Australian researchers are working on high-tech buoys that could alert lifeguards via satellite to sharks lurking offshore.
The idea is to create networks of buoys a few hundred metres from beaches, creating an unbroken detection perimeter, says Hamish Jolly, co-founder of Perth company Shark Mitigation Systems.
The company has unveiled work on a prototype of the "clever buoy", saying a polished version could be market-ready in as little as one year.
"We think it's going to be good for sharks and good for humans," Jolly says.
The prototype buoys are 25kg floating domes housing microprocessors and satellite transmitters.
They are connected by cable to a sonar transducer, which sits on the seabed and sends shark-detecting soundwaves to a radius of between 25 and 60 metres.
The sonar transducers are programmed to detect moving objects at least two metres in length.
But the plan is to fine-tune them to detect sharks based on the way they move through the water.
"All sea animals have unique signatures based on the way they swim. It's their fingerprint," Jolly says.
"The journey from here is to use these signatures, almost like face-recognition, to teach the software to hunt for the specific swimming characteristics of sharks."
Tests at Sydney Aquarium and the Abrolhos Islands off Western Australia have shown the technology can distinguish between stingrays and sharks based on their sonar signatures.
Jolly says the buoys could eventually detect the species of a shark by the way it swims. With testing, the sonar range should also increase, he says.
The system would beat present methods of detection, such as electronic tagging, which picks up only about five per cent of sharks that end up near beaches, he says.
The project is funded by Optus, and relays warnings via Optus Inmarsat satellites.
At the moment, the plan is for a shark detection to trigger a warning light onshore, but Jolly says such warnings could in future be sent to smartphones.
Shark Mitigation Systems have previously worked on high-tech swim suits that use special materials to camouflage swimmers in the water.