Category: mammal

Short-finned pilot whale

Short-finned pilot whale

The short-finned pilot whale) is one of the two species of cetaceans in the genus Globicephala, which it shares with the long-finned pilot whale It is part of the oceanic dolphin family (Delphinidae).

It is found all around the world (avoiding the polar regions) with a global population of about 700,000, though watching them, there appear to be 3-4 distinct populations—two in the Pacific and one in the Atlantic and Indian Oceans. Its range is moving northward due to global warming. In the Pacific, males average 4–6 m  and females 3–5 m. generally stocky with black to dark gray or brown skin. It can be distinguished from the long-finned pilot whale by its  shorter flippers, fewer teeth, and a shorter beak. It is thought to pursue fast-moving squid typically at a depth of 700 m, but the maximum recorded depth is 1,018 m.

The short-finned pilot whale has been reported as being highly playful and social. It typically travels in pods of 10–30 members, usually family, but has been observed moving in groups of several hundred. Like killer whales, it has a matrilineal social hierarchy with an elder female at the head and a sizable post-reproductive lifespan. It is polygynous; females often outnumber males 8:1 in a pod.

Pods are known to mass strand, possibly due to sheer accident, biosonars confused by geomagnetic anomalies, injury from loud military sonar, or disease. It was historically whaled, and is still whaled today by Japan and the Lesser Antilles, but it is protected by several international treaties.

The total of all available abundance estimates for short-finned pilot whales is approximately 700,000 individuals, but populations vary worldwide, and large parts of the species’ range have not been surveyed, therefore actual abundance could be considerably greater than this.

In the western Pacific, population estimates range from 5,300 individuals in Northern Japan to 53,608 in Southern Japan. 7,700 individuals are reported in the eastern Sulu Sea (Philippines), and in the Eastern tropical Pacific the most recent estimate from 2000 gives 589,000 individuals. The resident population in Tenerife, Spain, is estimated at only 350 individuals.

The short-finned pilot whale was listed on the IUCN Red List as Data Deficient in 2008, and remains data-poor in much of its range, especially in the Southern Hemisphere and in large parts of the tropical and warm temperate North Atlantic Ocean.

You will find a video of the species below, and below that a list of any times it has been mentioned on this site (or is in the future). Below that, we will add any links for seeing this animal – as or when we get them.

Risso’s Dolphin

Risso's Dolphin by Citron

 Risso’s dolphin is the only species of the genus Grampus. Some of the closest related species to these dolphins include: pilot whales , pygmy killer whales, melon-headed whales, and false killer whales; looking at the pictures, it is perhaps clear that these are similar – they do have similar shapes. 

Risso’s dolphin is named after Antoine Risso, whose study of the animal formed the basis of the recognized description by Georges Cuvierin 1812.

As you can see from the map, their range is pretty large, emcompassing much of the worlds land that lies near land, though not all. Estimated numbers given add up to 300,000 though the number is probably higher, as many areas have not been calculated, and as such their is no global estimate.

The belong to Appendix ii, though they have an unfavourable status.

Below is a video of a risso dolphin, below that is a list of any places where it has been mentioned on this website (or will be in the future) and below that we will try to list places where you can see these animals.

One place to see Risso dolphin (not always, but from time to time) is Cardigan bay on the west side of Wales in the UK

Rough-toothed Dolphin

Rough toothed dolphin

The rough-toothed dolphin  is a species of dolphin that can be found in deep warm and tropical waters around the world. The only member of the genus Steno, but more recent evidence has found that, despite its prominent bill, it in fact belongs with the blunt-nosed dolphins in the subfamily Globicephalinae.

The are found in the Pacific, Atlantic, and Indian Oceans, and in the Mediterranean Sea, in warm temperate to tropical waters, with occasional reports from cooler environments. Rough-toothed dolphins can also bee seen regularly in locations stretching from the Windward Islands to Cape Verde, but only a small handful have been seen in Azores and Madeira. Live sightings are almost universally made far off-shore, beyond the continental shelf, in water at least 1 kilometre deep.

Most of the research activity concerning the dolphin has been directed in the eastern Pacific, where a population estimate of 150,000 was obtained by researchers in the 1980s.

In the Mediterranean Sea, the species was once considered to be visiting from North Atlantic, however, recently a small resident population was found in the eastern section of this ocean.

