Atlantic spotted dolphin (Stenella frontalis)

French: Dauphin Tacheté De L'Atlantique
Spanish: Delfín Manchado Del Atlántico, Delfín Pintado
KingdomAnimalia
PhylumChordata
ClassMammalia
OrderCetartiodactyla
FamilyDelphinidae
GenusStenella (1)
SizeLength: 166 – 229 cm (2)
Weightup to 143 kg (2)

Classified as Data Deficient (DD) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

Often observed in the clear, shallow waters surrounding the Bahamas, the Atlantic spotted dolphin is said to be an intermediate in appearance between the bottlenose dolphin and pantropical spotted dolphin (4). Its sturdy body is light grey, with a dark grey ‘cape’ on the back, and a white belly (4). A light streak extends up the shoulder, ending just below the dorsal fin, one feature which differentiates this species from the similar pantropical spotted dolphin (2). As the name suggests, many individuals are patterned with spots, although not all. All calves are unspotted (4), but some will develop spots as they age, with a number of dolphins becoming so heavily spotted they appear white from a distance (2). The beak of the Atlantic spotted dolphin is fairly long and sharply demarcated from the melon, and the dorsal fin is tall and sickle-shaped. Atlantic spotted dolphins inhabiting the far-offshore waters of the Gulf Stream can be smaller and completely unspotted, even as adults (2).

Found only in the Atlantic, this spotted dolphin occurs from southern Brazil to New England in the west, to the coast of Africa in the east (4), generally between 50°N and 25°S (2).

The Atlantic spotted dolphin inhabits tropical and warm temperate waters. It is found most often in waters over the continental shelf, but may also inhabit deep oceanic waters in some areas (4). In the Bahamas, this species can be observed in clear, shallow waters, between 6 and 12 metres deep, over sandflats (2).

This social marine mammal forms groups consisting of up to 100 individuals (2); those inhabiting coastal areas generally form the smallest schools, of 5 to 15 dolphins (4). These schools, which may be segregated by age and sex, have a fluid structure, with dolphins joining and splitting into smaller groups, although long-term bonds are also formed within this gregarious social system (2) (5). In the Bahamas, Atlantic spotted dolphins are often known to associate with bottlenose dolphins as they travel and search for fish, squid and bottom-dwelling invertebrates on which to feed (2).

The Atlantic spotted dolphin is an acrobatic species, frequently riding the bow waves of boats (4), leaping out of the water, and playing at every opportunity (5). It is also capable of diving to up to 60 metres, remaining underwater for up to 6 minutes (2). It is known to be preyed on by sharks, but killer whales and other small-toothed whales may also be predators of this dolphin (2).

Mature female Atlantic spotted dolphins give birth every one to five years, with the average interval between births being three years. The young is nursed for up to five years, and females become sexually mature at an estimated eight to fifteen years of age (2).

There are two potential threats facing this dolphin; it is hunted in the Caribbean Sea, and possibly elsewhere along the coast of South America and West Africa, for food or bait (6), and it is killed incidentally in fisheries in many parts of its range when it becomes entangled in fishing gear (2). However, it is not known how many Atlantic spotted dolphins are killed in this manner, and therefore it is not known to what extent this species is threatened with extinction; consequently, the IUCN have classified this species as Data Deficient (1).

While the Atlantic spotted dolphin has been extensively studied in the Bahamas (2), information on the global status of this species is lacking (1). Further research may be required to determine this dolphin’s conservation status and what, if any, conservation measures need to be implemented. While hunting of the Atlantic spotted dolphin continues in some areas (6), elsewhere, dolphin-watching tours give the opportunity for people to see these charismatic animals at sea (5), and provide an incentive for local people to conserve them.

For further information on the conservation of dolphins see:

Authenticated (17/11/07) by William F. Perrin, Senior Scientist for Marine Mammals, National Marine Fisheries Service, Southwest Fisheries Science Centre.
http://swfsc.noaa.gov

  1. IUCN Red List (November, 2008)
    http://www.iucnredlist.org
  2. Perrin, W.F. (2008) Atlantic spotted dolphin. In: Perrin, W.F., Würsig, B. and Thewissen, J.G.M. (Eds) Encyclopedia of Marine Mammals. Second Edition. Academic Press, London.
  3. CITES (April, 2008)
    http://www.cites.org
  4. Jefferson, T.A., Leatherwood, S. and Webber, M.A. (1993) FAO Species Identification Guide. Marine Mammals of the World. FAO, Rome.
  5. Carwardine, M., Hoyt, E., Fordyce, R.E. and Gill, P. (1998) Whales and Dolphins. HarperCollins Publishers, London.
  6. Reeves, R.R., Smith, B.D., Crespo, E.A. and Notarbartolo di Sciara, G. (2003) Dolphins, Whales and Porpoises: 2002–2010 Conservation Action Plan for the World’s Cetaceans. IUCN/SSC Cetacean Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK.