Tuna are remarkable inhabitants of the ocean, renowned for their incredible power and speed. These highly migratory fish traverse vast distances, their streamlined bodies and muscular build making them effective predators. Tuna species vary significantly in size, ranging from smaller, more common varieties to giants.
Understanding Tuna Size Across Species
The size a tuna can achieve varies considerably among different species. Atlantic Bluefin tuna are the largest, commonly reaching lengths of 7 to 15 feet (2.1 to 4.6 meters) and weights between 550 and 2,000 pounds (250-907 kilograms). Mature adults typically average 6.6 to 8.2 feet (2 to 2.5 meters) and 496 to 551 pounds (225-250 kilograms). Southern Bluefin tuna are another sizable species, capable of reaching up to 8 feet (2.45 meters) in length and weights of 570 pounds (260 kilograms), though they are more commonly found at 5.9 feet (1.8 meters) and 220 pounds (100 kilograms).
Yellowfin tuna are substantial in size, often growing up to 400 pounds (180 kilograms), with some individuals reaching 440 pounds (200 kilograms). Their typical length ranges from 43 to 83 inches (110 to 210 centimeters). Bigeye tuna, named for their large eyes, can grow to about 8.2 feet (2.5 meters) in length and often exceed 400 pounds (180 kilograms).
Albacore tuna are generally smaller, reaching up to 4.6 feet (140 centimeters) in length and weighing around 90 pounds (40 kilograms). The smallest species is the Skipjack tuna. These fish typically grow to about 32 inches (80 centimeters) in length and weigh between 7 to 22 pounds (8-10 kilograms), though they can reach a maximum of 43 inches (108 centimeters) and 76 pounds (34.5 kilograms).
What Influences Tuna Growth
Several factors contribute to how large an individual tuna grows. Age plays a significant role, with longer-lived species generally achieving greater sizes. For instance, Atlantic Bluefin tuna can live for 15 to 30 years, and potentially longer than 35 years. Bigeye tuna have a maximum recorded age of 16 years, while Yellowfin tuna typically live for 5 to 10 years, and Skipjack tuna have a shorter lifespan of 8 to 12 years. Southern Bluefin tuna can live for at least 40 years.
Diet and the availability of food sources are important factors for growth. Tuna are opportunistic predators, and their diet evolves as they grow larger. Juvenile tuna may feed on zooplankton, while adults consume a variety of larger prey, including small fish like sardines, herring, mackerel, eels, as well as squid and crustaceans.
Water temperature also influences tuna growth and distribution. Each species has an optimal range. Southern Bluefin tuna, for example, prefer temperatures between 18 to 20 degrees Celsius (64-68°F) but can endure temperatures as low as 3 degrees Celsius (37°F) and as high as 30 degrees Celsius (86°F).
Bigeye tuna exhibit daily vertical migrations, diving to deeper, cooler waters during the day and returning to warmer surface waters at night, actively tracking their preferred temperatures. This ability to regulate body temperature through physiological adaptations allows them to maintain high metabolic rates necessary for growth and migration. Genetic predisposition also influences an individual’s potential for growth, with male Bigeye tuna sometimes growing larger than females.
Notable Tuna Catches
Anglers have landed impressively large tuna, setting records. The largest Atlantic Bluefin tuna ever recorded was caught off Nova Scotia, Canada, in 1979 by Ken Fraser, weighing an astounding 1,496 pounds (679 kilograms). Pacific Bluefin tuna also have a recorded all-tackle record weighing over 907 pounds (411 kilograms).
The International Game Fish Association (IGFA) all-tackle world record for Yellowfin tuna stands at 427 pounds (193.68 kilograms), caught by Guy Yocom off Cabo San Lucas, Mexico, in 2012. More recently, a potential new record Yellowfin weighing 443 pounds was caught by Earl Gill IV in 2024, pending official certification. For Bigeye tuna, the Atlantic record is 392 pounds, 6 ounces (177.9 kilograms), caught by Dieter Vogel in 1996, while the Pacific record is 435 pounds (197.3 kilograms), landed by Russel Lee in 1957.
The record for Albacore tuna is 88 pounds, 2 ounces (39.9 kilograms), set by Siegfried Dickemann in 1977. For Skipjack tuna, the world record was broken in 2020 by Joeri Van Laken with a catch weighing 46 pounds, 5 ounces (20.9 kilograms).