A number of orange lifebuoys have been found to have been 'deliberately' thrown into the water.
Jersey Coastguard say misuse of the devices is could have fatal consequences, if they aren't available in an emergency.
Coastguard and VTS Manager Dan Downey wants anyone who is throwing the buoys in the water to 'think again'.
"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."
There are 128 'strategically placed' flotation rings around the island's coast, which are designed to be thrown in the water for someone in distress.
Islanders are asked to report any damaged or missing life buoys to the Coastguard on 01534 447705.

Channel Islands Pride: What's on where?
Listed Victorian townhouse to be demolished for seven-storey office block on Esplanade
Plea to take care on coastline after surfer rescue
VIDEO: 'Great progress' as Amelia Seren (3) starts therapy following fundraiser
Sinking boat rescued during Jersey Air Display
Enforcement checks made on private boats coming to Jersey
Registration open to build own F1 car!
Haut du Mont trial: Island Energy 'placed health and safety at risk'