Shark Reporting.
In the age of drones this is how shark reporting should be done. The Coast guard or local surfing schools should fly a drone around and check to see whether there are any sharks present. If and when they spot a shark or groups of sharks they could temporarily close the beach until the threat is gone. It reduces the need for shark nets. It also reduces the need and desire to kill any shark that is spotted as people are informed ahead of this time.