The striped dolphin (''Stenella coeruleoalba'') is an extensively studied
dolphin
A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the ...
found in
temperate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
and
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
waters of all the world's oceans. It is a member of the
oceanic dolphin
Oceanic dolphins or Delphinidae are a widely distributed family of dolphins that live in the sea. Close to forty extant species are recognised. They include several big species whose common names contain "whale" rather than "dolphin", such as the ...
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
, Delphinidae.
Taxonomy
The striped dolphin is one of five species traditionally included in the genus ''
Stenella''; however, recent genetic work by LeDuc ''et al.'' (1999) indicates ''Stenella'', as traditionally conceived, is not a natural group. According to that study, the closest relatives of the striped dolphin are the
Clymene dolphin
The Clymene dolphin (''Stenella clymene''), in older texts known as the short-snouted spinner dolphin, is a dolphin endemic to the Atlantic Ocean. It is the only confirmed case of hybrid speciation in marine mammals, descending from the spinner ...
, the
common dolphin
The common dolphin (''Delphinus delphis'') is the most abundant cetacean in the world, with a global population of about six million. Despite this fact and its vernacular name, the common dolphin is not thought of as the archetypal dolphin, with ...
s, the
Atlantic spotted dolphin
The Atlantic spotted dolphin (''Stenella frontalis'') is a dolphin found in warm temperate and tropical waters of the Atlantic Ocean. Older members of the species have a very distinctive spotted coloration all over their bodies.
Taxonomy
The Atl ...
, and ''
"Tursiops" aduncus'', which was formerly considered a subspecies of the
common bottlenose dolphin
The common bottlenose dolphin or Atlantic bottlenose dolphin (''Tursiops truncatus'') is a wide-ranging marine mammal of the family Delphinidae. The common bottlenose dolphin is a very familiar dolphin due to the wide exposure it gets in captivi ...
. The striped dolphin was described by
Franz Meyen
Franz Julius Ferdinand Meyen (28 June 1804 – 2 September 1840) was a Prussian physician and botanist.
Meyen was born in Tilsit, East Prussia. In 1830 he wrote ''Phytotomie'', the first major study of plant anatomy. Between 1830 and 1832, he too ...
in 1833.
Description
The striped dolphin has a similar size and shape to several other dolphins that inhabit the waters it does (see
pantropical spotted dolphin
The pantropical spotted dolphin (''Stenella attenuata'') is a species of dolphin found in all the world's temperate and tropical oceans. The species was beginning to come under threat due to the killing of millions of individuals in tuna purse s ...
, Atlantic spotted dolphin, Clymene dolphin). However, its colouring is very different and makes it relatively easy to notice at sea. The underside is blue, white, or pink. One or two black bands circle the eyes, and then run across the back, to the flipper. These bands widen to the width of the flipper which are the same size. Two further black stripes run 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 or grey. All appendages are black, as well. At birth, individuals weigh about 10 kg (22 lb) and are up to a meter (3 feet) long. By adulthood, they have grown to 2.4 m (8 ft) (females) or 2.6 m (8.5 ft) (males) and weigh 150 kg (330 lb) (female) or 160 kg (352 lb) (male). Research suggested sexual maturity was reached at 12 years in Mediterranean females and in the Pacific at between seven and 9 years. Longevity is about 55–60 years.
Gestation
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregna ...
lasts about 12 months, with a three- or four-year gap between calving.
In common with other dolphins in its genus, the striped dolphin moves in large groups — usually up to thousands of individuals in number. Groups may be smaller in the Mediterranean and Atlantic. They may also mix with common dolphins. The striped dolphin is as capable as any dolphin at performing acrobatics — frequently breaching and jumping far above the surface of the water. Sometimes, it approaches boats in the Atlantic and Mediterranean, but this is dramatically less common in other areas, particularly in the Pacific, where it has been heavily exploited in the past. Striped dolphins are known as “streakers” throughout the eastern tropical Pacific due to their behavior of rapidly swimming away from vessels to avoid collisions
The striped dolphin feeds on small
pelagic fish
Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that do live on or near the bottom, and reef fish that are associated with coral reef ...
and
squid
True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...
.
