Orca types and populations

Research off the west coast of Canada and the United States in the 1970s and 1980s identified the following three types:

File:Orca pod southern residents.jpg

• Resident: These are the most commonly sighted of the three populations in the coastal waters of the northeast Pacific. The population structure of resident orcas in the Northwest Pacific is unknown; however, the whales regularly observed in the Avacha Gulf are considered to be the resident ecological type according to their behavior and appearance. {{cite journal |last1=Ivkovich |first1=Tatiana |last2=Filatova |first2=Olga A. |last3=Burdin |first3=Alexandr M. |last4=Sato |first4=Hal |last5=Hoyt |first5=Erich |title=The social organization of resident-type killer whales (Orcinus orca) in Avacha Gulf, Northwest Pacific, as revealed through association patterns and acoustic similarity |journal=Mammalian Biology |date=May 2010 |volume=75 |issue=3 |pages=198–210 |doi=10.1016/j.mambio.2009.03.006 |url=https://doi.org/10.1016/j.mambio.2009.03.006|url-access=subscription }} Residents' diets consist primarily of fish{{cite journal |last1=Ford |first1=J.K.B. |last2=Ellis |first2=G.M. |last3=Barrett-Lennard |first3=L.G. |last4=Morton |first4=A.B. |last5=Palm |first5=R.S. |last6=Balcomb |first6=K.C. |year=1998 |title=Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters |journal=Canadian Journal of Zoology |volume=76 |issue=8 |pages=1456–1471 |doi=10.1139/z98-089|bibcode=1998CaJZ...76.1456F }} and sometimes squid, and they live in complex and cohesive family groups called pods.{{cite book |last1=Berta |first1=Annalisa |first2=James L. |last2=Sumich |first3=Kit M. |last3=Kovacs |title=Marine mammals: evolutionary biology |url=https://archive.org/details/marinemammalsevo00bert |url-access=limited |publisher=Academic Press |year=2006 |page=[https://archive.org/details/marinemammalsevo00bert/page/n395 387] |isbn=978-0-12-088552-7}} Female residents characteristically have rounded dorsal fin tips that terminate in a sharp corner.{{sfn|Carwardine|2001|pp=40–47}} The grey or white area around the dorsal fin, known as the "saddle patch", often contains some black colouring in residents. They visit the same areas consistently. British Columbia and Washington resident populations are amongst the most intensively studied marine mammals anywhere in the world.{{sfn|Ford|Ellis|Balcomb|2000|p=23}} Resident orcas can be divided into at least three distinct communities; northern, southern and southern Alaskan. Southern Alaskan resident orcas are distributed from southeastern Alaska to the Kodiak Archipelago and number over 700 individuals. These whales consist of two interbreeding clans distinguished by acoustic calls and whose ranges overlap.{{cite journal|author=O Matkin, Craig|year=2013|title=Life history and population dynamics of southern Alaska resident killer whales (Orcinus orca)|journal=Marine Mammal Science|volume=30|issue=2|pages=460–479|doi= 10.1111/mms.12049}} The northern resident community lives in coastal and inland waters from southeastern Alaska to Vancouver Island. It consists of three clans and 16 pods{{sfn|Ford|Ellis|Balcomb|2000|p=45}} and number over 300 orcas total.{{cite report|author1=Towers, Jared R. |author2=Pilkington, James F. |author3=Gisborne, Brian |author4=Wright, Brianna M. |author5=Ellis, Graeme M. |author6=Ford, John K. B. |author7=Doniol-Valcroze, Thomas |year=2020|title=Photo-identification Catalogue and Status of the Northern Resident Killer Whale Population in 2019|publisher=Fisheries and Oceans Canada |url=https://waves-vagues.dfo-mpo.gc.ca/Library/40877012.pdf|accessdate=9 May 2022}} The southern resident community generally inhabits the inland waters of southern British Columbia and Washington, but can be found in the outer waters off Vancouver Island, Washington, Oregon and California. They consist of one clan and three pods, and number less than 80 individuals and are listed as endangered.{{sfn|Ford|Ellis|Balcomb|2000|p=47}}{{cite report|date=December 2021|title=Southern Resident Killer Whales (Orcinus orca) 5-Year Review: Summary and Evaluation|publisher=National Marine Fisheries Service|url=https://media.fisheries.noaa.gov/2022-01/srkw-5-year-review-2021.pdf|accessdate=9 May 2022}}

