As shark attack victim Ben Gerring continues to fight for his life more than two days after he was mauled, Premier Colin Barnett insists WA's beaches are safer than during a spate of fatal attacks several years ago.
Mr Gerring, 29, remained in a critical condition in Royal Perth Hospital on Thursday night after his leg was bitten off by a shark while surfing near Mandurah, south of Perth.
The attack is the most serious in WA since December 2014, when spear fisherman Jay Muscat was killed by a 4-5 metre great white near Albany, one of seven deaths in three years.
Mr Barnett said he believed a 4.2 metre great white shark that died after being caught on a baited drum line by the Department of Fisheries on Wednesday was probably responsible for the attack on Mr Gerring.
The shark was towed out to sea and dumped after samples and measurements were taken.
"It is highly probable - it was a 4-metre shark found in the exact same location the following day, within 24 hours so I think it is highly likely it was the shark," Mr Barnett said.
The policy to catch and kill the shark this week has variously been described as an inhumane, waste of money without evidence or not going far enough after the government abandoned a shark culling program in which sharks were shot after being hooked in 2014.
"We will always put public safety first and do not apologise for that ... presumably that shark was circling around in the one area for 24 hours and that to me is a threat," Mr Barnett said.
The fact there has been 12 fatal shark attacks in WA since 2000, compared to nine in the previous 84 years, showed something had changed, he said.
The balance now of using traps to catch sharks selectively was right, he said.
The government had spent $30 million since 2014 on shark warning systems, including aircraft and helicopters, swimming enclosures, tagging sharks and equipment for surf clubs.
"I think people are far safer, certainly if you swim in designated areas where surf patrols are in place," he said.
However, opposition fisheries spokesman Dave Kelly said Labor was completely against the catch and kill policy of using drum lines because it was expensive, not backed by evidence and did not make beaches safer.
Emerging technology to detect and repel sharks should be pursued, he said.
