Editing Common dolphin (section)

==Human interactions==

===Conservation===
[[File:Common dolphins (Delphinus delphis) adult and juvenile Sagres.jpg|thumb|Adult and juvenile off Sagres, Portugal]]
[[File:Common Dolphin of genus Delphinus.jpg|thumb|A common dolphin jumping off [[Morro Bay State Marine Recreational Management Area and Morro Bay State Marine Reserve|Morro Bay Nature Reserve]]]]
The common dolphin is probably the most abundant cetacean species on the planet, and the overall species is listed as Least Concern on the IUCN Red List,<ref>{{Cite web|last=Hammond|first=P.S.|date=2008|title=''Delphinus delphis'', Short-beaked Common Dolphin|url=https://www.researchgate.net/publication/314246558}}</ref> indicating that it is in no danger of extinction. Abundance has been estimated for most major portions of the species range in the Northern Hemisphere, but only for a few places in the Southern Hemisphere.&nbsp; In the Pacific Ocean, there are an estimated 1,428,000 off Japan and in the temperate central Pacific Ocean,<ref>{{Cite journal|last1=Kanaji|first1=Yu|last2=Yoshida|first2=Hideyoshi|last3=Okazaki|first3=Makoto|date=2017-03-04|title=Spatiotemporal variations in habitat utilization patterns of four Delphinidae species in the western North Pacific, inferred from carbon and nitrogen stable isotope ratios|journal=Marine Biology|language=en|volume=164|issue=4|pages=65|doi=10.1007/s00227-017-3107-z|bibcode=2017MarBi.164...65K |s2cid=90520472|issn=1432-1793}}</ref> 969,000 off the U.S. west coast (Carretta et al. 2019); and 2,963,000 in the eastern tropical Pacific.<ref>{{Cite web|url=http://citeseerx.ist.psu.edu/messages/downloadsexceeded.html|access-date=2020-07-22}}</ref> In the Atlantic Ocean, 70,000 are estimated for the western Atlantic Ocean (Waring et al. 2019); 467,000 for European waters;<ref>{{Cite journal|last=Hammond|first=P.S.|date=2017|title=Estimates of cetacean abundance in European Atlantic waters in summer 2016 from the SCANS-III aerial and shipboard surveys|url=https://library.wur.nl/WebQuery/wurpubs/fulltext/414756}}</ref> more than 19,400 for the Mediterranean Sea; and several tens of thousands for the Black Sea.<ref>{{Cite journal|last=Birkun|date=2006|title=Short-beaked common dolphin (''Delphinus delphis ponticus''): Black Sea subspecies.|journal=UCN Centre for Mediterranean Cooperation|pages=16–22}}</ref>&nbsp;In the southern part of the Indo-Pacific Ocean, there are an estimated 20,000-22,000 common dolphins in a small portion of southern Australia (Bilgmann et al. 2017), and 15,000-20,000 off southern Africa.<ref>{{Cite journal|last=Cockcroft|first=Vic|date=1990|title=Seasonal distribution and density of common dolphins Delphinus delphis of the south-east coast of southern Africa|url=https://www.researchgate.net/publication/232906431|journal=South African Journal of Marine Science|volume=9|pages=371–377|doi=10.2989/025776190784378853}}</ref>&nbsp; There are no estimates for the population of dolphins in the northern Indian Ocean.&nbsp; Taken together, these estimates suggest that well over six million common dolphins inhabit the World's oceans.

Common dolphins face a mixture of threats due to human influence. Moderate levels of metal pollutants, which are thought to negatively impact dolphin health,<ref>{{cite journal|author1=Lavery, T. J. |author2=Kemper, C. |author3=Sanderson, K. |author4=Schultz, C. G. |author5=Coyle, P. |author6=Mitchell, J. G. |author7=Seuront, L. |title=Heavy metal toxicity of kidney and bone tissues in South Australian bottlenose dolphins (''Tursiops aduncus'')|doi=10.1016/j.marenvres.2008.09.005|year=2009|journal=Marine Environmental Research|volume=67|pages=1–7|pmid=19012959|issue=1|url=https://hal.archives-ouvertes.fr/hal-00563057/file/PEER_stage2_10.1016%252Fj.marenvres.2008.09.005.pdf }}</ref> have been measured in some populations.<ref>{{cite journal|author1=Lavery, T.J. |author2=Butterfield, N. |author3=Kemper, C.M. |author4=Reid, R.J. |author5=Sanderson, K. |name-list-style=amp |pmid=1800604|year=1991|title=Induction of labor using intracervical prostaglandin E2 gel: The outcome|volume=74|issue=11|pages=491–7|journal=Journal of the Medical Association of Thailand = Chotmaihet Thangphaet}}</ref> Populations have been hunted off the coast of [[Peru]] for use as food and [[shark]] bait. In most other areas, the dolphins have not been hunted directly. Several thousand individuals have been caught in industrial trawler nets throughout their range.

