Tuna is a fish that lives in schools in almost all temperate seas of the world and feeds on small fish. It migrates in the spring, after spawning, heading back to colder waters where it is easier to find food.
Bluefin tuna has always been admired for the beauty of its shape and is sought after for the exceptional quality of its flesh. Its overfishing is not a new phenomenon! Since time immemorial, it has attracted humans because of its delicious flavor, but also for economic reasons, because of its high yield.
It was fished in every way possible in ancient times: fishing lines, tridents, spears, nets, and traps were all used. Greeks and Romans salted it, preserved it in olive oil, and smoked it. The Romans also used tuna entrails to make garum, while the neck and belly, the best pieces, were eaten fresh, and the rest was preserved.
In Japan, where the diet is centered on seafood, bluefin tuna is hugely popular: 80% of the tuna fished in the entire world is consumed in this country. There are strict quality criteria, mainly focusing on the fat content and flesh color. The otori and chutoro pieces are the best, with a fat content of around 25%.
A tuna steak should be firm but soft, without any sign of dryness or the slightest whiff of ammonia.
The origin and type of tuna should always be checked with the supplier.
The belly should be pink and fatty.
Fresh tuna can be bought from fish stores and wholesalers.
Frozen tuna is available sliced, with or without skin, with or without the central bone, from the United States, Vietnam, Indonesia, and Morocco (the species of tuna species should always be verified), and in vacuum-packed ready-to-cook steaks.
Tuna can also be bought dried, in fillets that have been salted and dried and/or smoked, in flakes (usually bonito) of varying size, or very finely grated.
Canned: plain, in oil, marinated, or flavored in various ways.
Tuna, when impeccably fresh, can be eaten raw: sushi, sashimi, ceviche, and tartar.
It must always be cooked quickly, otherwise the meat dries out and becomes chewy: it should be served quite rare, whether it is roasted, fried, broiled, or poached.
Canned tuna is often used in salads or quiches. Dried and sliced, it is used like ham.
In Japan, shavings of dried bonito are used to add flavor to broths, soups, and many sauces. The finest flakes are used as seasoning, in the same way as salt. They also go rather well with pasta, risotto, and even vegetables.
Fresh tuna goes off quickly. It can be kept for a maximum of 24 hours in the refrigerator or cold room at 4°C. The slices should be dried and then placed on a rack so that they are not left sitting in their own juice.
Frozen tuna must be put straight into the freezer, without interruption of the cold chain.
Dried, it will keep in a cool dry place in its original container.
Tuna is rich in protein, minerals, and B vitamins. It is a so-called oily fish: the majority of its fat consists of unsaturated fatty acids, including Omega 3.
However, it is the most contaminated fish: its flesh stores dangerous levels of mercury, a toxic metal, which comes from industrial waste discharged into the sea. Unfortunately, the bigger the tuna, the more of this metal it stores. This is why it is only recommended to eat tuna once or twice a week. Pregnant women are advised to avoid it entirely.
Albacore or yellowfin tuna (Thunnus albacares)
Quite slender, it is 60–150 cm long and weighs 10–60 kg. Its tail and back fins are yellow, hence its name. Its flesh is light pink and tasty. It is quite difficult to find fresh yellowfin tuna because it is primarily canned.
Bonito or skipjack tuna
Four species bear this name: the Australian bonito (Sarda australis), which lives off the coast of Australia; the Pacific bonito (Sarda chiliensis), found in the eastern Pacific; the Atlantic bonito (Sarda sarda), which is fished in the Atlantic, Mediterranean, and the Black Sea; and the Skipjack tuna (Katsuwonus pelamis), which lives in the Pacific Ocean.
Bonitos are smaller, weighing 5–10 kg. Their red meat is particularly tasty. In France, bonito is mainly available in summer (July through August). This is the most fished species in the world.
German bonito or albacore (Thunnus alalung_a)_
It can weigh 30–40 kg and grow up to 55–100 cm long. It has pinkish white, very tasty, flesh that is reminiscent of veal. Caught in the Bay of Biscay, the Atlantic, and the Pacific, it is found from May through October. In French, the word albacore refers to the yellowfin tuna, which can lead to confusion.
Blackfin tuna (Thunnus atlanticus)
It weighs a maximum of 12 kg. It is only fished in the southwest Atlantic. It has very delicate flesh.
Bigeye Tuna (Thunnus obesus)
It weighs 80–90 kg. Its flesh is pinkish red, and particularly fine. It is fished in the Atlantic all year round.
The giant of the family: it can weigh up to 600 kg. There are three species of bluefin tuna:
Northern bluefin tuna or Atlantic bluefin tuna (Thunnus thynnus). It lives in the Atlantic and the Mediterranean. This is the most sought-after species, and has therefore been overfished for many years. It is now endangered and so fishing for this tuna is (in theory) highly regulated.
Southern bluefin tuna (Thunnus maccoyii), which lives in all the oceans of the southern hemisphere.
Pacific bluefin tuna (Thunnus orientalis). It lives in the western Pacific Ocean and is farmed in Australia.
These last two species are less threatened.
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