Atlantic Spotted Dolphin
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The Atlantic Spotted Dolphin (Stenella frontalis) is a dolphin found in the Gulf Stream of the North Atlantic Ocean. Older members of the species have a very distinctive spotted coloration all over their body.
Taxonomy
The Atlantic Spotted Dolphin was first identified by Cuvier in 1828. There is considerable variation in the physical form of individuals in the species and specialists have long been uncertain as to the correct taxonomic classification. Currently just one species is recognised, however it is quite possible that a large, particularly spotty variant commonly found near Florida may be classified as a formal subspecies or indeed a species in its own right.Physical description
The coloring of the Atlantic Spotted Dolphin varies enormously as they grow. Calves are a fairly uniform grey colour. When the calves are weaned, they then begin to get their spots. Juveniles have some dark spots on their belly, and white spots of their flanks. Their back and dorsal fin are a darker grey than the rest of the body. As the animal matures the spots became denser and spread all over the body until at full physical maturation the body appears black with white spots.At full size Atlantic Spotted Dolphins are about 2.2-2.5m in length. They may easily be confused with the Common Bottlenose Dolphin and the Pantropical Spotted Dolphin when observed at sea.
In common with other species in its genus the Atlantic Spotted is a gregarious creature. It is a fast swimmer, keen bow-rider and prone to acrobatic aerial displays.
Population and distribution
The species is endemic to the temperate and tropical areas of the Atlantic Ocean. It has been widely observed in the western end of the Gulf Stream, between Florida and Bermuda. It is also present in the Gulf of Mexico. More infrequent sightings have been made further east, off the Azores and Canary Islands. Northerly sightings have been made as far north as Cape Cod across to the south-western tip of Spain. They are certainly present further south too as far as Rio Grande do Sul in Brazil and across to west Africa. However the distribution is poorly understood in these areas.About 20 years ago, there where only about 80 dolphins in the Bahamas. Now, 20 years later, there are almost 200 dolphins there. On account of their similar appearance to other dolphins in their range it is difficult to be sure of the Atlantic Spotted Dolphin's population. A conservative estimate is around 100,000 individuals.
Human interaction
Some Atlantic Spotted Dolphins, particularly some of those are around The Bahamas have become habituated to human contact. In these areas cruises to watch and even swim with the dolphins are common. Scientists have also taken advantage of the situation by attaching radio transmitters to the dorsal fins of some individuals and observing their movement patterns.Atlantic Spotted Dolphins are an occasional target of harpoon fishermen and every year some creatures are trapped and killed in gillnets. However these activities are not currently believed to threatening the survival of the species.
References
- Cetacean Specialist Group (1996). [Stenella frontalis]. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006. Database entry includes justification for why this species is listed as data deficient
- Whales Dolphins and Porpoises, Mark Carwardine, Dorling Kindersley Handbooks, ISBN 0751327816
- National Audubon Society Guide to Marine Mammals of the World, Reeves, Stewart, Clapham and Powell, ISBN 0375411410
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