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BC Conservation Data Centre: Conservation Status Report

Orcinus orca pop. 3
Killer Whale (Northeast Pacific Transient Population)

 
Scientific Name: Orcinus orca pop. 3
English Name: Killer Whale (Northeast Pacific Transient Population)
English Name Synonyms: Bigg's Orca
Killer Whale (West Coast Transient Population)
   
Provincial Status Summary
Status: S1
Date Status Assigned: March 31, 2021
Date Last Reviewed: March 21, 2021
Reasons: There are estimated to be 206 mature Northeast Pacific Transient individuals occurring throughout all coastal waters of BC. Main threats include elevated levels of environmental contaminants, acoustic and physical disturbance from vessels and other industrial activities, toxic spills and inadequate prey availability (Fisheries and Oceans Canada 2007; COSEWIC 2008).
 
Range
Range Extent: G = 200,000-2,500,000 square km
Range Extent Estimate (km2): 290,000
Range Extent Comments: Transient killer whales, also known as Bigg?s killer whales, occur throughout all coastal waters of British Columbia. Extent of movements beyond the continental slope is unknown. Outside of Canadian waters, this population is found from Glacier Bay, SE Alaska, to northern California. Its extent of occurrence has been estimated to be 290,000 km2 (COSEWIC 2008, Ford 2014).
Area of Occupancy (km2): I = >12,500
Area of Occupancy Estimate (km2): 154,986
Area of Occupancy Comments: Transient killer whales range widely in nearshore waters while foraging for their marine mammal prey. Their habitat includes all coastal inlets, fjords, straits and channels, and extends over the continental shelf in outer coast waters. The population?s area of occupancy has been estimated to be 154,986 km2 (COSEWIC 2008).
 
Occurrences & Population
Number of Occurrences: U = Unknown
Comments: Transient killer whales are highly mobile and groups may travel distances of >150 km per day in search of marine mammals, their primary prey. Compared to salmon-eating resident killer whales, they lack strong seasonality in their movements. Although their diet consists mostly of pinnipeds (harbour seals and sea lions), they tend not to linger near haul outs of these prey. Instead, the mostly catch pinnipeds in open waters (Ford et al. 2013). Individuals and their small kin groups may be found throughout the population?s overall range, but often have preferred areas within this range. For example, some groups are found mostly in south coast waters, others in north coast or Haida Gwaii waters (Ford et al. 2013). Because of the high mobility of these animals, the number of occurrences is difficult to determine (J. Ford, pers. comm. 2021).
Number of Occurrences with Good Viability / Ecological Integrity: U = Unknown
Number of Occurrences Appropriately Protected & Managed: A = None
Comments: Transient killer whales have an extremely wide range in coastal waters, and forage for marine mammal prey in all marine habitats, primarily in close proximity to coastlines. Attempts to identify areas of critical habitat have been difficult. Ford et al. (2013) noted that over 90% of all encounters with this population and all predation events were documented within 3 nautical miles (5.56 km) of shorelines. These nearshore waters were identified as potential critical habitat, but no critical habitat under the Species at Risk Act has yet been designated for this population (Fisheries and Oceans Canada 2019).
Population Size: B = 50 - 250 individuals
Comments: As of 2019, there were an estimated which 206 mature individuals in the population (total population size estimate was 349) (Towers et al. 2019).
 
Threats (to population, occurrences, or area affected)
Degree of Threat: U = Unknown
Comments: The four main threats to transient killer whales are (1) elevated levels of environmental contaminants, (2) acoustic and physical disturbance from vessels and other industrial activities, (3) toxic spills such as oil spills, and (4) inadequate prey availability (Fisheries and Oceans Canada 2007; COSEWIC 2008). Killer whales are susceptible to environmental contaminants such as PCBs and other organochlorines, which bioaccumulate upward through the marine food web and are stored in the whales? blubber. Transient killer whales tend to sequester higher levels of contaminants in their blubber than resident killer whales because they feed on marine mammals, which themselves accumulate contaminants (Ford et al. 2007; Fisheries and Oceans Canada 2007). Potential effects of these contaminants include reduced reproductive success and immunosuppression. Noise can potentially cause auditory masking of the whales? communication signals needed for coordination of group activities and reduce the effectiveness of passive listening, which transient killer whales use to detect and capture prey. The long-term effects of underwater noise are uncertain. Vessel movements and congestion near whales may disrupt life processes such as resting and foraging, as well as increasing risk of vessel strikes. Several killer whale deaths in recent years have been attributed to blunt force trauma, likely from collision by vessels (Raverty et al. 2020). Catastrophic oil spills are another threat to transient killer whales. The Exxon Valdez oil spill in Alaska is linked to the disappearance of several transient killer whales in Prince William Sound (Ford et al. 2007). Depletion of pinnipeds in BC waters from a century of exploitation and culling significantly reduced the prey base for mammal-hunting transient killer whales, and is likely the reason this population was so uncommon in the 1970s. Pinniped populations have rebounded over the past 50 years and prey reduction is no longer a current threat. (Ford et al. 2007).
 
