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Orcinus orca 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Cetartiodactyla Delphinidae

Scientific Name: Orcinus orca (Linnaeus, 1758)
Regional Assessments:
Common Name(s):
English Killer Whale, Orca
French Epaulard, Orque
Spanish Espadarte, Orca
Synonym(s):
Orcinus glacialis (Berzin & Vladimirov, 1983)
Orcinus nanus Mikhalev et al., 1981
Taxonomic Notes:

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.

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2017
Date Assessed: 2017-06-20
Assessor(s): Reeves, R., Pitman, R.L. & Ford, J.K.B.
Reviewer(s): Brownell, R.
Facilitator/Compiler(s): Lowry, L., Taylor, B.L., Chiozza, F., Pollock, C.M.
Justification:

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:

Geographic Range [top]

Range Description:

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.

The map shows the inferred range based on a very large number of observations at sea.

Countries occurrence:
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
Vagrant:
Germany
FAO Marine Fishing Areas:
Native:
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
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:No
Upper depth limit (metres):1000
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:

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).

Line-transect surveys have resulted in high estimates of abundance in several regions in the North Atlantic, 3,100 (CV=0.63) in Norwegian waters in the 1980s (Øien 1990) and 6,618 (CV=0.32) in Iceland and Faroe Islands waters also in the 1980s (Gunnlaugsson and Sigurjónsson 1990, Sigurjónsson et al. 1989). A long-term photo-identification study in coastal northern Norway resulted in an abundance estimate of 731 (CI = 505-1059) in 2003 (Kuningas et al. 2014). In central and southern European waters there are only two known populations of Killer Whales – one in the Strait of Gibraltar with 39 individuals in 2011 (Esteban et al. 2016) and the other a pod of nine individuals regularly seen around western Ireland and northwestern Scotland (Beck et al. 2013). Killer Whales are not common in the waters off the eastern United States. Line-transect surveys yielded an estimate of 133 (CV=49%) in the northern Gulf of Mexico in the early 2000s (Waring et al. 2006).

Several analyses of line-transect surveys have yielded abundance estimates for Killer Whales around Antarctica (Hammond 1984, Kasamatsu and Joyce 1995); however, some of the estimates have been considered biased by methodology and survey coverage (Branch and Butterworth 2001). More recent analyses that account for some of these biases resulted in an estimate of about 25,000 for waters south of 60°S (Branch and Butterworth 2001); however, there are still uncertainties related to coverage of areas in the pack ice, so true abundance could be higher. Densities are known to vary locally within Antarctic waters, ranging from very abundant to uncommon (Secchi et al. 2002, Pitman and Ensor 2003), and it has been recognized that Killer Whale densities are higher closer to the ice edge and within the marginal ice zone where the smaller, fish-eating Killer Whales can occur in aggregations of tens to hundreds of animals (Berzin and Vladimirov 1983, Pitman and Ensor 2003). A photo-identification study of type C Killer Whales (a small, fish-eating form) in McMurdo Sound from 2001-2015 estimated a population of at least 370 animals including 70 that were resident in the Sound each year during the summer; the remainder were mostly just passing through (Pitman et al. submitted). In the Antarctic Peninsula area, a photo-identification study of the three different ecotypes that occur there has to date (June 2017) identified at least 372 type A Killer Whales (specialist predators of Minke Whales; R. Pitman unpublished data). Photo-identification studies in the Prince Edward Island Archipelago (mainly around Marion Island) from 2006-2009 estimated a local population there of around 42 individuals (95% CI=35-50) that prey seasonally on Penguins and Elephant Seals (Reisinger et al. 2011). In other parts of the Southern Hemisphere, 119 (CV=0.20) Killer Whales have been estimated in New Zealand waters (Visser 2000), and 30 were identified off northern Patagonia, Argentina, during 1975-1997 (Lopez and Lopez 1985, Iñíguez 2001). No abundance estimates have been made for type D Killer Whales in the Southern Hemisphere.

According to Forney and Wade (2006), although the available data are far from complete, abundance estimates for sampled areas provided a minimum worldwide abundance estimate of about 50,000 Killer Whales of all types. Those authors noted that the total was likely higher, because estimates were not available for many high-latitude areas of the northern hemisphere and for large areas of the South Pacific, South Atlantic, and Indian Ocean.

Current Population Trend:Unknown
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:UnknownPopulation severely fragmented:No
Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

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.

Systems:Marine
Continuing decline in area, extent and/or quality of habitat:No

Use and Trade [top]

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).

Threats [top]

Major Threat(s):

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).