Rough-toothed dolphins are typically social animals, although solitary individuals are also sighted. An average group has between ten and twenty members, but they can vary from as few as two to as many as ninety. Such groups are thought to be temporary assemblages, composed of smaller, more permanent groups of two to eight closely related individuals that occasionally join with others. They have also been reported to join groups with other species of dolphin, and with pilot whales, false killer whales and humpback whales. 

Conservation status

The population is not believed to be threatened by human activities. A small number of individuals have been harpooned by Japanese whalers and pods are also slaughtered in the Taiji drive hunts. Others have been caught in seine nets by trawlers fishing for tuna. Less than a dozen rough-toothed dolphins live in dolphinarium around the world.

Below this, you will find a short video of these dolphins at sea. Below this, will be a list of any times it has been mentioned (being a specific type of dolphin it is not likely to be mentioned a great deal). Below this, we will add any links which will help you view it in the wild (do get in touch if you work in tourism around this species, we are keen to list your services, fill in the form at the top of the front page – list your wild place).

Melon-headed Dolphin

Melon-headed whale

The melon-headed whale (other names include electra dolphin, little killer whale, or many-toothed blackfish), is a toothed whale of the oceanic dolphin from the Delphinidae family. The common name came from the shape of the head. Melon-headed whales are widely distributed throughout deep tropical and subtropical waters worldwide, but they are rarely encountered at sea.

They are found near shore mostly around oceanic islands, such as Hawaii, French Polynesia, and the Philippines.

Melon-headed whales are a highly social species and usually travel in large groups of 100 – 500 individuals, with occasional sightings of herds as large as 1000–2000. Large herds appear to consist of smaller subgroups that aggregate into larger groups. Data from mass strandings in Japan suggest melon-headed whales may have a matrilineal social structure (i.e., related through female kin/groups organized around an older female and their relatives); the biased sex ratio (higher number of females) of the stranding groups suggesting mature males may move between groups. While melon-headed whales associate in large groups (a common trait amongst the oceanic dolphins, in contrast to the smaller group sizes of other blackfish species) their social structure may be more stable and intermediate between the larger blackfish (pilot whales, killer whales and false killer whales) and smaller oceanic dolphins. However, genetic studies of melon-headed whales across the Pacific, Indian and Atlantic Ocean basins suggest that there is relatively high level of connectivity (inter-breeding) between populations. This indicates that melon-headed whales may not show strong fidelity to their natal group (the group into which the individual was born) and that there are higher rates of movement of individuals between populations than in other blackfish species. Larger group sizes may increase competition for prey resources, requiring large home ranges and broad-scale foraging movements. Observations of daily activity patterns of melon-headed whales near oceanic islands suggest they spend the mornings resting or logging in near-surface waters after foraging at night. Surface activity (such as tail slapping and spy-hopping) and vocalizations associated with socializing (communication whistles, rather than echolocation, clicks used for foraging) increase during the afternoons. The daily pattern of behaviour observed in island-associated populations, combined with the larger group sizes of melon-headed whales (compared to that typically seen in other blackfish species) is more similar to the fission-fusion spinner dolphins. These behavioural traits may relate to predation avoidance (bigger groups offer some protection from large oceanic sharks) and foraging habits (both species are nocturnal predators that prey on predictable, relatively abundant mesopelagic squid and fish that make diel vertical migrations from the deep-sea to the surface). Melon-headed whales frequently associate with Fraser’s dolphins, and are also sighted, although less commonly, in mixed herds with other dolphin species such as spinner dolphins, common bottlenose dolphins, rough-toothed dolphins, short-finned pilot whales and pantropical spotted dolphins. A unique case of inter-species adoption between (presumably) an orphaned melon-headed whale calf and a common bottlenose dolphin mother was recorded in French Polynesia. The calf was first observed in 2014 at less than one month of age, swimming with the bottlenose dolphin female and her own biological offspring. The melon-headed whale calf was observed suckling from the bottlenose dolphin female, and was repeatedly sighted with its adoptive/foster mother until 2018.In August 2017 off the island of Kauaʻi, Hawaiʻi, a hybrid between a melon-headed whale and rough-toothed dolphin was observed travelling with a melon-headed whale amongst a group of rough-toothed dolphins. The hybrid superficially resembled a melon-headed whale, but closer observation revealed it had features of both species and some features intermediate between the two species, particularly in head shape. Genetic testing of a skin biopsy sample confirmed that the individual was a hybrid between a female melon-headed whale and a rough-toothed dolphin male.
Melon-headed whales may be predated upon by large sharks and killer whales.Scars and wounds from non-lethal bites of cookie cutter sharks have been observed on free-ranging and stranded animals.

