Special Status Species
Killer whale
Common name: Killer whale
Scientific name: Orcinus orca
Stock: Eastern North Pacific Southern Resident Killer Whale
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Range Habitat Movements
Abundance Natural History Threats
Conservation Research Gaps Recommended Actions

Listing Status
Endangered Species Act (?)
Status: Endangered (Eastern North Pacific Southern Resident Population)
Critical Habitat: In November 2006, NMFS designated critical habitat for Southern Resident killer whales. The designated area, just over 2,500 square miles, encompasses parts of Haro Strait and the U.S. waters around the San Juan Islands, the Strait of Juan de Fuca and all of Puget Sound (Figure 7 in Recovery Plan 2008)
Recovery Plan: Released January 2008
Five Year Status Review: March 2011

California Endangered Species Act (?)
Status: Not listed

Marine Mammal Protection Act (?)
Status: Depleted; strategic stock
Stock Assessment: Updated annually1

The World Conservation Union (IUCN) (?)
Status: Data Deficient

Convention on International Trade in Endangered Species (CITES) (?)
Appendix II

Convention on Migratory Species (CMS) (?)
Appendix II

Geographic Range

Killer whales have a cosmopolitan distribution and are found in all oceans of the world (Figure 1). Killer whales are found off the US west coast, from California north to Alaska, and are divided into three groups: transients, residents, and offshore ecotypes, depending on their morphology, ecology, genetics, and behavior.1 Southern resident killer whales are found mainly off the coast of Washington state, northern residents off the coast of British Columbia, and southern Alaskan residents off the coast of Alaska.2,3 Over 2500 square miles of critical habitat were designated in Washington state for Southern Resident killer whales in 2006 (J, K, and L pods).4 These areas include the inland waters around San Juan Islands, fall foraging areas in Puget Sound, and a transit corridor in the Straight of Juan de Fuca. There are three types of transient killer whales that occur in the northeastern Pacific. West coast transients range from central California north to approximately 56° N, the Gulf of Alaska transients range from southeastern Alaska to Kodiak Island in the west, and the AT1 transients are a small group of whales in Prince William Sounds and Kenai Fjords on the northern Gulf of Alaska.5


Killer whales from west coast transient, Eastern North Pacific Southern Residents, have been sighted in MBNMS. Monterey Bay is the southernmost portion of the range of the Eastern North Pacific Southern Resident Killer Whale stock.

Figure 1. The world-wide geographic distribution of killer whales Orcinus orca.
Access NOAA's Office of Protected Resources for more information.

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Killer whales are most common in coastal, temperate waters, particularly in regions of greater productivity. They occur in greatest densities at high latitudes, in areas of high prey abundance.


In the MBNMS, killer whales can be seen relatively close to shore, typically in spring.

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Migration and Movements

Southern Resident killer whales move seasonally as they track their main prey resource, salmon, on their migration. Movement of other stocks of killer whales between geographic areas has also been documented. For example, whales sighted in Southeast Alaska have been observed in Price William Sound, British Columbia and Puget Sound.6,7 Offshore killer whales have been observed as far south and southern California and as far north as the Bering Sea in Alaska.


Transient killer whales can be seen year-round in sanctuary waters, but are most common in spring, when they are searching for prey, such as newborn gray whale calves making the migration north with their mother. Resident killer whales can be observed at least once during the winter in Monterey Bay as they search for their disappearing prey, king salmon. Offshore killer whales are occasionally seen during winter months in Monterey Bay and they have the largest range of any killer whale.

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It is difficult to estimate killer whale abundance because of their wide-geographic distribution. In the northeastern Pacific, from the Aleutian Islands to California, a total population 1600 whales has been estimated based on photo-identification studies.3,8 In the waters off Washington and British Columbia, resident and transient groups number in the low hundreds. Photo ID has also been used to identify 450 whales off northern Norway9, 115 off New Zealand10, and 900 off the Russian Far East. Line-transect survey methods have led to estimates of 8500 killer whales in 19 million square kilometers in the eastern tropical Pacific and at least 25,000 in the Southern Ocean, for a total world-wide abundance estimate of a minimum of 50,000 whales.8 In 2010, there were 86 whales in three pods that comprised the Eastern North Pacific Southern Resident stock.11


When a rare sighting is made, offshore killer whales usually occur in large groups of 50-100 animals. More than 130 transient killer whales have been identified in Monterey Bay using photo-identification techniques.

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Natural History
Click here to view the natural history information of this species.


