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Orcinus orca 

Scope: Europe
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: Killer whales are presently considered to form a single cosmopolitan species, Orcinus orca (Rice 1998). Separate species status has been suggested for different morphological forms found in the southern Ocean (Mikhalev et al. 1981, Berzin and Vladimirov 1983, Pitman and Ensor 2003). Pitman et al. (2007) describe one of these as a dwarf form of killer whale. Killer whales in the eastern North Pacific are known to consist of at least two and maybe three distinct forms, colloquially known as ‘resident’, ‘transient’ and ‘offshore’ killer whales (Ford et al. 1994). Separate species status has also been suggested for at least two of these different forms, based on color pattern, diet, and morphological traits (Baird 1994, Baird et al. 1999). Genetic differences are found among these forms, with particularly marked differences between resident and transient forms (Stevens et al. 1989, Hoelzel and Dover 1991, Hoelzel et al. 1998, Barrett-Lennard 2000). The taxonomy of this genus is clearly in need of review, and it is likely that O. orca will be split into a number of different species or at least subspecies over the next few years (Reeves et al. 2004).

Assessment Information [top]

Red List Category & Criteria: Data Deficient (Regional assessment) ver 3.1
Year Published: 2007
Date Assessed: 2007-01-26
Annotations:
Needs updating
Assessor(s): Species account by IUCN SSC Cetacean Specialist Group; regional assessment by European Mammal Assessment team
Reviewer(s): Philip Hammond
Justification:
Orcinus orca is widespread and fairly abundant. Population trend data for this species are unavailable. Primary threats that could cause widespread declines include depletion of prey resources and contamination with persistent organic pollutants. Live-capture removals and direct takes are localized and do not appear to have had a high impact on the status of the species globally. Current threats for killer whales appear most serious in nearshore waters. 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 or in this case 78 years could not be ruled out. Therefore, the species is currently considered to be Data Deficient.

Additionally, regional subpopulations of killer whales can be small and highly specialized, and therefore vulnerable to over-exploitation and habitat deterioration. Several small subpopulations have already been recognized as having a high risk of extinction, including the Strait of Gibraltar subpopulation, which was provisionally assessed in 2006 as Critically Endangered (C2a(i,ii); D)(Reeves and Notarbartolo di Sciara 2006).

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. Killer whales can be seen in virtually any marine region, from the equator to polar waters. Although they are generally more common in nearshore areas and in higher productivity areas and/or higher latitudes, there appear to be no hard and fast restrictions of water temperature or depth on their range. The distribution extends to many enclosed or partially-enclosed seas, such as the Mediterranean Sea, Sea of Okhotsk, Gulf of California, Gulf of Mexico, Red Sea, and Persian Gulf. However, there are only extralimital records from the Baltic Sea and no records from the Black Sea.
Countries occurrence:
Native:
Albania; Denmark; Faroe Islands; France; Germany; Gibraltar; Iceland; Ireland; Italy; Monaco; Netherlands; Norway; Portugal; Russian Federation; Spain; United Kingdom
FAO Marine Fishing Areas:
Native:
Arctic Sea; Atlantic – eastern central; Atlantic – northeast; Atlantic – northwest; Atlantic – Antarctic; Atlantic – southwest; Atlantic – western central; Atlantic – southeast; Indian Ocean – eastern; Indian Ocean – Antarctic; Indian Ocean – western; Mediterranean and Black Sea; Pacific – southeast; Pacific – western central; Pacific – Antarctic; Pacific – southwest; Pacific – northwest; Pacific – northeast; Pacific – eastern central
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Although killer whales occur worldwide, densities increase by 1-2 orders of magnitude between the tropics and the highest sampled latitudes in the Arctic and Antarctic (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 western boundary currents such as the Gulf Stream, than in more productive eastern boundary currents such as the California Current. Line-transect surveys have resulted in estimates of abundance in several regions in the North Atlantic, including an abundance estimate of 3,100 (CV=63%) killer whales in Norwegian waters (Øien 1990), and an estimate of 6,618 (CV=32%) whales in Iceland and Faroes Islands waters (Sigurjónsson et al. 1989, Gunnlaugsson and Sigurjónsson 1990).
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Killer whales may occur in virtually any marine or estuarine habitat, but are most common in 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. Although they do not migrate, movements can be extensive; for instance, some killer whales have been documented to have moved between Alaska and central California, a distance of more than 2000 km. In the Antarctic, they readily enter areas of floe ice in search of prey (Pitman and Ensor 2003). Killer whales in some areas congregate seasonally in coastal channels to forage and occasionally enter river mouths.

