Jersey Coastguard is asking islanders to respect lifebuoys after several were thrown into the sea when they were not needed.
The reported incidents were at the harbour by Normans, St Aubin's Fort, and the north wall of St Helier Marina.
The service says the life-saving rings should only be used in emergencies.
They warn that if they are not used properly it could leave islanders who are in an actual emergency, in a life-threatening position without a lifebuoy to save them.
Coastguard and VTS Manager, Dan Downey, said: "Discarding a lifebuoy into the harbour when it isn't needed is vandalism and could cause death or life-threatening injury if the equipment is then not available when it's really needed by someone who's in trouble in the water. "We would appeal to those who have been discarding this vital life-saving equipment to think again before jettisoning lifebuoys into the harbour. This deliberate, senseless misuse could have fatal consequences." There are 128 lifebuoys strategically placed around the island. These sites are checked regularly, but anyone who sees that one is missing or damaged should call the Coastguard on 01534 447705.
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