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In the waters of the eastern tropical Pacific Ocean (ETP), here defined as extending from 25°N to 10°S latitude and the western coasts of the Americas as far as 150°W longitude, large-bodied yellowfin tuna (Thunnus albacares) associate with several species of dolphins: pantropical spotted (Stenella attenuata), spinner (S. longirostris) and, to a lesser extent, short-beaked common (Delphinus delphis) dolphins. These assemblages are often accompanied by multispecies flocks of seabirds (dominated by Procellariidae, Sulidae, and Laridae). The tuna, dolphins, and most of the seabird species are found throughout the tropics and although they associate to a certain degree in other tropical oceans of the world, the prevalence of this assemblage is a conspicuous feature and a hallmark of the ETP. There, habitat of tuna is compressed to the warm and shallow waters of the surface mixed layer by an extensive and hypoxic oxygen-minimum zone, and the association potentially decreases the risk of predation for dolphins and/or tuna (Scott et al., 2012). Seabirds benefit from increased feeding success because dolphins and tuna chase prey to the surface (Au and Pitman, 1986; Ballance et al., 1997).