Editing Great white shark (section)

===Natural threats===
====Interspecific competition and predation by orcas====
[[File:Comparison of size of orca and great white shark.svg|thumb|upright=1.35|Comparison of the size of an average orca and an average great white shark]]

Interspecific competition between the great white shark and the [[orca]] is probable in regions where dietary preferences of both species may overlap.<ref name="Competition" /> An incident was documented on 4 October 1997, in the [[Farallon Islands]] off [[California]] in the United States. An estimated {{cvt|4.7|–|5.3|m}} female orca immobilized an estimated {{cvt|3|–|4|m}} great white shark.<ref name="POWS">{{cite journal |last1=Pyle |first1=Peter |last2=Schramm |first2=Mary Jane |last3=Keiper |first3=Carol |last4=Anderson |first4=Scot D. |title=Predation on a white shark (''Carcharodon carcharias'') by a killer whale (Orcinus orca) and a possible case of competitive displacement |url=http://www.prbo.org/cms/docs/marine/MMS.pdf |volume=15 |issue=2 |pages=563–568 |journal=Marine Mammal Science |date=26 August 2006 |doi=10.1111/j.1748-7692.1999.tb00822.x |bibcode=1999MMamS..15..563P |access-date=8 May 2010|archive-url=https://web.archive.org/web/20120322070431/http://www.prbo.org/cms/docs/marine/MMS.pdf |archive-date=22 March 2012}}</ref> The orca held the shark upside down to induce [[tonic immobility]] and kept the shark still for fifteen minutes, causing it to suffocate. The orca then proceeded to eat the dead shark's liver.<ref name="Competition" /><ref name="POWS" /><ref name="Nature Shock">{{cite web |url=http://www.tvthrong.co.uk/nature-shock/nature-shock-series-premiere-whale-ate-great-white |title=Nature Shock Series Premiere: The Whale That Ate the Great White |publisher=Tvthrong.co.uk |date=4 October 1997 |access-date=16 October 2010 |archive-url=https://web.archive.org/web/20120406081857/http://www.tvthrong.co.uk/nature-shock/nature-shock-series-premiere-whale-ate-great-white |archive-date=6 April 2012 |url-status=dead}}</ref> It is believed that the scent of the slain shark's carcass caused all the great whites in the region to flee, forfeiting an opportunity for a great seasonal feed. Another similar attack apparently occurred there in 2000, but its outcome is not clear.<ref name="Turner">{{cite journal |last=Turner |first=Pamela S. |title=Showdown at Sea: What happens when great white sharks go fin-to-fin with killer whales? |journal=National Wildlife |volume=42 |issue=6 |publisher=[[National Wildlife Federation]] |date=Oct–Nov 2004 |url=http://www.nwf.org/News-and-Magazines/National-Wildlife/Animals/Archives/2004/Showdown-at-Sea.aspx|access-date=21 November 2009 |archive-url=https://web.archive.org/web/20110116235642/https://www.nwf.org/News-and-Magazines/National-Wildlife/Animals/Archives/2004/Showdown-at-Sea.aspx |archive-date=16 January 2011}}</ref> After both attacks, the local population of about 100 great whites vanished.<ref name="Nature Shock" /><ref name="Turner" /> Following the 2000 incident, a great white with a satellite tag was found to have immediately submerged to a depth of {{cvt|500|m|ft}} and swam to [[Hawaii]].<ref name="Turner" />

In 2015, a pod of orcas was recorded to have killed a great white shark off South Australia.<ref>{{cite web |title=Great white shark 'slammed' and killed by a pod of killer whales in South Australia |publisher=Australian Broadcasting Corporation |date=3 February 2015 |access-date=10 July 2015 |url=http://www.abc.net.au/news/2015-02-04/great-white-killed-by-killer-whales-in-sa/6069168 |archive-date=19 July 2015 |archive-url=https://web.archive.org/web/20150719051009/http://www.abc.net.au/news/2015-02-04/great-white-killed-by-killer-whales-in-sa/6069168 |url-status=live}}</ref> In 2017, three great whites were found washed ashore near [[Gansbaai]], South Africa, with their body cavities torn open and the livers removed by what is likely to have been orcas.<ref>{{Cite news |url=https://www.thesouthafrican.com/killer-whales-have-been-killing-great-white-sharks-in-cape-waters/ |title=Killer whales have been killing great white sharks in Cape waters |last=Haden |first=Alexis |date=6 June 2017 |work=The South African |access-date=27 June 2017 |archive-date=4 July 2017 |archive-url=https://web.archive.org/web/20170704055117/https://www.thesouthafrican.com/killer-whales-have-been-killing-great-white-sharks-in-cape-waters/ |url-status=live}}</ref> Orcas also generally impact great white distribution. Studies published in 2019 of orca and great white shark distribution and interactions around the Farallon Islands indicate that the cetaceans impact the sharks negatively, with brief appearances by orcas causing the sharks to seek out new feeding areas until the next season.<ref>{{cite journal |author=Jorgensen, S. J.|display-authors=etal |year=2019 |title=Killer whales redistribute white shark foraging pressure on seals |journal=Scientific Reports |volume=9 |issue=1 |page=6153 |doi=10.1038/s41598-019-39356-2|doi-access=free |pmid=30992478 |bibcode=2019NatSR...9.6153J |pmc=6467992}}</ref> It is unclear whether this is an example of [[competitive exclusion]] or [[Ecology of fear (concept)|ecology of fear]]. Occasionally, however, some great whites have been seen to swim near orcas without fear.<ref name="ScienceAlert 11-2019">{{cite news |last=Starr |first=Michell |title=Incredible Footage Reveals Orcas Chasing Off The Ocean's Most Terrifying Predator |publisher=Science Alert |url=https://www.sciencealert.com/watch-orcas-surround-and-scare-off-the-ocean-s-most-terrifying-predator |date=11 November 2019 |access-date=24 November 2019 |archive-date=11 November 2019 |archive-url=https://web.archive.org/web/20191111234146/https://www.sciencealert.com/watch-orcas-surround-and-scare-off-the-ocean-s-most-terrifying-predator |url-status=live}}</ref>

