English: Bigeye Tuna
Latin: Thunnus obesus 
Size + Weight:  Average today abt 90 cm abt 15-20 kg
Biggest Angled Fish:  333 kgs Peru, 1957 Russel Lee
Catching Areas:  37% Eastern Pacific
23% Western Pacific, 15 % Indian Ocean , 25% Atlantic Ocean
Catching Methods:  purse seining (small fish), long line (large fish)
Share of all Tuna Caught:  abt 8 % or 256000 m/t
Main Production Areas: Thailand, Philippines, Indonesia, Mexico, Venezuela, Ecuador, Colombia, Spain, Italy
Life Cycle:  About 5-7 years max
Major Markets:  Japan (sashimi)
Popular Product Forms:  Fresh (whole fish)
Fresh Fillets (sashimi) Bigeye tuna look a lot like Yellowfin. They are hard to distinct sometimes. They swim at greater depth then Skipjack and Yellowfin, and therefore have more fat to insulate them from the cold water. This makes them especially attractive for the Japanese sashimi market. Product Characteristics: The meat turns light gray and somewhat darkish after cooking or grilling. Its color makes it less fit for canning. The color and taste of big fish gets almost near to that of beef. In S-America sometimes baby -bigeye are used for canning, this is still marketed as light meat.
Future Supply: Scientists agree that the Bigeye resources are fully exploited and in some cases over-fishing are occurring. Through more purse-seine fishing activity on skipjack and yellowfin, the (by)-catch of small-size big-eye has increased a lot. On the other hand the less-efficient long-line fishing activity has decreased. This trend might be threatening the reproduction of the stocks. A precautionary approach towards the resources seems desirable.

The Bigeye tuna appears in areas where seawater temperatures range from 13°-29°C, but the optimum temperature is between 17° and 22°C. The variation in occurrence of Bigeye tuna is closely related to seasonal and climatic changes in surface temperature and the thermocline.
Juveniles and small adults of Bigeye tuna school at the surface in groups of their own or mixed with other tunas, the adults on the other hand stay in deeper waters.

Distinctive Features:
The Bigeye tuna is also one of the larger species, the body is at its deepest near the middle of first dorsal fin base. The first arch consists of 23 to 31 gill rakers. The pectoral fins are very long in smaller individuals, but moderately long (22 to 31% of fork length) in large individuals (over 110 cm fork length).

The lower sides and belly of a Bigeye tuna are whitish with a lateral iridescent blue band along the side. The first dorsal fin is deep yellow, second and anal fins are light yellow. The finlets are bright yellow and edged with black. The pectoral fin exceeds the edge of the second dorsal fin.
Size, Age, and Growth:
The maximum fork size length of a Bigeye tuna is over 200 cm; but more common to 180 cm. The all-tackle angling record for the Pacific Ocean is a 197.3 kg fish from Cabo Blanco, Peru in 1957. This fish was 236 cm long but it was not specified whether this is pertained in fork length or total length. In the Atlantic Ocean, the all-tackle angling record is a 170.3 kg fish with a fork length of 206 cm taken off in ocean city, Maryland, USA in 1977.
Maturity seems to be attained at 100 to 130 cm fork length in the eastern Pacific and the Indian Ocean, and about 130 cm in the central Pacific Ocean.

At the age of maturity (about 4 or 5 years old) and large adults (age over 10+) are known to spawn in the Gulf of Mexico and in the Mediterranean Sea. In the Pacific Ocean, spawning occurs northeast of the Philippines. Female Bigeye tuna can be weighing between 270 to 300 kg and may produce as many as 10 million eggs per spawning season.

Stock Status of Bigeye Tuna:
Regional Management Organization
State of Stock
Last Edited
North Pacific Ocean
Fully exploited
Year 2005
South Pacific Ocean
Fully exploited
Year 2005
Eastern Pacific Ocean
Year 2008
Western and Central Pacific Ocean
Year 2008
Indian Ocean
Fully exploited
Year 2008
North Atlantic Ocean
Fully exploited
Year 2007
South Atlantic Ocean
Fully exploited
Year 2007

The Atlantic Ocean's Bigeye tuna population has declined from a healthy abundance level in 1961 (and even as recently as 1986) to an over fished condition by 2002. However, the population has not yet reached a dangerously low level, which begins at 50% of the Maximum sustainable yield (MSY) level. Its overall abundance has declined by about 58%, and it is declining moderately rapidly. Currently it is listed as vulnerable in the redlist of IUCN.