UPDATE: Colin Barnett has defended his Government's plan to catch and kill great white sharks off WA beaches.
In a live chat at The West Australian this afternoon, the Premier said it was "a matter of human life coming first".
"The use of our coastline for swimming, surfing, diving [and] boating is part of the WA way of life," Mr Barnett said.
"We are trying to preserve that unique lifestyle."
Fisheries Minister Troy Buswell announced yesterday that the State Government will boost efforts to protect people in the ocean with "drum line arrays" set up in two zones.
Baited drum lines will be set one kilometre offshore - off the metropolitan coast and in the South West.
Great whites bigger than 3m will be targeted with the drum lines.
Mr Barnett said yesterday that the new measures would improve public safety and build on the State Government’s strong approach to shark hazard management.
Mr Barnett said today that research into shark behaviour was important and the State Government would continue that.
"However, with six fatalities in two years the Government formed the view we had to take some direct action," he said of the plan.
"The setting of drum lines will reduce risk for people using our coastline.
"It's a matter of human life coming first."
The decision had not been rushed. It was made in response to "widespread concern and fear within our community", Mr Barnett said.
The Premier said he was not sure what would happen to the shark carcasses, but assumed "they will be left out at sea".
The Government did not believe the plan would have "any long-term impact on the overall shark population".
Asked about what evidence supported "culls as a mitigation strategy for shark attacks", Mr Barnett said: "It may be a matter of semantics, but this is not a cull."
"The State Government will not be going out hunting sharks across the oceans," he said.
"What we will be doing is catching sharks that come within a very small area adjacent to metro and South West beaches.
"We do believe that will significantly reduce the risk of shark attack."
Mr Barnett said the drum lines would catch other sea life.
"However, the hooks used will be large and designed to catch larger sharks," he said.
"We hope any by-catch is kept to a minimum.
"The reason for not using shark nets is that the by-catch is far greater."
Mr Barnett said the Government's shark plan would be "assessed in various ways" to determine its success.
"Obviously, the numbers of sharks caught, and also any trends in the sightings of large sharks in close proximity to swimming and surfing areas," he said.
Asked if the Barnett Government expected to be legally challenged on its plan, the Premier replied: "I don't rule it out."
"Although I would stress we are only talking about catching sharks in State waters in prescribed zones where they are deemed to be a threat," he said.
The drum lines would be set through spring and summer.
"Most people support the Government taking measures to reduce the risk of shark attack," Mr Barnett said.
"At the same time, people do not have any hatred of sharks and simply want it to be dealt with quietly by Government.
"No one likes the idea of killing a shark, or any other creature."
Surf Life Saving WA posted a photo on social media today of a shark spotted at Scarborough at 2.40pm.
"Westpac Lifesaver Helicopter has re-sighted two 3m sharks at Scarborough Beach 30m offshore," SLSWA tweeted.
"Scarborough lifeguards have closed the beach."
Scarborough, Trigg and Brighton beaches were closed because of the sharks and SLSWA said the beaches would remain closed until 4pm.
About 5.20pm, a shark was seen 100m off Scarborough.
Lifeguards closed the beach and it will remained closed until 6am Thursday.
A motion by the Australian Greens was passed in the Federal Upper House today, calling for more research to understand shark population and behaviour.