Maguro Sushi
A Detailed Overview of True Tuna in Japanese Sushi Cuisine

Maguro (鮪) is the Japanese collective term for the eight species of the genus Thunnus. In upscale Japanese cuisine, the term frequently refers to the bluefin tunas, collectively known as hon maguro (本鮪, literally "true tuna") – the Pacific bluefin (T. orientalis), the Atlantic bluefin (T. thynnus), and the southern bluefin (T. maccoyii). For sushi and sashimi, the bigeye tuna (T. obesus), the yellowfin tuna (T. albacares), and to a lesser extent the albacore (T. alalunga) are also used.¹ Outside Japan, maguro in restaurant and trade contexts may refer to any tuna species; in upscale sushi restaurants, it typically refers to bluefin.

Culinarily, maguro is prized for the interplay of lean akami (赤身, lean red meat) and fatty toro (fatty tuna) – a range from lightly tart and metallic to rich and buttery.

The English term "tuna" is broader: it covers the entire tribe Thunnini, which depending on taxonomic delineation comprises four to five genera and 14 to 15 species, including the skipjack tuna (katsuo, 鰹).² In Japanese, tsuna – a loanword from English – refers primarily to processed tuna products such as canned tuna (tsuna kan), not to the fish itself. Conversely, certain fish carry maguro in their name without belonging to the genus: kajiki maguro (梶木鮪), for instance, refers to swordfish – a historically established vernacular name.

SUSHIPEDIA. Chutoro Bluefin Tuna Nigiri with Sturgeon Caviar. © SUSHIPEDIA

In the Edomae sushi tradition, maguro is considered the daikokubashira (大黒柱, mainstay) of a restaurant: among connoisseurs, the quality of a restaurant's maguro is said to reveal its standing.³ Raw akami nigiri (握り寿司), in particular, is served atop the shari (舎利, sushi rice) without further shigoto (仕事, preparatory work), so the quality of the fish is immediately apparent.⁴ In an omakase (chef's selection) course, akami typically appears in the middle portion – after the light white-fleshed fish (shiromi, 白身) and before the fattier cuts such as chūtoro (中トロ, medium-fatty tuna) and ōtoro (大トロ, fatty tuna belly).⁵ Flavor varies by species and cut: the dark-red lean flesh from the center of the body has a velvety texture and a subtly tart taste underscored by deep umami.

Toro refers to the fatty portions of the tuna, primarily along the belly. The flesh is tender, buttery-soft, and intensely rich, with a faint sweetness.

Experienced sushi shokunin (寿司職人, sushi artisans) store trimmed blocks of maguro on ice or under refrigeration for several days. Through this aging process, known in Japanese as jukusei (熟成, aging), proteins are enzymatically broken down into free amino acids, and the ATP stored in the muscle converts into the umami compound inosinic acid.⁷ The flesh loses much of its raw odor, develops more flavor, and becomes more tender. How long aging takes depends on the quality and condition of the maguro. If aged too long, the flesh loses its characteristic color.⁸ The sinew bands (suji, 筋), which hold together the fatty flesh, particularly in the belly, also soften during aging – with excessive storage, the flesh can lose its structure. Conversely, insufficiently aged maguro is tough and less aromatic.⁹

A study by the University of Tokyo's graduate school in cooperation with the restaurant chain Kura Sushi found that glutamic acid and inosinic acid reach their optimal ratio after 48 hours of aging.⁷ In high-end sushi restaurants, the aging process is tailored to the condition of the flesh and can last considerably longer.⁹ Whether aging succeeds – particularly in terms of microbiological quality – depends on temperature control, hygiene, and experience.

The fat content of tuna varies by species, season, and fishing region. It is typically highest shortly before spawning, when the fish accumulate fat reserves.

