Scientists will trial shark-detecting sonar technology in a great white shark nursery off Port Stephens in the hope it could prove a much-needed breakthrough to stop the spate of North Coast shark attacks.
The independent trial of the Clever Buoy sonar technology this week will determine whether it is reliable enough to be used at the popular beaches that have seen repeated shark attacks. Trials of eco-barriers at beaches in Ballina and Lennox Heads have failed because of rough conditions.
University of Technology, Sydney, marine biologist William Gladstone said six video cameras will be dropped into the shark-infested waters for six weeks to monitor the Clever Buoy's sonar beam to test whether it correctly detects every great white shark swimming past.
The five-hour battery life of the video cameras means they will need to be replaced daily.
"It is recognised as a nursery ground for juvenile great white sharks and aerial surveys have confirmed it is a congregation site," said Professor Gladstone, who designed the trial.
"We're not getting in the water. We are going to deploy them from a boat."
The Clever Buoy is designed to detect sharks swimming past, and then send an SMS message to lifesavers on the beach. A trial at Bondi Beach last summer was "promising", Professor Gladstone said.
The video cameras to be introduced at Port Stephens will confirm if the swimming objects detected by the sonar are sharks, and not big fish.
"If it works effectively and reliably, you could deploy a number of them to cover the beach entrance with sonar beam. The message would go back to the lifeguards if a shark enters, and they would decide what to do."
A separate trial at Sydney Aquarium will test if Clever Buoy can also determine between different shark species, based on swimming patterns and movement.
Professor Gladstone said there are other shark species also responsible for attacks– bull sharks, tiger sharks and bronze whalers. However, he said there are also other species, such as the grey nurse, that pose no threat to humans.
The Clever Buoy was one of a number of technologies funded under the Baird government's $16 million shark management strategy. Eco-barriers, which cost about $1 million to deploy, were a failure and removed from Lighthouse Beach at Ballina and from Lennox Head.
There have been three attacks on the North Coast in the past month.
Responding to the most recent attacks, the Baird government said it would deploy 100 "smart" drumlines on the North Coast and introduce legislation to allow a trial of mesh nets.
But both of these approaches are controversial, because of the danger to other marine life such as turtles and dolphins. Several hundred people protested in Ballina this month about the plan to install nets before Christmas, but Ballina Council endorsed the mesh net trial on Thursday.
NSW Greens marine spokesman Justin Field has said mesh nets can't guarantee public safety and there have been 21 shark encounters on netted beaches in the past 23 years.
Minister for Primary Industries, Niall Blair, said: "The way Clever Buoys are integrated into the NSW Shark Management Strategy will depend in part on the nature of the beach and conditions in each locality."
The trial will position a Clever Buoy about 1km offshore near Hawks Nest at Port Stephens to assess its capability to detect white sharks in field conditions.
His office confirmed the objective was to use this technology in some of the most challenging areas in NSW and in known shark-aggregation areas.
Clever Buoy was developed by Australian company Shark Mitigation Systems.
How it works:
- The system uses multi-beam sonar transducers mounted on the ocean floor to scan for marine life.
- On-board software interrogates a detected object's swimming pattern to determine whether it is a shark.
- The software instantly relays a message about the shark and its location to lifeguards so they can raise an alarm.
- The Clever Buoy has a VR2 receiver fitted and records information about any sharks nearby which have been previously tagged.
- The eight-week trial of Clever Buoy at Bondi Beach in February and March proved that sonar technology could be successfully used in east coast conditions.
