The Naval Service detained a Spanish registered fishing vessel 160 miles west of Loop Head at 1.30am this morning.
The detention, by the LE Niamh is in relation to an alleged breach of fishing regulations.
The vessel is currently being escorted to Castletownbere, Co. Cork where it is expected to arrive at 10.30pm. It will then be handed over to gardaí.
The Naval Service have carried out 1,030 boardings and 11 detentions of vessels off the Irish coast in 2011.