Sharks, as well as other sea creators can be harmed by nature polluted water etc.,,other sea animals, or by humans, nets, hooks, harpoons..Or they can die from natural causes.... So my answer is by humans ,nature or illness, and by other fish etc..
Sharks are arguably on the top of their food chain, but they have enemies. Man for one. And while sharks are highly resistant to disease. They can suffer blunt force or penetrating trauma. And they can be affected by toxins. Some dolphins and porpoises will kill sharks by repeatedly ramming them in the gills until the sharks die of suffocation. I have seen films of one particular killer whale known as CA2 that has developed a craving for great white shark livers. She has been tracked and recorded hunting great white sharks and just eating their livers. http://www.youtube.com/watch?v=W8GaDuCvYbE
10 months ago
Last edited at 10:46AM on 2/20/2013
Well, shark finning for one, is how people hurt sharks. It's become a big issue, where people in boats will catch sharks, cut off their fins, and throw them back in. The sharks are thrown in, still alive, and die from suffocation and bleeding to death. Its horrible, and needs to be stopped. we need sharks, they are very important to the environment. Not to mention, it's very cruel. http://en.m.wikipedia.org/wiki/Shark_finning . http://youtu.be/ggtxA4wuXzY