Feeding
The main prey of these orcas is the Bluefin Tuna ( Thunnus thynnus ).
Their diet can also include Blue shark (Prionace glauca)
and possibly sunfish (Mola mola)
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IB27 Leah with a tuna. ©Manu Esteve
Their main technique to hunt the tuna, is to chase the fish until it collapses.
It has been said, that in the past they were able to use Almadrabas to facilitate the hunt of the fish.
Bluefin Tuna Migration
The Iberian orca follow the tuna during its migration to the Mediterranean Sea, from the Bay of Biscay, along the coast of Galicia and Portugal.
Once the fish enters their spawning area, the orca won't follow, instead,they wait for it in the Strait of Gibraltar for them to return.
In Autumn they begin their journey back.
New technique
©Manuel Esteve
IB32 Mario taking a caught tuna.
Starting in the late 1990s, some families from this population began to interact with the Moroccan and Spanish boats that fish for bluefin tuna in the Strait by longline fishing.
The orca patrols among the boats and waits for one to start collecting line with the tuna already caught.
So that they just have to take it and share it with the rest of the pod.
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This behavior has been culturally taught from mother to offspring and has even spread to more individuals in the population who are not part of the original group that started it.
These interactions with fishing usually take place in an area known as "Las Bajas", in front of Tangier
Referencias
Sella M. (1929) Migrazioni e habitat del tonno (Thunnus thynnus L) studiati col metodo degli ami, con osservazioni su l’accrescimento, sul regime delle tonnare ecc. Venice: Univ.-Bibliothek Frankfurt an Main.
Guinet C., Domenici P., de Stephanis R., Barrett-Lennard L., Ford J.K.B. and Verborgh P. (2007) Killer whale predation on bluefin tuna: exploring the hypothesis of the endurance–exhaustion. Marine Ecology Progress Series 347, 111–119
Srour A. (1994) Développement de la nouvelle pêcherie artisanale au thon rouge dans la région de Ksar sghir. Note d’Information ISPM 26, 10–11.
de la Serna J.D., Alot E., Majuelos E. and Rioja P. (2004) La migración trófica post reproductiva del atún rojo (Thunnus thynnus) a través del estrecho de Gibraltar. Collective Volume of Scientific Papers ICCAT 56, 1196–1209
Lozano F. (1958) Los escómbridos de las aguas españolas y marroquíes y su pesca. Trabajo Instituto Español de Oceanografía 25, 254.
Aloncle H. (1964b) Note sur le thon rouge de la Baie Ibéro-Marocaine. Bulletin de l’Institut des Pêches Maritimes du Maroc 12, 43–59