Trend (in population, range, area occupied, and/or condition of occurrences)
Short-Term Trend: I = Increase of >25%
Comments: From 1975, when photo-identification studies began, to 2006, the population increased at approximately 6% per year due to recruitment and apparent immigration into coastal waters of BC. This growth has been attributed to a substantial increase in Harbour Seals and Steller Sea Lions, the principal prey of transient killer whales, since 1970 (Ford et al. 2007). More recently, the growth rate of the population between 2012 and 2018 has been estimated to be 4.1% per year (Towers et al. 2019).
Long-Term Trend: U = Unknown
Comments: The historical abundance of transient killer whales is unknown, but it may have been larger than at present. Between the mid 1800s and 1970, populations of harbour seals and sea lions, the main prey of these predators, were seriously depleted by harvesting and culling. Pinniped abundance has increased dramatically since then, and may be approaching or at pre-exploitation abundance (Ford et al. 2007). The continued growth of the transient killer whale population suggests that it has yet to reach the carrying capacity of its range.
 
Other Factors
Intrinsic Vulnerability: AB=Highly to moderately vulnerable.
Comments: Long-term monitoring of resident killer whales has shown that this salmon-eating ecotype is vulnerable to increased mortality and reduced reproduction if food availability becomes inadequate to sustain the population (Ford et al. 2010). The same is likely the case for mammal-eating transient killer whales, although prey abundance is no longer a threat for this population. However, intrinsic population growth rate is typically limited to less than 4% per annum in killer whales because of the late age of sexual maturity (about 12 years on average) and low calving rate (average interval between calves of 5 years in resident killer whales). As a result, recovery of populations from depletion could be protracted .
Environmental Specificity: Rank Factor not assessed
Other Rank Considerations:
 
Information Gaps
Research Needs: A wide range of studies have been identified as priorities for this population in DFO?s Action Plan (Fisheries and Oceans Canada 2019), including those designed to: monitor and refine knowledge of abundance and distribution in Canadian waters; continue existing monitoring programs for pinniped population abundance and distribution to assess prey availability; determine the short and long-term effects of chronic and acute forms of disturbance, including vessels and noise, on the physiology, foraging and social behavior of transient killer whales; and develop a greater understanding of the impacts of contaminants and other biological and non-biological pollutants on Transient Killer Whales.
Inventory Needs: For over 45 years, the population has been studied annually by photo-identification of whales using natural markings. This has led to a registry of all individuals, including years of birth and death, sex, age of reproduction in females, etc., maintained by DFO Science at the Pacific Biological Station. It is important that this annual census effort be continued to monitor population trends.
 
Stewardship
Protection: Killer whales are protected under the federal Marine Mammal Regulations of the Fisheries Act as well as the Species at Risk Act. The Marine Mammal Regulations were amended in 2018 to increase the minimum approach distance to killer whales from 100 m to 200 m as a measure to mitigate potential disturbance, and this was doubled to 400 m in 2020 for southern British Columbia coastal waters between Campbell River and just north of Ucluelet. There is currently no designated critical habitat for this population under SARA (J. Ford, pers. comm. 2021).
Management: The Action Plan for transient killer whales (Fisheries and Oceans Canada 2019) states that a key management approach is to develop and implement regulations, guidelines, sanctuaries or other measures to reduce or eliminate physical disturbance of transient killer whales. It lists 15 specific management measures that should be considered medium or high priorities.
 
