Killer Whales Gentle Giants or Viscous Killers



By: Tracy Woods
Killer Whales: Gentle Giants, or Viscous Killers?

Killer whales are an important subject of mythology for many
indigenous peoples, especially the Native Americans of the Pacific
Northwest. The whales have not been hunted extensively by humans,
although they have been hunted by some shore whaling operations, and
some individuals have been taken as aquarium show animals from the
waters around the Pacific Northwest and Iceland. Killer whales are
perceived by many near-shore fishermen to be in competition with human
fishing activity (Anheiser Busch 1).
The killer whale, or Orcinus orca can be found worldwide in all seas
from both tropics to Arctic and Antarctic oceans. They are one of the most
well known whales because of the captivity of Shamu at Sea World and the
other studies that are widely publicized (2). The male killer whale has an
average length of 6.7 to 7.0 meters and can weigh between 4,000 to 5,000
kilograms (Knight 5). The female killer whales are smaller having a length
of 5.5 to 6.5 meters and weighing 2,500 to 3,000 kilograms. They have 10
to 12 pairs of large conical teeth in each jaw (Evans 12).
Their coloration is very striking. They have black on the back and
sides and a white belly that extends as a rear-pointing lobe up the flukes
and less markedly near the head, and around the throat (15). They are also
white on the chin and underside of their flippers with a distinctive,
conspicuous white oval patch above and behind each eye. This coloration
varies depending on regional variations. Killer whales can have indistinct
gray saddles over their backs just behind their dorsal fin (Evans 16). This is
called countershading. Countershading enables the whales to be
camouflaged from their prey (Wolfe lecture). They have a stout
torpedo-shaped body with a conical-shaped head. Their flippers are large
rounded and paddle-shaped with a centrally-placed dorsal fin. The dorsal
fin is sickle-shaped in adult females, but very tall and erect in adult males.
There are some variations in morphology between regional populations but
vocal dialects vary more between pods than geographically. There is no
exact known population size. But the largest numbers are in the Antarctic
where the population is estimated at more than 160,000 (Wheelock Colege
1).
Killer whales may be solitary or live in groups of 2 to more than 50
animals. Food items include squid, fish, skates, rays, sharks, sea turtles,
sea birds, seals, sea lions, walrus, dolphins, porpoises, and large whales
such as fin whales, humpback whales, right whales, minke whales, and
gray whales. They are even known to attack the sperm whale and blue
whale. On the Atlantic coast of South America, as well as on islands of the
Indian Ocean, killer whales have been observed lunging through the surf
and coming right onto the beach in pursuit of elephant seals and sea lions
(Holt 17). After such an attack the whales have to wriggle and slide back
into depths adequate for swimming. In captivity, killer whales eat about 45
kg of food per day but free ranging animals probably require much more.
Although these are obviously proficient and voracious hunters, killer whales
are not known to have ever attacked a human (Evans 123).
At sea they are usually seen in "pods" of 5-20, although up to 150
have been seen together at one time. Large groups probably consist of
several pods which have temporarily aggregated. Pods themselves appear
very stable for many years, with little emigration or immigration (124).
They are highly cooperative and the group functions as a unit when
hunting, making these delphinids extremely efficient predators. Groups
usually contain adults of both sexes but sometimes females with young will
form their own groups (125).
Although much research has focused on killer whale pods around
Vancouver Island and on the mainland coast, very little is known about the
whales often found in the Queen Charlotte Islands, known as "offshore"
killer whales. This separate population of killer whales appears to share
similar behaviors and the fish-eating lifestyle particular to resident whales
but appear to maintain an offshore distribution and are unique in their
vocal dialects indicating they\'re unrelated to any transient or resident
pod. Offshore whales tend to be seen in large groups of 30 to 60, and are
seldom seen in protected coastal waters. At present, there are limited
details concerning the offshore population\'s range, social organization or
life history. However, we hope that it will be possible to fill in many of these
gaps in the future, and to determine if and how these offshore whales
might be related to the well-known inshore resident and transient
populations (Wheelock