Population and distribution
![Delfine im Golf von Korinth, Griechenland](https://upload.wikimedia.org/wikipedia/commons/7/74/Delfine_im_Golf_von_Korinth%2C_Griechenland.jpg)
The striped dolphin inhabits temperate or tropical, off-shore waters. It is found in abundance in the North and South Atlantic Oceans, including the Mediterranean (sightings and strandings have been reported rather recently in
Sea of Marmara
The Sea of Marmara,; grc, Προποντίς, Προποντίδα, Propontís, Propontída also known as the Marmara Sea, is an inland sea located entirely within the borders of Turkey. It connects the Black Sea to the Aegean Sea via the ...
) and
Gulf of Mexico
The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
, the
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
, 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 °C, though the standard range is 18-22 °C. In the western Pacific, where the species has been extensively studied, a distinctive migration 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; areas of low population density do exist. The total population is in excess of two million. The southernmost record is of a stranded individual nearby
Dunedin
Dunedin ( ; mi, Ōtepoti) is the second-largest city in the South Island of New Zealand (after Christchurch), and the principal city of the Otago region. Its name comes from , the Scottish Gaelic name for Edinburgh, the capital of Scotland. Th ...
, southern New Zealand in 2017.
Human interaction
Japanese whalers have hunted striped dolphins in the western Pacific since at least the 1940s. In the heyday of "striped dolphin drives", at least 8,000 to 9,000 individuals 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 Mediterranean population which is threatened by pollution, disease, busy shipping lanes, and heavy incidental catches in fishing nets such as long-liners, trawlers, gill nets, trammel and purse seine nets. . Recent threats include military sonar, and chemical pollution from near by harbors.
Hydrocarbons are also a major concern such has PCBs (polychlorinated biphenyls) and HCB (hexachlorobenzene). These are said to give problems to additional food chains as well as doing a full body test to see what hydrocarbons may be passed down through parturition and lactation.
Attempts have been made to keep the striped dolphin in captivity, but most have failed, with the exception of a few captured in Japan for the Taiji Whale Museum.
Striped dolphins are one of the targeted species in the
Taiji dolphin drive hunt
The Taiji dolphin drive hunt is based on driving dolphins and other small cetaceans into a small bay where they can be killed or captured for their meat and for sale to dolphinariums. The new primary killing method is done by cutting the spinal ...
.
Diet
The adult striped dolphin eats fish, squid, octopus, krill, and other crustaceans. Mediterranean striped dolphins seem to prey primarily on cephalopods (50-100% of stomach contents), while northeastern Atlantic striped dolphins most often prey on fish, frequently cod. They mainly feed on cephalopods, crustaceans, and bony fishes. They feed anywhere within the water column where prey is concentrated, and they can dive to depths of 700 m to hunt deeper-dwelling species.
Conservation
![Delfines-gijon](https://upload.wikimedia.org/wikipedia/commons/7/74/Delfines-gijon.jpg)
The eastern tropical Pacific and Mediterranean populations of the striped dolphin are listed on Appendix II
[Appendix II]
" of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009. of the Convention on the Conservation of Migratory Species of Wild Animals (
CMS
CMS may refer to:
Computing
* Call management system
* CMS-2 (programming language), used by the United States Navy
* Code Morphing Software, a technology used by Transmeta
* Collection management system for a museum collection
* Color managem ...
), since they have an unfavorable conservation status or would benefit significantly from international co-operation organized by tailored agreements.
On the IUCN Red List the striped dolphin classifies as vulnerable due to a 30% reduction in its subpopulation over the last three generations. These dolphins may also be an indicator species for long term monitoring of heavy metal accumulation in the marine environment because of its importance in the Japan pelagic food web as well as its ability to live for many years.
In addition, the striped dolphin is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (
ASCOBANS
Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas, often abbreviated to ASCOBANS, is a regional agreement on the protection of small cetaceans that was concluded as the Agreement on the Con ...
), the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (
ACCOBAMS), the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (
Pacific Cetaceans MOU) and the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (
Western African Aquatic Mammals MoU)
Conservation efforts have included having ship lines take a new path to their destination such as cruise lines as well as reduced human interaction close up. Feeding the dolphins has also become a problem, and has led to behavioral changes. This has also been suggested as another reason for mortality events.
Strandings and mortality
The striped dolphin once thrived, numbering 117,880 before 1990. Since then, the population has suffered from incidental catches in fisheries. Mortality has been considered unsustainable, but there is a lack of data which hampers conservation efforts.
