Shark finning is a barbaric and inhumane practice that could cause all sharks to become extinct in as little as a decade. Sharks are caught and their fins are sliced off; the still-living shark is then thrown back into the ocean to die. Shark fins are sold for upwards of $500/lb, and a bowl of shark fin soup sells for between $60 and $100.
Banning shark fin soup would decrease the demand of shark fins, making it less profitable for fisherman to continue finning, hopefully saving sharks from extinction.