Entanglement in fishing gear: Killer whales are occasionally captured in trawl and driftnet fishing gear.16

Vessel disturbance and strikes: Disturbance by motorized and non-motorized vessels can result in behavioral changes in dolphins and killer whales.29,30 Killer whales can be injured and killed from propeller blades and collisions with vessels.3,10,17 The waters off Washington state are frequented by private and commercial vessels (including whale-watching operators) and chronic disturbance and anthropogenic noise may interfere with whale forging and resting activities, and increase the risk of vessel strikes. Regulations have been implemented to help reduce the impact of vessels on the Southern Resident population, including prohibiting vessels from approaching whales within 200 yards and from intercepting the path of a whale.

Intentional take: Intentional take occurs in Japan, Greenland, Indonesia, and the West Indies.25 Killer whales have been captured live for display in parks and aquaria throughout the world. From 1964-1977, 63 Southern Residents were taken from waters off Washington state and British Columbia.26 Live captures also occurred off Iceland. Some fisherman view killer whales as a competitor (because they can remove fish from fishing gear) and intentional shooting of killer whales has occurred in areas of Alaska.

Habitat degradation and contaminants: Contaminants are a major threat to Southern Resident killer whales. This includes oil spills and other toxic pollution that occur in Puget Sound, the core habitat of this population. As top predators, killer whales are susceptible to bioaccumulation of organochlorine pollutants and Southern Resident killer whales have the highest levels of PCBs of any cetacean (whale, dolphin, and porpoise). PCBs may suppress the immune system and reduce reproductive output.27 Catastrophic oil spills can cause mortality of killer whales. The Exxon Valdez spill was correlated with the death of several whales that were seen swimming in the oil slicks.28

Declining prey resources: Chinook salmon stocks, the main prey of killer whales, have declined significantly due to overfishing and degradation of habitat. NMFS is working to restore salmon runs in Puget Sound, Washington, which will likely aid in the recovery of Southern Resident killer whales.


No threats are unique to the MBNMS.

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Conservation and Research

The Southern Resident population of killer whales was listed as Endangered under the US Endangered Species Act (ESA) in 2005 and are consequently considered strategic under the Marine Mammal Protection Act (MMPA). The National Marine Fisheries Service (NMFS) designated critical habitat for Southern Resident killer whales in November 2006. The recovery plan was released in January 2008 and the NMFS proposed vessel regulations in July 2009.
Much of the research being conducted on Southern Resident killer whales occurs in the waters of Washington State. The University of Washington Center for Conservation Biology collects scat samples (with the help of Tucker, a conservation canine) and levels of stress, reproductive, and nutrition hormones, in addition to toxicants can be examined. Hormone and toxin levels are then correlated to king salmon abundance (their principal prey) and vessel density to better understand threats to the population (link).
The Center for Whale Research has conducted a long-term photo identification study of Southern Resident killer whales near San Juan Island, which has provided baseline data on population dynamics, demography, social structure, and life history of the stock. The Center for Whale Research aims to develop, promote, and conduct benign studies of free swimming cetaceans (whales, dolphins, and porpoises). They have developed or employed molecular genetics studies using sloughed skin, statistical methods of population estimation using photo-ID, and acoustic monitoring and satellite telemetry techniques to study Southern Residents (link). The Northwest Fisheries Science Center (NWFSC) conducts ongoing research on Southern Resident habitat, foraging ecology, physiology, behavior, and acoustics (link).


CSCAPE – Collaborative Survey of Cetacean Abundance and the Pelagic Ecosystem (Principal Investigator: Karin Forney, NMFS Southwest Fisheries Science Center). CSCAPE was a collaboration between the National Marine Fisheries Service and the National Marine Sanctuary Program to assess the abundance and distribution of marine mammals and to characterize the pelagic ecosystem off the U.S. West Coast. The primary objective is to conduct a marine mammal assessment survey out to a distance of approximately 300 nautical miles, with additional fine-scale surveys within the NMS boundaries. A secondary objective is to characterize the pelagic ecosystem within the study area, through the collection of underway and station-based oceanographic and biological data, seabird studies, and acoustic sampling. A final objective is to conduct biopsy sampling and photo-identification studies of marine mammal species of special interest. The first surveys began in June 2005 and the program ended in December 2007.

Beach COMBERS – Coastal Ocean Mammal and Bird Education and Research Surveys (Project Leader: Hannah Nevins, Moss Landing Marine Laboratories). In 1997 the MBNMS began a beach survey program using trained volunteers to survey beached marine birds and mammals monthly at selected sections of beaches throughout the Monterey Bay area. Currently, the program monitors 45 km of beaches in the MBNMS. The program is a collaborative project between MLML, MBNMS, and other state and research institutions, with the specific goal of using deposition of beach cast carcasses as an index of the health of the sanctuary. The Marine Mammal Health and Stranding Response Program Network is notified of all stranded or dead cetaceans so that data can be collected and the cause of the stranding event determined.