Various cases of stranding over the years have been a cause for alarm. With an unfavorable conservation status and the increasing amount of debris piling in the ocean every year, striped dolphin's population is decreasing. 37 dolphins stranded off the Spanish Mediterranean coast were suffering from dolphin
morbillivirus
''Morbillivirus'' is a genus of viruses in the order ''Mononegavirales'', in the family ''Paramyxoviridae''. Humans, dogs, cats, cattle, seals, and cetaceans serve as natural hosts. This genus includes seven species. Diseases in humans associate ...
(DMV). The causes of these stranding have been changing from epizootic to enzootic.
Cetacean morbillivirus (CeMV) can be divided into six strains in cetaceans throughout the world, causing widespread mortality events in Europe, North America, and Australia. Studies have indicated that characteristics of CeMV may be more closely associated with disease in ruminants than carnivore species, which is representative of their evolutionary histories. Common disease presentation includes broncointerstitial pneumonia, encephalitis, lymphocytopenia, and increases in multinucleated cells. CeVM causes immunosuppression, increasing risk to secondary infection following acute resolution of clinical signs. Hypothesized transmission routes include via aerosol and trans-placentally.
The unusual mortality events (UMEs) among striped dolphins suggest that parasitic diseases may be increasing in the open ocean due to
anthropogenic causes. In addition, case reports indicate nematodes present in the brain of the striped dolphin, described as a single round and thin worm with numerous eggs in the subcortical lesions, including the optic nerve. It is hypothesized this worm belongs to the genus Contracaecum, the same genus which has been reported to infect the brains of sea lions. Caution should be employed when handling these animals due to the possibility of a serious injury if the right steps are not taken in order to ensure both human and animal safety.
See also
*
List of cetaceans
Cetacea is an infraorder that comprises the 94 species of whales, dolphins, and porpoises. It is divided into toothed whales (Odontoceti) and baleen whales (Mysticeti), which diverged from each other in the Eocene some 50 mya (unit), million years ...
*
Marine biology
Marine biology is the scientific study of the biology of marine life, organisms in the sea. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies s ...
References
# LeDuc, R.G., W.F. Perrin and A.E. Dizon (1999). Phylogenetic relationships among the delphinid cetaceans based on full cytochrome ''b'' sequences. Marine Mammal Science, vol. 15, no. 3:619-648.
# ''Striped Dolphin'' by Frederick I. Archer II in ''Encyclopedia of Marine Mammals'' pp. 1201–1203.
# Eds. C.Michael Hogan and C.J.Cleveland. 2011
Striped dolphin. Encyclopedia of Earth with content partner EOL, National Council for Science and Environment, Washington, DC# ''Whales Dolphins and Porpoises'', Mark Carwardine, Dorling Kindersley Handbooks,
# ''National Audubon Society Guide to Marine Mammals of the World'', Reeves, Stewart, Clapham and Powell,
[Martin, W. E., et al. “Nematode Damage to Brain of Striped Dolphin, Lagenorhynchus Obliquidens.” Transactions of the American Microscopical Society, vol. 89, no. 2, 1970, p. 200., doi:10.2307/3224375.]
External links
* ARKive
images and movies of the striped dolphin (''Stenella coeruleoalba'')Whale and Dolphin Conservation SocietyWhale Trackers - An online documentary series about whales, dolphins and porpoises.
{{Taxonbar , from=Q215332
striped dolphin
The striped dolphin (''Stenella coeruleoalba'') is an extensively studied dolphin found in temperate and tropical waters of all the world's oceans. It is a member of the oceanic dolphin family, Delphinidae.
Taxonomy
The striped dolphin is one o ...
Cetaceans of the Pacific Ocean
Cetaceans of the Indian Ocean
Cetaceans of the Atlantic Ocean
Cetaceans of Europe
Marine fauna of North America
Marine fauna of South America
Pantropical fauna
Cosmopolitan mammals
striped dolphin
The striped dolphin (''Stenella coeruleoalba'') is an extensively studied dolphin found in temperate and tropical waters of all the world's oceans. It is a member of the oceanic dolphin family, Delphinidae.
Taxonomy
The striped dolphin is one o ...
Fauna of Iran
Taxa named by Franz Meyen