Orca types and populations

The IUCN reported in 2008, "The taxonomy of this genus is clearly in need of review, and it is likely that O. orca will be split into a number of different species or at least subspecies over the next few years.

"[3] However, large variation in the ecological distinctiveness of different orca groups complicate simple differentiation into types.

[4] Mammal-eating orcas in different regions were long thought likely to be closely related, but genetic testing has refuted this hypothesis.

[38] Instead, recent studies using dietary tracers such as fatty acids and organic contaminants have shown how varied the diet of North Atlantic orcas is.

For example, orcas in the Eastern North Atlantic (Norway, Faroe Islands, Iceland) mainly feed on fish, specifically herring.

[44] The northwest Atlantic population is found year-round around Labrador and Newfoundland, while some individuals seasonally travel to the waters of the eastern Canadian Arctic when the ice has melted.

[49] A small population of orcas seasonally visits the northern point of the Valdes Peninsula on the east coast of Argentina and hunt for sea lions and elephant seals on the shore, temporary stranding themselves.

[52][53] A pair of male orcas, Port and Starboard, have become well known for hunting great whites and other sharks off the South African coast.

[67] More recently, complete mitochondrial sequencing indicates the types B and C be recognized as distinct species, as should the North Pacific transients, leaving the others as subspecies pending additional data.