{{Anchor|Bigg's}}

• Transient or Bigg's: The diets of these orcas consist almost exclusively of marine mammals.{{sfn|Carwardine|2001|pp=40–47}} They live in the same areas as residents, but the two avoid each other.{{cite journal | last1 = Baird | first1 = R.W. | last2 = Dill | first2 = L.M. | year = 1995 | title = Occurrence and behaviour of transient killer whales: seasonal and pod-specific variability, foraging behaviour, and prey handling | journal = Canadian Journal of Zoology | volume = 73 | issue = 7| pages = 1300–1311 | doi=10.1139/z95-154| bibcode = 1995CaJZ...73.1300B }}Barrett-Lennard LG, Ellis GM. 2001. Population structure and genetic variability in northeastern Pacific killer whales: Towards an assessment of population viability. Canadian Science Advisory Secretariat, Ottawa, Canada.{{sfn|NMFS|2005|p=23}} Transients generally travel in small groups, usually of two to six animals, but sometimes on rare occasions pods merge into groups of 200. They have less persistent family bonds than residents.Ford J.K.B. and, G.M. Ellis. 1999. Transients: Mammal-hunting killer whales of British Columbia, Washington, and Southeastern Alaska. UBC Press, Vancouver. Transients vocalize in less variable and less complex dialects.{{cite journal | last1 = Deecke | first1 = V.B. | last2 = Ford | first2 = J.K.B. | last3 = Slater | first3 = P.J.B. | year = 2005 | title = The vocal behaviour of mammal-eating killer whales: Communicating with costly calls | journal = Animal Behaviour | volume = 69 | issue = 2 | pages = 395–405 | doi = 10.1016/j.anbehav.2004.04.014 | s2cid = 16899659 }} Female transients are characterized by more triangular and pointed dorsal fins than those of residents.{{sfn|Carwardine|2001|pp=40–47}} The saddle patches of transients are solid and uniformly grey (in contrast to the residents saddle patches that often have more black-coloring).{{sfn|Carwardine|2001|pp=40–47}} Transients roam widely along the coast; some individuals have been sighted in both southern Alaska and California.{{sfn|NMFS|2005|p=24}} Transients are also referred to as Bigg's orca in honour of cetologist Michael Bigg. The term has become increasingly common and may eventually replace the transient label.{{cite news|url=http://www.nanaimodailynews.com/news/nanaimo-region/transient-label-is-pushed-aside-to-honour-renowned-whale-researcher-1.251303 |date=December 4, 2012 |title=Transient label is pushed aside to honour renowned whale researcher |first=Darrell |last=Bellaart |newspaper=Nanaimo Daily News |access-date=December 4, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20140301145934/http://www.nanaimodailynews.com/news/nanaimo-region/transient-label-is-pushed-aside-to-honour-renowned-whale-researcher-1.251303 |archive-date=March 1, 2014 }} The transient ecotype is estimated to have diverged 700,000 years ago.{{cite news |first=NICHOLAS |last=WADE |date=April 26, 2010 |newspaper=New York Times |url=https://www.nytimes.com/2010/04/27/science/27whale.html?src=sch&pagewanted=all&_r=0 |title=Cracking Orca's Code: It Comes in Several Types |access-date=February 17, 2017 |archive-date=July 1, 2017 |archive-url=https://web.archive.org/web/20170701045110/http://www.nytimes.com/2010/04/27/science/27whale.html?src=sch&pagewanted=all&_r=0 |url-status=live }} There are at least three different "stocks" of transients off North America, the AT1 stock which occurs from Prince William Sound to Kenai Fjords, the Gulf of Alaska/Aleutian Islands/Bering Sea (GOA/AI/BS) stock and the west coast stock which ranges from southeast Alaska to California. AT1 is considered a depleted stock; it was affected by the Exxon Valdez oil spill and declined from 22 individuals to eight between 1989 and 2004. The GOA/AI/BS stock may number around 500 whales while the west coast transients number over 320 orcas with over 200 along southeast Alaska, British Columbia and Washington and over 100 orcas off California.{{cite web|title=Killer Whales (Orcinus orca)|website=Alaska Department of Fish and Game|url=https://www.adfg.alaska.gov/index.cfm?adfg=killerwhale.printerfriendly|accessdate=9 May 2022}} California transients do not appear to intermingle much with those further north and west coast transients may be divided into sub-communities.{{cite book|author1-last=Ford|author1-first= J. K. B.|author2-last=Ellis|author2-first=Graeme M.|year=2009|title=Transients: Mammal-Hunting Killer Whales of British Columbia, Washington, and Southeastern Alaska|publisher=UBC Press|page=12|isbn=978-0774807173}}{{Anchor|North Pacific Offshore}}
• Offshore: A third population of orcas in the northeast Pacific was discovered in 1988, when a humpback whale researcher observed them in open water. As their name suggests, they travel far from shore and feed primarily on schooling fish.{{sfn|Ford|Ellis|Balcomb|2000|p=21}} However, because they have large, scarred and nicked dorsal fins resembling those of mammal-hunting transients, it may be that they also eat mammals and sharks.{{cite journal | last1 = Dahlheim | first1 = M.E. | last2 = Schulman-Janiger | first2 = A. | last3 = Black | first3 = N. | last4 = Ternullo | first4 = R. | last5 = Balcomb | first5 = K.C. | year = 2008 | title = Eastern temperate North Pacific offshore killer whales (Orcinus orca): Occurrence, movements, and insights into feeding ecology | url = https://digitalcommons.unl.edu/usdeptcommercepub/169 | journal = Marine Mammal Science | volume = 24 | issue = 3 | pages = 719–729 | doi = 10.1111/j.1748-7692.2008.00206.x | bibcode = 2008MMamS..24..719D | access-date = February 5, 2019 | archive-date = October 13, 2010 | archive-url = https://web.archive.org/web/20101013222440/http://digitalcommons.unl.edu/usdeptcommercepub/169/ | url-status = live | url-access = subscription }} They have mostly been encountered off the west coast of Vancouver Island and near Haida Gwaii. Offshores typically congregate in groups of 20–75, with occasional sightings of larger groups of up to 200.{{cite web |title=Killer whale (Orcinus orca) |website=NOAA Fisheries |publisher=Office of Protected Resources, National Marine Fisheries Service |url=http://www.fisheries.noaa.gov/pr/species/mammals/whales/killer-whale.html |access-date=August 15, 2017 |url-status=dead |archive-url=https://web.archive.org/web/20170709160557/http://www.fisheries.noaa.gov/pr/species/mammals/whales/killer-whale.html |archive-date=July 9, 2017 }} Little is known about their habits, but they are genetically distinct from residents and transients. Offshores appear to be smaller than the others, and females are characterized by dorsal fin tips that are continuously rounded.{{sfn|Carwardine|2001|pp=40–47}} They have been spotted in Monterey Bay in California.{{Cite web |date=2023-08-04 |title='Elusive' creatures — known for hunting sharks — spotted in rare California encounter |url=https://news.yahoo.com/elusive-creatures-known-hunting-sharks-171443075.html |access-date=2023-08-05 |website=Yahoo News |language=en-US}}