Killer whales are known to feed on a wide array of prey types, including most marine mammal species (except river dolphins and manatees), seabirds, sea turtles, many species of fishes (including sharks and rays) and cephalopods (Dahlheim and Heyning 1999, Ford and Ellis 1999, Ford 2002). Killer whales have a diversity of foraging tactics, including intentional beaching to gain access to seals onshore. They are known to use cooperative techniques to herd fish and to attack large prey (Dahlheim and Heyning 1999, Baird 2000).

Although a generalist as a species, at least some subpopulations specialize on particular types of prey (Bigg et al. 1990, Baird 2000). Studies in coastal waters of the eastern North Pacific, from California to Alaska, have described three distinct ecotypes of killer whales, referred to as residents, transients, and offshores. Although distinguished by ecological differences, there are also differences in coloration, external morphology, behavior and acoustics. The three ecotypes maintain social isolation from each other despite overlapping ranges.
Systems:Marine

Threats [top]

Major Threat(s): Killer whales have been exploited at low levels in several regions world-wide (Jefferson et al. 1993). Norwegian whalers in the eastern North Atlantic took an average of 56 whales per year from 1938 to 1981. Fishermen in many areas see killer whales as competitors, and intentional shooting of whales is known to occur. This problem is especially serious in Alaska, where depredation of longline fisheries is extensive (Jefferson et al. 1993). Killer whales are still taken in small numbers in coastal fisheries in Japan, Greenland, Indonesia, and the Caribbean islands (Reeves et al. 2003).

After 1976, Iceland has been involved in live-captures of killer whales for export. During the period 1976-1988, 59 whales were collected, of which 8 were released, 3 died and 48 (an average 3.7 per year) were exported (Reyes 1991 and ref. therein). In 1991, the lcelandic government announced that once current permits for live-capture expire, no new ones would be issued (Jefferson et al. 1993). Bycatch in trawl and driftnet fishing operations occur, but are considered rare (Dahlheim and Heyning 1999). Persistant, bioaccumulating contaminants have recently been found to present a serious potential risk to some killer whale subpopulations. Large-scale catastrophic oil spills have the potential to cause significant mortality of killer whales. Oil spills may also have an indirect effect by reducing prey abundance.

Disturbance may be a matter for concern in areas inhabited by killer whales and supporting whale-watching industries (Reyes 1991). Moving boats can disrupt activities such as foraging and resting, and underwater boat noise could affect social and echolocation signals of the whales or otherwise interfere with foraging (Erbe 2002, Williams et al. 2002). For example, close approaches by whale-watching vessels have been shown to result in avoidance responses by resident killer whales in British Columbia, which may have energetic costs for whales frequently subjected to whale watching activity (Williams et al. 2002, 2006). Fast-moving boats in the proximity of killer whales also present a risk of collision or injury from propellers. Visser (1999) reported propeller scars observed on killer whales in New Zealand.

There have been large-scale reductions in predatory fish populations (Myers and Worm 2003, Baum et al. 2003) and over-fishing and collapse of several important “prey” fish stocks world-wide (Jackson et al. 2001). The effects on killer whales of reductions in fish populations due to overexploitation are unknown. In some areas, populations could be vulnerable owing to dietary specialization. The depletion of the Mediterranean bluefin tuna stock is considered a source of concern for the survival of the Gibraltar killer whales (Cañadas and de Stephanis 2006).

Predicted impacts of global climate change on the marine environment may affect killer whales, and may affect some subpopulations more than others through changes in prey availability.

Conservation Actions [top]

Conservation Actions: The eastern North Atlantic subpopulation is included in Appendix II of the Convention on Migratory Species. The proposal to list all subpopulations of the killer whale in Appendix II was endorsed in 2002 by the Working Group of the CMS in Bonn (see Proceedings), as all the subpopulations were migratory and could profit from cooperative protective measures. Because killer whales are cosmopolitan in distribution, they may be present in virtually any marine protected area worldwide. Further studies on subpopulation structure, abundance and life history are needed.

Citation: Species account by IUCN SSC Cetacean Specialist Group; regional assessment by European Mammal Assessment team. 2007. Orcinus orca. The IUCN Red List of Threatened Species 2007: e.T15421A4581006. . Downloaded on 14 August 2018.
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