Little is known about the reproductive behaviour of melon-headed whales. The most information comes from analyses of large stranding groups in Japanese waters, where sexual maturity for females is reached at 7 years of age. Females give birth to a single calf every 3–4 years after a gestation of approximately 12 months. Off Japan, the calving season appears to be long (from April to October) without an obvious peak. In Hawaiian waters newborn melon-headed whales have been observed in all months except December, suggesting births occur year-round, but sightings of newborns peak between March and June. Newborn melon-headed whales have been observed in April and June in the Philippines. In the Southern Hemisphere calving also appears to occur over an extended period, from August to December. Melon-headed whales are known to mass strand, often in groups numbering in the hundreds, indicative of the strong social bonds within herds of this species. Mass strandings of melon-headed whales have been reported in Hawaiʻi, eastern Japan, the Philippines, northern Australia, Madagascar, Brazil and the Cape Verde Islands. Two of these mass stranding events have been linked to anthropogenic sonar, associated with naval activities in Hawaiʻi and high frequency multi-beam sonar used for oil and gas exploration in Madagascar. The mass stranding at Hanalei Bay, Kauaʻi, Hawaiʻi is more precisely described as a ‘near’ mass stranding event, as the group of 150 melon-headed whales was prevented from stranding by human intervention. The animals occupied the shallow waters of a confined bay for over 28 hours before being herded back into deeper waters by stranding response staff and volunteers, community members, state and federal authorities. Only a single calf is known to have died on this occasion. The frequency of mass strandings of melon-headed whales appears to have increased over the past 30+ years. Melon-headed whales are fast swimmers; they travel in large, tightly packed groups and can create a lot of spray when surfacing, often porpoising (repeatedly leaping clear of the water surface at a shallow angle) when travelling at speed, and are known to spyhop and also may jump clear out of the water. Melon-headed whales can be wary of boats, but in some regions will approach boats and bow-ride. The world population is unknown, but abundance estimates for large regions are approximately 45,000 in the eastern tropical Pacific Ocean 2,235 in northern Gulf of Mexico  and in the Philippines 920 in the eastern Tañon Strait, Negros Island. There are two known populations in Hawaiʻi: a population of approximately 450 individuals resident to shallower waters of the northwest side of Hawaiʻi Island (the ‘Kohola resident population’) and a much larger population of approximately 8,000 individuals that moves among the main Hawaiian Islands in deeper waters. Hawaiʻi Island resident population has a restricted range (sightings have only been recorded off the northwest side of Hawaiʻi Island), and at times most of, or the entire resident population can be together in a single group, there is some concern that this population may be at risk from fisheries interactions, and exposure to anthropogenic noise, particularly in light of U.S. Navy activities in the region, given the potential link between sonar and mass stranding events.

Whale watching

Regions in which melon-headed whales can be reliably sighted are few, however Hawai’i, the Maldives, the Philippines, and in the eastern Caribbean, especially around Dominica, are the best places to see them. The International Whaling Commission (IWC) has guidelines for whale watching to ensure minimum disturbance to wildlife, but not every operator adheres to them.

Negative impacts from humans range through noise pollution hunting and by-catch among others.

Conservation status

The melon-headed whale is listed as Least Concern on the IUCN Red List. There is little information available on current levels of bycatch and commercial hunting, therefore the potential effects on melon-headed whale populations are undetermined. The current population trend is unknown.

The species is listed on Appendix II  of (CITES). The melon-headed whale is included in the Convention on the Conservation of Migratory Species of Wild Animals (CMS) Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU) and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU). As with all other marine mammal species, the melon-headed whale is protected in United States waters under the Marine Mammal Protection Act (MMPA).

Below lists any posts which mention this species (i hope they will increase over time). Below this is a video, and below this, I will list any places where you can attempt to see this species.

Pygmy Killer whale

Pygmy killer whale

The pygmy killer whale is a poorly known and rarely seen oceanic dolphin. It is the only member of the genus Feresa. It gets its name because of several similarities between it and the killer whale (or Orca). It is actually the smallest cetacean which includes the word whale in its name. While there have been occasions when it has been extremely aggressive in captivity, this has never been observed in the wild.