In Japanese waters, kuro maguro (黒鮪, T. orientalis) reaches its best quality in autumn and winter. In the Tsugaru Strait off Oma, the period from September through December is considered peak season; in Katsuura, the months of January and February.¹⁰ The summer fishery – off Fukaura in Aomori Prefecture (June–July), for example – yields specimens with a more moderate fat content, prized as a distinct seasonal specialty.¹¹

For the Atlantic bluefin (T. thynnus), peak flesh quality falls in late spring, shortly before spawning. The eastern Atlantic stock migrates through the Strait of Gibraltar into the Mediterranean in spring, where it spawns from June through August. The traditional almadraba fishery off the Andalusian coast catches tuna in May and June – at this stage, immediately before reproduction, the flesh is at its fattiest.^12, 13 The western Atlantic stock spawns from mid-April through June in the Gulf of Mexico.¹⁴

The seasonal pattern for minami maguro (南鮪, T. maccoyii) is reversed in the southern hemisphere. It reaches its best quality during the austral winter – corresponding to spring and summer (April–September) in the northern hemisphere.¹⁰

For the remaining species: mebachi (目鉢, T. obesus) from Japanese waters peaks in autumn and winter (October–December), while kihada (黄肌, T. albacares) reaches its best quality in western Japan during the summer (June–August). Both species are caught year-round in tropical waters, where quality fluctuates.¹⁰

Farm-fattened maguro, by contrast, is available year-round in consistent quality.

Tunas are fast, highly migratory predators found in all tropical, subtropical, and temperate oceans. Because tunas ventilate their gills only through forward movement (ram ventilation), they must swim continuously. Bluefin tunas reach speeds of up to 80 km/h (50 mph) and cover thousands of kilometers on their annual migrations. The largest tuna ever documented was an Atlantic bluefin of 678 kg (1,496 lb), caught in 1979 off Nova Scotia.¹⁵

The albacore (T. alalunga), in Japanese binnaga, is distinguished by its conspicuously long pectoral fins. It reaches up to 1.20 m (4 ft) in length and 60 kg (132 lb) in weight and is found in temperate to tropical waters of all oceans, though rarely in the Sea of Japan.¹⁶ Binnaga is the world's most important raw material for canned tuna. In sushi restaurants, the fatty belly section is served as bintoro – predominantly in lower-priced establishments.

The yellowfin tuna (T. albacares), in Japan kihada, is found in the tropical and subtropical waters of all oceans and swims comparatively close to the surface.¹⁷ In Japan it is landed mainly in Shizuoka, Miyagi, and Okinawa; Shizuoka records the highest catch volume in Japan.¹⁸ With a total annual supply of around 112,000 metric tons (2022), kihada is the most consumed tuna species in Japan.¹⁹ The flesh is pale pink, low in fat, and mild in flavor – in Japan it is particularly popular in the Kansai region and in Nagoya.¹⁷ Besides its use as a sushi and sashimi ingredient, kihada serves worldwide as a major raw material for canned tuna.

The Pacific bluefin tuna (T. orientalis) is known in Japan as kuro maguro or hon maguro and is regarded as the finest tuna for culinary use.¹⁷ It is the largest tuna species found in Japanese waters: mature specimens exceed 3 m (10 ft) in length and weigh over 400 kg (880 lb).¹⁶ Its range spans the entire North Pacific – from Sakhalin and the Philippines in the west to the Gulf of Alaska and Baja California in the east. Life expectancy exceeds 20 years.¹⁷ Japan's total supply of kuro maguro in 2022 amounted to roughly 61,800 metric tons, derived from domestic fisheries, aquaculture, and imports – with imports accounting for the largest share.¹⁹ In high-end restaurants, kuro maguro is used almost exclusively for raw preparations such as sushi and sashimi.

The longtail tuna (T. tonggol), in Japan koshinaga, is the smallest species of the genus at up to 145 cm (4 ft 9 in) in length and roughly 36 kg (80 lb) in weight.²⁰ It is found in the Indo-Pacific and prefers coastal waters; in Japan it is landed mainly in Nagasaki, Yamaguchi, and Shimane.²⁰ Koshinaga has the lowest volume on Japanese markets of any tuna species and is correspondingly little known. Because it closely resembles young kuro maguro (yokowa), it carries the market nickname bake (化け, "doppelgänger").²⁰ In flavor it resembles meji maguro, but is traded at considerably lower prices.

