Stirling Council Fisheries staff who help look after the rivers say several life rings have been lifted from the banks this summer, with potentially fatal consequences.
The local authority has 39 life rings deployed across sections of the Forth and Teith where it has fishing rights and management responsibility.
Since the start of June, the total loss of equipment throughout the Stirling fishery area is close to 40 rings, which has an estimated cost of around £2000 to the council.
“This is a serious issue that we have encountered in the past and it could have dire consequences,” Fisheries Officer Scott Mason said.
“Some of these rings are having to be replaced on a daily basis and there’s a big question mark over why that’s happening. Lives will remain at risk while it goes unanswered.”
The Stirling Council has one of the last remaining publicly owned Council-run fisheries in Scotland and its season runs from February to October.
During the summer months, the rivers which flow through Stirling are seen as a hot spot for fishers as well as walkers, cyclists and tourists, further highlighting the need for appropriate safety equipment on site.
Earlier this summer, a woman was saved near Craigforth by anglers deploying a life ring after she became entangled in the riverbed.
The fisheries team also carried out a water rescue of an angler in Callander who had managed to fall in the river during a flood in March.
Situations like these highlight the importance of life rings and emphasise that these rings are on site as life-saving equipment.
Cllr Jim Thomson, convenor of the Environment and Housing Committee, said: “It might seem like a small thing but having enough life rings could be a matter of life and death.
“Their misuse and theft is a serious matter that could have fatal consequences.”
Cllr Danny Gibson, vice convenor, added: “The dangers of open water come up every year – whether that be in rivers or quarries or at local beauty spots, like water falls – so it’s mind boggling to think people would simply steal this life saving equipment.
“Hopefully the people taking these rings have a think before they act again, and ask themselves how they’d feel if they were in a situation where they needed access to one but it wasn’t there.”
Anyone who spots life rings being tampered with or removed should contact Police on 101.