Separate fish-eating and mammal-eating orca communities also exist off the coast of the Russian Far East and Hokkaido, Japan.{{cite journal|author1= Mitani, Yoko|author2=Kita, Yuki F.|author3=Saino, Shigeo|author4=Yoshioka, Motoi|author5=Ohizumi, Hiroshi|display-authors=etal|year=2021|title=Mitochondrial DNA Haplotypes of Killer Whales around Hokkaido, Japan|journal=Mammal Study|volume=46|issue=3|pages=205–211|doi=10.3106/ms2020-0072|s2cid=236221150 }} Russian orcas are commonly seen around the Kamchatka Peninsula and Commander Islands. Over 2,000 individual resident-like orcas and 130 transient-like orcas have been identified off Russia.{{cite web|url=https://us.whales.org/whales-dolphins/how-we-help/far-east-russia-orca-project-ferop/|title=Far East Russia Orca Project (FEROP)|website=us.whales.org|access-date=9 May 2022}} At least 195 individual orcas have been cataloged in the eastern tropical Pacific, ranging from Baja California and the Gulf of California in the north to the northwest coast of South America in the south and west towards Hawaii.{{cite report|author1=Olson, Paula A |author2=Gerrodette, Tim |year=2020|title=Killer Whales of the Eastern Tropical Pacific: A Catalog of Photo-Identified Individuals|url=https://swfsc-publications.fisheries.noaa.gov/publications/TM/SWFSC/NOAA-TM-NMFS-SWFSC-428.pdf|publisher=National Oceanic and Atmospheric Administration|accessdate=10 May 2022}} Orcas appear to regularly occur off the Galápagos Islands.{{cite journal |last1=Merlen |first1=Godfrey |year=1999 |title=The orca in Galapagos: 135 sightings |journal=Noticias de Galapagos |volume=60 |pages=2–8 |url=http://aquaticcommons.org/id/eprint/7462 |access-date=March 14, 2019 |archive-date=September 15, 2020 |archive-url=https://web.archive.org/web/20200915041637/http://aquaticcommons.org/7462/ |url-status=live }} Orcas sighted in Hawaiian waters may belong to a greater population in the central Pacific.{{cite web|title=Killer whales in Hawai'i|publisher=Cascadia Research.org|access-date=October 19, 2017|url=http://www.cascadiaresearch.org/hawaiian-cetacean-studies/killer-whales-hawaii|date=August 16, 2016|archive-date=October 20, 2017|archive-url=https://web.archive.org/web/20171020033329/http://www.cascadiaresearch.org/hawaiian-cetacean-studies/killer-whales-hawaii|url-status=live}}{{cite journal|author=Baird, R. W.|display-authors=etal|year=2006|title=Killer whales in Hawaiian waters: information on population identity and feeding habits|journal=Pacific Science|volume=60|issue=4|pages=523–530|doi=10.1353/psc.2006.0024|url=http://www.cascadiaresearch.org/files/Projects/Hawaii/Baird%20et%20al%20Hawaii%20killer%20whales.pdf|hdl=10125/22585|s2cid=16788148|access-date=October 23, 2017|archive-date=October 23, 2017|archive-url=https://web.archive.org/web/20171023063253/http://www.cascadiaresearch.org/files/Projects/Hawaii/Baird%20et%20al%20Hawaii%20killer%20whales.pdf|url-status=live|hdl-access=free}}

File:Orcinus orca (Vestfjord).jpg, Norway]]

