Dunedin City Council parks manager Lisa Wheeler was unsure when the two flotation devices were taken from the cabinets, but said it was the second time they had been removed this year.
Both buoys had to be replaced in March, and again yesterday, costing the council and ratepayers almost $3000.
Mrs Wheeler said the thefts and vandalism of the cabinets had angered staff.
While it had cost Dunedin ratepayers about $3000 in the past year, the greatest cost would come if someone fell in the water and needed the lifebuoy, she said.
''It's very frustrating. We're hugely disappointed.
''People are putting other people at risk without any sort of thought for other people's safety. It's just a silly thing to be doing.
''We put those things there for emergency use. We can't not have them.
''The frustrating thing is, not only do we have to up our monitoring of them if this is going to be a new trend, it's the ongoing replacement cost as well.
''So there's the financial side of things as well as the public safety.''
Mrs Wheeler said the cabinets were checked by council contractors three times a year to make sure the buoys were there.
However, if members of the public discovered they were missing, she encouraged them to inform the council so they could be replaced as soon as possible.
The lifebuoys were introduced by the Otago Regional Council about a decade ago, and responsibility for monitoring and maintenance of the devices has since been taken over by the DCC.
''They were put there because it [the wharf] is a great recreational fishing spot,'' Mrs Wheeler said.
''We encourage people to fish off the side of it and that encourages people to sit on the edge.''
The fact there were no lifebuoys in the cabinets did not seem to deter people from fishing off the wharf yesterday.