The bigeye tuna (T. obesus), in Japan mebachi, reaches up to 2.5 m (8 ft) in length and 210 kg (460 lb) in weight. It is found in the tropical and temperate waters of the Atlantic, Pacific, and Indian Oceans – but not in the Mediterranean and rarely in the Sea of Japan.¹⁷ Unlike most other tuna species, mebachi stays in deeper waters during the day and rises to the surface at night. The flesh is leaner than that of bluefin tuna and has a mild, broadly appealing flavor; mebachi does not yield a true ōtoro.¹⁶ In Japan it is traded primarily in the Kantō region and is the most frequently offered tuna in supermarkets and lower-priced sushi restaurants there.¹⁹

The southern bluefin tuna (T. maccoyii), known in Japan as minami maguro or indo maguro, lives exclusively in the southern hemisphere and reaches up to 245 cm (8 ft) in length and 260 kg (573 lb) in weight.¹⁷ After kuro maguro, it is considered the second-finest tuna for culinary use – its flesh is fatty enough to yield ōtoro, and at the Toyosu Market it occasionally commands higher prices than kuro maguro.^19, 21 Its season runs counter to the northern Pacific bluefin: minami maguro reaches its best quality in early summer, when kuro maguro carries little fat.²¹ The majority is exported to Japan as frozen product; farmed fish from Australia – particularly from Port Lincoln – increasingly supplements the supply. The IUCN classifies the species as critically endangered (CR); stocks have declined by over 90% since the 1960s.

The Atlantic bluefin tuna (T. thynnus), in Japan taiseiyō kuro maguro, is the largest species of the genus Thunnus: the IGFA record stands at 458 cm (15 ft) in length and 678 kg (1,496 lb) in weight.²² Its range encompasses the North Atlantic, the Mediterranean, the Caribbean, and the Gulf of Mexico; life expectancy is around 30 years. In the Mediterranean, taiseiyō kuro maguro is fattened on a large scale in net pens – a substantial share of this production goes to Japan as imports, accounting for close to half of the country's total kuro maguro supply.¹⁹ Culinarily it is on par with the Pacific kuro maguro: the flesh yields both high-quality akami and ōtoro.²² The IUCN upgraded the species in 2021 from endangered (EN) to least concern (LC).²³

The blackfin tuna (T. atlanticus), in Japan taiseiyō maguro, is the smallest species of the genus at around 1 m (3.3 ft) in length. It is found exclusively in the western Atlantic – from the Gulf of Mexico and the Caribbean to the Brazilian coast. In Japan it is neither imported nor traded and plays no role in sushi cuisine.

SUSHIPEDIA. Maguro Sushi - Know Your Tuna Meat Cuts · Sushipedia. © SUSHIPEDIA

In Japan, many fish species carry different names at different growth stages – a convention known as shusseuo (出世魚, lit. "promotion fish"). The name derives from the tradition of adopting a new name upon professional advancement; a fish whose naming follows this pattern is therefore considered auspicious.²⁴ Hon maguro also changes name as it grows but is traditionally not counted among the shusseuo. The reason lies in the archaic name shibi (鮪) for mature specimens: it sounded like shibi (死日, "day of death") and was considered a bad omen among samurai. The Edo-period chronicle Keichō Kenbunshū (慶長見聞集, ca. 1614) records that the sound of the word shibi "could be heard as shinichi and was therefore inauspicious."²⁵ From the mid-Edo period onward, the name maguro (真黒, lit. "entirely black," after the dark back color) came into use – the older designation shibi largely disappeared from everyday language.²⁶

Meji refers to young hon maguro weighing up to roughly 20 kg (44 lb).¹⁶ The flesh lacks the pronounced deep-red color of mature tuna – it more closely resembles that of katsuo (bonito). Since young tuna have not yet accumulated enough fat by summer, meji maguro is used for sushi or sashimi predominantly in winter.

Chūbō (中坊, lit. "middle boy") refers to tuna at an intermediate growth stage, weighing roughly 20 to 40 kg (44–88 lb).¹⁶ Fat content and flavor are already more pronounced than in meji, but do not yet reach the level of a fully mature fish.

Shibi (鮪) is the archaic Japanese name for tuna – it appears in the Kojiki and the Man'yōshū – and today refers to mature specimens from approximately 50 kg (110 lb) upward.¹⁶ Large hon maguro can exceed 3 m (10 ft) in length and 400 kg (880 lb) in weight; their life expectancy exceeds 20 years.

