Galway Bay fm newsroom - Inland Fisheries Ireland says farmed salmon found in the Dawros River in Letterfrack is a "serious cause for concern".
The fish were discovered by anglers fishing for wild Atlantic salmon on the river, known locally as the Kylemore River.
They had captured fish with poorly formed fins and other distinguishing features associated with farmed salmon.
Scientists from Inland Fisheries Ireland subsequently inspected various samples from the river and confirmed that the fish are of 'aquaculture origin'.
They say they're seriously concerned by the potential impact the presence of farmed salmon could have on the native wild Atlantic salmon.