Occurs worldwide in deep, warm temperate oceanic waters. It is
both pelagic and seasonally migratory, but has been known
to come fairly close to shore.
Just as the albacore (Thunnus alalunga)
has characteristically overextended pectoral fins, the yellowfin has overextended
second dorsal and anal fins that may reach more than halfway back to the
tail base in some large specimens. In smaller specimens under about 60
1b (27 kg) and in some very large specimens as well, this may not be an
accurate distinguishing factor since the fins do not appear to be as long
in all specimens.
This is probably the most colorful of all the tunas. The back is blue-black,
fading to silver on the lower flanks and belly. A golden yellow or iridescent
blue stripe runs from the eye to the tail, though this is not always prominent.
All the fins and finlets are golden yellow though in some very large specimens
the elongated dorsal and anal fins may be silver edged with yellow. The
finlets have black edges. The belly frequently shows as many as 20 vertical
rows of whitish spots.
The diet depends largely on local abundance, and includes flying fish,
other small fish, squid and crustaceans. Fishing methods include trolling
with small fish, squid, or other trolling baits including strip baits
and artificial hues as well as chumming with live bait fishing.