SUSHIPEDIA. Maguro Tuna Cross-section – Sushi Meat Quality Grades · Sushipedia. © SUSHIPEDIA

The body of a maguro is typically divided into three main sections.

• The foremost section is called kami.
• The middle section is called naka.
• The rear section is called shimo.

These three sections are further divided into back (se) and belly (hara) portions.²⁶ Head meat (nōten, 脳天, also tōniku, 頭肉) and collar meat (kama toro) are also utilized.

In the back meat, sinew density decreases from kami toward shimo; the middle section naka has the fewest sinews and commands the highest price.²⁶ In the belly meat the relationship is reversed: fat content is highest in the front area near the gills (hara kami) and decreases toward the tail.²⁷

SUSHIPEDIA. Maguro Tuna Akami Saku – Perfect for Sushi · Sushipedia. © SUSHIPEDIA

The flesh is classified by texture and fat content into several categories. Akami, the lean dark-red meat, is prized for its firm bite and pure, intense flavor. In contrast, toro refers to the fatty portions of the tuna with a buttery texture and full-bodied flavor. Toro is distinguished into ōtoro (大トロ, very fatty belly meat) and chūtoro (中トロ, medium-fatty meat). Ōtoro has the highest fat content, is heavily marbled, and is the most expensive grade.

The fatty meat is found primarily in older or larger specimens and especially in species that spend extended periods in cold waters. Ōtoro occurs only in kuro maguro (T. orientalis, T. thynnus) and minami maguro (T. maccoyii).²⁸ Smaller species such as the albacore (T. alalunga) or kihada (T. albacares) are lean – their flesh consists almost entirely of akami.²⁹

SUSHIPEDIA. Maguro Zuke Nigiri - Soy Sauce Marinated Tuna Sushi · Sushipedia. © SUSHIPEDIA

The lean meat of the maguro is known in Japanese as akami (赤身). Akami constitutes the largest share of a kuro maguro's flesh and is correspondingly less expensive than the fatty meat. The flesh is rich in proteins and minerals – its deep-red color results from a high concentration of myoglobin and hemoglobin, iron-containing proteins that also lend it a subtle metallic taste.³⁰ It carries a light sour note (sanmi, 酸味). As a rule, unspecified maguro sushi or sashimi refers to akami. The more expensive fatty meat is mentioned explicitly.

SUSHIPEDIA. Maguro Chutoro Saku – Premium Tuna for Sushi and Sashimi · Sushipedia. © SUSHIPEDIA

Before the spread of refrigeration, fresh tuna had limited shelf life. In the Edo period, as soy sauce production expanded in the Kantō region, the lean tuna flesh began to be cured in soy sauce – a technique known as zuke (漬け, soy marinade).³¹ The resulting maguro zuke (漬けマグロ) became one of the first nigiri sushi toppings. Fat-rich meat such as toro was unsuitable for this preservation method, as its high fat content prevented the sauce from penetrating.³¹

The salt in the soy sauce and the exclusion of air by the liquid extend the shelf life of the flesh.³² Moreover, soy sauce is rich in amino acids and amplifies the umami inherent in the tuna. As moisture is drawn out, the texture changes: the flesh becomes firmer, while the surface turns slightly tacky and velvety (nettori).³² In addition to plain soy sauce, individual blends containing sake and mirin (味醂, sweet rice wine) are used. Curing time varies according to personal preference, ranging from restrained and mild to intensely salty.

When breaking down a maguro, each block (kami, naka, shimo) is separated into an upper part near the backbone and an outer part near the skin (kawara). The upper, backbone-adjacent part has a characteristic triangular shape and is known as tenmi (天身).³³ It has the least sinew and the most intense tuna flavor.^26, 34 Tenmi is considered the highest quality of lean meat (tokujō no akami, 特上の赤身) and is distinguished by an even, dark-red color and a velvety texture.²⁶ The finest tenmi comes from the middle section (naka), where the sinews are least pronounced. For nigiri sushi and sashimi, it is one of the most sought-after akami cuts.

