Scientific Name
Thunnus obesus

Common Name
Bigeye tuna

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).

Classification

Classified By

Lowe, 1839

Class

Ray-finned fishes (Actinopterygii)

Order

Perch-like fish (Perciformes)

Family

Mackerels, tunas, bonitos (Scombridae)

Distribution

Region

Atlantic, Indian and Pacific

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).

Range

45°N - 43°S, 180°W - 180°E

Environment

Climate

Subtropical

Water Temperature From

13 °C

Water Temperature To

29 °C

Depth From - meters

0 m

Depth To - meters

250 m

Zone

pelagic-oceanic

Environment

Marine; pelagic-oceanic; oceanodromous (Ref. 51243); depth range 0 - 250 m (Ref. 168)

Trophic Level

4.49 s.e. 0.75 Based on diet studies.

Occurs in Marine / Salt water

True

Occurs in Brackish water

False

Occurs in Fresh Water

False

Occurs on Reefs

False

Is kept in Aquariums

False

Physical Size and Genetics

Maximum Length

250 cm

Common Length

180 cm

Phylogenetic Diversity Index

PD50 = 0.5039 many relatives (e.g. carps) 0.5 - 2.0 few relatives (e.g. lungfishes)

Human Uses and Population

Human Uses

Fisheries: highly commercial; gamefish: yes

Vulnerability

High to very high vulnerability (72 of 100)

Resilience

Medium, minimum population doubling time 1.4 - 4.4 years (K=0.11-0.23; tm=3; tmax=11; Fec=2 million)

Threat To Humans

Harmless

IUCN Red List Status

Vulnerable (VU) (A1bd)