|Scientific Name:||Orcinus orca (Linnaeus, 1758)|
Orcinus glacialis (Berzin & Vladimirov, 1983)
Orcinus nanus Mikhalev et al., 1981
This taxonomic unit is treated as a single species even though there is extensive and growing evidence that it is in fact a complex of multiple forms with morphological, genetic, ecological, and behavioral differences that merit subspecies if not also species designations. At the time of writing (June 2017), the Committee on Taxonomy of the Society for Marine Mammalogy (https://www.marinemammalscience.org/species-information/list-marine-mammal-species-subspecies/), which is generally regarded as the authority for marine mammal taxonomy, recognized a single killer whale species, Orcinus orca (Linnaeus, 1758), and two unnamed subspecies in the eastern North Pacific, the ENP resident killer whale (O. o. un-named subsp.) and the ENP transient killer whale (O. o. un-named subsp.) also known as Bigg’s killer whale. The Committee noted, however, “Other forms of killer whales in the North Pacific, North Atlantic and Antarctic [Southern] Ocean may warrant recognition as separate subspecies or even species, but the taxonomy has not yet been fully clarified or agreed (Morin et al. 2010; Foote et al. 2009, 2013).” One population (a “distinct population segment”) of the ENP resident subspecies (the “southern resident” population) was listed as Endangered under the Canadian Species at Risk Act in 2003 and the U.S. Endangered Species Act in 2005.
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Reeves, R., Pitman, R.L. & Ford, J.K.B.|
|Facilitator/Compiler(s):||Lowry, L., Taylor, B.L., Chiozza, F., Pollock, C.M.|
The Killer Whale, as the taxon is presently defined and recognized (Society for Marine Mammalogy 2017), does not meet any of the IUCN Red List criteria for a threatened status. Killer Whales are numerically abundant (at least tens of thousands of mature individuals) and very widely distributed. Experts agree that the present taxon likely includes more than one subspecies, and possibly multiple species. Some small regional populations are known to have declined significantly and would easily qualify for a threatened status if assessed individually (e.g., ENP southern residents, the Bluefin Tuna-dependent population associated with the Strait of Gibraltar), but there is insufficient evidence to support a global decline in the species abundance that would make it meet Criterion A. However, the statement in the previous species assessment (Taylor et al. 2013) still holds: “The combination of potential declines driven by depletion of prey resources and the effects of pollutants is believed sufficient that a 30% global reduction over three generations (77 years; Taylor et al. 2007) cannot be ruled out for some ‘groups’ that may [eventually] be designated as species.”
Although considerable effort continues to be made on improved understanding of the taxonomy of the genus Orcinus, the taxonomic issues have not been fully resolved. This is especially problematic due to the occurrence of sympatric, non-interbreeding ecotypes in the ENP, Antarctic, and possibly elsewhere. The taxon has previously been listed by IUCN as Data Deficient due to taxonomic uncertainty, and that listing should be continued until proper taxonomic units are described and Red List assessments of them can be carried out.
|Previously published Red List assessments:|
The Killer Whale is the most cosmopolitan of all cetaceans and may be the second-most widely ranging mammal species on the planet, after Humans (Rice 1998). Killer Whales may occur in virtually any marine habitat but are most common in cold-water areas of high marine productivity, particularly at higher latitudes and near shore (Dahlheim and Heyning 1999, Forney and Wade 2006). Sightings range from the surf zone to the open sea with no clear restrictions of water temperature or depth on their range. The distribution extends to many semi-enclosed seas such as the Mediterranean Sea, Okhotsk Sea, Gulf of California, Gulf of Mexico, Red Sea, and Persian Gulf.
Although Killer Whales occur worldwide, reported densities are 1-2 orders of magnitude lower in the tropics than in the highest latitudes in the Arctic and Antarctic where there has been sampling (Forney and Wade 2006). Killer Whales tend to be more common along continental margins; however, there is some variation in this general pattern that appears linked to ocean productivity. Killer Whales appear to be less common in warm western boundary currents, such as the Gulf Stream or the Kuroshio Current, than in more productive eastern boundary currents, such as the California Current. However, they are also common in cold-water western boundary currents such as the Oyashio and Falkland Currents.
