Authorities launched the expanded drone programme on Wednesday to protect beachgoers after a spate of shark attacks in Sydney and further across New South Wales.Data from Surf Life Saving NSW, which runs the programme, showed 73 shark sightings in greater Sydney by drone pilots on Wednesday and Thursday, with the greatest concentration at beaches north of the city, where 67 reports were made.The drones only report bull, tiger and white sharks, species considered most likely to attack humans.Lifesavers say it is likely some sharks are being spotted multiple times as they move through the ocean. But one group of 13 sharks swimming together was reported at a single beach at northern Sydney's South Narrabeen on Wednesday."Having so many drones out all day, they are picking up everything," said Surf Life Saving New South Wales spokeswoman Donna Wishart.'Scared and paranoid'

Scientists say there is no single solution to protecting people from sharks © DAVID GRAY / AFP

At northern Sydney's Dee Why Salty Surf School, owner Dan O'Connell was 15 minutes into a surf lesson on Friday when a drone spotted a shark near the beach and lifesavers evacuated the water for the second time that day.O'Connell had just succeeded in coaxing his students into the ocean by telling them a shark was unlikely to venture near the knee-high water where they were practising board moves."They were already scared and paranoid because the beach had been closed," he told AFP.Drones made three shark sightings on Thursday at Dee Why Beach, with another sighting on Friday morning closing the beach for an hour before it reopened, only to close again.Expecting beach closures will increase, O'Connell is diversifying his business to offer skateboarding lessons at the nearby carpark.'Fairweather surfers'School groups had cancelled surf lessons after a child was killed by a shark in Sydney Harbour in January, and a woman was mauled at popular Coogee Beach last month."It has been really hard," he said.