At least 15,000 whales are estimated to inhabit the North Atlantic.{{cite web|url=https://nammco.no/killer-whale/|title=Killer Whale|publisher=NAMMCO|accessdate=10 May 2022}} In the Northeast Atlantic, two orca ecotypes have been proposed.{{cite journal |url=http://www.orcanetwork.org/nathist/NoAtlantictypes.pdf |last1=Foote |first1=Andrew D. |journal=Molecular Ecology |last2=Newton |volume=18 |first2=Jason |issue=24 |pages=5207–17 |last3=Piertney |first3=Stuart B. |last4=Willerslev |first4=Eske |last5=Gilbert |first5=M. Thomas P. |year=2009 |pmid=20050301 |title=Ecological, morphological and genetic divergence of sympatric North Atlantic killer whale populations |doi=10.1111/j.1365-294X.2009.04407.x |bibcode=2009MolEc..18.5207F |s2cid=331555 |access-date=February 27, 2010 |archive-date=July 9, 2011 |archive-url=https://web.archive.org/web/20110709052810/http://www.orcanetwork.org/nathist/NoAtlantictypes.pdf |url-status=live }} Type 1 orcas consist of seven haplotypes and include herring-eating orcas of Norway and Iceland and mackerel-eating orcas of the North Sea, as well as seal-eating orcas off Norway.{{cite journal|author1=Jourdain, Eve|author2= Andvik, Clare|author3=Karoliussen, Richard|author4=Ruus, Anders|author5=Vongraven, Dag|author6=Borgå, Katrine|year=2020|title=Isotopic niche differs between seal and fish-eating killer whales (Orcinus orca) in northern Norway|journal=Ecology and Evolution|volume=10|issue=9|pages=4115–4127|doi=10.1002/ece3.6182|pmid=32489635 |pmc=7244801 |bibcode= 2020EcoEv..10.4115J}} Type 2 orcas consist of two haplotypes, and mainly feed on baleen whales. These two types have now been dropped from the classification, because of a lack of samples for type 2 (5 individuals) and how little it was representative of a potential ecotype.{{Cite journal |last=Foote |first=Andrew D. |date=January 2023 |title=Are "Type 2" killer whales long in the tooth? A critical reflection on the discrete categorization of Northeast Atlantic killer whales |url=https://onlinelibrary.wiley.com/doi/10.1111/mms.12964 |journal=Marine Mammal Science |language=en |volume=39 |issue=1 |pages=345–350 |doi=10.1111/mms.12964 |bibcode=2023MMamS..39..345F |issn=0824-0469|url-access=subscription }}

In the Mediterranean Sea, orcas are considered "visitors", likely from the North Atlantic, and sightings become less frequent further east.{{cite journal|author1=Hammond, P. S.|author2= Lockyer, C.|year=1988|title=Distribution of killer whales in the eastern north Atlantic|journal=Rit Fiskideildar|volume=11|pages=24–41|url=https://www.hafogvatn.is/static/research/files/rit_fisk_1988_xi_02.pdf}} However, a small year-round population exists in the Strait of Gibraltar, which numbered around 39 in 2011.{{cite journal|author1=Esteban, R.|author2=Verborgh, P.|author3=Gauffier, P.|display-authors=etal|title=Conservation Status of Killer Whales, Orcinus orca, in the Strait of Gibraltar|journal=Advances in Marine Biology|year=2016 |volume=75|pages=141–172|doi=10.1016/bs.amb.2016.07.001|pmid=27770983 |isbn=9780128051528 }} From 2020, this population started ramming vessels and damaging their rudders.{{cite journal |last1=Esteban |first1=Ruth |last2=López |first2=Alfredo |last3=de los Rios |first3=Álvaro Garcia |last4=Ferreira |first4=Marisa |title=Killer whales of the Strait of Gibraltar, an endangered subpopulation showing a disruptive behavior |url=https://onlinelibrary.wiley.com/doi/10.1111/mms.12947 |journal=Marine Mammal Science |date=October 2022 |volume=38 |issue=4 |pages=1699–1709 |doi=10.1111/mms.12947|bibcode=2022MMamS..38.1699E |url-access=subscription }} Distinct populations may also exist off the west coast of tropical Africa, which have generalized diets.{{cite journal|author=Weir, C. R.|author2=Collins, T.|author3=Carvalho, I.|author4=Rosenbaum, H. C.|year=2010|title=Killer whales (Orcinus orca) in Angolan and Gulf of Guinea waters, tropical West Africa|journal=Journal of the Marine Biological Association of the United Kingdom|volume=90|issue=8|pages=1601–1611|doi=10.1017/S002531541000072X|bibcode=2010JMBUK..90.1601W |s2cid=84721171|url=http://www.escolademar.pt/wp-content/uploads/pdf_docs/artigos/Weir_et_al_2010_final.pdf|archive-url=http://arquivo.pt/wayback/20140930081828/http://www.escolademar.pt/wp%2Dcontent/uploads/pdf_docs/artigos/Weir_et_al_2010_final.pdf|url-status=dead|archive-date=September 30, 2014}}

