Loughs Agency fishery officers recovered illegal nets in two separate incidents on the River Foyle last weekend.
In the first of these, fishery officers seized a 150m-long net containing 28 salmon at an area known as Rosses Bay.
A sea trout, millet and flounder were also caught in the net, which was found in an important holding water for salmon on their journey to the tributary rivers upstream.
Protection of this area is vital to ensure salmon populations are sustainable, the Loughs Agency says.
In a separate incident, another illegal net was seized on the Foyle at Porthall in Co Donegal after reports from a member of the public about suspicious activity near the river.
The net showed signs of recent use, with fresh salmon scales visible. The net was seized and will be destroyed once a court order has been granted.
Loughs Agency encourages the public to report suspicious activity directly and promptly using the 24-hour Response Line at +44 (0) 2871 342100 or through the WaterWatch reporting tool on its website.