The California Department of Fish and Game (CDFG) is not required to have research and monitoring programs for killer whales because this species is not listed as threatened or endangered under the California Endangered Species Act.


The International Union for the Conservation of Nature (IUCN) listed Killer whales, Orcinus orca as Data Deficient in 2008. They are also listed in Appendix II of CITES and Appendix II of CMS.


CIMT - Center for Integrated Marine Technologies The Center for Integrated Marine Technologies (CIMT) or Wind to Whales program conducted line transect surveys for marine mammals and seabirds in Monterey Bay and the waters off the Monterey Peninsula from 1997-2007.31,32 Wind to whales was an interdisciplinary, collaborative research project involving scientists from the University of California Santa Cruz, Moss Landing Marine Labs, the Monterey Bay Aquarium Research Institute, NMFS, and the MBNMS. Marine mammal observations were conducted with oceanographic and acoustic (prey) sampling to gain a comprehensive integrated understanding of the effect of spatial and temporal variability on the coastal upwelling ecosystem.

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Research Gaps

The Eastern North Pacific Southern Resident stock of killer whales is a small and vulnerable population. They are well studied in their core habitat in the inland waters of Washington State, but more information is needed on their spatial and temporal distribution in waters of the MBNMS. Research gaps could be filled by:

  • Increasing communication with whale-watching operators to document the season and location of killer whale sightings in MBNMS
  • Implementing aerial surveys of the entire MBNMS to determine the distribution and abundance of whales in Sanctuary waters
  • Initiating or improving photo-identification efforts to identify stocks and pods of killer whales that are using the MBNMS
  • Monitoring anthropogenic interactions to document the extent to which killer whales in MBNMS are exposed to vessel and acoustic disturbances

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Recommended Actions
  • Support conservation efforts to minimize intentional take, entanglement in fishing gear, habitat degradation, and contaminant loads, and help restore and protect declining prey resources.
  • Support and enforce vessel regulations to minimize disturbance, acoustic impacts, and vessel strikes of killer whales.

