Sydney:
An Australian firm said Monday it was working on developing a buoy which would protect swimmers and surfers against shark attacks by alerting lifeguards as soon as a predator nears.
Shark Mitigation Systems said it had combined with major Australian telecoms firm Optus to develop the shark detection technology which uses sonar to scan the water for a shark-like object and sends the alert via satellite.
"What we're trying to do is come up with a beach-based detection system that captures all sharks that come within the vicinity of the beach," Shark Mitigation Systems co-founder Hamish Jolly told AFP.
A spate of shark attacks have raised concerns in Australia in recent years, with the traditional defence of netting and the electronic tagging of some animals now boosted in Western Australia by a kill and capture approach.
"The idea of this is that it is non-invasive so it gives peace of mind to beach users but is keeping the shark safe as well," said Jolly, adding that tests had been promising and he hoped to have it ready commercially by mid-2015.
The technology draws on an approach used on underwater oil rigs to prevent seals from swimming into turbines.
But a key difficulty in this case has been defining the sonar characteristics of sharks to produce a software which basically amounts to the something like "face recognition for sharks".
"To a degree, sharks have been built by evolution to be hard to see on sonar, when you think about who they are trying to creep up on," explained Jolly.
"We've confirmed that we can see sharks using the sonar, and we've also captured the shark signature but we need to teach the system to be able to detect sharks versus another animals.
"Basically we need to teach it to look for the tell-tale signal characteristics of a shark's signature return, which is a lot to do with the swimming pattern so that we can differentiate it from a whale or a dolphin or either a diver or a swimmer."
Jolly said the 25 kilogramme (55 pound) buoy, which would communicate with sonar transducers mounted on a frame on the seabed, could end up being part of a suite of solutions to prevent shark attacks.
Last year he launched an "anti-shark wetsuit" which used discoveries about the predators' eyesight to design suits which confuse sharks' visual systems, playing on their sight and colour blindness to "hide" divers in the water.
Experts say attacks by sharks, which are common in Australian waters, are increasing as the population rises and water sports become more popular.
There have been 170 fatal attacks in the last 100 years in Australia, according to the national Shark Attack File based at Sydney's Taronga Zoo.