''Thunnus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of ocean-dwelling,

ray-finned Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilag ...

from the mackerel family,

Scombridae The mackerel, tuna, and bonito family, Scombridae, includes many of the most important and familiar food fishes. The family consists of 51 species in 15 genera and two subfamilies. All species are in the subfamily Scombrinae, except the butterf ...

. More specifically, ''Thunnus'' is one of five

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

which make up the

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English language, English is in the discipline of anthropology. This definition is contested, in p ...

Thunnini A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length ...

– a tribe that is collectively known as the

tuna A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: ...

s. Also called the true tunas or real tunas, ''Thunnus'' consists of eight

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of tuna (more than half of the overall tribe), divided into two

subgenera In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...

. The word is the

Middle Latin Medieval Latin was the form of Literary Latin used in Roman Catholic Church, Roman Catholic Western Europe during the Middle Ages. In this region it served as the primary written language, though local languages were also written to varying deg ...

form of the Greek (, "tuna, ") – which is in turn derived from (, "to rush; to dart"). The first written use of the word was by

Homer Homer (; grc, Ὅμηρος , ''Hómēros'') (born ) was a Greek poet who is credited as the author of the ''Iliad'' and the ''Odyssey'', two epic poems that are foundational works of ancient Greek literature. Homer is considered one of the ...

. Their coloring, metallic blue on top and shimmering silver-white on the bottom, helps camouflage them from above and below.

Atlantic bluefin tuna The Atlantic bluefin tuna (''Thunnus thynnus'') is a species of tuna in the family Scombridae. It is variously known as the northern bluefin tuna (mainly when including Pacific bluefin as a subspecies), giant bluefin tuna or individuals excee ...

, the largest member of this genus, can grow to long and weigh up to . All tunas are extremely strong swimmers, and the

yellowfin tuna The yellowfin tuna (''Thunnus albacares'') is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide. Yellowfin is often marketed as ahi, from the Hawaiian language, Hawaiian , a name also used there for the closel ...

is known to reach speeds of up to when pursuing prey. As with all tunas, members of this genus are

warm-blooded Warm-blooded is an informal term referring to animal species which can maintain a body temperature higher than their environment. In particular, homeothermic species maintain a stable body temperature by regulating metabolic processes. The onl ...

, which is a rare trait among fish; this enables them to tolerate cold waters and to dive to deeper depths. Bluefin tunas, for example, are found in

Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...

and

Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...

, and also in the tropical waters of the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

and the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

, where some individuals go each year to spawn. Due to

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in th ...

, the range of this genus has declined significantly, having been effectively extirpated from the

Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Roma ...

, for example.

Taxonomy

Based on morphology and short-length

mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

sequence data, the genus ''Thunnus'' is currently classified into two

: ''Thunnus (Thunnus)'' (the bluefin group), and ''Thunnus (Neothunnus)'' (the yellowfin group). However this classification has been questioned by a recent phylogenetic analysis of nuclear DNA sequence data, which resolved different relationships among species and did not support the traditional definition of the bluefin and yellowfin groups. Specifically, these analyses substantiated the division of Pacific and Atlantic Tuna in two separate species and suggested that Bigeye Tuna were actually a member of subgenus ''Neothunnus'', not subgenus ''Thunnus''. Earlier nuclear

ribosomal DNA Ribosomal DNA (rDNA) is a DNA sequence that codes for ribosomal RNA. These sequences regulate transcription initiation and amplification, and contain both transcribed and non-transcribed spacer segments. In the human genome there are 5 chromos ...

phylogenetic reconstructions also showed similar results. Thunnus spec 01

This genus has eight species in two

: * Subgenus ''Thunnus (

Thunnus ''Thunnus'' is a genus of ocean-dwelling, ray-finned bony fish from the mackerel family, Scombridae. More specifically, ''Thunnus'' is one of five genera which make up the tribe Thunnini – a tribe that is collectively known as the tunas. ...

)'': **

Albacore The albacore (''Thunnus alalunga''), known also as the longfin tuna, is a species of tuna of the order Perciformes. It is found in temperate and tropical waters across the globe in the epipelagic and mesopelagic zones. There are six distinct sto ...

