New regulations banning the sale of salmon caught with rods have been introduced by Stormont.
The measures come into effect on 1 June and bring Northern Ireland into line with the rest of the UK and the Republic of Ireland.
Fisheries Minister Caral Ni Chuilin said the move was the first step in a series of conservation measures aimed at protecting stocks.
She said the move would also deter poaching.
The ban has already been in place in Foyle and Carlingford Lough which are managed by the Loughs Agency.
The new regulations apply to rivers controlled by the department of culture, arts and leisure (DCAL).
Robbie Marshall, development officer of the Ulster Angling Federation, welcomed the legislation.
"It has been in existence in the Loughs Agency for some considerable time and this now closes the loophole that existed there," he said.
"It will mean that it will be more difficult for people to sell off salmon.
"As it stood there was a large loophole that somebody could say they caught a salmon in a DCAL area and sell it in the Loughs Agency area."
Chief fisheries officer, Seamus Connor said measures had been put in place to enforce the ban.
"We have a number of officers, in addition we also have private water bailiffs - these are angling club members who give their time up freely to carry out enforcement duties on their own river - we'll be supporting them and helping to train them to help ensure the ban is enforced," he said.
Ms Ni Chuilin said: "This ban brings the DCAL jurisdiction into line with the rest of Ireland and with Britain, effectively prohibiting the sale of salmon caught by rod and line across these islands.
"The introduction of this prohibition will encourage the practice of catch and release methods for salmon fishing until such methods become mandatory in 2014. It will also deter poaching if no outlet is available to sell salmon caught in this way.
"My officials are also working on the range of other legislative measures required to prohibit commercial salmon netting and implement mandatory catch and release for salmon angling in time for the 2014 seasons."
Ms Ni Chuilin said the ban on the sale of rod-caught salmon will also extend to sea-trout - there is already a ban in place in the Loughs Agency area and in the south of Ireland for sea-trout.