====Parasites====
The great white shark is the [[Host (biology)|definitive host]] of two species of [[Cestoda|tapeworms]] from the genus ''[[Clistobothrium]]'', these being ''[[Clistobothrium carcharodoni]]'' and ''[[Clistobothrium tumidum]]'', both of which infect the shark's [[Spiral valve|spiral intestine]].<ref name="Ruhnke1993">{{cite journal|last=Ruhnke|first=Timothy R.|title=A New Species of Clistobothrium (Cestoda: Tetraphyllidea), with an Evaluation of the Systematic Status of the Genus|date=February 1993|journal=[[Journal of Parasitology]]|publisher=[[Allen Press]]|volume=79|number=1|pages=37–43|doi=10.2307/3283274|jstor=3283274|url=https://www.jstor.org/stable/3283274|access-date=20 May 2024}}</ref> The former is believed to be transmitted to great whites through the consumption of infected cetacean prey, namely the [[spinner dolphin]] (''Stenella longirostris''), [[Risso's dolphin]] (''Grampus griseus''), and the [[common bottlenose dolphin]] (''Tursiops truncatus''), all of which serve as intermediary or paratenic hosts of the tapeworm.<ref name="Randhawa2011">{{cite journal|last=Randhawa|first=Haseeb S.|title=Insights using a molecular approach into the life cycle of a tapeworm infecting great white sharks|date=1 April 2011|journal=[[Journal of Parasitology]]|publisher=[[Allen Press]]|volume=92|number=2|pages=275–280|doi=10.1645/GE-2530.1|pmid=21506792 |url=https://www.researchgate.net/publication/51064300|access-date=20 May 2024}}</ref> The latter species of tapeworm's [[Disease vector|transmission vector]] is currently unknown, but it is unlikely to share the same intermediary hosts as ''[[Clisbotherium carcharodoni]]''.<ref name="Caira2020">{{cite journal|last1=Caira|first1=Janine N.|last2=Jensen|first2=Kirsten|last3=Pickering|first3=Maria|last4=Ruhnke|first4=Timothy R.|last5=Gallagher|first5=Kaitlin A.|title=Intrigue surrounding the life-cycles of species of ''Clistobothrium'' (Cestoda: Phyllobothriidea) parasitising large pelagic sharks|orig-date=4 April 2020|date=7 November 2020|journal=[[International Journal for Parasitology]]|publisher=Elsevier|volume=50|issue=13|pages=1043–1055|doi=10.1016/j.ijpara.2020.08.002|doi-access=free|pmid=32979336 }}</ref> The intensity of ''[[Clistobothrium carcharodoni]]'' infestations in affected great whites is extremely high; in one case, up to 2,533 specimens were recovered from the spiral valve of a single great white.<ref name="Randhawa2011"/>

There are two recorded instances of the ectoparasitic [[cookiecutter shark]] ''(Isistius brasiliensis)'' targeting [[wiktionary:subadult|subadult]] great whites off the coast of [[Guadalupe Island]]. However, the relative dearth of predation records indicates that great whites are not a common food source for cookiecutter sharks, and that [[cetaceans]] and [[pinnipeds]] - especially the [[Guadalupe fur seal]] (''Arctocephalus townsendi'') - are preferred over great whites; in part due to the higher caloric content of their [[blubber]], and in part due to the higher risk of retaliation from victimized great whites.<ref name=Hoyos-Padilla2013>{{cite journal|last1=Hoyos-Padilla|first1=Mauricio|last2=Papastamatiou|first2=Yannis P.|last3=O'Sullivan|first3=John|last4=Lowe|first4=Christopher G.|title=Observation of an Attack by a Cookiecutter Shark (''Isistius brasiliensis'') on a White Shark (''Carcharodon carcharias'')|date=1 January 2013|journal=[[Pacific Science]]|publisher=[[University of Hawai'i Press]]|volume=67|issue=1|pages=129–134|doi=10.2984/67.1.10|url=https://www.researchgate.net/publication/273689577}}</ref>