The northwest Atlantic population is found year-round around Labrador and Newfoundland, while some individuals seasonally travel to the waters of the eastern Canadian Arctic when the ice has melted.{{cite journal|author=Matthews, Cory J. D.|author2=Longstafe, Fred J.|author3=Lawson, Jack W.|author4= Ferguson, Steven H.|year=2021|title=Distributions of Arctic and Northwest Atlantic killer whales inferred from oxygen isotopes|journal=Scientific Reports|volume=11|issue=1|page=6739|doi=10.1038/s41598-021-86272-5|pmid=33762671 |pmc=7990931 |bibcode=2021NatSR..11.6739M }} Sightings of these whales have been documented as far south as Cape Cod and Long Island.{{cite journal |title=Historic and current distribution patterns, and minimum abundance of killer whales (Orcinus orca) in the north-west Atlantic |author=Jack W. Lawson |author2=Tara S. Stevens |name-list-style=amp |journal=Journal of the Marine Biological Association of the United Kingdom |year=2014 |volume=94 |issue=6 |pages=1253–1265 |doi=10.1017/s0025315413001409|bibcode=2014JMBUK..94.1253L |s2cid=84750726 }} This population is possibly continuous with orcas sighted off Greenland. Orcas are sighted year-round in the Caribbean Sea,{{cite journal|author1=Bolaños-Jiménez, Jaime|author2=Mignucci-Giannoni, Antonio A.|author3=Blumenth, Janice|display-authors=etal|year=2014|title=Distribution, feeding habits and morphology of killer whales Orcinus orca in the Caribbean Sea|journal=Mammal Review|volume=44|issue=3–4|pages=177–189|doi=10.1111/mam.12021|bibcode=2014MamRv..44..177B }} and an estimated 267 (as of 2020) are documented in the northern Gulf of Mexico.{{cite web|title=Killer Whale (Orcinus orca): Northern Gulf of Mexico Stock|publisher=NOAA|url=https://media.fisheries.noaa.gov/2021-07/f2020_AtlGmexSARs_GmexKiller.pdf?null|access-date=January 30, 2023}}

Recent studies using dietary tracers such as fatty acids and organic contaminants have shown how varied the diet of North Atlantic orcas is. For example, orcas in the Eastern North Atlantic (Norway, Faroe Islands, Iceland) mainly feed on fish, specifically herring. Meanwhile, those in the Central North Atlantic (Greenland) prefer to consume seals such as ringed, harp, hooded, and bearded seals. Finally, orcas in the Western North Atlantic (Eastern Canadian Arctic and Eastern Canada) tend to prey on other whale species, such as belugas and narwhals in the Arctic and baleen whales and porpoises in Eastern Canada.{{Cite journal |last1=Remili |first1=Anaïs |last2=Dietz |first2=Rune |last3=Sonne |first3=Christian |last4=Samarra |first4=Filipa I. P. |last5=Letcher |first5=Robert J. |last6=Rikardsen |first6=Audun H. |last7=Ferguson |first7=Steven H. |last8=Watt |first8=Cortney A. |last9=Matthews |first9=Cory J. D. |last10=Kiszka |first10=Jeremy J. |last11=Rosing-Asvid |first11=Aqqalu |last12=McKinney |first12=Melissa A. |date=2023-10-24 |title=Varying Diet Composition Causes Striking Differences in Legacy and Emerging Contaminant Concentrations in Killer Whales across the North Atlantic |url=https://pubs.acs.org/doi/10.1021/acs.est.3c05516 |journal=Environmental Science & Technology |language=en |volume=57 |issue=42 |pages=16109–16120 |doi=10.1021/acs.est.3c05516 |pmid=37818957 |bibcode=2023EnST...5716109R |issn=0013-936X|url-access=subscription }}{{Cite journal |last1=Remili |first1=Anaïs |last2=Dietz |first2=Rune |last3=Sonne |first3=Christian |last4=Samarra |first4=Filipa I. P. |last5=Rikardsen |first5=Audun H. |last6=Kettemer |first6=Lisa E. |last7=Ferguson |first7=Steven H. |last8=Watt |first8=Cortney A. |last9=Matthews |first9=Cory J. D. |last10=Kiszka |first10=Jeremy J. |last11=Jourdain |first11=Eve |last12=Borgå |first12=Katrine |last13=Ruus |first13=Anders |last14=Granquist |first14=Sandra M. |last15=Rosing-Asvid |first15=Aqqalu |date=June 2023 |title=Quantitative fatty acid signature analysis reveals a high level of dietary specialization in killer whales across the North Atlantic |journal=Journal of Animal Ecology |language=en |volume=92 |issue=6 |pages=1216–1229 |doi=10.1111/1365-2656.13920 |issn=0021-8790|doi-access=free |pmid=37055915 |bibcode=2023JAnEc..92.1216R |hdl=10852/102652 |hdl-access=free }}

