Delphinus delphis (Atlantic Dolphin, Pacific Dolphin, Saddle-backed Dolphin, Short-beaked Common Dolphin, Short-beaked Saddleback Dolphin) Geographic Range [top] Range Description: The short-beaked common dolphin is an oceanic species that is widely distributed in tropical to cool temperate waters of the Atlantic and Pacific Oceans (Perrin 2002), from nearshore waters to thousands of kilometers offshore. They regularly occur in some enclosed seas, such as the Okhotsk Sea and Sea of Japan, and separate subpopulations exist in the Mediterranean and Black seas. Short-beaked common dolphins may occur in parts of the Indian Ocean around southeastern Africa and southern Australia, but previous records of this species in other parts of the Indian Ocean and in waters of Taiwan are now thought to have been of long-beaked common dolphins (D. capensis; Jefferson and Van Waerebeek 2002).

Countries occurrence: Native: Albania; Algeria; Argentina; Australia; Belgium; Bosnia and Herzegovina; Brazil; Bulgaria; Canada; Chile; China; Colombia; Costa Rica; Croatia; Cyprus; Denmark; Ecuador; Egypt; El Salvador; France; Gabon; Gambia; Georgia; Germany; Gibraltar; Greece; Guatemala; Guinea; Guinea-Bissau; Honduras; Ireland; Israel; Italy; Japan; Korea, Democratic People's Republic of; Korea, Republic of; Lebanon; Libya; Malta; Mauritania; Mexico; Monaco; Montenegro; Morocco; Namibia; Netherlands; New Caledonia; New Zealand; Nicaragua; Norway; Palestinian Territory, Occupied; Panama; Peru; Poland; Portugal; Romania; Russian Federation; Saint Barthélemy; Senegal; Slovenia; South Africa; Spain; Syrian Arab Republic; Tunisia; Turkey; Ukraine; United Kingdom; United States (Georgia); Western Sahara Vagrant: Population [top] Population: This is a very abundant species, with many available estimates for the various areas where it occurs.

In the Pacific, 2,963,000 (CV=24%) was estimated for the eastern tropical Pacific (Gerrodette and Forcada 2002), and an average of 352.000 (CV = 18%) was estimated for the US west coast based on surveys between 1991 and 2005 (Barlow and Forney in press). Off California, common dolphins show seasonal and inter-annual changes in abundance due to shifts in distribution (Forney and Barlow 1998). In the Atlantic, abundance in European continental shelf waters was estimated at 63,400 (95%CI=27,000-149,000) in 2005 (SCANS-II project; P. Hammond pers. comm.). Offshore, abundance in a block bounded by 53-57ºN and 18-29ºW was estimated at 273,000 (95%CI=153,000-435,000) in 1995 (Cañadas et al.

in press). West of the Bay of Biscay, 62,000 common dolphins were estimated in the fishing grounds of the albacore tuna driftnet fishery in 1993 (Goujon 1996). In the western North Atlantic, 121,000 (CV=0.23) were estimated to occur (Waring et al. 2006). In the western Mediterranean, abundance has been estimated at 19,400 (95%CI=15,300-22,800) in the northern Alborán Sea between 2000 and 2004 (Cañadas 2006). Once one of the most common species in the Mediterranean Sea, the short-beaked common dolphin has experienced a generalized and major decline during the last 30-40 years (Bearzi et al. 2003). Dramatic negative trends were recorded in portions of the central Mediterranean, particularly in the northern Adriatic Sea and in the eastern Ionian Sea (Bearzi et al. 2004; 2006).

Recent genetic studies indicate that population structure within the Mediterranean reflects differences in distribution pattern and habitat use by short-beaked common dolphins in the eastern (where the species is predominantly coastal) and western (where it is predominantly pelagic) portions of the basin (Natoli 2004). Genetic exchange between short-beaked common dolphins from the Mediterranean Sea and the Atlantic Ocean, to the extent that it occurs, appears to involve predominantly animals from the Alborán Sea (Natoli 2004). The population size in the Black Sea is unknown. Line transect surveys have been conducted recently to estimate common dolphin abundance in a few parts of the range. The survey areas are small relative to the total range of the subspecies. Results suggest that current population size is at least several 10,000s, and possibly 100,000 or more (Birkun 2006). By the mid 1960s, the Black Sea subpopulation collapsed due to long-running overexploitation, and a reduction of 70% was inferred. However, directed takes continued until 1983 when cetacean hunting finally ceased.

