| Bigeye Tuna - (Thunnus obesus) | ||
| Maximum weight: | 500 lbs |
 |
| I.G.F.A. record: | 435 lbs | |
| Temperature range: | 13°C to 28°C
|
|
| Identifying features: | The body of the bigeye tuna is cigar-shaped (tapered at both ends). The head is pointed and the eye is relatively large. The color is dark metallic brownish blue to dark yellow on the back becoming gray or whitish below. There often is a bluish stripe on the side. In most individuals, the length of the pectoral fins should enable one to identify the species properly. Both bigeye and yellowfin tuna look similar, but bigeye tuna have pectoral fins which extend well past their anal fin, while yellowfin tuna have much shorter pectoral fins. Tuna which cannot be distinguished by external characteristics can be positively identified by liver characteristics. Bigeye tuna livers are striated (covered with blood vessels) along the trailing edges, while yellowfin tuna livers are smooth. Small bigeye tuna also may be distinguished from albacore by the characteristics of the liver. The liver is heavily striated in the albacore while the bigeye tuna liver is only striated along the trailing edges. | |
| Typical location: |
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. Feed on a wide variety of fishes, cephalopods
and crustaceans during the day and at night |
|