Below the dorsal fin lies a narrow piece of akami known as hireshita. The musculature in this region is heavily worked by the constant movement of the fin and, despite its low fat content, is remarkably tender. In sushi trade parlance, hireshita therefore carries the epithet "the toro of akami" (akami no toro).⁴ Because of its soft texture, the flesh is sliced thin and draped around the shari so that it envelops the rice – a shaping technique that differs from standard nigiri shaping.⁴ Hireshita belongs to the specialized vocabulary of itamae (板前, sushi chefs) and middlemen; the term rarely appears on ordinary menus.

SUSHIPEDIA. Maguro Negi Toro Gunkan Maki – Classic Sushi · Sushipedia. © SUSHIPEDIA

Chūtoro comes from parts of the back and belly and can account for up to 30% of the total mass. Accordingly, chūtoro is priced between lean and fatty meat. Within a block, dealers and sushi shokunin distinguish by position: the skin-side layer (kawagishi, 皮ぎし) is the fattiest part and is considered the premium part. The area adjacent to the bloodline (chi'aigishi, 血合いぎし) has few sinews and can be cleanly processed into saku blocks.³⁵

Along the upper edge of the back block, directly next to the dorsal fin, runs a strong sinew. The triangular piece between this sinew and the fin is called setoro (背トロ) or sankaku (三角, triangle).³⁵ It is the fattiest section of the entire back and is distinguished by fine-grained, evenly distributed fat deposits.³⁶ Setoro occurs in considerably smaller quantities than regular back chūtoro.

In particularly large and fatty specimens, a fine strip can be precisely separated between the chūtoro flesh and the skin. This elongated narrow section carries the nickname "pencil," which in Japanese is enpitsu. Enpitsu is marbled, tender, and full-bodied.⁶ Jiro Ono calls it the "king of chūtoro." Enpitsu requires tuna of exceptional quality. For this reason, this cut – even in the most exclusive sushi restaurants – is rarely available and is usually reserved for regular patrons.⁶ The term could not be confirmed as established outside the circle of Sukiyabashi Jiro.

In the middle section of the tuna, near the dorsal fin where the major vessels run, there is a cut known as hagashi or wakaremi. Because of its sinew-free texture, it is also called "stripeless chūtoro" (sujinashi no chūtoro, 筋なしの中トロ). Hagashi, together with enpitsu, ranks among the most coveted cuts of medium-fatty tuna. The preparation involves carefully separating or cutting into individual strips, which brings out the delicate, soft texture. This cut is highly prized for nigiri sushi.

In Japanese, toro is the umbrella term for the fatty portion of tuna. Before the Taishō era, the designation abu (from aburami, fatty meat) was in use. The name toro traces back to a regular customer of Yoshinozushi (吉野鮨本店) in Nihonbashi who, around 1918, suggested naming the fatty part after its melting texture (torotto).³⁷ Toro encompasses several quality grades distinguished by fat content and position on the fish.

SUSHIPEDIA. Maguro Otoro Saku – Exclusive Tuna Piece for Sushi · Sushipedia. © SUSHIPEDIA

Negitoro is a preparation of finely scraped or chopped tuna processed into a creamy mass and typically served as gunkan maki (軍艦巻き) or in rolls. The flesh comes either from the nakaochi (中落ち, flesh between the central bones) or from the sukimi (すき身, flesh scraped off the skin). The preparation is generally traced to Kintarōzushi (金太楼鮨) in Asakusa, which was among the first to put negitoro rolls on the menu in the 1960s.³⁸

The etymology of the name is disputed. The founder of Kintarōzushi, Maneyama Sadao (間根山貞雄), explained the name as a wordplay on the nearby restaurant Mugitoro in Asakusa: mugitoro → negitoro.³⁸ Japanese dictionaries – including the Kōjien and the Sanseido Kokugo Jiten – list negitoro as a compound of negi (scallion) and toro.³⁹ Alongside this, a popular theory holds that the name derives from negitoru (ねぎ取る, to scrape off) – derived from the construction term negiri (根切り, excavation), transferred to the scraping of flesh. The lexicographer Iima Hiroaki (飯間浩明), an editorial member of the Sanseido Kokugo Jiten, considers this a folk etymology: the verb negitoru is unattested outside this explanation and does not follow any productive word-formation pattern in Japanese.⁴⁰

