Orca (Killer Whales)
Whales, dolphins and porpoises are all cetaceans. Cetaceans are warm blooded, air breathing sea mammals that give birth to live young. In contrast to fish, their tail fins are horizontal in orientation, and move in an up and down motion, rather than the side to side motion used by fish.
Orca, or killer whales, are the largest members of the dolphin family. Male Orca can reach up to 30 feet in length, and their large, distinctive dorsal fins can be nearly 6 feet (two meters) tall. A large male can weigh up to 9 tons.
Three distinct populations
There are three different populations of Orca encountered along the West coast of North America. These three groups are genetically distinct and do not interact socially - in fact, observed behaviors indicate that they normally avoid contact with each other.
The three different populations have been given the following names by Orca researchers:
- residents
- transients
- offshores
Different territories
The resident population is comprised of groups of genetically related clans or extended family groups of Orca. These clans have established territories and fairly predictable patterns of movement within those territories. They travel in pods and sub-pods, often groups of up to 20 whales or more with individuals scattered over a wide area.
Northern residents range from southern Alaska to the waters around North and Central Vancouver Island. Southern residents range from the Campbell River south to Puget Sound.
Transients, on the other hand, have neither established territories nor predictable patterns of movement. They swim in small groups of two to five or six, usually in close physical proximity.
Researchers have recently had several encounters with the third known West Coast Orca population, currently labeled the "offshores". These whales have been encountered primarily in the open ocean, and in large groups of 30 to 60.
Different diets
One of the primary reasons residents, transients, and offshores exhibit different behaviors is that their diets are very different. Residents feed almost exclusively on fish, and exhibit a strong preference for salmon. At the moment it is believed that the offshores are exclusively fish eaters as well, but, given the relatively small number of encounters with the offshores, it can't be said with certainty.
Transient Orca feed primarily (and sometimes spectacularly) on marine mammals. Transients observed in waters of B.C. and Washington State have been seen preying on seals, sea lions, dolphins, porpoises, and other species of whales. Their diet, however, isn't strictly limited to marine mammals. Transient Orca have also been observed eating sea birds, and have even been witnessed attacking deer and moose that swim between islands in British Columbia and Alaska.
Different dorsal fins
One evidence of genetic differences between the resident, transient, and offshore populations is that there are subtle differences in the shape of their dorsal fins. These differences are most consistently seen in females. One such consistent difference is the shape of the fin tip. Resident dorsal fins tend to have a rounded tip that terminates in a sharp corner. The dorsal fins of offshores tend to have tips that are continuously rounded. Transient dorsal fins tend to be more pointed at the tip, more closely resembling the dorsal fin of a shark. The examples below are a bit exaggerated, but illustrate the described differences.
| Resident | Offshore | Transient |
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Ongoing research
You can help us learn more about Orca and their environment by supporting the research of Dr. John Ford and his students at the University of British Columbia. You can help support this very important research by visiting the Killer Whale Adoption Program homepage and adopting a killer whale. In addition to learning even more about the killer whales of the Pacific Northwest, you'll also be able to contribute to ongoing research by adopting the whale of your choice. If you adopt a whale, you'll not only have the satisfaction of knowing you're helping us to understand and protect killer whales and their environment, but you'll also receive a free copy of the Blackfish Sound: Underwater Communication of Killer Whales CD. You can hear excerpts from the Blackfish Sound CD on our Orca sounds page.