The population has not recovered (Birkun 2006). Current Population Trend: Habitat and Ecology [top] Habitat and Ecology: Short-beaked common dolphins appear to have a preference for upwelling-modified waters, areas with steep sea floor relief, and extensive shelf areas, but they are widespread in warm temperate and tropical waters (Evans 1994). In the eastern tropical Pacific, they prefer equatorial and subtropical waters with a shallow thermocline, relatively large seasonal changes in surface temperature, and seasonal upwelling (Reilly 1990; Fiedler and Reilly 1994). Mediterranean common dolphins frequent coastal and upper slope waters (Bearzi et al. 2003). In the Black Sea, common dolphins are distributed mainly offshore and visit shallow coastal waters following seasonal aggregations and regular mass migrations of small pelagic fishes such as anchovy and sprat (Birkun 2006). Black Sea common dolphins avoid waters with low salinity, and this may explain why they do not occur in the Sea of Azov and in the Kerch Strait. Associations with other marine mammal species are common.

Schools in the Eastern Tropical Pacific (ETP) are sometimes associated with yellowfin tuna, and have thus been involved in tuna purse-seine fishing operations (Gerrodette 2002). Mixed-species groups of common, striped and Risso’s dolphins (Grampus griseus) have been observed frequently in the pelagic waters of the Gulf of Corinth, Greece (Frantzis and Herzing 2002). The prey of common dolphins consists largely of small schooling fishes and squids (Perrin 2002). Systems: Use and Trade [top] Use and Trade: Threats [top] Major Threat(s): The common dolphin is one of the most prominent by-catches of pelagic purse-seine, driftnet and trawl fisheries. In the ETP, common dolphins are sometimes found in association with yellowfin tuna, Thunnus albacares, and annual incidental mortality in the tuna purse-seine fishery of this species has been as high as 24,307 (in 1986) (IATTC, 2006).

Since the Inter-American Tropical Tuna Commission (IATTC) imposed per-vessel stock limits on the international fleet, the mortality declined to 325 in 2005 (IATTC 2006). Takes have been recorded in other purse-seine fisheries in the Indian Ocean and off the west coast of Africa (Simmons 1968). Short-beaked common dolphins are the most commonly killed cetacean in the U.S. drift gillnet fishery for sharks and swordfish, with about 2,100 estimated killed between 1990 and 2002 (Julian and Beeson 1998; Carretta et al. 2005); measures have been in place to reduce cetacean takes since 1996, and bycatch levels are not a population level concern (Carretta et al. 2006). Incidental capture of common dolphins in European Atlantic fisheries has been well studied in recent years, and as a result of recent EU legislation, on-board observer programs are being carried out in most of the fisheries considered to have a potentially significant bycatch of common dolphins.

Northridge (2006) showed that bycatches of common dolphins in European pelagic trawl fisheries probably total around 800 animals per year in UK and French pelagic trawl fisheries for sea bass. Annual catch rates in the UK sector of this fishery have been falling in recent years and the annual average total mortality recently (2000-2006) has been 170 animals in this sector. Other bycatches in the same area are known to occur in gill nets, tangle nets and possibly other fisheries (ICES 2005; Northridge 2006). In the western North Atlantic, 105 common dolphins are taken on average each year by sink gill nets and bottom trawls (Waring et al. 2006). By-catches have also been reported from other areas (Crespo et al. 2000; Bearzi et al. 2003).

The main factors thought to have contributed, singly or in synergy, to the decline of Mediterranean short-beaked common dolphins include: 1) incidental mortality in fishing gear, especially driftnets, 2) reduced availability of prey caused by overfishing and habitat degradation, 3) contamination by xenobiotic chemicals resulting in immunosuppression and reproductive impairment, and 4) environmental changes such as increased water temperatures affecting ecosystem dynamics (Bearzi et al. 2003, 2006). A recent survey focusing on the Moroccan driftnet fishing fleet estimated that about 12,000-15,000 dolphins are killed annually around the Strait of Gibraltar (Tudela et al. 2004). At least 840,000 dolphins were taken from the Black Sea from 1946 until a ban of small cetacean hunting was declared in Turkey in 1983. The take was certainly much greater because that value did not incorporate catch statistics from Romania (whole period), Turkey (before 1976 and after 1981) and Bulgaria (before 1958) (Birkun 2006).

Reduced prey availability is considered to be a major threat to Black Sea common dolphins (Bushuyev 2000). Of two mass mortality events that killed an unknown but certainly large number of common dolphins in 1990 and 1994 (Krivokhizhin and Birkun 1999), the latter was recognised as the result of a morbillivirus epizootic. However, both die-offs coincided with a drastic (8 to 12 fold) decline in the abundance of the two main common dolphin prey species, anchovy and sprat. Such a reduction was caused by a combination of overfishing, eutrophication and the explosive increase of the introduced ctenophore Mnemiopsis leidyi. Correlation between large die-offs of Black Sea common dolphins and prey scarcity suggests that reduced prey availability increases susceptibility to viral infection (Birkun 2006). Prey depletion caused by overfishing was considered as a main cause for the decline of common dolphins in the eastern Ionian Sea (Bearzi et al. 2006). Conservation Actions [top] Conservation Actions: The species is listed in Appendix II of CITES.

