Considering that a male killer whale can attain a length of 32 feet and a female of 28 feet, it is not surprising that killer whales are considered as apex predators. Hence, they have nothing to fear from predators and there is no other marine life that eats killer whales. However, sharks being opportunistic predators will attack a whale that is old, young or ill when the opportunity arises.

Not much is known about the longevity of the killer whale, as researchers still are not sure what the life span of this mammal is. However, of late, researchers have found that in some parts of the world, calves of killer whales have very high mortality rate. For instance, in Pacific Northwest, around 43 percent of killer whale calves die within the first 6 months of their lives. In some other populations of the killer whales, nearly fifty percent of the calves perish in the first year of their lives. Researchers are trying to figure out the cause of the mortality, as killer whale does not have any predators that eat them. And, sharks would not be able to kill so many killer whale calves.

It is quite possible that killer whales calves may be succumbing to some sort of parasite or disease. Some of the parasites that infect killer whales include roundworms, tapeworms and flukes. And the diseases that afflict killer whales include stomach ulcers, skin diseases, tumors, viral infections, fungal infections and bacterial infection. Also, some killer whales can get coronary artery atherosclerosis and Hodgkin's disease.

Another cause for killer whales dying could be water pollution and competing with humans for fish. This competition is seen in the Bering Sea, where the whales and fishermen from Japan and Alaska are constantly competing to catch the black cod. The competition also exists in the Atlantic between fishermen from Brazil and killer whales trying to get to tuna and swordfish. Hence, it is common for fishermen to kill these whales. These whales are also killed by humans for their blubber in many oceans. Humans have been interacting with killer whales for centuries. In the ancient times, killer whales were considered vicious fish that would attack anything in water to satiate their hunger.

Some killer whales have tested positive for chemicals, like DDT and PCBs. This is particularly true in North Atlantic. Researchers still do not know whether the high levels of chemicals have an effect on them or not. The research in this sphere is ongoing.

At times, killer whales get stranded in shallow waters, near the shore. Researchers still do not know why this phenomenon occurs. It is possible that they get beached after swimming into shallow waters chasing their prey.

There are several reasons why killer whales are dying before reaching adulthood or in their adulthood. It is definitely not because of a predator. Most damage to killer whales is done by fishermen and sea pollution. Also, whale watchers are causing some amount of disturbance in areas, such as British Columbia and Puget Sound in North America. Whale watching has flourishing into a thriving business and many people go for tours to the cold waters around the Antarctica to see killer whales in their natural habitat. Researchers are certain that this is causing a problem for killer whale populations. Because of tours organized for watching whales, these whales are now avoiding shallow beaches in Antarctica, where they used to previously go to polish their skin against the sand and stones to get rid of parasites and algae. It seems that whale watchers are driving away these magnificent mammals into deeper waters. How this will impact the killer whale population only time will tell.

More Articles :

• Are Killer Whales Endangered ?
• Killer Whales Anatomy
• Life Cycle Of A Killer Whale
• Scientific Name For Killer Whale
• What Do Killer Whales Eat ?
• What Eats Killer Whales ?

Sea World: Longevity and Causes of Death
http://www.seaworld.org/infobooks/KillerWhale/deathkw.html