Spanish patrol boat Arnomendi

The primary mission of Arnomendi is to monitor and enforce maritime fishing. It helps to support the Ministry of Agriculture's presence in Spanish fishing grounds, and ensures compliance with national and international fishing regulations. Additionally, the ship is capable of search and rescue operations, forward naval presence, special operations missions, and scientific research. The carried zodiac boats allow for assistance at sea, medical evacuations, and vessel boarding and inspection.^[1]

Arnomendi is the third vessel in the Chilreu-class of patrol boats. It was constructed in the Vigo Shipyard of Pontevedra and was launched in January 2000. The Minister of Agriculture Ana Loyola de Palacio was the ship's sponsor. It entered service and was commission on 13 December 2000. The ship was originally intended to be named Alegranza, after the uninhabited Alegranza island, but the name was ultimately changed to Arnomendi for a mountain in Gipuzkoa along Spain's northern coast. Arnomendi was first based at Las Palmas, moved to Cartagena in 2010, and then to Ferrol in 2016.^[1]

The ship has carried out missions in Spanish fisheries in the Canary Islands and off Cádiz, and more recently in the Cantabrian Sea. In these deployments, it supported the Spanish northern bonito fishing fleet and bluefin tuna fishing fleet.^[1] One such deployment took place in 2020, supporting the "Costera del Bonito del Norte 2020" maritime campaign to surveil and protect a bonito fishing fleet in the Northern Atlantic.^[2] As of 2023, it had completed a total of eight campaigns in the international waters regulated by the Northwest Atlantic Fisheries Organization and seven in those of the North East Atlantic Fisheries Commission.^[1][3]

On 23 April 2014, British Gibraltar news reported that Arnomendi made a brief incursion into Gibraltar territorial waters and was challenged by HMS Scimitar. The incursion lasted roughly an hour before Arnomendi returned to international waters in the Strait of Gibraltar, and the incident caused the British Foreign Office to file a complaint with Spain.^[4]

In October 2015, Arnomendi participated in an international pelagic monitoring campaign with Ireland, the United Kingdom, France and Spain off the coast of Ireland.^[5]