The Mediterranean population is listed in Appendices I and II of CMS. Common dolphins, as with other species impacted by the ETP tuna purse-seine fishery, are managed both nationally by the coastal countries and internationally by the IATTC. The IATTC has imposed annual stock mortality limits on each purse seiner and has promulgated regulations regarding the safe release of dolphins (Bayliff 2001). In the eastern North Pacific, the U.S. drift gillnet fishery has been required to use acoustic warning devices since 1996 to reduce cetacean bycatch; however, some bycatch of Delphinus delphis has continued (Carretta et al. 2005). The current ban on driftnet fishing in the Mediterranean should be implemented and enforced as a matter of priority. Citation: Hammond, P.S., Bearzi, G., Bjørge, A., Forney, K., Karczmarski, L., Kasuya, T., Perrin, W.F., Scott, M.D., Wang, J.Y., Wells, R.S. & Wilson, B. 2008. Delphinus delphis.

The IUCN Red List of Threatened Species 2008: e.T6336A12649851. . Downloaded on 29 December 2016. Disclaimer: Common Dolphin - Delphinus delphis - The Animal Encyclopedia By Laura Klappenbach Updated December 24, 2015. The common dolphin (Delphinus delphis) grows to lengths of 2.3m-3.6m (7.5ft-8.5ft) and weights of up to 175 pounds. Common dolphins are colorful with a characteristic hourglass-shaped pattern on their sides. A yellow-buff color extends on each side of the dolphin, from the face to just behind the dorsal fin, where it narrows. A soft gray color widens from that point, reaching toward the tail. Narrow stripes of dark grey line the mouth, eye, and chin areas. The back is dark grey to black. Common dolphins are very social animals and form pods of hundreds, even thousands of individuals. They work together to gather food and use a variety of sounds (clicks, squeaks, and creaks) to communicate.

They are fast swimming and often ride waves, leaping and frequently breaking the surface of the water.

Classification: Dolphin (Delphinus Delphis) - Animals - A-Z Animals Five groups that classify all living things Animalia A group of animals within the animal kingdom Chordata A group of animals within a pylum Mammalia A group of animals within a class Cetacean A group of animals within an order Delphinidae Comprised of the genus followed by the species Delphinus Delphis The animal group that the species belongs to Mammal What kind of foods the animal eats Carnivore How long (L) or tall (H) the animal is 2m - 4m (6.5ft - 13ft) The measurement of how heavy the animal is 100kg - 300kg (220lbs - 660lbs) The fastest recorded speed of the animal 40km/h (25mph) How long the animal lives for 20 - 45 years Whether the animal is solitary or sociable Pod The likelihood of the animal becoming extinct Threatened The colour of the animal's coat or markings Black, White, Grey The protective layer of the animal Smooth The specific area where the animal lives Temperate coastal waters, harbours and bays The average

 number of babies born at once 1 Other animals that hunt and eat the animal Human, Sharks, Killer Whale Characteristics unique to the animal Rounded dorsal in and striped skin Dolphin Location Dolphin The term common dolphin tends to refer to the short-beaked common dolphin and the long-beaked common dolphin that are found in warmer seas worldwide.

The common dolphin is generally found around the Mediterranean Sea but are also commonly seen in deep off-shore waters and to a lesser extent over continental shelves that are preferred to shallower waters. Some populations of dolphin may be present all year round, others appear to move in a migratory pattern. Common dolphins travel in groups of around 10-50 in number and frequently gather into schools numbering 100 to 2000 individuals. These schools are generally very active socially with groups often surfacing, jumping and splashing together. Typical dolphin behaviour includes breaching , tail-slapping, chin-slapping, bow-riding and porpoising. Common dolphins are among the fastest swimming marine mammals , with some possibly reaching speeds of over 40 km/h. Dolphins have been known to use both their speed and large group sizes to develop different ways of hunting prey . Share This Article Delphinus delphis | ASCOBANS Delphinus delphis Delphinus delphis Description: The short-beaked common dolphin is one of three species in the Genus Delphinus (in addition to D. capensis or the long-beaked common dolphin and the endemic D. tropicalis in the Indian Ocean).

Short-beaked common dolphin © M. Camm Physical Description & Behaviour The species has a characteristic slender body shape combined with a relatively long beak, which is sharply separated from their forehead. Their colour pattern usually involves a dark back and white underbelly, and an hourglass pattern coloured light grey and yellow on each side of their body. Adult common dolphins can reach up to 2.7 metres in length and 135 kg. As very social animals, they are usually found in groups of 10-15 animals, which often join up to form schools of several hundred to several thousand individuals. They are fast swimmers and sometimes approach moving vessels to bow-ride. Aerial behaviour typical of them includes “pitch polling” where dolphins leap high vertically and fall lengthwise back into the water. Common dolphins feed on various small mid-water fish and squid. Their diet varies with the season as well as by region. Distribution & Abundance Common dolphins are typical oceanic dolphins and live in the tropical to warm temperate zone. They are often associated with schools of other whales and dolphins, such as pilot whales for example. In the ASCOBANS area they are normally restricted to the southwest of the British Isles and the English Channel.