In lower-priced restaurants, such as kaiten sushi (回転寿司) establishments, minced akami mixed with vegetable oil or shortening frequently serves as a substitute for genuine negitoro.⁴¹ This industrial variant goes back to the firm Akagi Suisan in Shibukawa (Gunma), which in 1987 developed a product from minced nakaochi with added vegetable fat and began distributing it at the Tsukiji Market from 1988.⁴²

Kama toro (鎌トロ) is one of the fattiest and rarest cuts of the tuna. The name derives from kama (鎌, sickle) – a designation for the area around the gill cover and pectoral fin, whose shape resembles a sickle blade. Kama toro is the fatty cut extracted from the interior of this bone structure, below the gill cover and in front of the belly.⁴³ The related term kamashita (カマ下) refers to the entire region below the kama, from which kama toro among other cuts is obtained.⁴⁴ From a single maguro, only two small pieces can be extracted.⁴⁵

Once removed, kama toro is distinguished by heavy marbling and very high fat content. In contrast to the kama region overall, which is riddled with bones and sinews, the cut itself is comparatively free of sinew.⁴⁵ Some connoisseurs prize kama toro above ōtoro – others find the fat content too intense.

SUSHIPEDIA. Tuna auction at the Tsukiji market in Tokyo, Japan. © SUSHIPEDIA

Ōtoro (大トロ) is the fattiest cut of the tuna. The prefix ō (大, here: exceedingly) marks it as the highest fat grade within the toro category, distinguished from chūtoro (中トロ, medium). Ōtoro comes predominantly from the front belly area (harakami, 腹上) and contains roughly 28 g of fat per 100 g according to the Japanese food composition tables – about twenty times that of lean akami.⁴⁶

Shimofuri (霜降り, frost pattern) refers to the finely marbled ōtoro within the harakami section in which white fat veins run through the red flesh – a pattern reminiscent of hoarfrost. The fine fat deposits give the flesh a delicate pinkish tone; as nigiri, shimofuri is sliced thin and at an angle (sogizukuri), since the high fat content would otherwise overwhelm the shari.⁴⁷

At the lower edge of the belly portion, where the ōtoro flesh thins toward the belly skin, lies the piece known as jabara (蛇腹, snake belly) or sunazuri (砂ずり).³⁵ It has a high fat content but also contains strong, closely spaced sinews.²⁶ The related haramo lies further outward, directly at the belly skin; it is the fattiest piece of the entire fish, but because of its firm sinew structure is predominantly served grilled or cooked.⁴⁴

Jabara can also be separated along the sinews into sinew-free strips using the hagashi technique.

Agoniku (顎肉, jaw meat) comes from the lower jaw of the tuna, a heavily worked muscle group connecting the head and the kama. Only one piece per fish is obtained. The flesh is fibrous, elastic, and rich in gelatin. Because of its firm structure, agoniku is not eaten raw but grilled with salt or prepared as a steak.²⁷

Nōten (脳天, lit. top of the head) refers to the flesh on the top of the tuna's head, above the eyes.²⁷ Only two pieces per fish are obtained, together accounting for 0.1–0.5% of body weight.²⁷ The fat content is comparable to that of chūtoro.⁴⁸ The sinew structure runs concentrically rather than in the parallel pattern found in the rest of the body. Alternative names include tsuno toro, hachi no mi (鉢の身), and tōniku (頭肉).²⁷

Hohoniku (頬肉) is the cheek meat of the tuna – the muscle that moves the jaw. Two pieces per fish are obtained, together weighing 80–100 g.²⁷ The flesh is fibrous and rich in collagen; it is predominantly served cooked, as a steak or grilled.²⁷

Tēru (from English "tail") refers to the tail section of the tuna, typically traded as a round cross-section slice. The tail stalk transmits the entire propulsive force to the caudal fin and is accordingly dense with muscle, sinew, and collagen.²⁶ Because of this structure, tēru is not suitable for raw consumption and is predominantly prepared as a steak. In some specimens, fat deposits extend into the tail – such pieces are considered particularly prized.²⁶

