Yellowfin tuna (Thunnus albacares) are a highly sought-after species known for their speed and size in tropical and subtropical oceans globally. Understanding the dimensions these fish can achieve, both typically and at their largest, offers insight into their biology and ecological role.
Average and Maximum Dimensions
Yellowfin tuna are among the larger tuna species. Most commercially caught individuals range between 40 to 60 kilograms (90-130 pounds). They commonly reach lengths of 1.1 to 2.2 meters (3.6 to 7.2 feet), often weighing around 180 kilograms (400 pounds).
The maximum reported sizes for yellowfin tuna include individuals documented reaching up to 2.4 meters (7 feet 10 inches) in length and weighing 200 kilograms (440 pounds). Other reports indicate maximum weights of up to 450 pounds.
The International Game Fish Association (IGFA) all-tackle world record for yellowfin tuna is 193.68 kilograms (426 pounds 15.75 ounces), caught off Cabo San Lucas, Mexico, in 2012. Another notable catch, weighing 427 pounds, was also recorded in Mexico in 2012. Unofficial reports suggest some yellowfin tuna have been caught weighing around 430 pounds, though these were not formally certified.
Measurements of tuna typically involve “curved fork length,” which follows the contour of the fish’s body from the tip of the jaw to the fork of the tail. Alternatively, “fork length” is a straight-line measurement. While scales provide the most accurate weight, formulas using girth and length measurements can offer estimates.
Factors Influencing Size
Biological and environmental factors contribute to the size yellowfin tuna achieve. Age plays a role in their growth, as these fish grow fast. Although their typical lifespan is around seven years, some studies suggest they can live for at least 15 years, with most individuals not exceeding six years of age. Young yellowfin tuna can reach about 60 centimeters in length within their first year.
Most yellowfin tuna attain reproductive maturity between two and three years of age, at a length of 100 to 105 centimeters (around 25 kilograms). Males tend to grow larger than females as they age. This difference in growth rates contributes to the variation observed in adult sizes.
Diet also influences their development. Yellowfin tuna are opportunistic feeders, consuming small fish, squid, and crustaceans. Younger tuna begin their diet with zooplankton, gradually transitioning to larger prey as they grow. The abundance and quality of these food sources impact their ability to reach larger sizes.
Environmental conditions, such as water temperature, dissolved oxygen levels, and thermocline depth, influence yellowfin tuna growth. They inhabit tropical and subtropical waters globally, preferring temperatures around 24°C (75°F) but tolerating 18-30°C (64-86°F). These fish often reside in the warm surface mixed layer of the ocean.