Monofilament drift-netting is thought to be responsible for the stranding of a large basking shark, found dead on the shores of Brandon Bay, Co Kerry, on Sunday evening.
The 3 metre female shark - they grow to up to three times that size - was found at Drom East, Cloghane wrapped in the netting, its mouth fully covered in the material used in several types of fishing, including tuna and the now banned salmon drift-net fishing.
Basking sharks, the second biggest type of shark, are harmless filter feeders. Like other large marine species they face extinction.
According to Mick O'Connell of the Irish Whale and Dolphin Group, basking sharks have been in the waters off Cork and Kerry since April. He said another basking shark was stranded due to monofilament netting a year ago at nearby Fermoyle beach.
The plankton feeders had "no reverse gear" and when they hit drift-netting there was no way out for them. Only a week ago a group of five sharks swam with divers off Brandon Point for 45 minutes, Mr O'Connell said. The largest of the sharks were more than 7m long.
Aidan Barry, chief executive of the South Western Fisheries Board, said under the salmon hardship scheme, monofilament nets were being collected from fishermen.
"Part of the reason we are collecting nets under the hardship scheme is to ensure they will not become an environmental problem," Mr Barry said. There was a general problem of abandoned nets "ghost fishing".