Over 50 individual whales have been cataloged in the northern Indian Ocean, including two individuals that were sighted in the Persian Gulf in 2008 and off Sri Lanka in 2015.{{cite web|title=A first ID match for the orcas of the Indian Ocean|date=November 11, 2015|publisher=Whale and Dolphin Conservation|url=http://us.whales.org/blog/2015/11/first-id-match-for-orcas-of-indian-ocean|access-date=October 19, 2017|archive-url=https://web.archive.org/web/20171020135236/http://us.whales.org/blog/2015/11/first-id-match-for-orcas-of-indian-ocean|archive-date=October 20, 2017|url-status=dead}}

File:Orcas in Punta Norte Valdes Peninsula - panoramio.jpg]]

A small population of orcas seasonally visits the northern point of the Valdes Peninsula on the east coast of Argentina and hunt for sea lions and elephant seals on the shore, temporary stranding themselves.{{cite web|url=https://patagoniaproject.com/orcas/|title=Orcas|website=Patagonia Project Wildlife Expeditions|accessdate=11 May 2022}} Similar behaviors occur among orcas off the Crozet Islands, which breach to grab elephant seals. These orcas also prey on Patagonian toothfish. 65 individuals have been documented in this area.{{cite journal|last1=Guinet|first1=C|last2=Tixer|first2=P|last3=Gasco|first3=N|last4=Duhmanel|first4=G|year=2015|title=Long-term studies of Crozet Island killer whales are fundamental to understanding the economic and demographic consequences of their depredation behaviour on the Patagonian toothfish fishery|journal=ICES Journal of Marine Science|volume=72|issue=5|pages=1587–1597|doi=10.1093/icesjms/fsu221|hdl=10536/DRO/DU:30103422|hdl-access=free}} Off South Africa, a distinctive "flat-tooth" morphotype exists and preys on sharks.{{cite journal|author1=Best, P. B.|author2=Meÿer, M. A.|author3=Thornton, M.|display-authors=etal|year=2014|title=Confirmation of the occurrence of a second killer whale morphotype in South African waters|journal=African Journal of Marine Science|volume=36|issue=2|pages=215–224|doi=10.2989/1814232X.2014.923783|bibcode=2014AfJMS..36..215B |hdl=2263/42023 |s2cid=3947611 |hdl-access=free}}{{cite journal|last1=Engelbrecht|first1=T. M.|last2=Kock|first2= A. A.|last3=O'Riain|first3= M. J.|year=2019|title=Running scared: when predators become prey|journal=Ecosphere|volume=10|issue=1|page=e02531|doi=10.1002/ecs2.2531|doi-access=free|bibcode=2019Ecosp..10E2531E }} A pair of male orcas, Port and Starboard, have become well known for hunting great whites and other sharks off the South African coast.{{cite news |last1=Jenkinson |first1=Orlando |title=Pair of Great White Shark-Eating Orca Return to Hunting Ground |url=https://www.newsweek.com/great-white-shark-eating-orca-return-hunting-ground-1670017 |access-date=2 March 2022 |agency=Newsweek |date=17 January 2022}}

Orcas occur throughout the waters of Australia, New Zealand and Papua New Guinea. They are sighted year round in New Zealand waters, while off Australia, they are seasonally concentrated off the northwest, in the inshore waters of Ningaloo Reef, and the southwest, at the Bremer region. Genetic evidence shows that the orcas of New Zealand and northwest and southwest Australia form three distinct populations.{{cite journal|author1=Reeves, Isabella M.|author2=Totterdell, John A.|author3=Barceló, Andrea|display-authors=etal|year=2022|title=Population genomic structure of killer whales (Orcinus orca) in Australian and New Zealand waters|journal=Marine Mammal Science|volume=38|issue=1|pages=151–174|doi=10.1111/mms.12851|bibcode=2022MMamS..38..151R |s2cid=237736039 }} New Zealand orcas mainly prey on sharks and rays.{{cite journal|author=Visser, Ingrid N.|year=2005|title=First Observations of Feeding on Thresher (Alopias vulpinus) and Hammerhead (Sphyrna zygaena) Sharks by Killer Whales (Orcinus orca) Specialising on Elasmobranch Prey|journal=Aquatic Mammals|volume=31|issue=1|pages=83–88|doi=10.1578/AM.31.1.2005.83|bibcode=2005AqMam..31...83V }}{{cite journal|author=Visser, Ingrid N.|year=1999|title=Benthic foraging on stingrays by killer whales (Orcinus orca) in New Zealand waters|journal=Marine Mammal Science|volume=15|issue=1|pages=220–227|doi=10.1111/j.1748-7692.1999.tb00793.x|bibcode=1999MMamS..15..220V }}

Around 25,000 orcas are estimated around the Antarctic,{{sfn|NMFS|2005|p=46}} and four types have been documented. Two dwarf species, named Orcinus nanus and Orcinus glacialis, were described during the 1980s by Soviet researchers, but most cetacean researchers are skeptical about their status, and linking these directly to the types described below is difficult.

