In Asian countries, shark fin soup ought to be prohibited because of the following factors: it happens to be cruel and unsustainable, as well as for the fact that there are actually alternate foods. The concept that we could benefit from a planet without sharks, betrays insufficient knowledge of the way the environment functions.
Outlawing a food, viewed as a delicacy, that has been consumed for centuries really doesn't address the cultural issues at play. It is kind of like moving to outlaw rhino horn as an herbal medicine; it sounds nice, and lets a lot of people feel very productive, but doesn't really change the underlying issues.
The killing of animals for food has been going on for a long time. It was okay when it was essential to one's survival but this day and age we have a wide variety of food that doesn't require the killing of an innocent animal. There is no need to kill a shark so some rich person can have a delicacy.
Many sharks are endagered, and the practice of eating shark fin soup has greatly contributed to this endangerment. In addition to this, the rest of the shark is often thrown away, which is a great waste of a natural resource. Sharks are vital and they need to be protected so they can stay alive.