The killer whale (Orcinus orca), also referred to as the orca whale or orca, and less commonly as the blackfish, is a toothed whale belonging to the oceanic dolphin family. Killer whales are found in all oceans, from the frigid Arctic and Antarctic regions to tropical seas.
There are three types of killer whales that live in the waters off the coast of western North America. These three assemblages have distinct differences in their diet, range, behaviour and social systems. They are the resident, transient, and offshore killer whales.
Killer whales along the coast of British Columbia and Washington are some of the best-studied whales in the world. Intensive field research in this region has been in progress for almost 30 years. In the early 1970’s photo-identification of killer whales was established by the late Michael Bigg of Fisheries and Oceans Canada.
Killer whales are distributed worldwide, including polar seas. They are rare in the Gulf of Mexico. Known in Texas on the basis of one stranding on South Padre Island and one sighting in waters off of Port Aransas.
Killer whales are the largest of the dolphin family. Adult males reach up to 9.4 m in length although 8.2 m is average. Females typically reach 7 m in length with the maximum about 8.5 m.
Killer whales are also important because of their role in marine ecosystems. As large, warm-blooded, apex predators, they necessarily have voracious appetites, making them potentially important in regulating their prey populations, including commercial fish species (e.g., salmon, bluefin tuna) and protected – and sometimes endangered – marine mammal populations (seals, sea lions, sea otters, whales, etc.). The potential for conflict with human interests is, of course, high and the more we know about ecology, taxonomy, distribution and abundance of killer whales, the more we can do to head off these conflicts.
Killer whales are cooperative pack hunters – much like wolves – and they need to communicate in order to coordinate their hunting activities, whether they are pursuing prey that is small and fast, or large and powerful (read dangerous). Over longer distances, they resort to vocalizations – their sounds carry for miles underwater even when visibility is reduced to just a few feet. But in the heat of pursuit, at close quarters, in often murky waters, having a conspicuous color pattern with clear landmarks may be an important asset for cooperative prey capture.
Little is known of actual mating encounters but genetic evidence (DNA analysis) shows that there is no mating within the matrilineal group. This behavior prevents inbreeding. How it is accomplished is unknown.
Males live an average life span of only 29 years, but some have lived to 50-60 years old. Male killer whales mature at about 12-14 years old.
Currently recognized as a single species, our recent genetic investigations have suggested that there may be multiple species of killer whales. Notably, our research has revealed that there are at least 4 distinct forms of killer whales in Antarctic and Southern Ocean waters, with distinct genetic differences and morphological differences.
The killer whale (Orcinus orca) is the top marine predator and perhaps the most widespread vertebrate on earth, occurring in all the world’s oceans. They prey on protected marine mammal populations and commercially important fish stocks, and we need to understand the impacts of this predation, particularly in rapidly changing ecosystems.