Yellowfin Tuna Facts (Thunnus albacares)

The yellowfin tuna (Thunnus albacares) is a large, swift fish that is known for its beautiful colors, graceful motion, and use in cooking as ahi and Hawaiian poke. The species name albacares means "white meat." While the yellowfin tuna is the albacore tuna in France and Portugal, albacore is the name given to the longfin tuna (Thunnus alalunga) in other countries.

Description

The yellowfin tuna gets its name for its yellow sickle-shaped tail, dorsal and anal fins, and finlets. The torpedo-shaped fish may be dark blue, black, or green on top with a silver or yellow belly. Broken vertical lines and a golden stripe on the side distinguish the yellowfin from other species of tuna.

The yellowfin is a large tuna. Adults may reach 6 feet in length and weigh 400 pounds. The International Game Fish Association (IGFA) record for a yellowfin is 388 pounds for a fish caught off Baja California in Mexico, but there is a pending claim for a 425-pound catch, also caught off Baja.

Habitat and Range

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Tuna Species Types

By Jennifer Kennedy

Yellowfin tuna live in all tropical and subtropical oceans except for the Mediterranean. They are usually found in water ranging from 59° to 88° F. The species is epipelagic, preferring deep offshore water above the thermocline in the top 330 feet of the sea. However, the fish can dive to depths of at least 3800 feet.

Yellowfin tuna are migratory fish that travel in schools. Movement depends on water temperature and food availability. The fish travel with other animals of a similar size, including manta rays, dolphins, skipjack tuna, whale sharks, and whales. They commonly aggregate under flotsam or moving vessels.

Diet and Behavior

Yellowfin fry are zooplankton that feed on other zooplankton. As they grow, the fish eat food whenever it is available, only swimming more slowly when satiated. Adults feed on other fish (including other tuna), squid, and crustaceans. Tuna hunt by sight, so they tend to feed during daylight hours.

Yellowfin tuna can swim up to 50 miles per hour, so they can capture fast-moving prey. The yellowfin tuna's speed is due partly to its body shape, but mainly because yellowfin tuna (unlike most fish) are warm-blooded. In fact, a tuna's metabolism is so high the fish must constantly swim forward with its mouth open to maintain sufficient oxygenation.

While fry and juvenile tuna are preyed upon by most predators, adults are sufficiently large and quick to escape most predators. Adults may be eaten by marlin, toothed whales, mako sharks, and great white sharks.

Reproduction and Offspring

Yellowfin tuna spawn throughout the year, but peak spawning occurs during the summer months. After mating, the fish release eggs and sperm into the surface water simultaneously for external fertilization. A female can spawn almost daily, releasing millions of eggs each time and up to ten million eggs per season. However, very few fertilized eggs reach maturity. Newly-hatched fry are nearly-microscopic zooplankton. Those that aren't eaten by other animals grow quickly and reach maturity within two to three years. A yellowfin tuna's life expectancy is about 8 years.

Conservation Status

The IUCN classified the conservation status of the yellowfin tuna as "near threatened," with a declining population. The survival of the species is important to the oceanic food chain because the yellowfin is a top predator. While it's impossible to measure the number of yellowfin tuna directly, researchers have recorded significant drops in catch sizes that indicate diminished population. Fishery sustainability varies dramatically from one location to another, however, so the fish is not threatened throughout its entire range. Overfishing is most significant in the Eastern Pacific and Indian Ocean.

Overfishing is the main threat to this species' survival, but there are other problems. Other risks include plastic pollution in the oceans, increasing predation of young, and decreasing availability of prey.

Yellow Fin Tuna and Humans

Yellowfin is highly valued for sport fishing and commercial fishing. It is the primary species of tuna used for canning in the United States. Most commercial fisheries use the purse seine method of fishing in which a vessel encloses a surface school within a net. Longline fishing targets deep-swimming tuna. Because tuna school with other animals, both methods carry significant risk of bycatch of dolphins, sea turtles, billfish, seabirds, and pelagic sharks. Fishermen seeking to reduce bycatch use streamers to scare away birds and select bait and locations to minimize the chance of fishing mixed schools.

Sources

• Collette, B.; Acero, A.; Amorim, A.F.; et al. (2011). "Thunnus albacares". The IUCN Red List of Threatened Species. 2011: e.T21857A9327139. doi:10.2305/IUCN.UK.2011-2.RLTS.T21857A9327139.en
• Collette, B.B. (2010). Reproduction and Development in Epipelagic Fishes. In: Cole, K.S. (ed.), Reproduction and sexuality in marine fishes: patterns and processes, pp. 21-63. University of California Press, Berkeley.
• Joseph, J. (2009). Status of the world fisheries for tuna. International Seafood Sustainability Foundation (ISSF).
• Schaefer, K.M. (1998). Reproductive biology of yellowfin tuna (Thunnus albacares) in the eastern Pacific Ocean. Bulletin of the Inter-American Tropical Tuna Commission 21: 201-272.