June 17, 2015, 5:49 am
For four long days, the team of researchers trawled the deep waters off WA’s south coast in the search for great whites.
Their task was to test existing deterrents, the Shark Shield and an electric anklet device and explore novel deterrents including bubbles, light and sound on great whites.
Five fatal shark attacks along the WA coast in just 10 months had left the community in shock and the State Government under pressure to tackle a growing public safety issue.
Premier Colin Barnett announced in December 2012 the Government would fund the University of WA Oceans Institute to the tune of $646,000 to research existing and novel deterrents.
The pressure was on for institute director Shaun Collin and his team and frustration mounted when during a four-day field trip in WA, they came across only one great white shark.
“We didn’t test the Shark Shield with white sharks in WA because ironically we couldn’t find any,” Professor Collin said.
So the team went to South Africa, where in the ocean near Cape Town, they were able to test the deterrents on about 60 great white sharks.
“We would get about 15 individuals a day and that was with no effort, just 10 minutes on the water,” shark biologist Ryan Kempster said.
“Specifically with the Shark Shield, we had upward of 30 or 40 individuals, certainly a robust number to really be sure of the results we’re presenting.
“It was over 90 per cent effectiveness.”
Neither the Shark Shield nor the electric anklet device were found to attract sharks, Professor Collin said.
UWA is now collaborating with WA company Shark Shield Pty Ltd to field test their surfboard-mounted electrical shark deterrent, which is being developed as part of another State Government research grant program.
After finding sharks became accustomed to “bubble curtains”, the scientists later discovered that if a “high-intensity bubble burst” was directed at a single shark on cue, it was much more effective.
Dr Kempster said he believed the key could lie in producing bubbles in pulses or in unpredictable sequences that sharks could not expect.
The team tested the deterrents separately using two floating rigs — one of which was used as a control — in the ocean and attaching the deterrent being tested just above a canister of bait.
A long strip of extremely bright flashing lights was switched on when white sharks approached the bait but it did not deter the sharks.
Similarly, white sharks were not deterred by a loud “disturbing” artificial sound being played underwater or the call of their predator, the killer whale.