Yellowfin tuna (Thunnus albacares)

Yellowfin tuna (used with permission from the Inter-American Tropical Tuna Commission)

Although yellowfin tuna are smaller than bluefin tuna, they are certainly not wimps. Tipping the scales at as much as 400 pounds, yellowfin are known to put up such a good fight that the Hawaiians named them Ahi, meaning fire.

Yellowfin tuna are globally distributed in tropical and temperate waters. They are targeted by commercial and recreational fishermen throughout their range and comprise one of the most important international tuna fisheries. As a result of this extensive fishery, considerable effort has been expended to examine tuna movements and stock structure. While a tremendous amount of data has been collected for smaller yellowfin, less information is available for larger animals.

Studies of other fish species have demonstrated that habitat use, movement patterns, and behaviors may differ profoundly from one age class to another. PIER strives to answer the following questions regarding yellowfin research:

• Do size-related differences exist in yellowfin tuna?
• Do they exhibit similar habitat preferences?
• Can we identify the physical and biological parameters that influence movements and behaviors specifically of large yellowfin tuna?

Early in 2000, PIER initiated a project to examine the large-scale movement patterns and habitat preferences of large yellowfin tuna off of California and Mexico. More than a dozen fish have been tagged, ranging in size from 60 to 200 pounds. The results from this study will provide important information on the movements of large yellowfin tuna and how those are influenced by physical and biological factors.