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.

New website helps children and families navigate the digital world
More time in Jersey for French day-trippers
Rapist jailed more than two decades after his crime
Jersey Airport to see 20,000 passengers in the run up to Christmas
Both winning CI Christmas Lottery Tickets sold in Jersey
Jersey churches host free Christmas events in the Royal Square
Support service set up for carers of people with mental illness
New Jersey Opera House CEO appointed