Normal day to day patrolling by the Naval Service on fishery protection takes place within Ireland's 200 miles exclusive fishery limit. Occasionally, the Naval Service carry out patrols outside the 200 miles limit.
In August and September 1990, a Naval Service vessel conveyed EU fishery inspectors on fishery surveillance patrols on behalf of the EU in international waters bordering on the Canadian 200 miles zone. This operation arose from the requirements of the North-West Atlantic Fisheries Organisation Convention (NAFO) in accordance with Council Regulation 1956/88. During the patrols, a total of 27 fishing vessels of various nationalities were boarded by the EU inspectors who passed on the results of the boardings to the EU Commission. Community financial assistance was made available to Ireland to offset the additional costs incurred by the Naval Service in undertaking this operation.
In 1994 and 1995, the Naval Service undertook patrols of the tuna fishery. The patrols took place in ICES (International Council for the Exploitation of the Sea) zone 8 E which commences 270 nautical miles south of Ireland and extends for a further 300 nautical miles. The purpose of the patrols was to monitor tuna fishing by Irish registered fishing vessels in the area and to ensure that the Commission Regulation which prohibits the use or retention on board any fishing vessel fishing for tuna of one or more driftnets whose individual or total length is more than 2.5 kilometres was enforced. Each member state is responsible for monitoring the activities of its own vessels engaged in fishing in this area.