Northeast Pacific Transient Killer Whale population (or Bigg’s Killer Whale)

Orcinus orca

SARA Status
No Status
NS
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

SARA Status

  • No Status NS
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX
COSEWIC Status
Not at Risk
NR
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

COSEWIC Status

  • Not at Risk NR
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

Description

The Killer Whale (Orcinus orca) is the largest member of the dolphin family. Its size, distinctive black and white markings, and tall dorsal fin characterize the species. Adult males may reach overall lengths of eight to nine metres and weigh up to five tonnes. Females are smaller and measure seven metres and four tonnes. Some females have been known to live up to 80-90 years, but the average lifespan of a whale in the wild is more likely 30-50 years.

The first sight of a killer whale is usually the iconic triangular dorsal fin, which may measure up to 1.8 metres in the males. In females and young whales, the fin is curved and less than one metre high. The dorsal fin and the distinctive coloration of mainly black above and white below with an oval white patch behind each eye provide unmistakable features for species identification.

Three distinct groups, or ecotypes, of killer whale inhabit Canadian Pacific waters: resident, offshore, and transient or Bigg's killer whale as they are more commonly referred to now. Bigg's killer whales feed primarily on marine mammals, while resident killer whales feed exclusively on fish (primarily salmon) and cephalopods. Offshore killer whales are the least understood of the three ecotypes and consume primarily fish, with shark species playing a dominant role in their diet. Although the three ecotypes exhibit overlapping ranges, they are acoustically, genetically and culturally distinct from each other and have different dietary preferences. Research suggests that Bigg's killer whales have been genetically separated from all other killer whales for about 750,000 years.

Killer whales have a female-dominant or matriarchal social structure. However, in contrast to resident killer whale behaviour, where individuals closely associate with their matriline (mother and descendants) throughout their lives, Bigg's killer whale offspring may disperse and form groups with individuals from other maternal lineages. Typical sizes of Bigg's killer whale groups are three to six animals, though temporary associations of over 30 whales have been observed. The tendency to form smaller groups is likely a result of their foraging ecology, as energy intake is maximized when they forage in groups of three individuals.

Bigg's killer whales are stealth predators that rely on passive listening to locate and approach prey without detection, but often vocalize during or immediately following predation events. Bigg's killer whales share a common set of distinct stereotyped calls and do not exhibit the dialect variations observed in the resident killer whale vocalizations.

Habitat

Killer whales are one of the most widely distributed mammals in the world. They are known to occur in all of the world's oceans and most seas, but are most commonly found in productive coastal waters in high latitude regions. In Canadian Pacific waters, they have been observed in inshore channels and inlets, along the outer coast, and in pelagic waters over the continental shelf and beyond.

Bigg's killer whales are non-migratory and spend the majority of their life within the coastal waters of British Columbia. As they are marine mammal hunting specialists, their habitat overlaps that of their prey species, especially harbour seals, harbour porpoises, Steller sea lions, and Dall's Porpoises. An important feature of Bigg's killer whale habitat is the underwater acoustic environment, which must be of sufficient quality (i.e., low levels of ambient noise) to allow prey to be detected through passive listening. However, once the prey has detected the presence of killer whales, it is likely better for the group to move out of the area and seek other prey elsewhere. This creates the need for an extensive habitat where prey is distributed over great distances to increase the likelihood of foraging success.

Threats

Bigg's killer whales are long-lived upper trophic level predators that are considered to be at risk due to small population size (521 individuals were identified between 1990 and 2011), very low reproductive rate (one calf approximately every five years), and high levels of chemical contaminants that are persistent, bioaccumulative and toxic.

Because they rely on stealth and passive listening to detect prey, Bigg's killer whales are at risk of habitat degradation through acoustic disturbance from underwater noise. Other threats that may impede recovery are biological pollutants, trace metals, physical disturbance, toxic spills, collisions with vessels, and decreased prey availability.

Northeast Pacific Transient Killer Whale population

Killer whale

Killer Whale - Orcinus orca
Photo credit: B. Peters © Fisheries and Oceans Canada

Scientific Name: Orcinus orca
SARA Status: Threatened (2003)
COSEWIC Status: Threatened (2008)
Region: Pacific ocean

© Shutterstock

© Shutterstock

Did You Know?

Dr. Michael Bigg (1939-1990), a Fisheries and Oceans scientist, is recognized as the founder of modern research on Killer Whales. Dr. Bigg conducted the first population census of the animals and established the use of photo-identification as a key tool to unlock the social relationships, travel patterns, and foraging behaviour of various individuals and populations.

While studying the Resident Killer Whale population, Bigg and his colleagues would occasionally encounter small groups of Killer Whales that would not mix with the Residents, and referred to these animals as “Transients”. Due to his dedication and insight, we now recognise that this population is distinct and ecologically specialized, and refer to them as “Bigg's” Killer Whales, to honour his substantial contribution to science.

Related information