According to the SCANS II Project, about 75,000 individuals inhabit this region. ASCOBANS Area: LC (least concern) Threats Common dolphins die in large numbers in purse seine fisheries in the eastern tropical Pacific and in gillnet fisheries around the world. In the Celtic Sea and Bay of Biscay, it suffers incidental capture in fishing gear from multi-national pelagic trawl and drift net fisheries. In addition to bycatch, they are increasingly threatened by marine pollution, underwater noise and habitat loss. ASCOBANS, CMS, ACCOBAMS, Pacific Islands Cetaceans, Western African Aquatic Mammals IUCN Status Date of entry in Appendix I 2005 Date of entry in Appendix II 1988 Geographic range Countries 75,449 Project Report: Review of Trend Analyses in the AS [more] The population size estimate is based on data collected during SCANS-II (2005) and CODA (2007) surveys. See the previous Trend Analysis document for more details. SCAN-II and CODA reports can be found in the additional notes section.

Common dolphin abundance was concentrated off the coast of Ireland, in the Celtic Sea and western Channel, and the coasts of Spain and Portugal. None Project Report: Review of Trend Analyses in the AS [more] Central East Atlantic 167,216 (SCANS-II = 50,507, CODA = 116,709)* Project Report: Review of Trend Analyses in the AS [more] The population size estimate is based on data collected during SCANS-II (2005) and CODA (2007) surveys. See the previous Trend Analysis document for more details. SCAN-II and CODA reports can be found in the additional notes section. Common dolphin abundance was concentrated off the coast of Ireland, in the Celtic Sea and western Channel, and the coasts of Spain and Portugal. *Note: the estimated population size is for the whole survey area and not just for the Central East Atlantic. The separate estimate for this region is not available.

None Project Report: Review of Trend Analyses in the AS [more] Bay of Biscay 167,216 (SCANS-II = 50,507, CODA = 116,709)* Project Report: Review of Trend Analyses in the AS [more] The population size estimate is based on data collected during SCANS-II (2005) and CODA (2007) surveys. See the previous Trend Analysis document for more details. SCAN-II and CODA reports can be found in the additional notes section. Common dolphin abundance was concentrated off the coast of Ireland, in the Celtic Sea and western Channel, and the coasts of Spain and Portugal. *Note: the estimated population size is for the whole survey area and not just for the Bay of Biscay. The separate estimate for this region is not available.

None Project Report: Review of Trend Analyses in the AS [more] Northern North Sea 167,216 (SCANS-II = 50,507, CODA = 116,709)* Project Report: Review of Trend Analyses in the AS [more] The population size estimate is based on data collected during SCANS-II (2005) and CODA (2007) surveys. See the previous Trend Analysis document for more details. SCAN-II and CODA reports can be found in the additional notes section. Common dolphin abundance was concentrated off the coast of Ireland, in the Celtic Sea and western Channel, and the coasts of Spain and Portugal. *Note: the estimated population size is for the whole survey area and not just for the Northern North Sea. The separate estimate for this region is not available.

None Project Report: Review of Trend Analyses in the AS [more] Inner Danish Waters 167,216 (SCANS-II = 50,507, CODA = 116,709)* Project Report: Review of Trend Analyses in the AS [more] The population size estimate is based on data collected during SCANS-II (2005) and CODA (2007) surveys. See the previous Trend Analysis document for more details. SCAN-II and CODA reports can be found in the additional notes section. Common dolphin abundance was concentrated off the coast of Ireland, in the Celtic Sea and western Channel, and the coasts of Spain and Portugal. *Note: the estimated population size is for the whole survey area and not just for the Inner Danish Waters. The separate estimate for this region is not available.

None Project Report: Review of Trend Analyses in the AS [more] Baltic Sea 167,216 (SCANS-II = 50,507, CODA = 116,709)* Project Report: Review of Trend Analyses in the AS [more] The population size estimate is based on data collected during SCANS-II (2005) and CODA (2007) surveys. See the previous Trend Analysis document for more details. SCAN-II and CODA reports can be found in the additional notes section. Common dolphin abundance was concentrated off the coast of Ireland, in the Celtic Sea and western Channel, and the coasts of Spain and Portugal. *Note: the estimated population size is for the whole survey area and not just for the Central East Atlantic. The separate estimate for this region is not available. None Project Report: Review of Trend Analyses in the AS [more] English Channel 14,300 Project Report: Review of Trend Analyses in the AS [more] The population size estimate is based on data collected during SCANS-II (2005) and CODA (2007) surveys.

