17) WHALES
The study of fossils indicates that the ancestors of today's
whales gradually returned from land to live in the sea. Modern-
day whales are large, aquatic mammals. They have little hair,
breathe air using lungs (unlike fish which use gills to take
oxygen from the water), and give birth to live young which are
nursed with milk from their mother. The young are cared for
until they are old enough to look after themselves.
Whales have nostrils, called blowholes, which open on the top of
the head so that the whale can breathe air out and rapidly suck
fresh air in without stopping swimming. The whale's body is
streamlined so it can swim more easily. The tail has developed
into a powerful horizontal fin called a fluke, and the forelimbs
have become flippers which the whale uses to steer and change its
position in the water. Some whale species seem to be able to
communicate over long distances.
There are two groups of whales, the baleen whales and the toothed
whales. Baleen whales include the blue, sei, fin, Bryde's,
humpback, bowhead, minke, grey, right and pygmy right whales.
All but the bowhead and grey whales can be found in South African
waters. These whales have a filter (baleen or whalebone) in their
mouths which filters tiny shrimp-like creatures called krill from
the seawater. These small animals are the whales' food.
Toothed whales include the sperm, beaked, killer (or orca),
beluga, narwhal, and pilot whales as well as all dolphins and
porpoises. These whales eat fish and squid.
HUNTING
Whales have been hunted by people for at least 4 000 years. In
more recent times, the advent of commercial whaling in the open
seas (in the 1700s and 1800s), and the development of the
explosive cannon (1868) has resulted in a plundering of the
world's whale stocks. Whales used to be hunted for a variety of
products, including oil, whalebone and meat. The only product
with special value today is the meat, most of which is eaten in
Japan.
CONSERVATION ACTION
Commercial whale hunting is controlled by the International
Whaling Commission (IWC). In 1982 the IWC introduced an
indefinite ban on commercial whaling from 1986. Despite this
moratorium, Japan, Norway and Iceland have used a loophole in the
agreement to continue to kill small numbers of whales for
`scientific research'. However, it is believed that these catches
do not pose a threat to the survival of the whale populations
concerned. Iceland has now left the IWC, and Norway will resume
commercial whaling during 1993.
There is concern for the conservation of several smaller cetacean
species including the river dolphins of the Far East and the
Vaquita in Mexico, which are reduced to as few as 200 animals in
some species, and gravely threatened by habitat destruction.
WHALE SPECIES FOUND IN SOUTHERN AFRICAN WATERS
Thirty-seven species of cetaceans (whales, dolphins and
porpoises) are found in South African waters, including the
following:
THE BLUE WHALE
This is the largest living animal on earth and weighs up to
130 000 kg, or as much as 30 elephants. It can grow up to 30 m
in length. A favourite target of the 20th century whaling fleets,
the blue whale was nearly exterminated before it was given world-
wide protection in 1967. It is estimated that whaling has
reduced the total world population to less than 10 000, from a
pre-whaling figure of 300 000.
THE HUMPBACK WHALE
Named for the distinctive hump behind the dorsal fin, this is an
agile and acrobatic whale, often leaping out of the water and
slapping its tail and flippers on the water. The most amazing
characteristic of the humpback is its song - a fascinating
pattern of grunts, squeals, squeaks, moans and hums in repeated
sequences that may go on for 20 minutes or more. This species
has been protected worldwide since 1963, and is now showing signs
of recovery in South African waters.
THE SOUTHERN RIGHT WHALE
Commonly found close inshore around Cape Town and round the coast
to Port Elizabeth, its range is between 300 and 550 South. These
whales come close inshore to mate and to have their calves during
the winter and spring months, but have been sighted during the
summer months as well. Gestation is approximately one year, and
calves are suckled for nine months to twelve months. Females
breed about once every three years, or less frequently.
Scientists identify individual whales by the distinctive white
callosities (wart-like outgrowths of the skin that are covered
with parasites) on the head. The whale has twin blowholes on the
top of its head which expel air under great pressure. This
condenses and forms a distinctive V-shape about 4 m high.
Whalers called it the right whale because it was the `right'
whale to kill -it moved slowly, hugging the shoreline, provided
a lot of oil, and floated when dead.
Hunting of the southern right whales almost destroyed the
species. Fewer than 100 of these whales survived off the South
African coast when it was protected in 1940. Subsequently this
number has increased to over 1 000 - one of the world's most
important whale conservation success stories.
THE SPERM WHALE
One of the best known of the world's whales as it featured in
Herman Melville's book Moby Dick. It is easily recognised by its
huge head and row of large white teeth in the lower jaw. Sperm
whales probably dive deeper than any other whale - 900 m or more
- and find their food in the lower areas of the ocean. The head
of the sperm whale contains a huge amount of very fine, clear oil
(called spermaceti).
DID YOU KNOW?
* There is an international ban on the commercial whaling of all
whales. Debate within the IWC around lifting the ban on whaling
applies only to the minke whale, whose numbers are plentiful. The
numbers of other whale species are far too low to consider
allowing commercial whaling of those species.
WHAT YOU CAN DO
* Become informed about the complex issues surrounding whale
conservation, particularly the issue of sustainable utilisation.
* Beached whales can be reported to one of the contacts listed
below.
* Go whale watching - Captour (address below) publish a "Whale
route" pamphlet which outlines where to see whales on the Cape
coast.
FURTHER READING
OCEANS OF LIFE OFF SOUTHERN AFRICA.
A. Payne and R. Crawford. Vlaeberg Publishers, Cape Town, 1989.
WHALES, DOLPHINS AND PORPOISES.
R. Harrison and M. Bryden. Timmins, Cape Town, 1988.
SECRETS OF THE SEAS.
Illustrated guide to marine life off southern Africa. A. Payne
and R. Crawford (eds). Vlaeberg Publishers, Cape Town, 1992.
SEA GUIDE TO WHALES OF THE WORLD.
L. Watson. Hutchinson, London, 1981.
All books are available from Russel Friedman Books, PO Box 73,
Halfway House 1685. Tel. 011-7022300/1.
USEFUL CONTACTS
South African Museum.
PO Box 61, Cape Town 8000. Tel.021-243330.
ORI.
PO Box 10712, Marine Parade, 4056. Tel. 031-373536.
Port Elizabeth Museum.
PO Box 13147, Humewood, 6013. Tel. 041-561051.
The Dolphin Action and Protection Group.
National Save The Whales Campaign. PO Box 22227, Fish Hoek 7975.
Tel. 021-782 5845.
Captour Information Service.
PO Box 1403, Cape Town, 8000. Tel. 021-418 5214.
|
