Thunnus obesus (Lowe, 1839)
Bigeye tuna

Big eye Thon aux gros yeux,  Thon gros yeux,  Thon obèse, 

Thunnus obesus
photo by Chow, S.

 Family:  Scombridae (Mackerels, tunas, bonitos), subfamily: Scombrinae
 Max. size:  250 cm TL (male/unsexed); max.weight: 210 kg; max. reported age: 11 years
 Environment:  pelagic-oceanic; depth range 0 - 250 m, oceanodromous
 Distribution:  Atlantic, Indian and Pacific: in tropical and subtropical waters. Absent in the Mediterranean. Highly migratory species, Annex I of the 1982 Convention on the Law of the Sea (Ref. 26139).
 Diagnosis:  Dorsal spines (total): 13-14; Dorsal soft rays (total): 14-15; Anal spines: 0-0; Anal soft rays: 14-14; Vertebrae: 39. A large species, deepest near the middle of the first dorsal fin base. Lower sides and belly whitish; a lateral iridescent blue band runs along the sides in live specimens. The first dorsal fin is deep yellow, the second dorsal and anal fins are light yellow, the finlets are bright yellow edged with black.
 Biology:  Occur in areas where water temperatures range from 13°-29°C, but the optimum is between 17° and 22°C. Variation in occurrence is closely related to seasonal and climatic changes in surface temperature and thermocline. Juveniles and small adults school at the surface in mono-species groups or mixed with other tunas, may be associated with floating objects. Adults stay in deeper waters (Ref. 5377). Eggs and larvae are pelagic (Ref. 6390). Feed on a wide variety of fishes, cephalopods and crustaceans during the day and at night (Ref. 9340). Meat is highly prized and processed into sashimi in Japan. Marketed mainly canned or frozen (Ref. 9684), but also sold fresh (Ref. 9340).
 IUCN Red List Status: Vulnerable (A2bd) (Ref. 96402)
 Threat to humans:  harmless
 Country info:  Also Ref. 168, 5503.

 Entered by: Luna, Susan M. - 17.10.90
 Modified by: Sampang-Reyes, Arlene G. - 24.03.15
 Checked by: Luna, Susan M. - 19.08.99

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