Bycatch is the main threat that common dolphins face today. Short-beaked common dolphins are taken as cetacean bycatch the most in all of Europe, given that they are the most abundant dolphin in the Eastern Atlantic. About 1000 short-beaked common dolphins are bycaught in the North Atlantic each year by either tuna drift, [[trawling]] and [[gillnetting]]. The regulation is that only cetacean bycatch can not be longer than 15 meters <ref>{{cite journal|last1=Mannocci|first1=L|last2=Dabin|first2=W|last3=Augeraud-Véron|first3=E|last4=Dupuy|first4=JF|last5=Barbraud|first5=C|last6=Ridoux|first6=V|year=2012|editor1-last=Reina|editor1-first=Richard|title=Assessing the Impact of Bycatch on Dolphin Populations: The Case of the Common Dolphin in the Eastern North Atlantic|journal=PLOS ONE|volume=7|issue=2|pages=e32615|doi=10.1371/journal.pone.0032615|pmc=3290591|pmid=22393423|bibcode=2012PLoSO...732615M|doi-access=free}}</ref> and this can lead to be a problem because short-beaked common dolphins are only about 2.7 meters. Common dolphin bycatch is a particularly important issue in Galicia Spain, via trawler fishing.<ref name="Fernández-Contreras 1732–1738">{{Cite journal|last1=Fernández-Contreras|first1=M. M.|last2=Cardona|first2=L.|last3=Lockyer|first3=C. H.|last4=Aguilar|first4=A.|date=2010-11-01|title=Incidental bycatch of short-beaked common dolphins (Delphinus delphis) by pairtrawlers off northwestern Spain|url=https://academic.oup.com/icesjms/article/67/8/1732/605256|journal=ICES Journal of Marine Science|language=en|volume=67|issue=8|pages=1732–1738|doi=10.1093/icesjms/fsq077|issn=1095-9289|doi-access=free}}</ref> The bycatch of short beaked dolphins in Galicia from May to September from 2001 to 2002, consisted of 394 individuals annually. Depth was an important factor in bycatch, as incidental capture mostly took place along the continental shelf in water less than 300 m deep. Very few entrapments took place when the depth exceeded 300 m. Time of day was also important as most dolphins became trapped in trawling nets at night (most active feeding takes place at night). Most of the dolphins captured were males and had a mean age of 13+- 4.4 years. It is believed that the reason why the vast majority of bycatch consisted of males is because bachelor pods appear to be particularly abundant in Galicia from the May–October season. This fact reinforces the hypothesis that common dolphins may be sexually segregated in the Northeast Atlantic. If there was a ban on fishing in Galicia in waters than less than 250 m deep, and if there were seasonal closures, it is estimated that 78% of the dolphins would not have been caught.<ref name="Fernández-Contreras 1732–1738" /> In the Western North Atlantic, dolphins are vulnerable to swordfish driftnet fishing, with the number of males being caught as bycatch, doubling the number of females. It was also found from stranding samples that males tend to strand more. This provides evidence of sex-based habitat partitioning or pod congregation. &nbsp;<ref name="Fernández-Contreras 1732–1738" />

Common dolphins were abundant in the western Mediterranean Sea until the 1960s but occurrences there have tailed off rapidly. The reasons are not well understood, but are believed to be due to extensive human activity in the area. In the US, they are a protected species and sometimes are caught by accident in some trawler nets as by-catch, though despite this they are still quite common throughout their range. Despite these potential threats, the short-beaked common dolphin is considered to be Least Concern by the [[IUCN]] Red List, and the long-beaked common dolphin is listed as Data Deficient.<ref name="iucn status 19 November 2021" />

The short-beaked common dolphin ''Delphinus delphis'' is listed globally on Appendix II<ref name="Appendices">[https://web.archive.org/web/20110611112003/http://www.cms.int/documents/appendix/Appendices_COP9_E.pdf Appendices I and II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS)]. effective 5 March 2009</ref> of the Convention on the Conservation of Migratory Species of Wild Animals (CMS).<ref>[http://www.cms.int/reports/small_cetaceans/data/d_delphis/d_delphis.htm Convention on Migratory Species page on the Short-beaked common dolphin]. Cms.int. Retrieved on 2014-01-04.</ref> As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009 of the [[Convention on Migratory Species|Convention on the Conservation of Migratory Species of Wild Animals]] (CMS) as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. The Mediterranean population of the short-beaked common dolphin is also listed on Appendix I,<ref name="Appendices" /> as this population has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them. In addition, the species is also covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas ([[ASCOBANS]])<ref>[http://www.ascobans.org Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas]. Ascobans.org. Retrieved on 2014-01-04.</ref> and the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area ([[ACCOBAMS]]).<ref>[http://www.accobams.org Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area]. Accobams.org. Retrieved on 2014-01-04.</ref>