Version
Author: J. Ford (2021) S. Cannings, L. Ramsay, and A. Teucher (previous versions)
Date: March 31, 2021
 
References

Towers, J.R., Sutton, G.J., Shaw, T.J.H., et al. 2019. Photo-identification Catalogue, Population Status, and Distribution of Bigg?s Killer Whales known from Coastal Waters of British Columbia, Canada. Can. Tech. Rep. Fish. Aquat. Sci. 3311: vi + 299 p.
Barlow, J., K.A. Forney, P.S. Hill, R.L. Brownell, J.V.Carretta, D.P. DeMaster, F. Julian, M.S. Lowry, T. Ragen, and R.R. Reeves. 1997. U.S. Pacific Marine Mammal Stock Assessments: 1996. NOAA Tech. Memo. NMFS. NOAA-TM-NMFS-SWFSC-248.
Canada Gazette. 2018. Regulations Amending the Marine Mammal Regulations: SOR/2018-126. Part II, Volume 152, Number 14
Fisheries and Oceans Canada. 2019. Action Plan for the Transient Killer Whale (Orcinus orca) in Canada [Proposed]. Species at Risk Act Action Plan Series. Fisheries and Oceans Canada, Ottawa. iv + 34 pp.
Ford, J.K.B, G.M. Ellis, P.F. Olesiuk, et al. 2010. Linking killer whale survival and prey abundance: food limitation in the oceans? apex predator? Biology Letter 6:139-142. Published on-line before print September 15, 2009.
Ford, J.K.B. 2014. Marine Mammals of British Columbia. Royal BC Museum Handbook, Mammals of BC, volume 6. Royal B.C. Mus., Victoria, BC. 460 pp.
Ford, J.K.B., E.H. Stredulinsky, J. R. Towers, et al. 2013. Information in Support of the Identification of Critical Habitat for Transient Killer Whales (Orcinus orca) off the West Coast of Canada DFO Can. Sci. Advis. Sec. Res. Doc. 2012/155. iv + 46 p.
Ford, J.K.B., G.M. Ellis, and J. W. Durban. 2007. An assessment of the potential for recovery of West Coast transient killer whales using coastal waters of British Columbia. Research Document 2007/088. Canadian Science Advisory Secretariat, Fisheries & Oceans Canada, Ottawa, ON.
Ford, J.K.B., G.M. Ellis, and K.C. Balcomb. 1997. Killer whales: the natural history and genealogy of Orcinus orca in British Columbia and Washington State. UBC Press, Vancouver, BC. 102pp.
Hoelzel, A.R. 1991. Analysis of mitochondrial DNA variation in the Killer Whale; implications for cetacean conservation. Rep. of the Int. Whaling Commission, Spec. Issue (13):225-233.
Hoelzel, A.R., and G.A. Dover. 1991. Genetic differentiation between sympatric Killer Whale populations. Heredity 66:191-195.
Leatherwood, S., and R. R. Reeves. 1983. The Sierra Club handbook of whales and dolphins. Sierra Club Books, San Francisco. 302 pp.
Matkin, C.O., and E.L. Saulitis. 1994. Killer whale (Orcinus orca) biology and management in Alaska. Contract Rep. T75135023, Marine Mammal Commisssion, Washington, DC. 46pp.
Mayr, E., and P.D. Ashlock. 1991. Principles of Systematic Zoology. 2nd ed. McGraw-Hill Inc., New York, NY. 475pp.
Osborne, R., J. Calambokidis, and E.M. Dorsey. 1988. A guide to marine mammals of Greater Puget Sound. Island Publ., Anacortes, WA. 191pp.
Raverty, S. J. St. Leger, D.P. Noren, et al. 2020. Pathology findings and correlation with body condition index in stranded killer whales (Orcinus orca) in the northeastern Pacific and Hawaii from 2004 to 2013. PLOS One. 15(12): e0242505.
Stevens, T.A., D. Duffield, E. Asper, K. Hewlett, A. Bolz, L. Gage, and G. Bossart. 1989. Preliminary findings of restriction fragment differences in mitochondrial DNA among Killer Whales (Orcinus orca). Can. J. Zool. 67:2592-2595.
Wiles, G. 2016. Periodic status review for the killer whale in Washington. Washington Department of Fish and Wildlife, Olympia, Washington. 26+iii pp.
 

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Suggested Citation:

B.C. Conservation Data Centre. 2021. Conservation Status Report: Orcinus orca pop. 3. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 10, 2026).