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Killer Whales

About AquaFacts: AquaFacts are a resource for students who are looking for information on the animals at the Aquarium or other Aquarium-related topics. Here, we’ve compiled some of the most frequently asked questions that we’ve received about killer whales. The answers come from our biologists and from reputable sources that we reference at the end of this page. If you have a question about killer whales that’s not addressed in this page or the references below, please feel free to email our librarian.

Killer Whales Credit: Lance Barrett-Lennard

Questions & Answers

How can I identify a killer whale?

Killer whales are distinctively marked black-and-white dolphins. While they can be found all over the world, there are three distinct assemblages (groups): residents, Bigg’s (transients) and offshore. Each assemblage has major differences in behaviour and social organization, and subtle differences in appearance such as the dorsal (back) fin and saddle patch. Individual killer whales are commonly identified by patterns in the grey saddle patch located immediately behind the dorsal fin, and by natural markings (scars, nicks, etc.) on the dorsal fin itself.

Resident killer whales specialize in hunting salmon. They primarily hunt Chinook, but chum salmon are also eaten during the fall. The residents’ social organization is based on small mother-led (matrilineal) groups called matrilines, which can include three to fifteen individuals. Bigg’s are marine mammal “specialists,” preying on harbour seals, sea lions, elephant seals, porpoises and baleen whales such as minke whales and gray whale calves. Unlike residents, Bigg’s   may leave their mother’s group around the time they mature. Offshore killer whales are poorly known, but tend to travel in groups of 30 to 60 individuals, probably preying on large oceanic fish such as sharks and halibut.

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Photos: Lance Barrett-Lennard

How do killer whales reproduce?

Some females give birth to their first calf at age 12, but most give birth at age 14-15. Usually single young are born; there is one documented case of twins in B.C. The length of pregnancy (gestation period) in aquarium killer whales has been recorded at close to 17 months and the maximum calving rate is one every three years. Females stop giving birth at approximately 40 years of age. Calves nurse from their mothers for at least one year, and sometimes up to 2 or 3 years.

How long do killer whales live?

Field studies in B.C. suggest that males live to a maximum of 55 years while females may reach 70-80 years of age. Average life expectancy is estimated at about 30 years for males and 50 years for females.

Where do we find killer whales, and how many are found in British Columbia?

Residents seem to be common on the coast from April to November, but some pods have been seen in inshore waters throughout the year. Some may go offshore or into mainland inlets during the winter. During the summer months, southern resident pods are commonly seen in Haro Strait and the San Juan Islands, and northern residents are often seen in the Johnstone Strait area.

Bigg’s killer whales are found along the B.C. coast year-round, and are constantly on the move in search of their prey.  They are often found in areas where seals are abundant. A Bigg’s pod may range up to 1,500 km along the coast from Alaska to California; resident pods have been known to travel up to 2,200 km.

 

How many killer whales are there in BC?

There are approximately 300 northern and southern residents and 225 transients in B.C./Washington waters. At least 200 offshore killer whales have also been identified. The South East Alaska resident population is just over 300 killer whales, and there are numerous other populations of transient killer whales in California and Alaska that are distinct from local populations.

How do killer whales pass the time?

Activities of both residents and Bigg’s can be grouped into four major categories: looking for food (foraging), resting, socializing and travelling. All of these seem to happen both day and night. Foraging is the most common activity, comprising about 60 percent of their daily activity. Resident pods in B.C. forage cooperatively and prey is often shared between individuals, particularly between mature females and juveniles. Mature males may sometimes hunt and eat independently from the rest of their group.

Members of Bigg’s pods cooperate to chase, corner and kill their prey, and share their kill with group members. When resting, pod members slow down, group together tightly, become mainly silent and dive synchronously for 4-5 minutes or longer. Resting periods tend to last two to three hours. Socializing also consists of sexual interactions and play among pod members. Beach rubbing is a traditional social behaviour among some northern resident pods.

What behaviours are killer whales commonly observed to perform?

Sticking their head out of the water (spyhopping) and aerial displays, such as breaching, tail slapping and dorsal-fin slapping, are most commonly seen during socializing episodes. These behaviours may represent play, but may also occur in other contexts such as foraging. Spyhopping seems to be a way of looking at the whales' surroundings; killer whales often spyhop when boats approach closely. Aerial behaviours are most likely displays of social excitement, dominance, or aggression. Transients may breach to startle or confuse prey, and tail-slap to stun or injure prey.

How do killer whales communicate?

Resident killer whales are very vocal. They echolocate frequently and exchange calls and whistles to maintain contact with each other while traveling and foraging.. Resident pods have distinct dialects consisting of a set of 7 to 17 distinct stereotyped calls. All members of a pod will use all of these calls.. Calls do not seem to have specific meanings, such as nouns and verbs in human language, but may be used in different contexts.

In most pods, some calls are unique to the group and some calls are shared with other pods. Shared calls usually have pod-specific "accents." Pods with dialects that have a few calls in common are considered to belong to the same "clan." Pods within a clan have probably descended from a common ancestral group and are therefore more closely related to each other than to pods from other clans. Different clans often occur in the same area and pods from different clans may travel together. Pod-specific dialects probably convey information about pod relationship and are important in maintaining the cohesion and identity of the group. Slight changes to standard call formats communicate additional information such as the identity, location and emotional state of the vocalizing individual.



Facts & References

Key Facts

  • Newborns are around 2 m long and weigh approximately 150 kg.
  • Adult males can reach 9.8 m and 10,000 kg; females reach 8.5 m and 7,500 kg.
  • The dorsal fin of males is approximately 1.7 m tall; females 1 m tall
  • Side (pectoral) flippers of males may reach 2.5 m long and are much broader than those of the females.
  • Top speed during travel or when chasing prey is roughly 45 km/h.
  • Typical dive times are less than five minutes; the maximum recorded locally was 15 minutes, in a transient pod.
  • The maximum dive depth is unknown; killer whales in B.C. are unlikely to dive very deep as their prey is usually found in the top 100 m of the water.

Did You Know?

  • Tail flukes of mature males curl downward, unlike those of females
  • A few mature males in the wild in B.C. and Alaska have bent dorsal fins
  • Like most other dolphins, killer whales have well developed eyesight (both above and below the water)

How Can I Adopt A Killer Whale?

Adopt a killer whale and help support ground-breaking research on wild killer whales. Learn more about the BC Wild Killer Whale Adoption Program at www.killerwhale.org

How Can I help With Killer Whale Research In British Columbia?

If you see a whale or dolphin off the coast of British Columbia, we would love to hear about it. Report your sighting at www.wildwhales.org


References

  1. American Cetacean Society. 2007. Orca Fact Sheet
  2. Barrett-Lennard, Lance G., and Graeme M. Ellis. 2001. Population structure and genetic variability in northeastern Pacific killer whales: towards an assessment of population viability. Canadian Scientific Advisory Secretariat, Department of Fisheries and Oceans Research Document 2001/065.
  3. Ford, John K.B., Graeme M. Ellis, and Kenneth C. Balcomb. 2000. Killer Whales: A Study of their Identification, Genealogy, and Natural History in British Columbia and Washington State. Second edition. Vancouver: UBC Press.
  4. Ford, John K.B. and Graeme M. Ellis. 1999. Transients: Mammal-Hunting Killer Whales of British Columbia. University of Washington Press.

Permission is granted by the Vancouver Aquarium Marine Science Centre for classroom teachers to make copies for non-commercial use. This permission does not extend to copying for promotional purposes, creating new collective works, or resale.

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