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.

Date set for new vape tax to take effect
Youth Assembly backs vape ban, but narrowly rejects social media ban
Public Health Jersey issues advice following UK meningitis outbreak
Ports of Jersey to takeover running of harbour café
Teams decided for de Putron Final 2026
Number portability issue between Coop Mobile and JT resolved
Former teacher jailed and placed on Sex Offenders register
Opponents ask if St Mary solar plans have been 'abandoned'