The prime minister, Tony Abbott, has hosed down suggestions of shark culls after the deaths of two people in the space of a week, saying you might not get “the guilty one”.

Abbott, who is a long-term surf club member, told Fairfax Radio culling sharks is a “vexed” question which he “should probably leave to the state governments”.

"There is always the issue of getting the ‘guilty one', so to speak," he told Greg Cary on Brisbane radio station 4BC on Monday.

"All of us know there are some risks when we go into the water, but thank God, over the years we've managed to take measures to reduce the risks, with meshing off many beaches, a tremendous surf lifesaving movement, and of course if you suspect that it’s the wrong time of year or the wrong time of day or the wrong place, well you don’t go into the water,” he said.

Over the weekend 19-year-old Port Macquarie man Zac Young died after he was bitten by what appeared to be a tiger shark while bodyboarding near Coffs Harbour in northern NSW.

Last week a 35-year-old father of two, Chris Boyd, was killed while surfing at Umbies off Gracetown in Western Australia.

After Boyd’s death some surfers demanded a cull of large sharks swimming near popular beaches and the WA premier, Colin Barnett, said it was under consideration.

"I don't know if it's a cull as such – and maybe that means different things to different people – but I certainly acknowledge that the public is demanding that sharks, where they stay around popular swimming or surfing areas, should be destroyed. I'm in that camp," said Barnett.