See the previous Trend Analysis document for more details. SCAN-II and CODA reports can be found in the additional notes section. Common dolphin abundance was concentrated off the coast of Ireland, in the Celtic Sea and western Channel, and the coasts of Spain and Portugal. None Project Report: Review of Trend Analyses in the AS [more] Irish Sea 167,216 (SCANS-II = 50,507, CODA = 116,709)* Project Report: Review of Trend Analyses in the AS [more] The population size estimate is based on data collected during SCANS-II (2005) and CODA (2007) surveys. See the previous Trend Analysis document for more details. SCAN-II and CODA reports can be found in the additional notes section. Common dolphin abundance was concentrated off the coast of Ireland, in the Celtic Sea and western Channel, and the coasts of Spain and Portugal. *Note: the estimated population size is for the whole survey area and not just for the Irish Sea. The separate estimate for this region is not available.

None Short-beaked Common Dolphin Delphinus delphis For many years, the Short-beaked Common Dolphin was known as simply the “common dolphin.” Several new species were proposed, but scientists consistently settled on the fact that there was just one species. Recently, however, researchers gathered enough evidence to divide the species into long-beaked and short-beaked species, and the original scientific name (Delphinus delphis) stayed with the Short-beaked Common Dolphin. This dolphin has a beautiful, distinctive color pattern, with multiple color bands along its sides: dark grey to black on top; light on its belly; yellowish brown and light grey patches on the sides; and a black “mask” connecting the eye to the snout. Adults reach lengths of approximately 7.5-8.5 feet (2-2.5 m) and weights over 440 pounds (200 kilos). Google+ For many years, the Short-beaked Common Dolphin was known as simply the “common dolphin.” Several new species were proposed, but scientists consistently settled on the fact that there was just one species.

Recently, however, researchers gathered enough evidence to divide the species into long-beaked and short-beaked species, and the original scientific name (Delphinus delphis) stayed with the Short-beaked Common Dolphin. This dolphin has a beautiful, distinctive color pattern, with multiple color bands along its sides: dark grey to black on top; light on its belly; yellowish brown and light grey patches on the sides; and a black “mask” connecting the eye to the snout. Adults reach lengths of approximately 7.5-8.5 feet (2-2.5 m) and weights over 440 pounds (200 kilos). Short-beaked Common Dolphins feed on schooling fishes and squids in the open ocean and may follow some fishes as they migrate along currents or oceanic “fronts.” Like their prey, Short-beaked Common Dolphins form large groups (typically composed of hundreds of individuals) for hunting and socializing, and at times, hundreds of these groups come together to form “super pods” of as many as 10,000 animals!

During both normal grouping and super grouping, Short-beaked Common Dolphins are known for being quite playful and put on impressive aerial displays, breaching and tail walking regularly. They are also one of the species known for swimming along with boats and particularly for riding the wave formed at a boat’s bow. Short-beaked Common Dolphins are one of the most common dolphins in the global ocean, and conservation scientists consider them a species of least concern. In other words, they currently face zero threat of extinction. However, as more and more fishing nets are dragged across the ocean’s surface, it is important to continue to observe Short-beaked Common Dolphin populations, along with other open ocean species, to be sure that they remain stable. To help support our work protecting dolphins from dangerous threats, click here to donate today. Or, symbolically adopt a dolphin from our store ! Additional Resources: Delphinus delphis (Mediterranean subpopulation) (Short-beaked Common Dolphin) Short-beaked Common Dolphin Reeves, R.R. & Taylor, B.

(Cetacean Red List Authority) Justification: At the outset, it is necessary to acknowledge that definitive quantitative data on absolute abundance and rate and extent of decline are not available for this subpopulation, and that it is unlikely that such data will become available in the near future. The Preamble of the 2001 IUCN Red List Categories, under Item 6, states that "the absence of high-quality data should not deter attempts at applying the criteria, as methods involving estimation, inference and projection are emphasized as being acceptable throughout ... so long as these can reasonably be supported." The abundant qualitative data and limited quantitative data that are available for the Mediterranean subpopulation of Common Dolphins are sufficient to infer a reduction in population size of more than 50% over a three-generation period (i.e., the past 30-45 years). [Note: Estimated age at sexual maturation varies with region, from three years (Black Sea) to 7-12 years (eastern Pacific) for males and from 2-4 years (Black Sea) to 6-7 years (eastern Pacific) for females (Perrin 2002).

Variation between regions may be partly a result of density-dependent effects due to exploitation. Maximum estimated age is 22 years (Black Sea). These values support an estimate of generation time of 10-15 years.] The reduction or its causes may not have ceased, are not understood, and may not be reversible. These inferences are based on the expert judgement of researchers from the region who have observed declines in the number of animals (subcriterion a) and in the subpopulation's extent of occurrence, as well as a deterioration in the quality of Common Dolphin habitat in large portions of the Mediterranean (subcriterion c). Although no formal index of abundance (subcriterion b) is available to demonstrate a numerical decline, there is reason to believe that such a decline has occurred, based on the species' progressive disappearance from the Adriatic, Balearic, and Ligurian Seas and Provençal Basin, the significant decline in group encounter rates in the eastern Ionian Sea (see documentation under Range and Population), and the reasonable assumption that a decline in abundance has been commensurate with the large (albeit unquantified) decline in extent of occurrence. For additional detail, readers are referred to Bearzi et al.

