The anglers are being asked to practice catch and release fishing for September. The regulation is in force on the rivers Suir, Barrow and Nore and other tributaries in the region.
Any salmon and sea trout caught must be returned to the water immediately in an effort to preserve stocks, the directive says.
David Byrne of the Central Fisheries Board said that the decision was not taken lightly but that stocks in the area need urgent protection.
“We took the move following the identification of eight fishery districts as being below their conservation limits. We are one of them.
“The advice came from the Standing Scientific Committee of the National Salmon Commission. The national conservation limit is a level whereby if stocks fall below it, not enough salmon are returning to the rivers to sustain the current population.”