Bluefin tuna are large, fast-swimming ocean predators. They traverse vast oceanic distances, growing rapidly to significant sizes.
Understanding Bluefin Tuna Growth
Bluefin tuna exhibit fast growth, especially in early life. Larval Pacific bluefin tuna, for instance, can double their body weight every three to four days in their first week, gaining 4-6% in body length daily. This rapid initial growth allows them to quickly increase in size. While growth continues throughout their lives, the rate generally slows as they age, a characteristic known as indeterminate growth.
Different bluefin tuna species vary in their growth timelines. Pacific bluefin tuna mature around 3 to 5 years, typically at 100 to 150 cm and 50–60 kg. Atlantic bluefin tuna mature quickly, often between three to five years, reaching about one meter. Southern bluefin tuna are slower growing, reaching 50 cm in their first year and maturing between 8 and 10 years old, typically measuring 130 to 150 cm at maturity.
Key Factors Affecting Growth
The availability of food significantly influences how quickly bluefin tuna grow. These fish have a high metabolic rate, requiring substantial caloric intake to fuel their powerful muscles and maintain warm bodies. Their diet includes schooling fish like mackerel, herring, and eels, plus invertebrates such as squid and crustaceans. As they grow, their prey increases in size, transitioning from tiny zooplankton as larvae to larger fish and invertebrates as adults.
Water temperature and habitat also influence bluefin tuna growth. Warmer waters promote faster metabolism and quicker growth. Bluefin tuna can regulate their body temperature, inhabiting a wide range of depths from 0 to 550 meters. Their extensive migratory patterns expose them to varying temperatures and food sources, impacting their overall growth and size.
Reaching Full Potential: Lifespan and Size
Bluefin tuna attain large sizes due to continued growth over long lifespans. Atlantic bluefin tuna live for up to 50 years, making them the longest-living tuna species. Pacific bluefin tuna typically live up to 26 years, though their average lifespan is around 15 years. Southern bluefin tuna can live beyond 40 years.
The maximum size achieved varies among species. Atlantic bluefin tuna are the largest, with recorded specimens reaching 3.84 meters (12.6 feet) long and weighing 679 kg (1,497 lb). Some sources indicate they can reach 4.6 meters (15 feet) and weigh 907 kg (2,000 pounds). The world record for an Atlantic bluefin tuna stands at 1,496 pounds, caught off Nova Scotia in 1979. Pacific bluefin tuna can reach 3 meters (9.8 feet) in length and 550 kg (1,210 lb). Southern bluefin tuna can grow up to 2.5 meters (8 ft 2 in) and weigh around 260 kg (570 lb).