==== Mass stranding events ====
On June 8, 2009, a [[Cetacean stranding|mass-stranding event]] (MSE) occurred in Falmouth Bay, Cornwall, United Kingdom. It is believed the MSE was likely caused by naval involvement, as all other factors which cause MSEs in cetaceans appear unlikely to have influenced the event. During the event, 26 common dolphins washed ashore, and about the same number floated back out to sea. There were three other MSEs in the UK before this event, all of unknown cause, from the years 1915 to 1938, but with what are believed to be lower counts of stranded dolphins.<ref>{{Cite journal|last1=Jepson|first1=P. D.|last2=Deaville|first2=R.|last3=Acevedo-Whitehouse|first3=K.|last4=Barnett|first4=J.|last5=Brownlow|first5=A.|last6=Brownell Jr|first6=R. L.|last7=Clare|first7=F. C.|last8=Davison|first8=N.|last9=Law|first9=R. J.|last10=Loveridge|first10=J.|last11=MacGregor|first11=S. K.|year=2013|editor1-last=Fahlman|editor1-first=Andreas|title=What Caused the UK's Largest Common Dolphin (Delphinus delphis) Mass Stranding Event?|journal=PLOS ONE|volume=8|issue=4|pages=e60953|doi=10.1371/journal.pone.0060953|pmc=3640001|pmid=23646103|last17=Seibel|last24=Fernández|last12=Morris|first12=S.|last13=Murphy|first13=S. A.|last14=Penrose|first14=R.|last15=Perkins|last16=Pinn|first16=E.|first24=A.|first23=A. A.|first17=H.|last23=Cunningham|first22=N.|last22=Tregenza|first21=M. L.|last21=Tasker|first20=V.|last20=Simpson|first19=E.|last19=Sierra|first18=U.|last18=Siebert|first15=M. W.|bibcode=2013PLoSO...860953J |doi-access=free}}</ref>

===Captivity===

Common dolphins are not common in captivity. But on at least three occasions, a beached common dolphin in California was nursed back to health at [[SeaWorld San Diego]], but deemed unfit to release back to the ocean. These common dolphins remained at SeaWorld with the bottlenose dolphin exhibit. On one occasion, a male common dolphin managed to impregnate one of the female bottlenose dolphins in the exhibit, leading to four hybrid births.<ref name="hybrid">{{cite journal|title=Captive-born bottlenose dolphin × common dolphin (''Tursiops truncatus'' × ''Delphinus capensis'') intergeneric hybrids|author1=Zornetzer H.R. |author2=Duffield D.A. |journal=Canadian Journal of Zoology |volume=81 |issue=10 |pages=1755–1762 |date=October 1, 2003|doi=10.1139/z03-150|bibcode=2003CaJZ...81.1755Z }}</ref> One of the resulting common dolphin/bottlenose dolphin hybrids remained at SeaWorld, San Diego (alternately under the name Cindy or Bullet) while the other (named CJ) was kept at [[Discovery Cove]], and was moved to SeaWorld Orlando in 2016.

Other than at SeaWorld, at least 90 common dolphins are known to have been captured from the wild and kept in captivity. Captured common dolphins are said to be difficult to keep in captivity.<ref name="TheCommon" />

The behavior of captive common dolphins is not very well studied. However, a study was conducted in New Zealand of common dolphin reacting to swimmers at [[Marineland of New Zealand|Marineland]].<ref>{{Cite journal |date=2003 |title=Behavioural responses of captive common dolphins Delphinus delphis to a 'Swim-with-Dolphin' programme |journal=Applied Animal Behaviour Science}}</ref> Unlike bottlenose dolphins (which demonstrated antagonistic or sexual behaviors), the common dolphins retreated to the refuge center of the pool, where swimmers were not allowed. They did not leave the refuge section until the swimmers left. The dolphins also surfaced much more frequently, which is a possible indicator of stress. Aggressive and playful behavior among the dolphins decreased when swimmers were present. This behavior is consistent with wild common dolphins off of New Zealand, as they actively avoid swimmers.<ref>{{Cite journal|last=Kyngdon|first=D.|date=2003|title=Behavioural responses of captive common dolphins Delphinus delphis to a 'Swim-with-Dolphin' programme.|journal=Applied Animal Behaviour Science|volume=81|issue=2|pages=163–170|doi=10.1016/S0168-1591(02)00255-1}}</ref>