Fishermen in many areas see Killer Whales as competitors, and intentional shooting is known to occur. This problem was especially serious in Alaska, where depredation of longline fisheries is extensive (Jefferson et al. 1993, Yano and Dahlheim 1995, Donohue et al. 2003), and retaliation for depredation was credited with contributing to a temporary population decline at Crozet Island, in the Southern Ocean (Poncelet et al. 2010). Depredation of longline catches appears to be a recent and increasing phenomenon, and now occurs in many regions (e.g., Aleutian Islands and Southeast Alaska, South Georgia, Crozet Islands, and several other Southern Ocean Subantarctic island areas, Australia, and other locations in the South Pacific). Increased depredation of Toothfish hooked in fisheries in the Crozet Archipelago appears to have had a positive effect on calving rates of female Killer Whales (Tixier et al. 2015).

Incidental mortality in trawl, longline and driftnet fishing operations occurs, but is considered rare (Dahlheim and Heyning 1999, Muto et al. 2016).

Persistent bio-accumulating contaminants present a serious potential risk to some Killer Whale populations. Ross et al. (2000) reported that total polychlorinated biphenyl (PCB) concentrations were very high in three Killer Whale populations (2 resident and 1 transient) frequenting the coastal waters of British Columbia, Canada. Transient Killer Whales were particularly contaminated due to their high trophic position in the marine ecosystem. PCB levels in most Killer Whales sampled were greater than levels established at which adverse effects occur in Harbor Seals, suggesting that the majority of free-ranging Killer Whales in this region are at risk of toxic effects. The southern resident and transient Killer Whales of British Columbia and Washington are considered among the most PCB-contaminated cetaceans in the world (Ross et al. 2000).  More recently, Jepson et al. (2016) found very high mean blubber PCB concentrations in Killer Whales in Europe. Small or declining populations of Killer Whales in the northeastern Atlantic (e.g., the very small population associated with the Strait of Gibraltar) have been associated with low recruitment, which is consistent with PCB-induced reproductive toxicity. Also, increasing levels of polybrominated diphenyl ethers which, like PCBs, can cause immunotoxicity, neurotoxicity, and reproductive impairment, have become a concern in the southern resident population in British Columbia and Washington (Mongillo et al. 2012).


Disturbance is another concern in areas where Killer Whales are subject to whale-watching tourism. Moving boats can disrupt foraging and resting, and underwater boat noise can affect social and echolocation signals of the whales or otherwise interfere with foraging (Erbe 2002, Williams et al. 2002, Noren et al. 2009). For example, close approaches by whale-watching vessels have been shown to result in avoidance responses by resident Killer Whales in British Columbia, which presumably has energetic costs to whales that are frequently subjected to this activity (Williams et al. 2002, 2006). Fast-moving boats in the proximity of Killer Whales also present a risk of vessel strikes (e.g., Visser 1999).

 

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.


There have been large-scale reductions in predatory fish populations (Myers and Worm 2003; Baum et al. 2003) along with overfishing and collapse of several important “prey” fish stocks worldwide (Jackson et al. 2001). There have also been large declines in some marine mammal populations but many of those populations have recovered or are recovering under protection, and this may mean that some mammal-eating populations of Killer Whales are recovering as well. The same is not likely true of many fish-eating populations, however.


Due to their dietary specialization, some populations of Killer Whales could be especially vulnerable to a reduction of their food supply. In British Columbia and Washington State, many Pacific Salmon stocks have significantly declined as a result of overfishing, habitat degradation, and reduced survival at sea. Declines in survival and reproductive rates of resident Killer Whales were found to correlate with a multi-year reduction in Chinook Salmon abundance in coastal British Columbia and Washington State (Ward et al. 2009, Ford et al. 2010). Mammal-eating Killer Whales along the west coast of North America likely experienced periods of reduced prey availability due to depletion of pinniped populations prior to 1970 (Ford and Ellis 1999). Depletion of Bluefin Tuna stocks in the Mediterranean Sea has almost certainly had a serious impact on the survival of Killer Whales near the Strait of Gibraltar (Cañadas and de Stephanis 2006, Esteban et al. 2016).

How global climate change and its impacts on the marine environment will affect the different populations and ecotypes of Killer Whales is uncertain (e.g., Learmonth et al. 2006). However, in the Arctic, declining extent and duration of sea ice has given Killer Whales more access to marine mammal prey (Belugas, Narwhals, Bowhead Whales) that depend on ice for refuge from predation (Ferguson et al. 2010, Higdon et al. 2012, George et al. 2015). Similarly, in the Antarctic, the abundance and availability of Killer Whale prey is mediated through the presence of ice (e.g., Pitman and Durban 2012), which means that many species, including both Killer Whales and their prey, face an uncertain future.

Conservation Actions [top]

Conservation Actions:

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.

Further studies on subpopulation structure, abundance and life history are needed for most regions. Regional populations of Killer Whales can be small and highly specialized, and therefore vulnerable to over-exploitation, disturbance, prey reductions and habitat deterioration. Several small populations are already recognized as having a high risk of extinction. Many similarly small and threatened populations may exist worldwide but have not yet been adequately studied and described (e.g., Foote et al. 2013).


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 14 December 2017.
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