Native:Algeria; American Samoa; Anguilla; Antarctica; Antigua and Barbuda; Argentina; Aruba; Australia; Bahamas; Bangladesh; Barbados; Belize; Benin; Bermuda; Bonaire, Sint Eustatius and Saba; Brazil; British Indian Ocean Territory; Brunei Darussalam; Cambodia; Cameroon; Canada (Newfoundland I); Cape Verde; Cayman Islands; Chile; China; Cocos (Keeling) Islands; Colombia; Comoros; Congo; Congo, The Democratic Republic of the; Cook Islands; Costa Rica; Côte d'Ivoire; Cuba; Curaçao; Denmark; Djibouti; Dominica; Dominican Republic; Ecuador (Galápagos); El Salvador; Equatorial Guinea; Falkland Islands (Malvinas); Faroe Islands; Fiji; France; French Guiana; French Polynesia; French Southern Territories (Kerguelen); Gabon; Gambia; Ghana; Gibraltar; Greenland; Grenada; Guadeloupe; Guam; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Heard Island and McDonald Islands; Honduras; Iceland; India; Indonesia; Iran, Islamic Republic of; Ireland; Israel; Italy; Jamaica; Japan; Kenya; Kiribati; Liberia; Madagascar; Malaysia; Maldives; Marshall Islands; Martinique; Mauritania; Mexico; Micronesia, Federated States of ; Monaco; Morocco; Mozambique; Myanmar; Namibia; Nauru; Netherlands; New Caledonia; New Zealand; Nicaragua; Nigeria; Niue; Northern Mariana Islands; Norway; Oman; Pakistan; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Portugal; Puerto Rico; Russian Federation; Saint Barthélemy; Saint Helena, Ascension and Tristan da Cunha; Saint Kitts and Nevis; Saint Lucia; Saint Martin (French part); Saint Pierre and Miquelon; Saint Vincent and the Grenadines; Samoa; Senegal; Sierra Leone; Singapore; Sint Maarten (Dutch part); Solomon Islands; Somalia; South Africa; South Georgia and the South Sandwich Islands; Spain; Sri Lanka; Suriname; Svalbard and Jan Mayen; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Timor-Leste; Togo; Tonga; Trinidad and Tobago; Tunisia; United Arab Emirates; United Kingdom; United States (Aleutian Is., Hawaiian Is.); United States Minor Outlying Islands; Uruguay; Vanuatu; Venezuela, Bolivarian Republic of; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Wallis and Futuna; Western Sahara; Yemen
|FAO Marine Fishing Areas:|
Arctic Sea; Atlantic – southeast; Atlantic – northeast; Atlantic – eastern central; Atlantic – northwest; Atlantic – Antarctic; Atlantic – western central; Atlantic – southwest; Indian Ocean – western; Indian Ocean – eastern; Indian Ocean – Antarctic; Mediterranean and Black Sea; Pacific – northwest; Pacific – southeast; Pacific – northeast; Pacific – southwest; Pacific – eastern central; Pacific – western central; Pacific – Antarctic
|Range Map:||Click here to open the map viewer and explore range.|
Killer Whale populations have been relatively well-studied in the North Pacific. In the Eastern Tropical Pacific, a line-transect survey resulted in an estimate of 8,500 (CV=0.37) in 1986-1990 (Wade and Gerrodette 1993). A catalogue of 86 individuals was compiled for waters around the Baja California peninsula, Mexico, from 1972-1997 (Guerrero-Ruiz et al. 1998). A shipboard line-transect survey of the Hawaii EEZ in 2002 resulted in an estimate of 349 (CV = 0.98) Killer Whales (Barlow 2006). The southern resident population that inhabits the inland waters of Washington State and southern British Columbia numbered 77 whales in June 2017 (K.C. Balcomb, Center for Whale Research, pers. comm., 13 June 2017); it is depleted due to past live removals and is listed as endangered under the U.S. Endangered Species Act and Canada’s Species at Risk Act. The northern resident population in British Columbia numbered 290 in 2014 and had been increasing at a mean rate of 2.2% per annum since 1974 (Towers et al. 2015). A photographic catalogue of the west coast transient population in British Columbia and Southeast Alaska included 272 individuals in 2012 (Towers et al. 2012). This population was estimated to have increased at an average annual rate of about 2% in the two decades ending in 2006 (Ford et al. 2007). Bayesian mark-recapture modelling estimated that there were 300 offshore-type Killer Whales (95% CL 257–373) in the region from Alaska to California in 2012 (Ford et al. 2014). Shipboard line-transect surveys extending out to 300 nm offshore in 2005 and 2007 resulted in an estimate of 691 (CV=0.49) off California, Oregon and Washington (Carretta et al. 2016); these estimates likely include whales from the aforementioned west coast transient, southern resident, northern resident, and offshore populations. A line-transect survey from the Aleutian Islands to the Gulf of Alaska resulted in an estimate of abundance for transient Killer Whales of 251 (CV=0.51) (Zerbini et al. 2007), while the AT1 transient population (which inhabits Prince William Sound and waters of the Seward Peninsula, Alaska) numbered only 7 animals in 2010 (Matkin et al. 2012). Over 700 unique individual resident Killer Whales were photo-identified over the course of a field study during 1984-2010 in coastal waters of the Gulf of Alaska (Matkin et al. 2014). Only a subset of pods within this population were regularly encountered, and those pods increased in abundance at an average rate of 3.5% per annum during the study. A line-transect survey from the Aleutian Islands to the Gulf of Alaska resulted in an estimate of 991 (CV=0.52) resident Killer Whales and 251 (CV=0.51) transient Killer Whales (Zerbini et al. 2007).
