Marine Mammals
Orca
Orcinus orca
ALSO KNOWN AS
Killer whale, Blackfish, Aarluk
DISTRIBUTION
Global: All latitudes in all oceans
ECOSYSTEM/HABITAT
Coastal to open ocean
FEEDING HABITS
Predator
TAXONOMY
Order Cetacea (whales, dolphins, and porpoises), Family Delphinidae (dolphins)
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Orcas are highly adaptable. They are found in every ocean in the world and likely have the largest geographic distribution of any species, after humans. They are one of the ocean’s top predators. In fact, their nickname “killer whale” comes from their reputation of being ferocious predators, exhibiting dramatic behaviours when toying with their prey. Orcas and other dolphins are thought to be some of the smartest animals on the planet, challenging the great apes (chimpanzees and gorillas) for the top spot. They are also extremely curious, often approaching people to investigate.
Orcas are highly social and live in complex matriarchal groups called pods. Both female and male offspring remain with their mothers for their entire lives. Their pods are tightknit groups led by older females that provide decades of knowledge to support the pod.
Orcas are highly adaptable. They are found in every ocean in the world and likely have the largest geographic distribution of any species, after humans. They are one of the ocean’s top predators. In fact, their nickname “killer whale” comes from their reputation of being ferocious predators, exhibiting dramatic behaviours when toying with their prey. Orcas and other dolphins are thought to be some of the smartest animals on the planet, challenging the great apes (chimpanzees and gorillas) for the top spot. They are also extremely curious, often approaching people to investigate.
Orcas are highly social and live in complex matriarchal groups called pods. Both female and male offspring remain with their mothers for their entire lives. Their pods are tightknit groups led by older females that provide decades of knowledge to support the pod.
Easily identified by their characteristic black and white markings, orcas also have a distinctive triangular dorsal fin which can reach almost two metres long in males. Most of their body is black, with white eye patches, bellies and unique patches behind their dorsal fins called a saddle patch. These markings are used by scientists to identify individuals using photo identification methods.
Orcas are the largest member of the dolphin family, with adult males reaching lengths of eight to nine metres and weighing up to five tonnes. Females are typically smaller than males. Though there are many different populations of orcas around the world, they are all currently considered one species. There are five distinct populations of orcas in Canada, each with unique genetic populations and cultural distinctions, such as hunting, behaviour and diet. There are four on the Pacific coast of Canada – Southern Resident, Northern Resident, West Coast Transient and Offshore populations – and one in the Arctic/Atlantic Ocean – Northwestern Atlantic and Eastern Arctic population.
Female orcas tend to live up to 80 to 90 years, longer than males who have an estimated lifespan of around 50 years. Orcas reach sexual maturity at 15 years old and have one baby at a time, carrying the pregnancy for 15 to 18 months before spending up to two years nursing them. Typically, orcas take an average of 5 years between pregnancies. Birth usually occurs in non-summer months and a newborn orca can be up to 2.4 metres in length – about the size of a motorcycle! Social bonds of orcas are extremely strong so it is not uncommon for a young orca to stay in the same pod it was born in for their entire life.
While there is no longer a directed fishery for orcas, historically they were captured for sale into the marine parks trade. In 2019, Canada banned whales, dolphins and porpoises from being bred or held in captivity.
One of the main threats facing orcas is decreasing prey availability. In some cases, the main food source for orcas is also a species important to commercial fishing. For example, the endangered Southern Resident orcas on Canada’s west coast rely almost entirely on Chinook salmon. There have been full and partial closures of Chinook salmon fisheries along British Columbia’s coast in order to protect the Resident orcas. Additional fishing threats come from entanglement in gear and salmon aquaculture, which can bring physical disturbances and contaminants to orca’s habitat and prey species.
In Canada, orcas are protected under the Fisheries Act Marine Mammal Regulations, making it illegal to harm, harass or kill any orca in Canadian waters. Common threats for orcas worldwide are lack of food, chemically contaminated prey, oil spills, sound pollution and physical disturbances and ship strikes. There are five populations of orcas in Canada, with different statuses under COSEWIC:
- Southern Residents: Endangered
- Northern Residents: Threatened
- Offshore: Threatened
- West Coast Transient: Threatened
- Atlantic/Eastern Arctic: Special Concern
These populations have different threats and therefore require different conservation efforts.
The Southern Resident orcas are the most at-risk population in Canada, with population decline expected to continue. In 2019, there were only 76 individuals left, but their population has ranged between 70 to 99 individuals since 1976. The Northern Residents are slightly larger with approximately 300 whales in 2017. Both groups have multiple stressors such as reduction in prey availability, ship strikes, sound pollution and aquaculture. In Canada, an action plan has been put in place for both populations of Resident orcas, highlighting the many factors needed for successful conservation.
Both Offshore and Transient orcas are also facing a decline in their food sources. Offshore orcas travel in large groups in the open ocean, where more than one third of their entire population can be in one group. This makes them especially vulnerable to disturbance events such as oil spills and seismic testing, which have the potential to affect a large portion of their population at once.
Little is known about the threats facing the Northwestern Atlantic and Eastern Arctic population, but habitat degradation and pollution are likely large factors.
Committee on the Status of Endangered Wildlife in Canada
Fisheries and Oceans Canada – northeast Pacific offshore population
Fisheries and Oceans Canada – northeast Pacific northern resident population
Fisheries and Oceans Canada – northeast Pacific southern resident population
Fisheries and Oceans Canada – northeast Pacific transient population
Fisheries and Oceans Canada – northwest Atlantic/eastern Arctic population
Government of Canada – action plan
