Did you know?
Tunas are the fastest fish in the world; in fact, bursts of speed exceeding 20-30 mph are not unusual. They have streamlined bodies specifically adapted for efficient swimming, large white muscle masses useful for swimming long distances, and red muscle masses for short bursts of speed when chasing prey or escaping predators.
Tunas have physiological adaptations that enable them to migrate down to cold, deep ocean waters and up to warm, surface waters, increasing the fish's available habitat. They have circulatory heat exchangers that can regulate their body temperatures, and their circulatory system can maintain their body temperature above that of the water in which they live.
Yellowfin population levels are high, but the Eastern Pacific yellowfin stock is currently subject to overfishing.
The tuna industry, through participating governments, works within the framework of the Agreement on the International Dolphin Conservation Program to minimize dolphin bycatch in the Eastern Pacific Ocean purse seine fishery. NOAA's National Marine Fisheries Service has recently launched a new website for tracking and verifying dolphin-safe tuna products. For more information, go to .
Yellowfin is low in saturated fat and sodium and is a very good source of protein, thiamin, selenium, and vitamin B6. For more on nutrition, see Nutrition Facts. (USDA)
About 25% of all yellowfin tuna sold in the U.S. comes from U.S. fisheries; the rest is imported.
Life History and Habitat
Life history, including information on the habitat, growth, feeding, and reproduction of a species, is important because it affects how a fishery is managed. High reproductive potential in yellowfin tuna means they may respond to management actions more rapidly than species that reproduce slowly and in small numbers.
Geographic range: Yellowfin tuna are found throughout the Pacific Ocean, roughly within latitudes 40 degrees North and 40 degrees South but most abundant between 20 degrees North and 20 degrees South.
Habitat: Yellowfin is a tropical species, occupying the surface waters of all warm oceans. Yellowfin favor water temperatures between 64 and 88 degrees Fahrenheit. Larval and juvenile yellowfin stay in surface waters while adults are increasingly found at greater depths.
Life span: Relatively short; likely to be a maximum of 6 to 7 years
Food: Yellowfin are opportunistic feeders at all life stages, feeding on whatever prey is available at the time. They feed primarily during the day. Larvae feed on crustacean zooplankton. Juveniles prey on epipelagic or mesopelagic members of the oceanic community or pelagic post-larval or pre-juvenile stages of island-, reef-, or bottom-associated organisms. Adults feed on crustaceans, cephalopods (octopus, squid, etc.), and fish. Off the west coast of Baja California, Mexico, and southern California, pelagic red crab and northern anchovy are also important parts of the diet.
Growth rate: Growth and development are rapid in the early years of life but gradually slow thereafter.
Maximum size: 7.8 feet in length; 440 pounds in weight
Reaches reproductive maturity: Between 2 and 3 years of age at minimum lengths of 2 and 2.26 feet for females and males, respectively
Reproduction: Yellowfin tuna have high "fecundity" (reproductive potential) and spawn frequently. They are "serial spawners," meaning they are capable of repeating spawning almost daily, with millions of eggs per spawning event.
Spawning season: Peak spawning during spring and fall
Spawning grounds: Yellowfin tuna spawn over broad areas of the Pacific. They spawn throughout the year in tropical waters and seasonally at higher latitudes at water temperatures over 75 degrees Fahrenheit.
Migrations: Yellowfin are capable of large-scale movements and move freely within the broad regions of favorable water temperature. They are known to make seasonal excursions to higher latitudes as water temperatures increase with season (the extent and nature of which is unknown).
Predator/prey interactions: Larger adults prey on large squid and fish species. There is a high degree of cannibalism of juvenile tunas among large yellowfin in the southern Philippines. Predators of larval and juvenile tuna include fish, seabirds, porpoises and other animals; predators of adult tuna include marine mammals and sharks.
Distinguishing characteristics: Yellowfin have a very long second dorsal fin and anal fin, which may reach well over 20% of the fish's length. Their coloring is black metallic dark blue and changes from yellow to silver on the belly, which has about 20 broken, nearly vertical lines. The dorsal and anal fins and finlets are bright yellow.