The following figures are available for Killer Whales in the Russian Far East, all representing photo-identified individuals and therefore “minimum” counts (Filatova et al. 2014, Erich Hoyt, Whale and Dolphin Conservation, pers. comm. 12 June 2017): Avacha Gulf/eastern Kamchatka (1999-2013) – resident type 688, transient type 26 (note that rate of new discovery is very low indicating this may be close to actual levels of abundance, and site fidelity is much higher than in the Commander Islands); Commander Islands (2008-2013) - residents > 800, transients 18 (note that rate of new discovery is high so actual abundance is certainly higher and about 80% of the identified individuals were encountered in only one year); western Okhotsk Sea (from Udskaya Gulf to Sakhalin Gulf, mainly Academiya Gulf) (2011-2013) – residents none, transients 55 (note that no dedicated study was carried out, only opportunistic sightings along with beluga research; also this is the population that has been subject to live-capture since 2010).
|Current Population Trend:||Unknown|
|Habitat and Ecology:|
Killer Whales are known to feed on a wide array of prey, including most marine mammal species (except river dolphins and Manatees), seabirds, sea turtles, many species of fish (including sharks and rays) and cephalopods (Dahlheim and Heyning 1999, Ford and Ellis 1999, Ford 2009). They have a diversity of foraging tactics, including intentional beaching to capture pinnipeds on shore, creating waves to wash seals off ice floes, and using cooperative techniques to herd fish and to attack large prey such as Tuna and large whales (Dahlheim and Heyning 1999, Baird 2000, Pitman and Durban 2012).
Although Killer Whales are a generalist as a species, at least some subpopulations (ecotypes and/or morphotypes) specialize on particular types of prey (Bigg et al. 1990, Baird 2000). Studies in coastal waters of the ENP, from California to Alaska, have described three distinct ecotypes of Killer Whales, referred to as residents, transients (or Bigg’s Killer Whales), and offshores. Although distinguished by ecological differences, there are also differences in coloration, external morphology, behavior and acoustics (Ford and Ellis 2014). The three ecotypes maintain social isolation from each other (i.e., no interbreeding) despite sometimes overlapping ranges. The ENP residents are Pacific Salmon specialists and have a strong preference for one species, the Chinook Salmon (Ford and Ellis 2006). Transients in coastal waters of the ENP focus their foraging on pinnipeds and small cetaceans but also take large whales, especially calves, opportunistically. Killer Whales in coastal Norway specialize on Herring (Simila et al. 1996) and in the Strait of Gibraltar on Bluefin Tuna (Cañadas and de Stephanis 2006). Some Killer Whales in New Zealand may forage selectively on rays and other elasmobranchs (Visser 1999), and in Western Australia, Killer Whales take scores of Humpback Whale calves for several months a year (Pitman et al. 2015). Off the south coast of Western Australia one group of Killer Whales forages, at least seasonally, on Beaked Whales (Wellard et al. 2106). In the Antarctic, there are five described ecotypes of Killer Whales, each of them morphologically distinct with different habitat and prey preferences. One type specializes on Minke Whales and Elephant Seals taken in open water, one eats mostly ice-associated seals taken off ice floes, another regularly preys on penguins but is probably mainly a fish-eater, another rarely seen form has only been observed depredating Patgonian Toothfish from commercial longlines, and the smallest form appears to be entirely a fish-eater (Pitman and Ensor 2003, Pitman et al. 2011, Durban et al. 2016).