File:Antarctic Killer Whale Types.png

• Type A or Antarctic orcas look like a "typical" orca, a large, black-and-white form with a medium-sized white eye patch, living in open water and feeding mostly on minke whales.
• Type B1 or pack ice orcas are smaller than type A. It has a large white eye patch. Most of the dark parts of its body are medium grey instead of black, although it has a dark grey patch called a "dorsal cape"{{cite journal|last1=Evans |first1=W. E. |last2=Yablokov |first2=A. V. |last3=Bowles |first3=A. E. |year=1982 |title=Geographic Variation in the Color Pattern of Killer Whales (Orcinus orca) |url=http://www.kasatka.com/kirsten/ColorVariation.pdf |journal=Reports of the International Whaling Commission |volume=32 |pages=687–694 |url-status=dead |archive-url=https://web.archive.org/web/20110713135402/http://www.kasatka.com/kirsten/ColorVariation.pdf |archive-date=July 13, 2011 }} stretching back from its forehead to just behind its dorsal fin. The white areas are stained slightly yellow. It feeds mostly on seals. Type B1 orca are abundant between Adelaide Island and the mainland Antarctic peninsula.{{Cite journal |last1=Fearnbach |first1=Holly |last2=Durban |first2=John W. |last3=Ellifrit|first3=David K.|last4=Paredes|first4=Alyssa|last5=Hickmott|first5=Leigh S.|last6=Pitman|first6=Robert L.|doi=10.1111/mms.12846|title=A decade of photo-identification reveals contrasting abundance and trends of Type B killer whales in the coastal waters of the Antarctic Peninsula|journal=Marine Mammal Science|volume=38 |issue=1 |pages=58–72|year=2022|bibcode=2022MMamS..38...58F |s2cid=237808561 |url=https://repository.library.noaa.gov/view/noaa/53106 }}
• Type B2 or Gerlache orcas are morphologically similar to Type B1, but smaller. This ecotype has been recorded feeding on penguins and seals, and is often found in the Gerlache Strait.
• Type C or Ross Sea orcas are the smallest ecotype and live in larger groups than the others. Its eye patch is distinctively slanted forwards, rather than parallel to the body axis. Like type B, it is primarily white and medium grey, with a dark grey dorsal cape and yellow-tinged patches. Its only observed prey is the Antarctic cod.
• Type D or Sub-Antarctic orcas were first identified based on photographs of a 1955 mass stranding in New Zealand and six at-sea sightings since 2004. The first video record of this type was made in 2014 between the Kerguelen and Crozet Islands,{{cite web|url=http://www.sciencealert.com/watch-first-video-footage-of-rare-type-d-orcas|title=First video footage of rare 'Type D' orcas|author=Gough, Myles|date=January 9, 2015|publisher=Science Alert|access-date=January 11, 2015|archive-date=January 14, 2015|archive-url=https://web.archive.org/web/20150114210138/http://www.sciencealert.com/watch-first-video-footage-of-rare-type-d-orcas|url-status=live}} and again in 2017 off the coast of Cape Horn, Chile.{{cite magazine|url=https://news.nationalgeographic.com/2018/03/animals-orcas-killer-whales-antarctica/|title=Mysterious orcas filmed underwater for first time|last=Tennenhouse|first=Erica|date=March 1, 2018|magazine=National Geographic|access-date=April 12, 2019|archive-date=March 31, 2019|archive-url=https://web.archive.org/web/20190331064450/https://news.nationalgeographic.com/2018/03/animals-orcas-killer-whales-antarctica/|url-status=dead}} It is recognizable by its small white eye patch, narrower and shorter than usual dorsal fin, bulbous head (similar to a pilot whale), and smaller teeth.{{cite web |url=http://www.grindtv.com/outdoor/nature/post/sea-shepherd-documents-rare-type-d-orcas/ |title=Sea Shepherd documents rare 'Type D' orcas |publisher=GrindTV |access-date=January 6, 2015 |date=January 5, 2015 |archive-url=https://web.archive.org/web/20150111014221/http://www.grindtv.com/outdoor/nature/post/sea-shepherd-documents-rare-type-d-orcas/ |archive-date=January 11, 2015 |url-status=dead }} Its geographic range appears to be circumglobal in sub-Antarctic waters between latitudes 40°S and 60°S. Although its diet is not determined, it likely includes fish, as determined by photographs around longline vessels, where Type D orcas appeared to be preying on Patagonian toothfish.{{cite journal |last1=Pitman |first1=Robert L. |last2=Durban |first2=John W. |last3=Greenfelder |first3=Michael |last4=Guinet |first4=Christophe |last5=Jorgensen |first5=Morton |last6=Olson |first6=Paula A. |last7=Plana |first7=Jordi |last8=Tixier |first8=Paul |last9=Towers |first9=Jared R. |title=Observations of a distinctive morphotype of killer whale (Orcinus orca), type D, from subantarctic waters |journal=Polar Biology |date=August 7, 2010 |volume=34 |issue=2 |pages=303–306 |doi=10.1007/s00300-010-0871-3 |s2cid=20734772 }}{{cite web |last=Rejcek |first=Peter |url=http://antarcticsun.usap.gov/science/contenthandler.cfm?id=2117 |title=The Antarctic Sun: News about Antarctica – Killer News |publisher=Antarcticsun.usap.gov |access-date=February 16, 2011 |archive-date=October 15, 2011 |archive-url=https://web.archive.org/web/20111015085420/http://antarcticsun.usap.gov/science/contenthandler.cfm?id=2117 |url-status=dead }}