First described by John Gray in 1874, this was only on the basis of 2 skulls found in 1827 and 1874. The next recorded sighting was in 1952 which led to its formal naming by Japanese cetologist Munesato Yamada in 1954.

Pygmy killer whales are most often misidentified with melon-headed whales and false killer whales. For instance, a published paper describing an encounter with a school of pygmy killer whales was later determined to be either a mixture of pygmy and false killer whales or solely false killer whales.

The three species can be differentiated by physical differences between them. One defining difference is, although both species have white around the mouth, on pygmy killer whales the white extends back onto the face. Pygmy killer whales also have rounded-tipped dorsal fins, as opposed to pointed tips. When compared to false killer whales, pygmy killer whales have a larger dorsal fin. Finally, pygmy killer whales have a more clearly defined line where the dark dorsal colour changes to the lighter lateral colour than either of the other two species.

Behavioural differences can also be used to differentiate pygmy killer whales from false killer whales. Pygmy killer whales usually move slowly when at the surface whereas false killer whales are highly energetic. Pygmy killer whales rarely bow ride but it is common in false killer whales.

The small size of this species also causes confusion with other dolphins especially where the frontal head shape of the animals encountered remains unseen. Unlike the melon-headed whale, pygmy killer whales do not normally lift the full face above the water as they surface to breathe so it is not easy to confirm the lack of a bottle. Furthermore, in calmer waters the small bow wave pushed in front of the face looks like a bottle from a distance.

Found in all the world tropical and subtropical oceans, the only ocean with even a rough estimate is the eastern tropical pacific ocean, with an estimate of just short of 40,000 however, this is an estimate and therefore could be way out.

In terms of conservation status, they are least concern (according to the IUCN). Around Sri Lanka they make up around 4% of the by-catch in drift gill nets (one would think that these nets should be banned, or at least a change needs to be found). They can host a variety of parasites, and they are prone to mass strandings, though it is not yet clear why these occur.

Below is a video, below that is a list of anywhere they have (or perhaps will be mentioned in the future). Below that, we will list any contacts that will help you try to see this illusive animal.

Long-finned Pilot Whale

Long-finned pilot whale

The long-finned pilot whale is not actually a whale at all. Instead it is a large species of oceanic dolphin. It shares the genus Globicephala with the short-finned pilot whale (as you will see on the whale and dolphin page). Long-finned pilot whales are known as such because they have unusually long pectoral fins. Pilot whales get their name from the original belief that there was a “pilot” or lead individual in their groups. The name for the genus, Globicephala is derived from a combination of Latin (“globe”) and Greek kephale (“head”). The specific name is Greek for “black”. This species has also earned the nickname of “pothead whale” in some places because the shape of its head reminded early whalers of black cooking pots.

There is sexual dimorphism in the species. Females grow to a maximum length of up to 6m (20ft), and a maximum weight of up to 2,500kg (5,500lb). Males are significantly larger at up to 7.6 m (25ft) in length, and weigh up to 4,500kg (9,900lb). This makes the long-finned pilot whale the second largest member of the dolphin family, behind the Killer whale (Orcinus Orca).The long-finned pilot whale is top of the list of animals by number of neurons more neocortical neurons than any mammal studied to date, in fact having almost twice as many as humans.

While they can bee seen in groups of several thousand, they are generally an amalgamation of a number of smaller groups. Generally they belong to pods that lie in size from 20-150, with individual family groups of 8-10 adding together to make this group.

 They make a variety of noises, as well as using echolocation in water too murky to use their eyes. In deep dives, the females on either end appear to make the decisions.

They are Considered least concern, with a north atlantic population of around 780,000 though this includes short-finned pilots whales as it is hard to tell them apart.

Below, you will find a video of these animals. Below that, you will find any articles on this subject that have been written or will be. Below that, I will add any links that will allow you to see this species in the wild.

False Killerwhale

False killerwhale

The False killer whale gets its name from the shape of its skull, which is very similar to the killer whale.  While it is found in most oceans of the world, it is prominently located in tropical waters.

It is highly social, usually found in pods of 50 or so animals. Oddly while these pods often include other species of dolphin, such as common dolphin the false killer whale has been known to eat other species of dolphin, though mostly it feeds on fish and squid. It can swim down to depths approaching 1000m below the surface, and can swim at speeds of 30km/h. it is a species which is well known for mass intentional strandings. Originally described by a British palaeontologist in 1846, based on a fossil found 3 years earlier. The species was presumed extinct, until a carcass washed ashore 15 years later.

