Tuna is a saltwater fish that belongs to the tribe Thunnini, a sub-grouping of the mackerel family (Scombridae) – which together with the tunas, also includes the bonitos, mackerels, and Spanish mackerels. Thunnini comprises fifteen species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max. length: 50 cm (1.6 ft), weight: 1.8 kg (4 lb)) up to the Atlantic bluefin tuna (max. length: 4.6 m (15 ft), weight: 684 kg (1,508 lb)).
The bluefin averages 2 m (6.6 ft), and is believed to live for up to 50 years.
Yellowfin Tuna (Thunnus albacares) is often marketed as ahi, from the Hawaiian ʻahi, a name also used there for the closely related bigeye tuna. The species name, albacares (“white meat”) can also lead to confusion: in English, the albacore tuna (Thunnus alalunga) is a different species, while yellowfin is officially designated albacore in French and referred to as albacora by Portuguese fishermen.
Tuna and mackerel sharks are the only species of fish that can maintain a body temperature higher than that of the surrounding water. An active and agile predator, the tuna has a sleek, streamlined body, and is among the fastest-swimming pelagic fish – the yellowfin tuna, for example, is capable of speeds of up to 75 km/h (47 mph). Found in warm seas, it is extensively fished commercially, and is popular as a game fish. As a result of overfishing, stocks of some tuna species, such as the southern bluefin tuna, are close to extinction.
Tuna Loin (Natural)
Tuna Loin (CO-Treated)
Tuna loin are the largest cuts of meat that processors cut from a whole tuna fish. There are four loins on each fish. Several species of tuna are popular, such as the yellowfin, bigeye, bluefin and albacore tuna.
During tuna landing, the tuna is checked and graded according to the folloiwng grade:
AAA, AA, A, B+, B, B-, C, D
Longline fishing uses a long mainline made of tarred rope or nylon monofilament to which are attached hundreds or thousands of branchlines, each with a single baited hook. The mainline can be from 5 to 100nm long. The line is suspended in the water by floatlines attached to floats, which may have flagpoles, lights, or radio beacons. Longlines are usually set and hauled once daily and are allowed to drift freely, or soak, for several hours while fishing. Longlines are set, either by hand or mechanically, while the boat steams away from the line and are usually hauled mechanically while the boat steams toward the line. The species targeted are tuna and some billfish.