Striped Dolphin Taxonomy Physical Description Population And

The Striped Dolphin (Stenella coeruleoalba) is an extensively studied dolphin that is found in temperate and tropical waters of all the world's oceans.

1 Taxonomy

The Striped Dolphin is one of five species in the genus Stenella. It was discovered by Meyen in 1833. The specific name coeruleoalba refers to the characterisitic blue and white stripes on the flanks.

2 Physical description

The Striped Dolphin has a similar size and shape to several other dolphins that inhabit the waters that it does (see Pantropical Spotted Dolphin, Atlantic Spotted Dolphin, Clymene Dolphin). However its coloration is very conspicious and makes them relatively easy to distinguish at sea. The underside is white or pink. There are one or two dark blue bands that run from the bottom of the eye to the flipper. These bands widen to the width of the flipper which are the same size. There are two further blue stripes running from behind the ear - one is short and ends just above the flipper. The other is longer and thickens along the flanks until it curves down under the belly just prior to the tail stock. Above these stripes the dolphin's flanks are coloured light blue. The back, dorsal fin, melon and beak are dark blue. There is also a dark blue patch around the eyes. The lips are white. The tail stock is the same mid-blue colour as the middle stripe of the flank. At birth individuals weigh about 10kg and are up to a metre long. By adulthood they have grown to 2.4m (females) or 2.6 metres (males) and weigh 150kg (female) or 160kg (male). Research suggest that sexual maturity was reached at 12 years in Meditterranean females and in the Pacific at between 7 and 9 years. Longevity is about 55-60 years. Gestation lasts approximately 12 months and there is a three or four year gap between calving.

In common with other dolphins in its genus, the Striped Dolphin moves in large groups - usually in excess of 100 individuals in size. Groups may be smaller in the Meditterranean and Atlantic. They may also mix with Common DolphinThe Common Dolphin Delphinus delphis is the name given to two, or occasionally one species of dolphin, making up the genus Delphinus . Prior to the mid-1990s, most taxonomists only recognised one species in this genus, the Common Dolphin Delphinus delphiss. The Striped Dolphin is as capable as any dolphin at performing acrobatics - frequently breaching and jumping far above the surface of the water. Sometimes approaches boats in the Atlantic and Meditterranean but this is dramatically less common in other areas, particularly in the Pacific where it has been heavily exploited in the past.

3 Population and distribution

The Striped Dolphin likes temperate or tropical, off-shore waters. It is found in abudance in the North and South Atlantic Oceans, including the Meditterranean and Gulf of Mexico, the Indian Ocean and the Pacific Ocean. Roughly speaking it occupies a range running from 40° N to 30° S. It has been found in water temperatures ranging from 10 to 26 degrees celsius, though the standard range is 18-22 degrees. In the western Pacific, where the species has been extensively studied, a distinctive migratory pattern has been identified. This has not been the case in other areas. The dolphin appears to be common in all areas of its range, though that may not be continuous and aras of low population density do exist. The total population is in excess of two million.

4 Human interaction

Japan has hunted Striped Dolphin in the western Pacific since at least the 1940s. During the "Striped Dolphin drive" heyday at least 8-9 thousand species were killed each year and in one exceptional year 21,000 individuals were killed. Since the 1980s, following the introduction of quotas, this number has fallen to around 1,000 kills per year. Conservationists are concerned about the Meditterranean population which is threatened by population, disease, busy shipping lanes and heavy incidental catches in fishing nets.

Attempts have been made to keep the Striped Dolphin in captivity. However these have all failed, with animals dying within two weeks due to failure to feed.

5 References

Striped Dolphin by Frederick I. Archer II in Encyclopedia of Marine Mammals pp. 1201-1203. BooksEnthsiast.com
Whales Dolphins and Porpoises, Mark Carwardine, Dorling Kindersley Handbooks, BooksEnthsiast.com
National Audubon Society Guide to Marine Mammals of the World, Reeves, Stewart, Clapham and Powell, BooksEnthsiast.com

Cetaceans

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