Atlantic spotted dolphin - Stenella frontalis

Scientific Name	Stenella frontalis
Author	(G. Cuvier, 1829)
Taxonomic Rank	Species
Taxonomic #	552460
Common Names	English: Atlantic Spotted Dolphin Spanish: Delfín embridado
Taxonomic Parents	Kingdom: Animalia   Phylum: Chordata     Subphylum: Vertebrata       Class: Mammalia         Subclass: Theria           Infraclass: Eutheria             Order: Cetacea               Suborder: Odontoceti                 Family: Delphinidae                   Genus: Stenella
Taxonomic Children
Synonyms (since 1950)	Delphinus doris Delphinus froenatus Delphinus pernettensis Stenella pernettyi Clymenia frontalis Delphinus frontalis Prodelphinus frontalis Stenella fontolis Delphinus fraenatus Prodelphinus froenatus Delphinus plagiodon Stenella plagiodon Stenella fontalis

Taxonomic data is courtesy of the Integrated Taxonomic Information System (ITIS)

Atlantic spotted dolphins begin life with unspotted background coloration. Young animals look much like slender bottlenose dolphins, with a dark cape, light gray sides, spinal blaze (variable in its development), and white belly. Development of larger spots on both dorsal and ventral surfaces progresses as the animal ages; some individuals become so heavily spotted that the cape margin and spinal blaze are obscured. However, in some populations, adults are essentially unspotted (these are generally in offshore areas).

The Atlantic spotted dolphin in many ways resembles the Indo-Pacific bottlenose dolphin more than it does the pantropical spotted dolphin. In body shape, it is intermediate between the two, with a moderately long but rather chunky beak. There is a distinct crease between the melon and beak and 30-42 teeth in each tooth row.

Adults are up to 2.3 m long and 143 kg in weight. Newborn Atlantic spotted dolphins are 0.8-1.2 m long.

Atlantic spotted dolphins can be most easily confused with bottlenose dolphins (although they do not overlap in distribution with the Indo-Pacific species). The differences in size and robustness are good clues, but may require a trained eye to distinguish. Heavy spotting is a good characteristic for Atlantic spotted dolphins; however, some may be nearly unspotted and some bottlenose dolphins may have spotting and blotches on the belly and sides. Pantropical spotted dolphins also may be difficult to distinguish, but attention to body robustness, beak and dorsal fin shape, and color pattern differences will allow them to be separated.

Range:Tropical/Warm temperate

This species is found only in the Atlantic Ocean, from southern Brazil to New England in the west, and to the coast of Africa in the east (the exact limits off West Africa are not well known). Their tropical to warm temperate distribution is mostly over the offshore continental shelf, but they also inhabit some deep oceanic waters.

Habit:Shelf/Slope

Small to moderate groups, generally of less than 50 individuals, are characteristic of the Atlantic spotted dolphin. Coastal groups usually consist of 5-15 animals. These are acrobatic animals and they are known to be avid bowriders. Studies of Atlantic spotted dolphins off the Bahamas, which allow people to swim with them, show that these animals have a fluid group structure, like that of bottlenose and other small dolphins. There is not much known of the species' life history, but tropical populations would be expected to have a protracted breeding season.

Diet dominated by:Fish > squid > other invertebrates

A wide variety of epi- and mesopelagic fishes and squids, as well as benthic invertebrates, are taken by this species.

Feeding mode:Seizing

Known prey species:

Fish: Peprilus paru, Isopisthus parvipinnis, Raneya fluminensis, Orthopristis ruber, Cynoscion guatucupa, Ariosoma opithophthalma, Trichiurus lepturus

Cephalopods:Loligo plei, Loligo sanpaulensis

Main threats:

Fisheries bycatch

Conservation status:

The IUCN lists this species is “data deficient, in that too little is known to evaluate its conservation status. The U.S. government does not list the Atlantic spotted dolphin as threatened or endangered. Incidental catches in fisheries are known for several areas of the range (Brazil, the Caribbean, off the east coast of the United States, and in Mauritania). No direct killing is known, other than occasional catches in the Caribbean dolphin fisheries. Based on two 1998 surveys, NMFS estimated the population of all spotted dolphins in the western North Atlantic (including S. frontalis and S. attenuata) to be 52,279 (CV=0.87). Data from surveys between 1991 and 1994 was used to estimate the northern Gulf of Mexico Stock at 32,123 (CV=0.44), although NMFS considers this an underestimate due to survey limitations.

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

CITES web-page

International Whaling Commission

U.S. NMFS Stock Assessment Reports

Genetics Genbank

Images Google Images

Museum Collections Smithsonian Institution

Herzing, D.L. 1997. The life history of free-ranging Atlantic spotted dolphins (Stenella frontalis) Age classes, color phases, and female reproduction. Marine Mammal Science13576-595.

Perrin, W.F. 2002. Stenella frontalis. Mammalian Species 702:1-6.

Perrin, W.F. 2002. Atlantic spotted dolphin Stenella frontalis. Pp. 49-51 in W.F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.

Perrin, W.F., et al. 1987. Revision of the spotted dolphins, Stenella spp. Marine Mammal Science 3:99-170.

Perrin, W.F., D.K. Caldwell, and M.C. Caldwell. 1994. Atlantic spotted dolphin Stenella frontalis (G. Cuvier, 1829). Pp. 173-190 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Volume 5 The first book of dolphins. Academic Press.