A firearm was discharged by alleged offenders as fisheries officers responded to reports of an illegal net on the upper tidal River Suir late last month.
Nobody was injured in the incident as Inland Fisheries Ireland officers seized a boat, net and nine wild salmon near Carrick-on-Suir during a routine patrol on the night of Tuesday 28 July.
Gardai attended the scene and the matter is being investigated, the fisheries body adds.
IFI director David McInerney said: “The salmon caught by this illegal net were on the final leg of an arduous journey to reach their native spawning rivers.
“The fish were fresh in from the sea, having survived a journey from either the coastal waters off west Greenland or the Faroe Island, before being cruelly killed by an illegal net, a few miles from their final destination.
“It cannot be stressed enough that nobody should purchase wild salmon that does not carry either a green or white gill tag through the mouth and gill clearly displaying the name Inland Fisheries Ireland.
“I would like to highlight the dedication and courage demonstrated by the officers in tackling illegal fishing in the face of significant personal danger.”