Types B and C live close to the ice, and diatoms in these waters may be responsible for the yellowish colouring of both types.{{cite journal |author1=Pitman, Robert L. |author2=Ensor, Paul |year=2003 |url=http://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Programs/Ecology/PitmanandEnsor2003JCRM.pdf |title=Three forms of killer whales (Orcinus orca) in Antarctic waters |journal=Journal of Cetacean Research and Management |volume=5 |issue=2 |pages=131–139 |doi=10.47536/jcrm.v5i2.813 |s2cid=52257732 |access-date=January 9, 2010 |archive-date=April 27, 2020 |archive-url=https://web.archive.org/web/20200427185038/https://swfsc.noaa.gov/uploadedFiles/Divisions/PRD/Programs/Ecology/PitmanandEnsor2003JCRM.pdf |url-status=live }}Gorter, Uko. [http://www.acspugetsound.org/whulj/newsletters/Whulj-v5-n2-2004-may.pdf Newsletter of the Puget Sound Chapter of the American Cetacean Society] {{Webarchive|url=https://web.archive.org/web/20061106065123/http://www.acspugetsound.org/whulj/newsletters/Whulj-v5-n2-2004-may.pdf |date=November 6, 2006 }}, Spring 2004. Retrieved February 16, 2010. Mitochondrial DNA sequences support the theory that these are recently diverged separate species.{{cite journal |last1=Pitman |first1=Robert L. |last2=Robertson |first2=Kelly M. |last3=Leduc |first3=Richard G. |title=Mitochondrial sequence divergence among Antarctic killer whale ecotypes is consistent with multiple species |journal=Biology Letters |volume=4 |issue=4 |pages=426–9 |year=2008 |pmid=18524738 |pmc=2610147 |doi=10.1098/rsbl.2008.0168}} More recently, complete mitochondrial sequencing indicates the types B and C be recognized as distinct species, as should the North Pacific transients, leaving the others as subspecies pending additional data.{{cite journal |title=Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species |first1=Phillip A |last1= Morin |first2=Frederick |last2= Archer |first3=Andrew D |last3= Foote |first4=Julia |last4= Vilstrup |first5=Eric E |last5= Allen |first6=Paul |last6= Wade |first7=John |last7= Durban |first8=Kim |last8= Parsons |first9=Robert |last9= Pitman|journal=Genome Research | doi=10.1101/gr.102954.109 |pmid=20413674 |volume=20 |pages=908–916 |year=2010 |issue=7 |pmc=2892092}} Advanced methods that sequenced the entire mitochondrial genome revealed systematic differences in DNA between different populations. A 2019 study of Type D orcas also found them to be distinct from other populations and possibly even a unique species.

{{reflist}}

• {{Cite report |last=Baird |first=Robin W. |date=April 1999 |title=Status of Killer Whales in Canada |url=http://courses.washington.edu/mb351/readings/baird.pdf |publisher=Committee on the Status of Endangered Wildlife in Canada |url-status=dead |archive-url=https://web.archive.org/web/20111108150031/http://courses.washington.edu/mb351/readings/baird.pdf |archive-date=November 8, 2011}}
• {{Cite book |last=Carwardine |first=Mark |year=2001 |title=Killer Whales |location=London |publisher=BBC Worldwide |isbn=978-0-7894-8266-2|url=https://archive.org/details/killerwhales00carw}}
• {{Cite book|last1=Ford |first1=John K. B. |last2=Ellis |first2=Graeme M. |last3=Balcomb |first3=Kenneth C. |title=Killer Whales |edition=Second|year=2000|publisher=UBC Press|location=Vancouver, BC|isbn=978-0-7748-0800-2|url=https://books.google.com/books?id=yTmbu_CFomAC&pg=PP1}}
• {{cite web |publisher=National Marine Fisheries Service (NMFS) Northwest Regional Office |author=NMFS |year=2005 |url=http://www.nwr.noaa.gov/Marine-Mammals/Whales-Dolphins-Porpoise/Killer-Whales/Conservation-Planning/upload/SRKW-propConsPlan.pdf |title=Conservation Plan for Southern Resident Killer Whales (Orcinus orca) |location=Seattle, U.S. |access-date=January 2, 2009 |archive-url=https://web.archive.org/web/20080626121719/http://www.nwr.noaa.gov/Marine-Mammals/Whales-Dolphins-Porpoise/Killer-Whales/Conservation-Planning/upload/SRKW-propConsPlan.pdf |archive-date=June 26, 2008 |url-status=dead}}

Category:Biogeography

Category:Orcas

Category:Population ecology

Category:Population genetics