Yellowfin tuna has flesh coloration that ranges from pink in small fish to deep red in large fish. Large fish have greater potential to have a higher fat content than smaller fish, a desirable attribute for raw fish products, as well as for searing and broiling.
Because Yellowfin Tunas undergo such an amazing transformation in size (from being nearly microscopic to being one of the largest open ocean predators), they eat a wide variety of prey, throughout their lifetimes. At a young age, they eat tiny zooplankton, and their prey increases in size as they do. As adults, they eat fairly large bony fishes and squids. Similarly, Yellowfin Tunas are eaten by a wide variety of predators. When they are newly hatched, they are eaten by other fishes that specialize on eating plankton. At that life stage, their numbers are reduced dramatically. Those that survive face a steady increase in the size of their predators. Adult Yellowfins are not eaten by anything other than the very largest billfishes, toothed whales, and some open ocean shark species.
The famous dolphin-safe logo on tuna may tell you that its not caught in a way that deliberately catches or sets nets around dolphins, but it’s no guarantee. And of course, ‘dolphin-safe’ tells you nothing about impacts on other species.
Purse seining largely took over commercial tuna fisheries in the 1960s and 1970s. Today, purse seines account for more of the commercial catch than any other method. The purse-seine fishery primarily operates in the Pacific Ocean, in the historic tuna grounds of the San Diego tuna fleet in the eastern Pacific, and in the islands of the western Pacific, where many U.S. tuna canneries relocated in the 1980s, but significant purse-seine catches are also made in the Indian Ocean and in the tropical Atlantic Ocean, especially in the Gulf of Guinea by French and Spanish vessels.
The peak spawning period for yellowfin tuna, Thunnus albacares, occurs during summer months; however spawning also occurs throughout the year. Eggs are fertilized externally after mating when they are released into the water.
Reproduction occurs year-round, but is most frequent during the summer months in each hemisphere. It is believed that 79°F (26°C) is the lower temperature limit for spawning. In the tropical waters of Mexico and Central America, it has been determined that yellowfin spawn at least twice a year. Each female spawns several million eggs per year. Among tunas, larval yellowfin can be identified by the presence of a single spot of black pigment under the chin and a lack of pigment on the tail. In profile, the center of the eye is above the line of the body axis. Postlarvae and small juveniles are very difficult to distinguish from related species because these diagnostic characters become obscured. The juveniles grow quickly, weighing approximately 7.5 pounds (3.4 kg) at 18 months and 140 pounds (63.5 kg) at 4 years.
Today, yellowfin tuna are a major sport fish pursued by sport fishermen in many parts of the world. Thousands of anglers fish for yellowfin tuna along the eastern seaboard of the United States, particularly in North Carolina and New England. Yellowfin are also a popular gamefish among anglers fishing from US Gulf Coast ports, San Diego, and other ports of southern California. Larger “long-range” boats in the San Diego fleet also fish in Mexican waters, searching for yellowfin tuna in many of the grounds that the San Diego pole-and-line tuna clippers used to fish. The yellowfin tuna is also a highly prized catch in the offshore sport fisheries of South Africa, Australia, and New Zealand. Sport fishing for yellowfin tuna exists on a smaller scale in many other parts of the world.