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Cited References
1. Hoelzel AR, Dahlheim ME, Stern SJ (1998) Low genetic variation among killer whales (Orcinus orca) in the Eastern North Pacific, and genetic differentiation between foraging specialists. J. Heredity 89:212-128.
2. Matkin CG, Ellis E, Saulitis L, Barrett-Lennard, Matkin D(1999) Killer whales of southern Alaska. North Gulf Oceanic Society. 96pp.
3. Ford JKB, Ellis GM, Balcomb KC (2000) Killer whales: The natural history and geneology of Orcinus orca in British Columbia and Washington. 2nd edition. University of British Columbia Press, Vancouver, BC and University of Washington Press, Seattle. 104pp
4. National Marine Fisheries Service (April 14, 2011) Protective regulations for killer whales in the Northwest region under the Endangered Species Act and Marine Mammal Protection Act. Federal Register Vol. 76 No. 72:20870-20890
5. Ford JKB, Ellis GM (1999) Transients: mammal-hunting killer whales of British Columbia, Washington, and southeastern Alaska. UBC Press, Vancouver, British Columbia.
6. Leatherwood S, Matkin CO, Hall JD, Ellis GM (1990) Killer whales, Orcinus orca, photo_identified in Prince Willim Sound, Alaska 1976 to 1987. Can Field Nat 104:362-371
7. Dahlheim ME, Ellifrit DK, Swenson JD (1997) Killer whales of Southeast Alaska: a catalogue of photoidentified individuals. National Marine Mammal Laboratory, AFSC, NMFS, NOAA, 7600 Sand Point Way NE, Seattle, WA 98115. 79 pp.
8. Forney KA, Wade P (2006) Worldwide distribution and abundance of killer whales. In: Estes JA, Brownell Jr RL., DeMaster DP, Doak DF, Williams TM (eds), Whales, Whaling and Ocean Ecosystems, pp. 145-162. University of California Press.
9. Similä T (1997) Sonar obesrvations of killer whales (Orcinus orca) feeding on herring schools. Aquatic Mammals 23:119-125
10. Visser IN, Mäkeläinen P (2000) Variation in eye-patch shape of killer whales (Orcinus orca) in New Zealand waters. Marine Mammal Science 26:232-240
11. National Marine Fisheries Service Stock Assessment for the Eastern North Pacific Southern Resident Stock (2011) Northwest Fisheries Science Center, US Department of Commerce
12. Reeves RR, Stewart BS, Clapham PJ, Powell JA (2002) National Audubon Society Guide to Marine Mammals. Chanticleer Press, Inc. RR, Stewart BS, Clapham PJ, Powell JA (2002) National Audubon Society Guide to Marine Mammals. Chanticleer Press, Inc. New York. 537pp.
13. Ford JKB, Ellis GM, Olesiuk PF, Balcomb KC (2009) Linking killer whale survival and prey abundance: food limitation in the oceans' apex predator? Biol. Lett. doi:10.1098/rsbl.2009.0468
14. Yamada TK et al. (2007) Biological indices obtained from a pod of killer whales entrapped by sea ice off northern Japan. IWC Scientific Committee Meeting Document SC/59/SM12
15. Ford JKB, Ellis GM, Barrett-Lennard LG, Morton AB, Palm RS, Balcomb KC. (1998) Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters. Canadian Journal of Zoology 76:1456-1471
16. Dahlheim ME, Heyning JE (1999) Killer whale Orcinus orca (Linnaeus, 1758). Pp 281-322. In: S. Ridgway and R. Harrison (eds.). Handbook of Marine Mammals. Academic Press, San Diego, California
17. Visser IN (1999) Benthic foraging on stingrays by killer whales (Orcinus orca) in New Zealand waters. Marine Mammal Science 15:220-227
18. Saulitis E, Matkin C, Barrett-Lennard L, Heise L and Ellis G (2000) Foraging strategies of sympatric killer whale (Orcinus orca) populations in Prince William Sound, Alaska. Marine Mammal Science. 16:94-109
19. Ford JKB, Ellis GM (2006) Selective foraging by fish-eating killer whales Orcinus orca in British Columbia. Mar Ecol Prog Ser 316: 185-199.
20. Dahlheim ME, Schulman-Janiger A, Black N, Ternullo R, Ellifrit D, Balomb KC III (2008) Eastern temperate North Pacific Offshore Killer Whales (Orcinus orca): occurrence, movements, and insights into seeding ecology. Mar Mamm Sci 24:719-729
21. Baird RW, Dill LM (1996) Ecological and social determinants of mammal-eating killer whales: group stability and dispersal patterns. Canadian Journal of Zoology 78:2096-2105
22. Barrett-Lennard LG, Ford JKB, Heise KA (1996) The mixed blessing of echolocation: differences in sonar use by fish-eating and mammal-eating killer whales. Animal Behaviour 51:553-565
23. Olesiuk PF, Ellis GM, Ford JKB (2005) "Life History and Population Dynamics of Northern Resident Killer Whales (Orcinus orca) in British Columbia". Canadian Science Advisory Secretariat, Fisheres & Oceans, Canada.
24. Duffield DA, Odell DK, McBain JF Andrews B. (1995) Killer whale (Orcinus orca) reproductions at Sea World. Zoo Biology 14:417-430.
25. Reeves RR, Smith BD, Crespo EA, Notarbartolo di Sciara GN (2003) "Dolphins, Whales and Porpoises: 2002-2010. Conservation Action Plan for the World's Cetaceans." IUCN/SSC Cetacean Specialist Group, IUCN, Gland, Switzerland.
26 Olesiuk PF, Bigg MA, Ellis GM (1990) Life history and population dynamics of resident killer whales (Orcinus orca) in the coastal waters of British Columbia and Washington State. Rep Int Whal Comm Spec Iss 12:209-242
27. Ross PS, Ellis GM, Ikonomou MG, Barrett-Lennard LG, Addison RF (2000) Foraging strategies of sympatric killer whale (Orcinus orca) populations in Prince William Sound, Alaska. Mar Mamm Sci 12:94-109
28. Dahlheim ME, Matkin CO (1994) Assessment of injuries to Prince William Sound killer whales. In: T. R. Loughlin (ed.), Marine mammals and the Exxon Valdez, pp. 163-172. Academic Press
29. Lusseau D (2003) Effects of tour boats on the behavior of bottlenose dolphins: using Markov chains to model anthropogenic impacts. Conservation Biology 17(6):1785-1793
30. Williams R, Lusseau D, Hammond PS (2006) Estimating relative energetic cost of human disturbance to killer whales (Orcinus orca). Biological Conservation 133:301-311
31. Benson SR, Croll DA, Marinovic BB, Chavez FP, Harvey JT (2002) Changes in the cetacean assemblage of a coastal upwelling ecosystem during El Niño 1997-98 and La Niña 1999. Prog Oceanogr 54:279−29
32. Burrows JA, Harvey JT, Newton KM, Croll DA, Benson SR (2012) Marine mammal response to interannual variability in Monterey Bay, California. Mar Ecol Prog Ser 461:257-271


Thank you to Julia Burrows, doctoral student at Duke University, for compiling this information as part of her duties as a NOAA Nancy Foster Scholar.

Content Last Modified: October 3, 2012

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