Long-distance migrations have been documented for high-latitude Killer Whales. Matthews et al. (2011) satellite-tracked an individual for 5,400 km (and 38° of latitude) from the eastern Canadian Arctic into the central North Atlantic. Durban and Pitman (2012) tracked Killer Whales from the Antarctic Peninsula to southern Brazil and back – a non-stop roundtrip of almost 9,400 km, and Pitman et al. (in prep.) tracked fish-eating ecotype Killer Whales from the Ross Sea to north of New Zealand and back – a >11,000 km roundtrip covering 48° of latitude. Many Antarctic Killer Whales appear to be highly philopatric. In the Antarctic, some ecotypes readily enter areas of floe ice in search of prey, while others hunt only in open water (Pitman and Ensor 2003, Pitman and Durban 2012). Killer Whales in some areas congregate seasonally in coastal channels to forage and occasionally enter river mouths.
|Continuing decline in area, extent and/or quality of habitat:||No|
|Use and Trade:||
During the period 1962-1977, at least 65 Killer Whales were live-captured in British Columbia and Puget Sound, Washington (Bigg 1982). In addition, from 1976-1988, 59 Killer Whales were captured alive off Iceland: eight were released, three died and 48 (average 3.7 per year) were exported (Sigurjónsson and Leatherwood 1988). Small numbers of Killer Whales have also been live-captured in Japanese waters (Fisher and Reeves 2005). Killer Whales are still in demand for display in aquariums and amusement parks, especially in China. Most recent captures and exports have been of animals in the Russian Far East (Fisher and Reeves 2005, Filatova et al. 2014). Of 21 Killer Whales known to have been live-captured in the western Sea of Okhotsk from 2012-2016, at least 13 of them were exported to China between 2013 and 2016 (Filatova et al. 2017).
Killer Whales have been exploited (i.e., deliberately hunted) in several regions. Norwegian whalers in the eastern North Atlantic took an average of 56 whales per year from 1938 to 1981. Whalers in Japan took an average of 43 per year in coastal waters from 1946 to 1981. Soviet commercial whalers took an average of 26 Killer Whales annually from 1935 to 1979, primarily in the Antarctic, and then took 916 animals in the 1979/80 Antarctic season (Dahlheim and Heyning 1999,). Killer whales are also taken in small numbers for food (or as a population control measure) in coastal fisheries in Japan, Greenland, Indonesia, and the Caribbean islands (Reeves et al. 2003).
Potential disturbance and acoustic masking effects of increasing ambient noise levels associated with shipping and other vessel traffic is a growing concern in some regions (Williams et al. 2014). Disturbance responses and masking of echolocation signals in areas with heavy ship activity have the potential to disrupt foraging behavior and reduce prey acquisition with possible population-level consequences (Williams et al. 2014, Veirs et al. 2016).
The Exxon Valdez oil spill in Alaska in March 1989 was strongly correlated with the subsequent loss of Killer Whales from transient and resident pods that had been seen swimming near or through oil slicks early in the spill (Dahlheim and Matkin 1994). The AT1 pod had at least 22 individuals when first censused in 1984, before the spill. Eleven individuals have been missing from this pod since 1990 and two more since 1992. Four more whales from this pod died in the early 2000s and there have been no recorded births within the pod since 1984. As of 2012, only 7 of the original 22 AT1 pod members remained. A resident Killer Whale pod affected by the oil had failed to recover 16 years after the spill (Matkin et al. 2008, 2012). Oil spills may also have indirect effects on Killer Whales by reducing prey abundance.
The Killer Whale is listed in Appendix II of the Convention on International Trade in Endangered Species and Appendices I and II of the Convention on Migratory Species (CMS). The eastern North Atlantic as well as the ENP populations are included in Appendix II of CMS.
|Citation:||Reeves, R., Pitman, R.L. & Ford, J.K.B. 2017. Orcinus orca. The IUCN Red List of Threatened Species 2017: e.T15421A50368125.Downloaded on 26 September 2018.|
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