Tourism angling bodies in the north east and midlands are concerned that some foreign nationals are not aware that the netting of fish is illegal.
The Eastern Regional Fisheries Board and the Erne-Lakeland Tourism Organisation said at the weekend they had received reports that fish were being illegally netted, particularly by people from eastern Europe who were eating the fish as a delicacy at weekend parties.
More lake bailiffs are being appointed in Co Monaghan.
Frankie Poyntz, secretary of Castleblayney Anglers' Association, said yesterday that a number of foreign nationals had been intercepted with netted fish. "It was made very clear to them that this wasn't allowed. The illegal netting may now be stopped in this area but it seems to be happening on a large scale elsewhere," he said.
Multilingual signs warning against netting have been erected. An Erne-Lakeland Tourism spokesman said it had "become a very serious issue" as hundreds of coarse fish had been removed from waters. "It is posing a huge threat to cross-channel tourist-angling," he said.