Until the Edo period, fresh tuna was available only in the coastal towns where it was landed. The spread of soy sauce and the zuke technique enabled the first long-distance trade in lean tuna flesh. The fatty toro could not be preserved this way, as its fat content prevented the soy sauce from penetrating – it spoiled quickly and was regarded as a low-grade fish (gezakana, 下魚) well into the postwar period.^49, 50 The derogatory expression neko matagi (猫またぎ, "even a cat would step over it") reflects this disdain.⁵¹ Only modern refrigeration technology and growing purchasing power in the postwar era changed the perception: toro rose from waste product to the most expensive sushi topping.⁵²

As a source of top-grade kinkai hon maguro (近海本鮪, nearshore-caught bluefin tuna), Oma in Aomori Prefecture holds a special place. The designation Ōma maguro is registered as a regional collective trademark (chiiki dantai shōhyō, 地域団体商標) with the Japan Patent Office.⁵⁴ Oma gained national attention in 1994, when a hon maguro of 440 kg (970 lb) was landed there – to this day the heaviest documented specimen from the Tsugaru Strait.⁵⁵ Other important fishing grounds for high-end sushi include waters off Shizuoka and Miyagi, around Sado, and in Katsuura Bay.

SUSHIPEDIA. Size Classifications of Hon Maguro Tuna. © SUSHIPEDIA

Japan is the world's largest market for tuna: the country consumes over 27% of global tuna production and accounts for roughly 80% of the global sashimi market.⁵⁶ Although the national catch – approximately 116,000 metric tons in 2022 according to the FAO – places Japan only fifth among fishing nations, total supply through extensive imports far exceeds domestic fisheries.¹⁹

SUSHIPEDIA. Global Maguro Tuna Production vs. Japanese Demand. © SUSHIPEDIA

Of the eight species, three dominate Japan's sushi and sashimi cuisine: kuro maguro as the premium product, mebachi as the most widely traded everyday fish, and kihada as the highest-volume species overall.¹⁹

SUSHIPEDIA. Global Catches of Thunnus Tuna by Species. © SUSHIPEDIA

Until the 1960s, hon maguro was a comparatively affordable fish. The postwar economic boom, the spread of deep-freezing technology, and the global expansion of sushi cuisine from the 1980s onward drove demand sharply upward.

Price depends on species, quality, season, fishing region, and catch method. In regular daily trading at the Toyosu Market, the per-kilogram price for fresh wild-caught hon maguro ranges from several thousand to tens of thousands of yen depending on quality; farmed fish is considerably cheaper, and frozen kihada maguro costs only a few hundred yen per kilogram. A single top-quality bluefin tuna can already fetch several million yen in daily trading – the bids at the New Year auction, however, exceed this level a hundredfold.⁵⁷

Every year on January 5, the hatsuzeri (初競り, first auction of the year) takes place at Toyosu Market (before 2018, at Tsukiji). The ichiban maguro (一番マグロ, the fish that fetches the highest bid) has little to do with ordinary market value. The auction serves as an advertising platform where major sushi chains and specialty wholesalers compete for the first fish – the ensuing media coverage is the actual objective.⁵⁸

The price trajectory of the hatsuzeri illustrates this mechanism: until 2010, bids rarely exceeded 10 million yen. In 2013, the price surpassed the 100-million mark for the first time (155.4 million yen). In 2019 – the first New Year after the move from Tsukiji to Toyosu – it reached 333.6 million yen. The current record is held by a 243 kg (536 lb) Oma maguro that was sold on January 5, 2026, for 510.3 million yen – purchased by the chain Sushizanmai, which then served the fish to its customers at regular prices. Since 2000, the ichiban maguro has come almost exclusively from Oma.⁵⁸

SUSHIPEDIA. Global Tuna Catch Volumes. © SUSHIPEDIA

Globally, roughly two-thirds of tuna is caught by purse seine, about one-tenth by longline.⁵⁶ The stocks of all three bluefin species have been considerably reduced by decades of overfishing. The IUCN lists minami maguro as critically endangered (CR) – stocks have declined by over 90% since the 1960s. Kuro maguro is classified as vulnerable (VU); taiseiyō kuro maguro was upgraded in 2021 from endangered (EN) to least concern (LC).²³ The Pacific kuro maguro reached its historical low point in 2010: according to the ISC, spawning biomass stood at just 1.7% of the pre-fishery baseline – roughly 12,000 metric tons.⁵⁹ In the eastern Atlantic, the ICCAT science committee estimated actual catches between 1998 and 2007 at 50,000 to 61,000 metric tons annually – far exceeding the official quotas.⁶⁰