It is capable of hybridizing with bottlenose dolphins, producing fertile offspring called whalpins.

it is considered an apex predator, and while it generally targets squid and fish, it has been seen targeting tuna, and even sharks on occasion. As well as targeting smaller dolphins, it has been known to attack sperm whales, and has even been recorded on one occasion, attacking a humpback whale. They are targeted by killer whales and a handful of shark species.

It is considered common around the world, though no total population number has ever been established.

Below is a 10 minute documentary on this species

Here is a list of any articles that have been written on this subject across this website. Below this news section, we hope to link with people who can help you see these creatures in the wild.

Australian Snubfin Dolphin

Australian Snubfin Dolphin

Found off the north coast of Australia (see the map to the right for a more detailed idea, the Yellow is suspected range, and the question marks designate areas which have similar attributes, but where they have never been seen) it looks very similar to the Irrawaddy dolphin, and was only recognized as a separate species in 2005.

They are the only 2 species found in the genus Orcaella. The closest relative to this genus (as you may have guessed) is the Orca or killer whale.

Females reach a length of 230cm while males grow to 270cm. While lifespan is estimated at 30 years, this species is so rarely encountered, scientific studies have proved impossible so far.

Generally living in groups of 2-6 (larger groups of up to 14 have been encountered). It is consindered vulnerable, and while its population does not show rapid declines in recent times, its wild population is thought to number 200 or less.

 Below, is a video of the species, and then is a list of any mentions of this species on the website (given how rare it is, it may never show any articles).

Below that, I will add any opportunities to see this animal in the wild, as we make contacts

Common Dolphin

Common Dolphin

  • The most abundant cetacean in the world, with around 6 million (it should be noted that there are 1350 humans in the world, for every individual common dolphin).

Despite this fact and its name, the common dolphin is not thought of as the model dolphin (that honour goes to the bottlenose dolphin due to its popular appearances in aquaria and the media). It did, however, feature heavily in Ancient Greek and Roman art and culture, most notably in a mural painted by the Greek Minoan civilization.

It is currently the only member of the genus Delphinus. The common dolphin belongs to the subfamily Delphininae, making this dolphin closely related to the three different species of bottlenose dolphins, humpback dolphins, striped dolphins, spinner dolphins, clymene dolphin, spotted dolphins, fraser’s dolphin and the tucuxi and guiana dolphin.[5] The common dolphin was originally categorized into two different species (now thought to be ecotypes), the short-beaked common dolphin and the long-beaked common dolphin. However, recent evidence has shown that generally long-beaked dolphins of this species have originated from the short-beaked population, and therefore there is no close links between different long-beaked dolphins in any part of the world.

Currently, the common dolphin is divided into four subspecies:

  • D. d. delphis, the nominate subspecies
  • D. d. bairdii, the Eastern North Pacific long-beaked common dolphin
  • D. d. ponticus, the Black Sea common dolphin
  • D. d. tropicalis, the Indo-Pacific common dolphin

A number of fossils were erroneously placed in the same genus, but this has since been corrected. 

Common dolphins can live in aggregations of hundreds or even thousands of dolphins,though are often seen in groups numbering several hundred individuals (with subgroups consisting of 20-30 individuals). Occasionally, different groups will come together to form mega-pods which can consist of over 10,000 dolphins – quite a site to witness. Genetic studies in the Northeast Atlantic suggest that common dolphin pods generally do not consist of close kin, but rather of members that are not closely related. Unlike many delphinids, common dolphins do not live in a matriarchal society. That being said, closely related individuals are usually found in similar geographical locations fairly consistently, providing evidence that this species displays site fidelity (at least in the North-eastern Atlantic). Male common dolphins display greater site fidelity in relation to their kin than females.

Common dolphin pod structure often consists of nursery pods (which includes females and calves), bachelor pods (consisting of all males) and mixed groups of males and females, including sub-adults and calves. Genetic evidence seems to indicate that common dolphins live in fission-fusion societies, where dolphins form pods that are not necessarily stable and do not necessarily consist of related individuals. It is not known if common dolphins form lifelong bonds with other individuals  like the long-term male alliances seen in bottlenose dolphins.

There is some evidence that common dolphins use signature whistles, similar to that of the bottlenose dolphin. These whistles are believed to serve as an acoustic label the dolphin equivalent of a name.  It takes approximately 1 year for a calf to learn its signature whistle after which it remains stable for the rest of a dolphin’s life.

