Great White sharks text messaging lifeguards?

Sharks are an ever-present threat in Perth waters Photo: Amos Nachoun / Barcroft USA

More than 70 white pointers have been tagged by scientists is Western Australia in a world first trial that will send beach lifesavers a text message when one of the predators swims close to the Perth shoreline.

Wildlife officials and scientists will also receive the text or email warning when any of the tagged sharks move to within 500m of metropolitan beaches.

The text messages will be triggered less than two minutes after a shark swims over any one of 18 acoustic seabed receivers.

Since the receivers were installed in May, Department of Fisheries' senior research scientist Dr Rory McAuley said sharks had been picked up in Perth waters on four occasion, PerthNow reports.

The last detection was in September.

"The use of the technology that delivers real-time notifications of tag detections hasn't been used in an operational sense anywhere else in the world," Dr McAuley told the website.

The study is aimed at unlocking the secrets of shark migration patterns and how they relate to attacks on humans.

"The information we are hoping to collect will hopefully provide us some answers to the questions we are always asking about how long white sharks spend off our beaches, whether they come back, is there a season, do they come back one year after the other."

In all, researchers hope to tag 100 sharks over the next two years.

The sharks are fitted with the satellite-tracking darts by researchers who shoot or stab the devices into the flank of the animals.

"I think the public's fear of sharks stems largely from a fear of the unknown," Dr McAuley said.

"Any information we can find out about the real risk of people encountering sharks at the beach will hopefully alleviate people's concerns to some degree."

Shark are an ever-present threat in the waters off Perth. Nine years ago, a man was killed by a white pointer in waist-deep water off Cottesloe Beach.

Since then, there have been a dozen shark attacks in Western Australia, two of them fatal.