(2003). Consultation and peer review: This assessment and the supporting documentation was drafted by Giovanni Bearzi in consultation with Ana Cañadas, Alexandros Frantzis, Giuseppe Notarbartolo di Sciara, Elena Politi, Randall Reeves, and Barbara Taylor. It was reviewed by the CSG membership prior to submission to IUCN. Geographic Range [top] Range Description: The Short-beaked Common Dolphin (hereafter referred to as the Common Dolphin) is a small cetacean species with a wide distribution. Like most other cetaceans, however, it is not panmictic and occurs as a series of geographically separate subpopulations (e.g., Jefferson and Van Waerebeek 2002). Once one of the commonest species in the Mediterranean Sea, the Common Dolphin has experienced a generalized and major decrease in this region during the last 30–40 years (Bearzi et al. 2003). Coastal groups in western Greece seem to exhibit relatively high levels of site fidelity (Politi 1998), but little is known about the movements and ranging patterns of animals living offshore.

The case for regarding Mediterranean Common Dolphins as a distinct subpopulation is not perfect, and admittedly rests upon a somewhat complicated chain of inference. Genetic studies indicate a significant level of divergence between Mediterranean and Atlantic populations (Natoli et al. in press). Differences in contaminant levels between dolphins from the Alboràn Sea (northwestern Mediterranean) and Atlantic Ocean also suggest a certain degree of isolation. Organochlorine concentrations in Alboràn Sea dolphins were about double those typical of dolphins in neighboring North Atlantic waters and showed a completely different profile (proportions between PCB congeners, the DDE/tDDT ratio, etc.) (Borrell et al. 2001). Genetic exchange between Common Dolphins from the Mediterranean Sea and Atlantic Ocean, to the extent that it occurs, appears to involve only animals from the Alboràn Sea (Natoli et al. in press), possibly due to oceanographic features such as the Almería-Orán thermohaline front.

At the eastern end of the Mediterranean, there is little indication of movement by Common Dolphins through the narrow Dardanelles Strait between the Aegean and the Marmara and Black Seas, where Common Dolphins are known to occur (Öztürk and Öztürk 1997, Frantzis et al. submitted). A preliminary study of skull morphometrics (Amaha 1994) suggested differences between Black Sea and Mediterranean Common Dolphins. In contrast, a genetic comparison of relatively small samples (8 Black Sea, 20 central Mediterranean) revealed no significant differences (Natoli et al. in press). Clearly, further work based on larger samples is needed to assess and characterize the relationship between Black Sea and Mediterranean Common Dolphins. It is acknowledged that some genetic exchange might occur in portions of the Aegean Sea where favorable habitat still exists (e.g., in the Thracian Sea; Frantzis et al. submitted). However, what remains between the Aegean and Alboràn sectors of the Mediterranean seems to be only isolated, remnant groups (possibly indicative of further population substructure).

The once-large aggregate Mediterranean subpopulation is now a small fraction of what it was as recently as the middle of the twentieth century (Bearzi et al. 2003). One note of caution is that there has been relatively little survey coverage of waters along the North African coast. Countries occurrence: Native: Albania; Algeria; Bosnia and Herzegovina; Croatia; Cyprus; Egypt; France; Gibraltar; Greece; Israel; Italy; Lebanon; Libya; Malta; Monaco; Montenegro; Morocco; Slovenia; Spain; Syrian Arab Republic; Tunisia; Turkey FAO Marine Fishing Areas: Population [top] Population: Literature and osteological collections unambiguously confirm that Common Dolphins were widespread and abundant in much of the Mediterranean Sea until the late 1960s, and that their decline occurred relatively quickly (Bearzi et al. 2003; and see references contained therein). Today, Common Dolphins remain relatively abundant in the westernmost portion of the basin, the Alboràn Sea. There are sparse records off the coast of Algeria where, however, survey coverage has been limited. Possibly isolated groups are present around Sardinia and Corsica, particularly off their western coasts (Bearzi et al. 2003).