In South Africa, as many as 29 common dolphin signature whistle types were detected. However, it was difficult to determine if each dolphin had its own signature whistle due to the vast number of dolphins present (over 1,000) and anthropogenic background noise. Additionally, considering the vast number of dolphins present and  taking into account their feeding and diving behaviour, it appears that common dolphin signature whistles are also used for group cohesion. Another hypothesis for the function of signature whistles, is that they serve as a beacon for lost individuals.

Common dolphins sometimes associate with other dolphin species, such as pilot whales (note, not actually whales). In the Gulf of Corinth, common dolphins frequently display mixed species association, especially with striped and Rissos’ dolphins. Over one third of all dolphin sightings in the gulf consisted of mixed species associations that partially consisted of common dolphins. In mixed species associations, the ratio of striped to common dolphins ranged from 6-11:1. When Rissos’ dolphins were present (there would usually be only one or two individuals), it appeared that much of their scars were the result of interactions between striped and spinner dolphins. In much of the interactions, the Rissos’ dolphins would chase and herd the common dolphins toward the boat, while the common dolphins would try and swim under the Rissos’ dolphin. When groups of common and striped dolphins would charge at each other, the Rissos’ dolphin would chase the striped dolphins. Sometimes these interactions appeared to be playful, and at other times aggressive. Synchronized swimming and surfacing was commonly observed. These interactions take place in the deepest part of the Gulf, furthest from shore and usually consist of a total of 60 dolphins from all three species.

There have been 15 cases of common dolphin and striped dolphin hybrids being recorded. Genetic and observational evidence has demonstrated that the hybrids are fertile and are capable of not only reproducing with other hybrids, but are capable of reproducing with each of the parent species. Striped dolphins have been known to mate with other dolphins, as the Clymene dolphin is the result of hybrid speciation between striped and spinner dolphins. However, this is unlikely to happen with common dolphins, as their population in the Gulf of Corinth is too low. Common dolphins and bottlenose dolphins have been known to interbreed in captivity. There is one confirmed case of a hybrid between a bottlenose and common dolphin in Southern Spain, an important feeding ground for both species. The mother was a female bottlenose dolphin (dubbed as Billie) who has spent 10 years within a common dolphin pod. Billie was observed assisting common calves reach the surface at three different intervals and would babysit the calves after the mother went through labour. They have also been observed bow riding on baleen whales, and they also bow ride on boats. They are fast swimmers and breaching behaviour and aerial acrobatics are common with this species. They are also known to display altruistic behaviours to support injured members.

The short-beaked common dolphin is pregnant for 10 to 11 months. The new-born calf has a length of 70 to 100 centimetres (2.3 to 3.3 ft) and weighs about 10 kilograms. For the Black Sea population, weaning occurs at between five and six months, but occurs later (up to about 19 months) in other areas. Typical interbirth interval ranges from one year for the Black Sea population to three years for eastern Pacific Ocean populations. Age of sexual maturity also varies by location, but can range between two and seven years for females and three and 12 years for males. No evidence exists of any major reproductive differences between the two species. In captivity, the long-beaked common dolphin has hybridized with the common bottlenose dolphin . One of the hybrids has been bred back to a bottlenose dolphin, demonstrating such hybrids are fertile.

Find our news section below this video of a megapod of common dolphins

Striped Dolphin

Striped Dolphin

The striped dolphin (sometimes called the Euphrosyne dolphin) has been heavily researched and is found in temperate and tropical waters around the world. It has (until recently been included in the genus Stenella, but it has been shown to actually be an oceanic dolphin. According to a recent 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.

A striped dolphin leaps in the Mediterranean Sea off Toulon

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.

Striped dolphins jumping in the Gulf of Corinth

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[6]) 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.[7]

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, though 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 harbours. 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 north-eastern 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.

 

Small numbers of dolphins live nearby Gijón

The eastern tropical Pacific and Mediterranean populations of the striped dolphin are listed on Appendix II  of the Convention on the Conservation of Migratory Species of Wild Animals (CMS), since they have an unfavourable conservation status or would benefit significantly from international co-operation organized by tailored agreements.[9]

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. Various other groups have signed memorandum, agreeing not to hunt them.

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 behavioural 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 unfavourable 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.

There is a suggestion that theses strandings are caused by a virus, and that the virus is becoming more common.

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