There is a huge demand for shark fins   in Asian countries. As a result, many sharks are caught and killed. In Palau, where more than half of tourists are drawn by diving excursions, each reef shark brings in about $179,000 in tourism revenue annually, or about $1.9 million during its lifetime. Due to overexploitation and lack of proper management, many shark species are under considerable risk of unrecoverable decline with some species having declined to near extinction in recent years. According to reports, sharks are being killed at an alarming rate of up to 273 million worldwide per year. Some experts predict that if the killing continues at the current rate many shark species will be lost forever. It can be very dangerous. Sharks are very important and they should be protected. In a study of the east coast of the United States, 11 species of sharks were eliminated from their range. Of the 14 species of ocean life that those sharks used to eat, the populations of 12 exploded and caused great damage to the ecosystem. For example, the cownose ray   population was no longer kept under control by sharks and so grew out of control. As a result, the rays destroyed the population of bay scallops  , their favorite food. The scallop fishery, which had been in good condition for over 100 years, was wiped out. Also, the removal of the scallops most likely had an effect on water quality as they were no longer there to perform their function of cleaning the water. Sharks play a vital role in the oceans in a way that the average fish does not. Most sharks serve as top predators at the pinnacle of the marine food pyramid, and so play a critical role in ocean ecosystems. Directly or indirectly they regulate the natural balance of these ecosystems. Sharks tend to eat very efficiently, going after the old, sick, or slower fish in a population, keeping that population healthy. Sharks help keep many populations of ocean life to the right size so that those prey   species don't cause harm to the ecosystem by becoming too populated. The ocean ecosystem is made up of very complex food webs. For the most part, sharks are at the top of these webs and are considered by scientists to be"keystone"species, meaning that removing them may cause the whole structure to fall apart, including key fisheries such as tuna and other important fish species that maintain the health of coral reefs. Therefore, we should protect sharks because doing so is to protect the whole ecosystem. What's the main reason for killing sharks in Asia?
Shark fins are in great need. People kill them out of fear. Sharks often attack swimmers. Sharks break the balance of the sea.