The yellowfin can reach 6 feet and weigh over 400 pounds.  Catches of around 100 pounds are common.  It is one of the most valued of all the tunas commercially, and highly prized as a big game fish.  Yellowfins hit the bait near the surface very hard and fast, then fight from the depths. 
They are extraordinarily strong and you don’t catch them as much as go to war with them!

Yellowfins run in fast-moving schools that feed on squid, flying fish and small fish.  They often travel in company with porpoises, and with birds diving to feed on the baitfish driven to the surface.  Both are clues to the possible presence of a school.

When we see a potential for yellowfins we generally rebait some of the lines with small surface-running artificial lures and put a small lure on the down rigger in case they are deep and cannot be seen.  Once contact is made we follow the school aided by the birds and/or porpoises and our GPS systems. 

Yellowfin makes up a third of the world catch of tuna.  Its flesh is excellent and has traditionally made up the majority of canned tuna in the USA.  Now, due to changes in fishing methods brought on by porpoise protection issues, it is second to skipjack tuna.