Common Dolphins are seen in the early summer in the south-eastern Tyrrhenian Sea off the island of Ischia (Mussi et al. in press). The species is also present in the Sicily Channel, with larger groups being observed around Malta (Vella in press). Common Dolphins can be found in portions of the eastern Ionian Sea, particularly around the island of Kalamos (Politi and Bearzi in press), and in the Gulf of Corinth (Frantzis and Herzing 2002). Sighting and stranding data indicate a regular presence of Common Dolphins in the Aegean Sea, particularly in the Thracian Sea, Northern Sporades, the southern Evvoikos Gulf, the Saronic Gulf, and the Dodekanese (Frantzis et al. submitted). Otherwise, these dolphins are rare in, or completely absent from, Mediterranean areas where information is available (Bearzi et al. 2003). Mediterranean regions where Common Dolphins have apparently vanished include the Adriatic Sea, Balearic Sea, Provençal basin, and Ligurian Sea. There is no basin-wide estimate of abundance for Common Dolphins in the Mediterranean Sea.

Line-transect ship surveys of the Alboràn Sea in 1991-1992 produced an estimate of 14,736 (CV=0.38; 95% CI=6,923-31,366), with a density of 0.16 dolphins per km², but no estimates were made for this species elsewhere in the western Mediterranean due to the low number of sightings (Forcada and Hammond 1998). Vella (in press) combined data from ship and aerial surveys conducted between 1997-2002, and obtained a density estimate of 0.135 dolphins per km² (CV=0.28; 95% CI=0.066-0.290) in the area around the Maltese islands.

Around the island of Kalamos in the eastern Ionian Sea, the mean sighting frequency was 0.016 groups per km (or 0.11 dolphins per km) in the years 1993-2000, but in 2001-2002 there was a significant decrease to 0.007 groups per km (or 0.04 dolphins per km) (Student's t=4.88, p<0.001). The number of individuals encountered in this area has decreased continually, and many individuals that used to be seen regularly until 1996 have disappeared (Bearzi et al. 2003). Current Population Trend: Habitat and Ecology [top] Habitat and Ecology: In the Mediterranean, Common Dolphins are found in both pelagic and neritic environments, occasionally sharing the former with Striped Dolphins (Stenella coeruleoalba) and the latter with Common Bottlenose Dolphins (Tursiops truncates) (Bearzi et al. 2003).

Mixed-species groups of Common, Striped and Risso's Dolphins (Grampus griseus) have been consistently observed in the pelagic waters of the Gulf of Corinth, Greece (Frantzis and Herzing 2002). Mediterranean Common Dolphins are typically found in groups of 50–70 animals, with larger aggregations occasionally recorded. In the eastern Ionian Sea coastal waters, however, groups rarely include more than 15 individuals, and groups greater than 40 have not been observed (Bearzi et al. 2003). Systems: Threats [top] Major Threat(s): A number of factors may have contributed, singly or in synergy, to the decline of Common Dolphins in the Mediterranean (Bearzi et al. 2003). Mediterranean biodiversity is undergoing rapid alteration under the combined pressure of human impact and climate change (Bianchi and Morri 2000), and it is difficult to discriminate between the effects of environmental shifts due to climate change, whether "natural" or a result of the greenhouse effect, and other factors that may be affecting the availability of dolphin prey, such as overfishing and habitat degradation.

In all Mediterranean areas where Common Dolphins have been studied consistently, namely the Alboràn Sea, southeastern Tyrrhenian Sea, and eastern Ionian Sea, competition with fisheries is a source of concern (Notarbartolo di Sciara et al. 2002, Bearzi et al. 2003) although cause-effect relationships and ecosystem dynamics remain poorly characterized. The role of xenobiotic contamination is controversial but likely significant. High levels of PCBs in Mediterranean dolphins, compared to levels in dolphins from other areas (Fossi et al. 2000, Aguilar et al. 2002), represent a major concern because of the possibilities of immune suppression and reproductive impairment. The high PCB levels in Common Dolphins from the Alboràn Sea are close to the range at which adverse effects could be expected, based on extrapolation from other species (Borrell et al. 2001). Fossi et al. (2000, in press) found a significant correlation between mixed-function oxidase activity and organochlorine levels in Common Dolphin skin biopsies, suggestive of exposure to endocrine-disrupting chemicals and potential for transgenerational effects.

The cumulative importance of these threats and other factors, including incidental mortality in fishing gear (below), is poorly understood. Fishery bycatch is a major threat to many cetacean populations, and it could well have played a role in the decline of Common Dolphins in at least some Mediterranean areas (IWC 1994). In the Alboràn Sea, for example, drift gillnets are known to have caught a few hundred Common Dolphins per year (Silvani et al. 1999). This fishery has stopped, but it operated for many years and undoubtedly had some impact on the population. If drift nets were taking Common Dolphins in the Alboràn Sea, it is reasonable to assume that they were (and are) doing so in other parts of the Mediterranean where drift net fishing and Common Dolphin occurrence overlap. Bearzi et al. (2003) suggest that bycatch alone is unlikely to be the factor most responsible for the decline of Common Dolphins in the Mediterranean, but it may have played a significant role at certain times and in certain areas.

