wang pers. comm.).

A few Rough-toothed Dolphins are killed incidentally in tuna purse seines in the eastern tropical Pacific: 21 were estimated killed during the period 1971-75 and 36 died in a single net haul in 1982. Small numbers are also taken as by-catch in gillnet and driftnet fisheries in Sri Lanka, Brazil, the central North Pacific and probably elsewhere around the world in tropical and warm-temperate waters (Miyazaki and Perrin 1994). Monteiro-Neto et al. (2000) reported on fishery-related mortality along the coast of Ceara State, northeast Brazil, commenting on the possible conservation implications for the local subpopulations. Seasonally, incidental catches were more frequent during the austral spring (October-December). Rough-toothed Dolphins are also taken by gill nets, driftnets and pelagic long-lines in Taiwan (J. Wang pers. comm.).

Conservation Actions [top]

Conservation Actions: The species is listed in Appendix II of CITES.

The biology, life history, population size, and separation into subpopulations, as well as migratory behaviour are insufficiently known. Research on this species should be encouraged.

Classifications [top]

9. Marine Neritic -> 9.1. Marine Neritic - Pelagic
suitability:Suitable  major importance:Yes
10. Marine Oceanic -> 10.1. Marine Oceanic - Epipelagic (0-200m)
suitability:Suitable  major importance:Yes

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
In-Place Species Management
In-Place Education
  Included in international legislation:Yes
  Subject to any international management/trade controls:Yes
5. Biological resource use -> 5.4. Fishing & harvesting aquatic resources -> 5.4.3. Unintentional effects: (subsistence/small scale) [harvest]
♦ timing:Ongoing    
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

1. Research -> 1.2. Population size, distribution & trends
1. Research -> 1.5. Threats
3. Monitoring -> 3.1. Population trends

♦  Food - human
 Local : ✓ 

Bibliography [top]

Carretta, J. V., Forney, K. A., Muto, M. M., Barlow, J., Baker, J., Hanson, J. and Lowry, M. S. 2006. U.S. Pacific marine mammal stock assessments: 2005. NOAA Technical Memorandum NMFS-SWFSC.

Fulling, G. L., Mullin, K. D. and Hubard, C. W. 2003. Abundance and distribution of cetaceans in outer continental shelf waters of the U.S. Gulf of Mexico. Fishery Bulletin 101: 923-932.

IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.2). Available at: (Accessed: 17 October 2012).

Keller, R. W., Leatherwood, S. and Holt, S. J. 1982. Indian Ocean cetacean survey, Seychelle Islands, April through June 1980. Reports of the International Whaling Commission 32: 503-515.

Maigret, J. 1994. Steno bredanensis (Lesson, 1828) - rauhzahndelphin (auch langschnauzendelphin). In: D. Robineau, R. Duguy and M. Klima (eds), Handbuch der saugetiere Europas, pp. 269-280. AULA-Verlag Wiesbaden.

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

Monteiro-Neto, C., Alves-Junior, T. T., Avila, F. J. C., Campos, A. A., Costa, A. F., Silva, C. P. N. and Furtado-Neto, M. A. A. 2000. Impact of fisheries on the tucuxi (Sotalia fluviatilis) and rough-toothed dolphin (Steno bredanensis) populations off Ceara state, northeastern Brazil. Aquatic Mammals 26(1): 49-56.

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

Reeves, R. R. and Notarbartolo Di Sciara, G. 2006. The status and distribution of cetaceans in the Black Sea and Mediterranean Sea. IUCN Centre for Mediterranean Cooperation, Malaga, Spain.

Ritter, F. 2002. Behavioural observations of rough-toothed dolphins (Steno bredanensis) off La Gomera, Canary Islands (1995-2000), with special reference to their interactions with humans. Aquatic Mammals 28(1): 46-59.

Wade, P. R. and Gerrodette, T. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific. Reports of the International Whaling Commission 43: 477-493.

Waring, G. T., Josephson, E., Fairfield, C. P. and Maze-Foley, K. 2008. U.S. Atlantic and Gulf of Mexico marine mammal stock assessments - 2007. NOAA Technical Memorandum. NOAA.

Watkins, W. A., Tyack, P., Moore, K. E. and Notarbartolo Di Sciara, G. 1987. Steno bredanensis in the Mediterranean Sea. Marine Mammal Science 3(1): 78-82.

Weir, C.R. 2006. Sightings of rough-toothed dolphins (Steno bredanensis) off Angola and Gabon, south-east Atlantic Ocean. European Cetacean Society Newsletter, Abstracts 20: 216.

Citation: Hammond, P.S., Bearzi, G., Bjørge, A., Forney, K.A., Karkzmarski, L., Kasuya, T., Perrin, W.F., Scott, M.D., Wang, J.Y. , Wells, R.S. & Wilson, B. 2012. Steno bredanensis. In: . The IUCN Red List of Threatened Species 2012: e.T20738A17845477. . Downloaded on 22 February 2018.
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