SYDNEY • High-tech shark-spotting drones are patrolling dozens of Australian beaches this summer to quickly identify underwater predators and deliver safety devices to swimmers and surfers faster than traditional lifesavers.

As hundreds of people lined up in early morning sun to take part in a recent ocean swimming race at Bilgola beach, north of Sydney, they did so in the knowledge the ocean had been scanned for sharks.

"It is cool to see technology and ocean swimming getting together, and hopefully more people will feel safer and get involved," said 20-year-old competitor Ali Smith.

A drone camera captures thousands of images to develop an algorithm that can identify different ocean objects. The software can differentiate between sea creatures like sharks which it can recognise with more than 90 per cent accuracy, compared to about 16 per cent with the naked eye.

"We can identify 16 different objects, like sharks, whales, dolphins, surfers, different kinds of boats and many other objects of interest," said software designer Nabin Sharma from the University of Technology Sydney.

Swimmers and surfers can be alerted in real time so they can get to safety, Dr Sharma said.

The drone is a welcomed technical intervention that can also drop safety devices to distressed swimmers, just moments after they have been identified.

"The reason the drone is so important is sometimes we can't see over the waves, so having the drone is that little piece of extra prevention for us," said Bilgola Surf Lifesaving Club president Romilly Madew.

There have been several shark attacks off Australia's vast coastline this year.

Experts say incidents are increasing as water sports become more popular and bait fish move closer to shore, but fatalities remain rare, with just 47 in the past 50 years.

AGENCE FRANCE-PRESSE