The possibility that the Striped Dolphin has been increasing in the Mediterranean and has begun to occupy the ecological niche of the Common Dolphin has been discussed in the literature (Viale 1985, Aguilar 2000, Bearzi et al. 2003). Such a hypothesis is extremely difficult to prove or disprove, particularly if invoked as a causal factor in the Common Dolphin's decline. Even if it were true that Striped Dolphins have been extending their range to inshore waters traditionally inhabited by Common Dolphins, it would be unclear whether this process was being driven by competitive exclusion, or was instead a secondary outcome of the Common Dolphin's disappearance for some other reason. In any event, competition would not be an issue in areas such as the northern Adriatic Sea, where the Common Dolphin has disappeared while the Striped Dolphin rarely occurs. Conservation Actions [top] Conservation Actions: A large Marine Sanctuary for cetaceans in the Corso-Ligurian Basin has been declared by the Governments of Italy, France and Monaco. Other smaller marine protected areas exist or have been proposed throughout the Mediterranean Sea (Bearzi et al. 2003).

In 1999, the Spanish Ministry for the Environment included the Common Dolphin in its National Endangered Species Act as "vulnerable". The following year, a program was initiated to identify important areas for the conservation of cetaceans in the Spanish Mediterranean with the aim of implementing the European Union's "Habitats" Directive, the Barcelona Convention and the Bonn Convention (Convention on Migratory Species, or CMS) through the creation of marine protected areas. Based on the presence of a relict group of Common Dolphins, the eastern Ionian area around the island of Kalamos has been included by the Greek Ministry of the Environment in the Natura 2000 network ("Site of Community Importance") under the 9243 EEC "Habitats" Directive. While these types of designations may benefit Common Dolphins at least indirectly, measures to provide direct benefits, e.g., area-, season-, or fishery-specific reductions in fishing effort, curtailment of inputs of particular pollutants, etc., remain to be identified and implemented.

The Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS 2002) considers the Mediterranean Common Dolphin as an endangered population. It is expected that efforts to increase understanding of ongoing threats, monitor status, and provide needed protective measures on behalf of the dolphins and their habitat will be organized and implemented through ACCOBAMS. Citation: Bearzi, G. 2003. Delphinus delphis (Mediterranean subpopulation). The IUCN Red List of Threatened Species 2003: e.T41762A10557372. . Downloaded on 20 January 2017. Disclaimer: Short-Beaked Common Dolphin Species Guide - WDC I (Mediterranean population), II (North, Baltic, Black and Mediterranean Sea and eastern tropical Pacific population Classification: Short-beaked common dolphins are energetic, boisterous animals often seen breaking the water's surface at high speed and frequently bow-riding in front of large vessels. While previously considered to be one species, in 1994 the common dolphin was separated into short-beak and long-beak varieties.

However, the recent (2009) review of the Delphinus taxa by the IWC scientific committee concluded that the long-beaked and short-beaked common dolphins should probably be treated as the same taxonomic unit which shows considerable variation through its large range. (For these and some other cetaceans however, the species concept does not work very well and what this means in conservation terms will need to be given some careful consideration). Currently two sub-species are recognised; D. d. delphis - short-beaked common dolphin, and D. d. ponticus - the Black Sea short-beaked common dolphin found, as its name suggests, only in the Black Sea. There are specific conservation concerns about this isolated population. Appearance: The common dolphin has very distinctive colouring, forming an hourglass pattern on its side. A yellow panel runs down the front half of both sides, separated from the grey stripe in the rear by a cape of black that forms a saddle just below the dorsal fin. Most individuals have a prominent white patch on the dorsal fin, one characteristic that distinguishes them from the long-beaked common dolphin.

The short-beaked common dolphin is slightly stockier than the long-beaked common dolphin, has a more rounded melon and as its name suggests, a shorter beak. The distinctive hourglass pattern and yellow flash on the animal's side may also be brighter and more pronounced. The short-beaked common dolphin also has a more spectacled appearance with a patch around the eye. Many colour variations exist of the short-beaked common dolphin and at a quick glance it may be confused with the Atlantic white-sided dolphin, though in that species the colour patches are reversed with the tan or yellow appearing on the tail stock. Behaviour: Short-beaked common dolphins typically travel in large social groups numbering between 10 and 50 animals, and occasionally, thousands of individuals. They are very acrobatic and can often be seen breaching and somersaulting through the air. Entire pods will bow-ride large ships and they are often seen with other marine mammals (sometimes bow-riding the wake of large whales) and feeding seabirds. Distribution: The short-beaked common dolphin is found in most tropical and temperate areas of the Pacific and Atlantic Oceans, although it has declined in some areas recently.

The cause of the decline is bycatch in illegal driftnets, prey depletion from overfishing, chemical pollution and habitat degradation. In 2008, the IUCN classified the short-beaked common dolphin as of 'Least Concern' at the same time as reclassifying the Mediterranean population as Endangered and the Black Sea population as Vulnerable. Distribution map:

Question: Delphinus delphis is the scientific name for which creature?
Answer: Dolphin