Tuna - Yellowfin
name: Tuna - Yellowfin
other names: Son Tuna, Ahi
Distinguishing the Yellowfin Tuna from the Blackfin or Bigeye is sometimes difficult as many visual features are similar. Finlets of the Yellowfin are yellow, trimmed in black. Gold stripe along side. Light underside usually shows spots and/or wavy lines. Second dorsal and anal fins of very large individuals are elongated and lunette - a feature not found on any other Tuna.
Adults often form schools with other tuna species, mainly bigeye and skipjack tuna. They school primarily by size and larger fish will also school with porpoises. Though yellowfin tuna are sometime found near shore, this only occurs when forage suddenly becomes abundant there, and for the most part they can stay around the edges of continental shelves. Though they can withstand cooler water, yellowfin tuna prefer warm water and are found mainly in waters between 62 and 80 F. Yellowfin tuna, particularly young fish, usually school below the surface but over deep water, often several hundred feet. They avoid depths because of their intolerance for low concentrations of oxygen.
The yellowfin's diet varies depending upon the food available in a given area. Various bait fish and crustaceans make up the bulk of yellowfin's diet. The feed most often at or near the surface and are often active at night.
Yellowfin tuna spawn mainly in the spring and summer, when water temperatures reach 78 F. But in many tropical waters they may spawn year round. They are prolific breeders, with large females able to deposit up to 8 million eggs and both sexes may spawn every few days over the spawning period. Yellowfin tuna disperse the eggs and milt into the water, and the eggs are unguarded.
Yellowfin tuna often congregate around floating objects such as grass, debris and other objects that support ample bait fish habitat. Feeding birds at the surface are another clue to their presence. Angling efforts are mostly targeted near the surface but often over depths of several hundred feet. Trolling with live or dead bait and shallow-running lures is a common tactic. Casting with jigs and still fishing with live or bait is another common method, usually done in conjunction with chumming an area with cut or ground up bait fish.
