People aged under 25 will be banned from renting Rottnest accommodation under a plan in response to this week's drunken and antisocial behaviour on the island.
Known as "juvie leavers", the end-of-school pilgrimage has seen hundreds of teenagers, mostly aged 14 to 16, involved in drunken parties, vandalism, verbal abuse, smoking and underage sex.
Many of the young offenders are supervised by guardians as young as 18, who are buying them "truckloads of alcohol" and letting them run amok.
Island holidaymaker Paul Robinson said he saw "outrageous and sub-human behaviour" from juveniles on the island this week.
He said it would not be condoned for any other group in any other setting in WA.
Tourism Minister Kim Hames has sought an urgent briefing on the situation from the Rottnest Island Authority but said parents needed to take more responsibility for their children.
Assistant police commissioner for the metropolitan region, Stephen Brown, said the crux of the issue was the failure of parents to supervise children properly.
"We (the police) are basically the streetsweeper at the back end of the day," he said. "More needs to be done by the parents and the people who are responsible for supervising these kids.
"What do the parents of these kids think they are really up to?"
Director of ferry company Rottnest Express and chairman of the Rottnest Island Business Community, Ian Dawson, said that the behaviour of the young people deterred others from visiting the island.
"It has been very upsetting for many regular holidaygoers," he said. "I know some have already cancelled and won't be returning."
Mr Dawson collected more than 40 hire bikes from the island yesterday, most of them stolen and many of them destroyed by teenagers.
RIA chairman Laurie O'Meara said he was concerned about the impact of "juvie leavers" on the wellbeing of the teenagers and the island's reputation as a holiday destination. He said social networking sites such as Facebook accentuated the problem.
Mr O'Meara said that having 18-year-olds in charge was "a bit suss", so the authority would look to increase the age to 25 before people could rent island accommodation.
Dr Hames expected the RIA to respond appropriately and, if extra resources and staff were needed next year, they would get them.
But he said parents needed to take greater responsibility and not expect the police and island authorities to be babysitters. They needed to ensure their children were properly supervised, which meant someone older than 18.