A truly global resource, yellowfin inhabit warm waters of the Atlantic, Pacific and Indian Oceans. The Mediterranean is the only warm sea where yellowfin are not fished commercially.
The Hawaiian name, ahi, refers to both yellowfin and bigeye tuna. Ahi tuna has a texture that is similar to beef, with a much more mild flavor, and is often eaten raw as sashimi or sushi.
Yellowfin is one of the largest tunas. It has a mild, meaty flavor. Some say the flavor is similar to swordfish. It is more flavorful than albacore, but leaner than bluefin. When cooked, the meat turns from a bright red to brown or grayish tan. It is firm, yet moist, with large flakes.
Whether it’s caught off Ecuador, Hawaii or Bali, almost all of the true “sashimi-grade” fresh yellowfin and bigeye tuna is sold to Japanese buyers who pay a premium price for 200,000 tons a year, compared to 55,000 tons consumed in the U.S. Yellowfin and bigeye are graded both by fat content and color, which can be an objective exercise, as standards can vary from supplier to supplier, depending both upon the experience of the grader and the condition of the market.
Fish with the highest fat content and the brightest red bring a premium price. The amount of myoglobin in a tuna’s muscle determines its color: the more myoglobin, the redder the flesh. The amount of myoglobin is a function of a tuna’s age, physical activity and species. After the flesh of a tuna is exposed to air, an iron ion in the myoglobin molecule will start to oxidize, which turns the meat brown. For that reason, it is important to keep tuna loins and steaks wrapped in plastic.