Whales

DIFFERENT POPULATIONS

There are three different populations of Orcas encountered along the West coast of North America. These three groups appear to be genetically different and do not interact socially--in fact, observed behaviours indicate that they normally avoid contact with each other.

The three different populations have been given the following names by Orca researchers:

                Offshore                     Resident                      Transient 

DIFFERENT DORSAL FINS

There is 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 off shores 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 above are a bit exaggerated, but illustrate the described differences. 

DIFFERENT TERRITORIES

The resident population is comprised of groups of genetically related clans or extended family groups of Orcas. 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.

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 "offshore". 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 off shores exhibit different behaviours 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 off shores are exclusively fish eaters as well, but, given the relatively small number of encounters with the off shores, it can't be said with certainty.

Transient whales feed primarily 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 killer whales have also been observed eating sea birds, and the stomach of a dead transient whale recovered up in Alaska contained the remains of a moose. Apparently the moose chose the wrong moment to swim from one Alaskan island to another--something that moose, deer and other land animals frequently do.

GRAY WHALES

Gray Whales also known as: California Gray Whale, Devilfish, Mussel-Digger, Scrag Whale-Baleen Whale have no teeth.
Baleen is long thick bristles that filter food from silt on the ocean's floor.

Unlike most baleen whales, the gray whale must get its food from the sediment on the ocean floor. The amphipods the whales eat can be found there.