Found in warm temperate waters of the Atlantic, Pacific
and Indian Ocean, this schooling, pelagic, seasonally migratory
species is suspected of making rather extensive migrations.
Schools big eye tuna generally
run deep during the day. The pectoral fins may reach to the second dorsal
fin. The second dorsal and ana1 fins never reach back as far as those
of large yellowfin tuna (Thurwus albacares).
The vent is oval or teardrop shaped, not round as in the albacore. The
first dorsal fin is deep yellow. the second dorsal fin and the anal fins
are blackish brown or yellow and may be edged with black. The finlets
are bright yellow with narrow black edges. The tail does not have a white
trailing edge like that of the albacore.
Generally, there are no special markings on the body, but some specimens
may have vertical rows of whitish spots on the venter At one time it was
not recognized as a separate species but considered a variation of the
yellowfin tuna. they are similar in many respects, but the bigeye's second
dorsal and anal fins never grow as long as those of the yellowfin.
In the big eye tuna the margin of the liver is striated and the right
lobe is about the same size as the left lobe, in the yellowfin tuna the
liver is smooth and the right lobe is clearly longer than either the left
or the middle lobe.
Its diet includes squid, crustaceans, mullet, sardines, small makerels
and some deep water species. Fishing methods are trolling deep with squid,
mullet or other small baits, or artificial lures and live bait fishing
in deep waters with similar baits. It is an excellent food or sport fish,
an important commercial species taken mainly by longlines and sometimes
by purse seines. It is marketed canned, frozen and salt-dried. In Hawaii
it is marketed fresh.