Origin – Vietnam, Pacific Islands
- Presentation – Filles, Loins, Saku, Steaks
Fisheries and habitat
The yellowfin tuna is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide.
The yellowfin tuna is often marketed as ahi tuna, from its Hawaiian name ʻahi although the name ʻahi in Hawaiian also refers to the closely related bigeye tuna. Although the species name “albacares” might suggest otherwise, the fish usually known as albacore is a different species of tuna, Thunnus alalunga. The yellowfin tuna is however sometimes referred to as albacora by French and Portuguese fishermen.
Habitat and behaviour
Yellowfin tuna are epipelagic fish that inhabit the mixed surface layer of the ocean above the thermocline. Sonic tracking has found that although yellowfin tuna, unlike the related bigeye, mostly range in the top 100 m (330 feet) of the water column and penetrate the temperature barrier of the thermocline relatively infrequently, they are capable of diving to considerable depths. An individual tagged in the Indian Ocean with an archival tag spent 85% of its time in depths shallower than 75 m but was recorded as having made three dives to 578 m, 982 m and an incredible 1160 m. Deeper diving and cruising behaviour seems to happen more often in the daytime, changing to shallower swimming behaviour at night, probably in response to the vertical movement of prey items in the deep scattering layer.
The yellowfin tuna is one of the largest tuna species, reaching weights of over 300 lbs – significantly smaller than the Atlantic and Pacific bluefin tunas that can reach over 1,000 lbs and slightly smaller than the bigeye tuna and the southern bluefin tuna.
Although mainly found in deep offshore waters, yellowfin tuna can be found close to shore when suitable conditions exist. Mid-ocean islands such as the Hawaiian archipelago, other island groups in the Western Pacific, Caribbean and Indian Ocean, as well as the volcanic islands of the Atlantic such as Ascension Island often find yellowfin feeding on the baitfish these areas concentrate very close to the shoreline. Yellowfin tuna will also venture well inshore of the continental shelf when water temperature and clarity are suitable and when there is an abundant food source to exploit.
Diet and predation
Yellowfin tuna consume a wide variety of feed items ranging from other fish to pelagic crustaceans, and squid. Like all tunas their body shape is evolved for speed, enabling them to pursue and capture even fast-moving baitfish such as flying fish, saury and mackerel. Schooling species such as myctophids or lanternfish and similar pelagic driftfish, anchovies, sardines and squid are frequently taken. Large yellowfin will also prey on smaller members of the tuna family such as frigate mackerel and skipjack tuna.
In turn, yellowfin tuna are preyed upon when young by other pelagic hunters including larger tuna, seabirds and predatory fishes such as wahoo, sharks and billfishes. As they increase in size and speed, yellowfin become able to escape most of their predators. Fully adult yellowfin tuna are threatened only by the largest and fastest hunters such as toothed whales, particularly the false killer whale, pelagic sharks such as the mako and great white, and large blue marlin and black marlin. Industrial tuna fishing is by far the most significant cause of mortality in adult yellowfin tuna.
Use as food
In terms of whether the yellowfin tuna fishing industry is sustainable, the jury is out. The Audubon’s Seafood Guide (a guide for what types of marine food products are not eco-friendly) lists yellowfin tuna that have been troll-caught as “OK” but those that have been long-line caught as “Be Careful”.
Yellowfin is becoming a popular replacement for the severely depleted supplies of Southern bluefin tuna.