Thunnus alalunga

Author: (Bonnaterre, 1788)

Thunnus alalunga (Bonnaterre, 1788)

Status in World Register of Marine Species:
Accepted name: Thunnus alalunga (Bonnaterre, 1788) (updated 2009-06-25)

Diagnosis: a large species with an elongate, fusiform body, deepest at a more posterior point than in other tunas (at, or only slightly anterior to, second dorsal fin rather than near middle of first dorsal fin base). Eyes rather large. Gillrakers 25-31 on first arch. Second dorsal fin clearly lower than the first; pectoral fins remarkably long, usually 30% of fork length or longer, reaching well beyond origin of second dorsal fin (usually up to second dorsal finlet). Liver striated on ventral surface. Colour: second dorsal and anal fins light yellow, anal finlets dark; posterior margin of caudal fin white. Size: to 127 cm fork length, 40 kg, common to 100 cm.

Habitat: epipelagic and mesopelagic in the high seas, found below the thermocline or at temperatures of 17-21° C. Schooling and migratory. Food: a variety of epipelagic and mesopelagic fishes, including anchovy, saury, lantern-fishes, and hatchet-fishes and also squids, and crustaceans. Reproduction: spawns in the summer in the Mediterranean. Eggs and larvae planktonic.

Distribution: found from the Azores and the Canaries north to Ireland. Occurs in the western Mediterranean and in the northern part of the eastern Mediterranean, including the Adriatic but not the Black Sea. Elsewhere, cosmopolitan, often extending into cooler waters than most tunas.

Eggs, larvae and young stages. Ehrenbaum, 1924: 20, fig. 4a 4h (larvae) (?) | Padoa, 1956: 484, fig. 313-314 (eggs), 315-318 (larvae), 319-322 (post-larvae) (?) | Bini, 1968, 6: 50, 1 fig.
Otoliths (sagitta). Chaine, 1957: 496, pl. 3 | Fitch and Craig, 1964: 204, fig. 6d.