Killer Whale - Northeast Pacific (offshore)
- No Status NS
- Special Concern SC
- Threatened TH
- Endangered EN
- Extirpated EX
|Not at Risk
- Not at Risk NR
- Special Concern SC
- Threatened TH
- Endangered EN
- Extirpated EX
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 this unmistakable species. Adult males may reach lengths of eight to nine metres and weigh up to five tonnes; females are smaller, measuring at maximum about seven metres and four tonnes. The average length of adult Killer Whales in Canadian Pacific waters, however, is smaller than these maximum lengths.
Three distinct groups, or ecotypes, of Killer Whale inhabit the waters off British Columbia, each exhibiting different prey preferences, dialects and social organization. The Resident, Bigg's (also called Transient) and Offshore Killer Whale ecotypes are believed to be socially and genetically isolated, despite sharing the same waters. Resident Killer Whales feed exclusively on fish (primarily salmon) and cephalopods, while Bigg's Killer Whales feed primarily on marine mammals. Offshore Killer Whales are the least understood of the three ecotypes, but are believed to primarily consume fish, with shark species comprising a significant part of their diet.
The first sight of a Killer Whale is usually of its iconic triangular dorsal fin, which can reach up to 1.8 metres in height on an adult male. In females and young Killer Whales, the dorsal fin is curved and less than one metre tall. Offshore Killer Whales tend to be smaller and have more nicks and notches in their dorsal fins than the Resident and Bigg's Killer Whale ecotypes.
Offshore Killer Whales have a matrilineal social structure similar to Resident and Bigg's Killer Whales, but are unique in that they are very sociable with each other, across the entire population. They are mostly encountered in large aggregations, often in groups of 50 to more than 100 individuals. In 2013, the population of Offshore Killer Whales was estimated to consist of approximately 300 individuals.
Killer Whales are the most widely-distributed mammals in the world. Although they are more commonly found in areas associated with high ocean productivity, in the mid to high latitudes, they can tolerate temperature ranges from polar to tropical waters. In Canada, Killer Whales are found in all three oceans, but are less common in Atlantic and Arctic regions. In British Columbia, they have been observed throughout almost all marine waters, including long inlets, narrow passages and deep embayments, as well as occasionally up brackish river channels.
Offshore Killer Whales appear to be the widest-ranging Killer Whale ecotype in the northeast Pacific Ocean; those identified in British Columbia have also been seen from the Bering Sea to southern California. The population is known as ‘Offshore' due to its range relative to the coast; they are infrequently encountered in inshore waters, and predominantly inhabit continental shelf-edge and outer Canadian Pacific waters.
Perhaps the most important aspect of habitat for Offshore Killer Whales is the abundance and availability of their prey. In British Columbia, Offshore Killer Whales are known to prey on Pacific Sleeper Shark, Blue Shark, North Pacific Spiny Dogfish, Chinook Salmon, and Pacific Halibut. The acoustic environment is also an important element of their habitat; an ocean quiet enough for the transmission and reception of their echolocation clicks and vocalizations is essential for navigation, foraging, cultural and social purposes.
While a variety of threats may directly or indirectly impact Offshore Killer Whales, they are particularly vulnerable to harmful events (e.g. oil spill, underwater explosion) as they are typically found in large groups, where at least one third of the population may be present in a given time and place.
The greatest threats to Offshores include a reduction in prey availability, exposure to contaminants from prey, toxic spills, and acute acoustic disturbance (e.g. mid-frequency active sonar, seismic surveying, marine construction). Chronic acoustic disturbance, physical disturbance, interactions with commercial fisheries and aquaculture, direct killing and climate change are other human-related threats that have potential to jeopardize the Offshore Killer Whale population.
Natural factors may also impact the survival of Offshore Killer Whales: diseases; fixed dietary preferences and corresponding decreases in prey supply; inbreeding depression (i.e. the genetic deterioration of the population due to breeding of related individuals); tooth wear, likely caused by eating very abrasive shark skin; and mass stranding or natural entrapment.
What's being done?
Killer Whales are listed on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which sets controls on the international trade and movement of species that have been, or may be, threatened due to commercial exploitation. International trade of Killer Whales, or parts thereof, by any member countries of CITES requires export permits from the country of origin. Canada is a member of CITES.
The Offshore Killer Whale population is listed as Threatened and protected under Canada's Species at Risk Act (SARA). They are also protected by the Fisheries Act's Marine Mammal Regulations. These regulations make it an offence to kill, harm or harass Offshore Killer Whales. Fisheries and Oceans Canada has collaborated with other organizations to develop whale watching guidelines, and additional public outreach measures are being taken to minimize potentially negative interactions between boats and whales.
Because they were previously listed as Special Concern under SARA, a Management Plan for the Offshore Killer Whale was finalized in December 2009. A recovery strategy is being developed, reflecting its updated Threatened status.
What can you do?
Killer Whales will get the protection they need only if all Canadians work together to reduce threats. Learn more about Killer Whales and be aware of man-made threats to their survival. Do your best to reduce these threats wherever possible to protect Offshore Killer Whale's habitat. Get involved with the Habitat Stewardship Program (HSP), the Aboriginal Fund for Species at Risk (AFSAR), or a conservation organization.
Join a stewardship program such as the British Columbia Cetacean Sightings Network. The Network's main goals are to identify key habitats and help reduce threats. The Network also solicits reports of whale, dolphin and turtle sightings from mariners along British Columbia's coast. Find out more.
While out on the water, follow the ‘Be Whale Wise: Marine Wildlife Guidelines for Boaters, Paddlers, and Viewers', to reduce negative interactions between boats and whales. You can also join the British Columbia Killer Whale Adoption Program, operated in conjunction with the Vancouver Aquarium. Find out more.
Scientific Name: Orcinus orca
SARA Status: Threatened (2011)
COSEWIC Status: Threatened (2008)
Region: Pacific Ocean
Though their exact diet remains unknown, Offshore Killer Whales seem to mostly prey on sharks. They have been observed eating Pacific Sleeper Sharks, Blue Sharks and North Pacific Spiny Dogfish. While these species provide valuable sources of lipids (fats) that are important for the whales' sustenance, it is hypothesized that sandpaper-like shark skin is responsible for the extreme tooth wear seen in Offshore Killer Whales – sometimes worn down to the gums.
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