WHAT CAUSES WHALES TO DIE?
By Mike E.
The average life span of a whale is 70 to 80 years, however
the lifespan of a whale depends on its living conditions and habitats.
Whales are classified as either baleen or toothed. Baleen whales' diets usually consist entirely of plankton (the small organisms that live in the ocean.) Toothed whales eat fish, squid, and larger sea animals. The Orca, or killer whale, is a toothed whale that eats seals, sea lions, larger fish, and even other whales!
Whales are aquatic mammals. Because they are mammals, they breathe air and can drown. They cannot dry out, or they will die. Whales are also conceived in the mother and drink her milk. Mammals are warm-blooded, so they don't depend on the temperature of the water to keep themselves warm.
Whales are the largest mammals on earth. In fact, they
are the largest animal too. The largest whale ever recorded was 113 feet long
from head to fluke. It's weight was 170 tons. This whale was a blue whale.
There are seventy-six different varieties of whales on
earth; all seventy-six vary in shape and size. Dolphins and porpoises are
included in the whale family.
What causes whales to die? There are many things that cause whales to die. The most commonly known cause of death is beaching, but little is known about ways whales beach themselves. There are many theories and thoughts on the matter.
One thought is that one whale is sick and beaches itself
to die. But unknowingly, the rest of the pod follow and get stuck on shore.
If the whales are not saved, they will dry out and die. This is very serious
because many whales are lost at one time. In northern regions, such as Alaska
and Canada, Beluga whales get stuck ashore when the tide goes out. When this
happens if the whale just waits, it will be rescued by the high tide. But
there is a greater threat to the Belugas than drying out. Polar Bears! The
polar bear will attack the helpless whale and eat it. The beached whales
are also vulnerable to hunters and poachers.
Another cause of whale deaths is entanglement in fishing
nets. Whales don't always see the net and can swim into them. If a whale gets
caught in the net and is stranded under water, it eventually run out of air
and drowns. Remember whales are mammals and they do need air to breathe!
Porpoises are the largest victims. In 1986, in U.S. waters alone, 20,500
porpoises were killed due to entanglement in fishing nets. The number of
porpoise deaths has decreased since then due to the use of special nets and
techniques which avoid porpoise capture, but the number is still too large
because some fishermen don't use the nets and techniques.
Whales are also killed by whalers and poachers. In some
countries, such as Japan, it is legal to hunt whales. In this century two
million whales have been killed. That's two million more than we can afford!
The reason whales are still being hunted is for the products
that whales can provide. Whale products include things such as lubricants,
pet food, shoe polish, paint, margarine, car wax, soap, fertilizer and machine
oil.
Boats have a large influence on whales. Often whales and
boats collide. The amount of damage depends on the size of the boat and the
size of the whale. If a small boat hits a large whale, the chance of the
whale being injured is slight, but the chance of human injury is great. If
a boat is big and the whale is small, chances are that the whale will sustain
internal or external injury; these injuries can cause death. Unfortunately
some species, such as the right whale, show no fear of boats.
Pollution is another cause of whale death. One commonly
known form of pollution is oil spills. Whales will swim into a polluted area
and get things, such as oil or plastic, stuck in their blow holes. Because
this pollution is blocking their blow holes, the whales suffocate and die.
Sharks can also present some danger depending on the size of the whale and size of the shark. Baby whales are vulnerable to shark attack if it is not possible for the whale to escape or for the other whales to protect it.
WORKS CITED
Allen, Scott. "Trying to do the right thing." The Boston Globe, 25 September 1995, pp. 25 & 27.
McCoy, J.J. The Plight of the Whales. New York: Franklin Watts, 1989.
Norris, Kenneth S. "White Whale of the North--Beluga". National Geographic , June 1994, pp. 6-30.
Zoobooks. Whales. San Francisco: Wildlife Education, Ltd. 1996
Sea World. "Longevity and Causes of Death." http://crusher.bev.net/education/SeaWorld/baleen_ whales/deathbw.html