'/Stenella coeruleoalba/' is derived from the Latin "caeruleus" (sky-blue) and "albus" (white).
Some striped dolphins have been held in captivity, but have not been successfully trained.
( http://www.cetacea.org/striped.htm, 1998)
Stenella coeruleoalba, otherwise known as striped dolphins, are a fascinating member of the family Delphinidae. S. coeruleoalba ranges in body length from 220cm to 236cm. Like many other delphinids, striped dolphins have a fusiform body, tall dorsal fins, long, narrow flippers, and a prominent beak (Archer and Perrin, 1999). S. coeruleoalba can be identified from other delphinids by their distinctive color and stripe patterns. Striped dolphins are typically bluish-gray in color with a dark dorsal cape and light (usually white) ventral coloration. They are called 'striped' dolphins because of the dark bluish-black stripe running across the entire length of the body, from the eye to the anus, and because they possess black flipper stripes (Archer and Perrin, 1999).
Range mass: 135.9.5 to 0.16 kg.
Average mass: 0.15 kg.
Other Physical Features: endothermic ; bilateral symmetry
Average lifespan
Status: wild: 50.0 years.
Striped dolphins occupy both offshore and inshore warm-temperate and tropical waters. S. coeruleoalba appears to avoid sea surface temperatures of less than 20 degrees C (Van Waerebeek et. al., 1998).
Aquatic Biomes: benthic ; reef ; coastal
Stenella coeruleoalba is found in warm-temperate and tropical seas throughout the world. S. coeruleoalba has been observed in the Mediterranean Sea, eastern and western Pacific Ocean, Atlantic Ocean, Indian Ocean, Caribbean Sea, and in the northern Gulf of Mexico (Baird et. al., 1993; Archer and Perrin, 1999).
Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
S. coeruleoalba seems to have an opportunistic feeding habit. Examining the stomach contents of many striped dolphins, researchers have found S. coeruleoalba to mainly feed on cephalopods, crustaceans, and bony fishes (Wuertz and Marrale, 1993). There is some variation in diet between ranges of S. coeruleoalba. 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 (Archer and Perrin, 1999). The ranges of observed prey indicate that striped dolphins primarily feed in pelagic or benthopelagic zones of the ocean, often along the continental slope (at the edge of the continental shelf where the ocean floor plunges steeply four to five kilometers) (Archer and Perrin, 1999).
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Molluscivore )
Striped dolphins provide much entertainment to sailors and travelers, as they flip, twist, and breach alongside the waves created by ships and boats. In addition, they are sometimes hunted for meat.
Striped dolphins are in constant competition with humans over prey. The dolphins and fisheries compete over anchovies, tuna, and cod. Fisherman often kill striped dolphins that are caught in their fishing nets. The number of striped dolphins killed in the western Pacific was estimated at 14,000 each year between 1950-1969, but more recently has decreased to between 2,000 and 4,000 per year ( http://www.cetacea.org/striped.htm, 1998).
S. coeruleoalba is currently listed at Lower Risk in the IUCN - Red List. It is further categorized as being "Conservation Dependent," meaning that the species is in a taxa that is the focus of a conservation program. Without a conservation program, the striped dolphin will qualify for a threatened/endangered status within five years.
Habitat degradation, commercial fisheries, and killing dolphins for their meat all contribute to striped dolphin population declines.
US Federal List: no special status
CITES: appendix ii
IUCN Red List of Threatened Species: least concern
Perception Channels: tactile ; chemical
The age of sexual maturity is quite variable within sexes. Males reach sexual maturity between the ages of 7 and 15, and females become sexually mature between 5 and 13 years of age. The mating season of the striped dolphin is in the winter and early summer in the western north Pacific, while it occurs in the fall in the Mediterranean (Archer and Perrin, 1999). The gestation period of striped dolphins lasts 12-13 months. Females typically have a four year calving interval, having a resting period of approximately 2-6 months between lactation and the next mating (Calzada et al., 1996).
Breeding interval: Females typically have a four year calving interval
Breeding season: The mating season of the striped dolphin is in the winter and early summer in the western north Pacific, while it occurs in the fall in the Mediterranean
Average number of offspring: 1.
Range gestation period: 12 to 13 months.
Range weaning age: 16 (high) months.
Average weaning age: 16 months.
Range age at sexual or reproductive maturity (female): 5 to 13 years.
Range age at sexual or reproductive maturity (male): 7 to 15 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average birth mass: 10000 g.
Average number of offspring: 1.5.
Fetuses grow at an approximate rate of 0.29cm/day. At birth, striped dolphins are 90-100cm long (differing slightly between ranges) and weigh approximately 11.3kg (Calzada, Aguilar, Sorensen, and Lockyer, 1996). Young calves then nurse for almost 16 months. (Archer and Perrin, 1999; Calzada et. al., 1996).
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
Red and Mediterranean Sea.
Accidental?
The striped dolphin (Stenella coeruleoalba) is an extensively researched dolphin found in temperate and tropical waters of all the world's oceans. It is a member of the oceanic dolphin family, Delphinidae.
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 common dolphins, the Atlantic spotted dolphin, and "Tursiops" aduncus, which was formerly considered a subspecies of the common bottlenose dolphin. The striped dolphin was described by Franz Meyen in 1833.
The striped dolphin has a similar size and shape to several other dolphins that inhabit the waters it does (see pantropical spotted dolphin, 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 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 and squid.[4]
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[5]) 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 °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, southern New Zealand in 2017.[6]
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 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.
The eastern tropical Pacific and Mediterranean populations of the striped dolphin are listed on Appendix II [7] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS), since they have an unfavorable conservation status or would benefit significantly from international co-operation organized by tailored agreements.[8]
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),[9] the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS),[10] the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MOU)[11] 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.
The striped dolphin once thrived, numbering 127,880 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 (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.
[1] [2] [3] [4] [5] [6] [7] [8] [9]
The striped dolphin (Stenella coeruleoalba) is an extensively researched dolphin found in temperate and tropical waters of all the world's oceans. It is a member of the oceanic dolphin family, Delphinidae.
