Summer comes and all of the old fears and myths about sharks reappear as we hit the beaches. Shark attacks, thankfully, are very rare. What humans ought to be fearful about is the survival of an essential species.

Humans kill 73 million sharks every year, nearly all for consumption, mainly in shark fin soup. The fins are cut off and the bodies dumped overboard, a barbaric practice known as finning. Commercial fishermen are taking more and more sharks for their meat as well.

Nearly a third of shark species in the open oceans are threatened with extinction. Losing these top predators creates a cascading imbalance. The species whose numbers the sharks once controlled begin to explode; they then wipe out smaller fish, some of which humans depend on for food. Water quality suffers. Healthy oceans require sharks, and without healthy oceans, healthy fisheries are impossible.

Though the appetite for shark fin soup is greatest in Asia, the carnage is global. There are no international limits on the numbers of sharks that may be taken. At a recent meeting in Spain, regional fishing organizations agreed to begin collecting data and considering measures to conserve sharks. That is barely a beginning. What is needed is a global agreement to establish serious catch limits and end finning.