Editing Dolphin (section)

=== Impacts of climate change ===
{{See also|Effects of climate change on oceans}}
Dolphins are marine mammals with broad geographic extent, making them susceptible to climate change in various ways. The most common effect of climate change on dolphins is the increasing water temperatures across the globe.<ref name="Evans-2013-2">{{Cite journal |last1=Evans |first1=Peter G.H. |last2=Bjørge |first2=Arne |date=November 28, 2013 |title=Impacts of climate change on marine mammals |url=https://www.seawatchfoundation.org.uk/wp-content/uploads/2015/05/Evans-Bj%C3%B8rge_2013.pdf |journal=MCCIP Science Review 2013}}</ref> This has caused a large variety of dolphin species to experience range shifts, in which the species move from their typical geographic region to cooler waters.<ref name="Würsig-2001"/><ref>{{Cite journal |last1=Salvadeo |first1=CJ |last2=Lluch-Belda |first2=D |last3=Gómez-Gallardo |first3=A |last4=Urbán-Ramírez |first4=J |last5=MacLeod |first5=CD |date=2010-03-10 |title=Climate change and a poleward shift in the distribution of the Pacific white-sided dolphin in the northeastern Pacific |url=https://www.int-res.com/abstracts/esr/v11/n1/p13-19/ |journal=Endangered Species Research |language=en |volume=11 |issue=1 |pages=13–19 |doi=10.3354/esr00252 |issn=1863-5407 |doi-access=free}}</ref> Another side effect of increasing water temperatures is the increase in [[Harmful algal bloom|harmful algae blooms]], which has caused a mass die-off of bottlenose dolphins.<ref name="Evans-2013-2" />

In [[California]], the 1982–83 [[El Niño]] warming event caused the near-bottom spawning [[market squid]] to leave southern California, which caused their predator, the [[pilot whale]], to also leave. As the market squid returned six years later, [[Risso's dolphin|Risso's dolphins]] came to feed on the squid. [[Bottlenose dolphin|Bottlenose dolphins]] expanded their range from southern to central California, and stayed even after the warming event subsided.<ref name="Würsig-2001">{{Citation |last1=Würsig |first1=Bernd |title=Global Climate Change and Marine Mammals |date=2001 |url=https://doi.org/10.1007/978-1-4615-0529-7_17 |work=Marine Mammals: Biology and Conservation |pages=589–608 |editor-last=Evans |editor-first=Peter G. H. |place=Boston, MA |publisher=Springer US |language=en |doi=10.1007/978-1-4615-0529-7_17 |isbn=978-1-4615-0529-7 |access-date=2021-05-01 |last2=Reeves |first2=Randall R. |last3=Ortega-Ortiz |first3=J. G. |editor2-last=Raga |editor2-first=Juan Antonio}}</ref> The [[Pacific white-sided dolphin]] has had a decline in population in the southwest [[Gulf of California]], the southern boundary of their distribution. In the 1980s they were abundant with group sizes up to 200 across the entire cool season. Then, in the 2000s, only two groups were recorded with sizes of 20 and 30, and only across the central cool season. This decline was not related to a decline of other marine mammals or prey, so it was concluded to have been caused by climate change as it occurred during a period of warming. Additionally, the Pacific white-sided dolphin had an increase in occurrence on the west coast of [[Canada]] from 1984 to 1998.<ref>{{Cite journal |last1=Salvadeo |first1=CJ |last2=Lluch-Belda |first2=D |last3=Gómez-Gallardo |first3=A |last4=Urbán-Ramírez |first4=J |last5=MacLeod |first5=CD |date=2010-03-10 |title=Climate change and a poleward shift in the distribution of the Pacific white-sided dolphin in the northeastern Pacific |url=https://www.int-res.com/abstracts/esr/v11/n1/p13-19/ |journal=Endangered Species Research |language=en |volume=11 |issue=1 |pages=13–19 |doi=10.3354/esr00252 |issn=1863-5407 |doi-access=free}}</ref>

In the [[Mediterranean]], [[Sea surface temperature|sea surface temperatures]] have increased, as well as [[salinity]], [[upwelling]] intensity, and sea levels. Because of this, prey resources have been reduced causing a steep decline in the [[short-beaked common dolphin]] Mediterranean subpopulation, which was deemed endangered in 2003. This species now only exists in the [[Alboran Sea]], due to its high productivity, distinct ecosystem, and differing conditions from the rest of the Mediterranean.<ref>{{Cite journal |last1=Cañadas |first1=A. |last2=Vázquez |first2=J.A. |date=2017-07-01 |title=Common dolphins in the Alboran Sea: Facing a reduction in their suitable habitat due to an increase in Sea surface temperature |journal=Deep Sea Research Part II: Topical Studies in Oceanography |language=en |volume=141 |pages=306–318 |bibcode=2017DSRII.141..306C |doi=10.1016/j.dsr2.2017.03.006 |issn=0967-0645 |doi-access=free}}</ref>