At the CITES conference in March 2010 in Doha, Monaco and the European Union proposed an international trade ban on bluefin tuna. Japan and Canada – both with substantial economic interests in the bluefin fishery – opposed the motion. It failed with 20 votes in favor, 68 against, and 30 abstentions.⁶¹ In parallel, the responsible fisheries organizations pursued quota reductions: ICCAT tightened its recovery plan for the eastern Atlantic from 2006, and WCPFC and IATTC restricted juvenile catches in the Pacific to half from 2015 onward.⁵⁹

These measures have yielded results. The Pacific kuro maguro recovered to roughly 144,000 metric tons of spawning biomass by 2022 – twelve times the 2010 low – reaching the recovery target 13 years ahead of schedule.^59, 62 WCPFC and IATTC consequently decided in 2024 to raise the catch quota for large fish (over 30 kg) by 50% starting in 2025.⁶² In the eastern Atlantic as well, ICCAT classified fishing pressure as no longer excessive in 2017 and gradually increased the total allowable catch to 40,570 metric tons (2023–2025), with a further increase to 48,403 metric tons for 2026–2028.⁶⁰ Taiseiyō kuro maguro spawns in two genetically distinct populations – one in the Mediterranean and one in the Gulf of Mexico.²³ The massive overfishing of the late 1990s concentrated on the Mediterranean spawning grounds, where up to 99% of the purse-seine catch went directly into ranching operations.⁶³ The subsequent recovery was aided in part by an exceptionally strong 2003 birth cohort, which has been linked to the Mediterranean heat wave of that year.²³ Minami maguro, by contrast, remains the most severely threatened species – a comparable recovery has not yet occurred.

SUSHIPEDIA. Origin of Bluefin Tuna by Country. © SUSHIPEDIA

The majority of tuna marketed worldwide as "farmed" comes from ranching: wild-caught fish are fattened in nearshore net pens until they reach market weight.^64, 65 The Mediterranean region is the center of this practice – ICCAT recorded 69 licensed fattening operations there in 2022 with a total capacity exceeding 71,000 metric tons, distributed across Italy, Malta, Croatia, Spain, Turkey, and other littoral states.⁶³ Roughly 78% of Mediterranean production is short-term fattening of mature fish (over 30 kg, less than one year of holding); only in Croatia are juvenile fish also raised over a period of up to three years.⁶³ In Australia, ranching of minami maguro dominates, particularly at the Port Lincoln site.²¹

Distinct from ranching is full-cycle aquaculture (kanzen yōshoku, 完全養殖), in which the entire life cycle takes place in captivity. At Kindai University, after over 30 years of research, the closed life cycle for bluefin tuna was achieved for the first time in 2002; Kindai maguro has been commercially available since 2004.⁶⁶ In 2010, Maruha Nichiro followed as the first private company.⁶⁷ At peak output, the three largest operations – Maruha Nichiro, Nissui, and Kyokuyo – together produced over 1,800 metric tons annually (2020).⁶⁷ Since then, however, the industry has contracted drastically: Kyokuyo ceased operations in 2024, Nissui withdrew, and Maruha Nichiro reduced production for 2025 to 50 metric tons – roughly 5% of the peak.⁶⁷ The causes are a combination of rising feed costs (one kilogram of weight gain requires roughly 15 kg of feed fish), the recovery of wild stocks, and consequent declining market prices.⁶⁶

The flesh of fattened tuna is softer than that of wild-caught fish, and controlled feeding produces consistently high fat levels, resulting in a higher yield of toro.²¹ In high-end cuisine, wild-caught fish continues to be preferred on flavor grounds.¹⁶ The Japanese government nonetheless maintains in its strategy for a sustainable food system (Midori no Shokuryō Shisutemu Senryaku) the target of raising the share of hatchery-produced juveniles for kuro maguro to 100% by 2050 – in 2019 it stood below 2%.⁶⁶