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Whales
Killer
Whale (Orcinus orca)
Orcas
frolicking off Victoria, with the Olympic Mountains
of Washington State in the background
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The
Killer Whale is, apart from humans, the most widespread
mammal in the world. Still, it is well known in only a
few areas, and one of these is the coastal waters of British
Columbia. In the early 1970's, researchers developed a
system of photo-identifying individual whales, in order
to better understand their natural history, and monitor
the population. Every whale has identifying features on
its dorsal fin, and the gray "saddle patch"
behind the dorsal fin, and an extensive catalogue of Orca
"mug shots" is now on file, each taken from
the whale's left side.
It
was soon learned that these animals have a well-established
family structure, travelling in groups called pods.
Some of the pods lived in the northern part of the Strait
of Georgia (the "northern resident" pods),
and others remained in the southern half of the strait,
and the Strait of Juan de Fuca (the "southern residents").
It was also discovered that there were other pods that
seemed to move more randomly. They became known as the
"transient" whales. While they looked similar,
it was learned that they fed exclusively on marine mammals,
while the resident whales appeared to feed only on fish.
A third group, which appears occasionally off the west
coast, is still poorly understood. Each
pod is structured around the oldest female, with males
remaining in their mothers' pods. These groups communicate
vocally underwater, and each pod uses a slightly different
dialect.
Orca
Whales, Vancouver Island - Photo Tourism BC
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Because
Killer Whales have been identified individually for
some years now, their lives are becoming better known.
The bulls are larger, reaching a weight of 9,000 kilograms,
and a length of almost ten meters. A bull's dorsal fin
may be almost six feet high. Maturity may not be reached
until the age of 15 to 20 years. Cows are thought to
live longer than the bulls, with average life expectancy
estimated to be 50 years. Some cows may be as old as
80.
With
well-understood movements, the Killer Whale has become
an extremely popular attraction for British Columbia
visitors. Many companies offer whale watching cruises
on Vancouver Island. As concern grows about the negative
effects of whale watching, these companies are working
very hard to self-monitor their activities. There is
to date no evidence that the whales are suffering because
of humans' fascination with them.
Gray
Whale (Eschschrictius robustus)
Gray
Whale Tail
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Each
spring, some 20,000 Gray Whales move past the western
shore of Vancouver Island, en route to summer feeding
grounds in the Bering Sea. The 30 ton giants can be
seen from shore, as early as February, with females
and calves passing in April and early May. They return
by the same route in the fall, to their calving and
wintering areas in the lagoons of Baja California. Gray
Whales belong to the family known as baleen whales,
which feed by straining huge mouths full of sea-bottom
mud through filter-like baleen plates.
Tiny marine organisms are thus captured by the baleen,
and then swallowed by the whale. These large and slow
animals are often encrusted with barnacles and other
marine life, visible when they surface.
Gray
Whales were almost hunted to extinction in the early
1900's, but have recovered well since their hunting
was banned in 1947. Whale watching expeditions are available
from the west coast of Vancouver Island.
Humpback
Whale (Megaptera novaeangliae)
Humpback
Whale Tail
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The
Humpback Whale is one of the medium sized baleen whales.
They are distinctive for their long pectoral flukes, and
pale undersides.
Of a global population of some 10,000, about 2000 inhabit
the north Pacific. They breed in waters off Mexico and
Hawaii, and migrate to the north Pacific to feed in the
summer. Like
other baleen whales, Humpbacks feed by sieving seawater
through the fan-like baleen plates that hang from the
roofs of their mouths.
This species is unique in that several whales may create
a ring of bubbles called a "bubble-net", to
concentrate small fish and crustaceans into an area, so
they can be more easily consumed. These
large whales can stay submerged for about thirty minutes,
but usually are down for shorter periods. On the surface,
they engage in spy-hopping, flipper-flapping, tail-slapping,
and breaching. Once
quite common even in inshore waters, the Humpback Whale
is currently listed as threatened, and its numbers are
recovering. |