In northwest Europe, many dolphin species have experienced range shifts from the region's typically colder waters. Warm water dolphins, like the short-beaked common dolphin and [[striped dolphin]], have expanded north of western Britain and into the northern [[North Sea]], even in the winter, which may displace the [[White-beaked dolphin|white-beaked]] and [[Atlantic white-sided dolphin]] that are in that region. The white-beaked dolphin has shown an increase in the southern North Sea since the 1960s because of this. The [[rough-toothed dolphin]] and [[Atlantic spotted dolphin]] may move to northwest Europe.<ref name="Evans-2013-2"/> In northwest [[Scotland]], white-beaked dolphins (local to the colder waters of the North Atlantic) have decreased while common dolphins (local to warmer waters) have increased from 1992 to 2003.<ref>{{Cite journal |last1=MacLeod |first1=Colin D. |last2=Bannon |first2=Sarah M. |last3=Pierce |first3=Graham J. |last4=Schweder |first4=Caroline |last5=Learmonth |first5=Jennifer A. |last6=Herman |first6=Jerry S. |last7=Reid |first7=Robert J. |date=2005-08-01 |title=Climate change and the cetacean community of north-west Scotland |url=https://www.sciencedirect.com/science/article/abs/pii/S0006320705000789 |journal=Biological Conservation |language=en |volume=124 |issue=4 |pages=477–483 |doi=10.1016/j.biocon.2005.02.004 |bibcode=2005BCons.124..477M |issn=0006-3207}}</ref> Additionally, [[Fraser's dolphin]], found in tropical waters, was recorded in the UK for the first time in 1996.<ref name="Evans-2013-2"/>

[[River dolphin|River dolphins]] are highly affected by climate change as high evaporation rates, increased water temperatures, decreased precipitation, and increased [[Ocean acidification|acidification]] occur.<ref name="Würsig-2001" /><ref name="Gomez-Salazar-2012">{{Cite journal |last1=Gomez-Salazar |first1=Catalina |last2=Coll |first2=Marta |last3=Whitehead |first3=Hal |date=2012-12-01 |title=River dolphins as indicators of ecosystem degradation in large tropical rivers |url=https://www.sciencedirect.com/science/article/abs/pii/S1470160X12000805 |journal=Ecological Indicators |language=en |volume=23 |pages=19–26 |doi=10.1016/j.ecolind.2012.02.034 |bibcode=2012EcInd..23...19G |issn=1470-160X}}</ref> River dolphins typically have a higher densities when rivers have a lox index of freshwater degradation and better water quality. {{Explain|date=April 2025}}<ref name="Gomez-Salazar-2012" /> Specifically looking at the [[Ganges river dolphin]], the high evaporation rates and increased flooding on the plains may lead to more human river regulation, decreasing the dolphin population.<ref name="Würsig-2001" />

As warmer waters lead to a decrease in dolphin prey, this led to other causes of dolphin population decrease. In the case of bottlenose dolphins, [[Mullet (fish)|mullet]] populations decrease due to increasing water temperatures, which leads to a decrease in the dolphins' health and thus their population.<ref name="Würsig-2001" /> At the Shark Bay World Heritage Area in Western Australia, the local [[Indo-Pacific bottlenose dolphin]] population had a significant decline after a marine heatwave in 2011. This heatwave caused a decrease in prey, which led to a decline in dolphin reproductive rates as female dolphins could not get enough nutrients to sustain a calf.<ref>{{Cite journal |last1=Wild |first1=Sonja |last2=Krützen |first2=Michael |last3=Rankin |first3=Robert W. |last4=Hoppitt |first4=William J.E. |last5=Gerber |first5=Livia |last6=Allen |first6=Simon J. |date=2019-04-01 |title=Long-term decline in survival and reproduction of dolphins following a marine heatwave |journal=Current Biology |language=en |volume=29 |issue=7 |pages=R239–R240 |doi=10.1016/j.cub.2019.02.047 |issn=0960-9822 |pmid=30939303 |doi-access=free|bibcode=2019CBio...29.R239W |hdl=1983/1a397eb9-1713-49b5-a2fb-f0d7c747e724 |hdl-access=free }}</ref> The resultant decrease in fish population due to warming waters has also influenced humans to see dolphins as fishing competitors or even bait. Humans use [[Dusky dolphin|dusky dolphins]] as bait or are killed off because they consume the same fish humans eat and sell for profit.<ref name="Würsig-2001" /> In the central Brazilian Amazon alone, approximately 600 [[Pink River Dolphin|pink river dolphins]] are killed each year to be used as bait.<ref name="Gomez-Salazar-2012" />