, ''T. alalunga'' ( Bonnaterre, 1788) **

Southern bluefin tuna The southern bluefin tuna (''Thunnus maccoyii'') is a tuna of the family (biology), family Scombridae found in open southern Hemisphere waters of all the world's oceans mainly between 30th parallel south, 30°S and 50th parallel south, 50°S, to ...

, ''T. maccoyii'' ( Castelnau, 1872) **

Bigeye tuna The bigeye tuna (''Thunnus obesus'') is a species of true tuna of the genus '' Thunnus'', belonging to the wider mackerel family Scombridae. In Hawaiian, it is one of two species known as ahi, the other being the yellowfin tuna. Bigeye tuna are ...

, ''T. obesus'' (Lowe, 1839) **

Pacific bluefin tuna The Pacific bluefin tuna (''Thunnus orientalis'') is a predatory species of tuna found widely in the northern Pacific Ocean, but it is migratory and also recorded as a visitor to the south Pacific. In the past it was often included in '' T. thyn ...

, ''T. orientalis'' (

Temminck Coenraad Jacob Temminck (; 31 March 1778 – 30 January 1858) was a Dutch aristocrat, zoologist and museum director. Biography Coenraad Jacob Temminck was born on 31 March 1778 in Amsterdam in the Dutch Republic. From his father, Jacob Temmin ...

Schlegel Schlegel is a German occupational surname. Notable people with the surname include: * Anthony Schlegel (born 1981), former American football linebacker * August Wilhelm Schlegel (1767–1845), German poet, older brother of Friedrich * Brad Schlege ...

, 1844) **

, ''T. thynnus'' (

Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...

1758 Events January–March * January 1 – Swedish biologist Carl Linnaeus (Carl von Linné) publishes in Stockholm the first volume (''Animalia'') of the 10th edition of Systema Naturae, 10th edition of ''Systema Naturae'', the sta ...

) * Subgenus ''Thunnus (

Neothunnus ''Thunnus (Neothunnus)'' is a subgenus of ray-finned bony fishes in the Thunnini, or tuna, tribe. More specifically, ''Neothunnus'' is a subgenus of the genus ''Thunnus'', also known as the "true tunas". ''Neothunnus'' is sometimes referred t ...

)'': **

Yellowfin tuna The yellowfin tuna (''Thunnus albacares'') is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide. Yellowfin is often marketed as ahi, from the Hawaiian language, Hawaiian , a name also used there for the closel ...

, ''T. albacares'' ( Bonnaterre, 1788) **

Blackfin tuna The blackfin tuna (''Thunnus atlanticus'') is a species of tuna in the family Scombridae. It is occasionally referred to as the bermuda tuna, blackfinned albacore, or deep bodied tunny. They are the smallest tuna species in the genus ''Thunnus'', ...

, ''T. atlanticus'' (

Lesson A lesson or class is a structured period of time where learning is intended to occur. It involves one or more students (also called pupils or learners in some circumstances) being taught by a teacher or instructor. A lesson may be either one ...

, 1831) **

Longtail tuna ''Thunnus tonggol'' is a species of tuna of tropical Indo-West Pacific waters. It is commonly known as the longtail tuna or northern bluefin tuna.Hutchins, B. & Swainston, R. (1986). ''Sea Fishes of Southern Australia.'' pp. 104 & 141. Allen, G. ...

, ''T. tonggol'' (

Bleeker Bleeker is a Dutch occupational surname. Bleeker is an old spelling of ''(linnen)bleker'' ("linen bleacher").

Species

Until recently, seven ''Thunnus'' species were thought to exist, and Atlantic bluefin tuna and Pacific bluefin tuna were

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

of a single species. In 1999, Collette established that based on both molecular and morphological considerations, they are, in fact, distinct species. Tuna sizes

Overfishing

The worldwide demand for

sushi is a Japanese cuisine, Japanese dish of prepared , usually with some sugar and salt, accompanied by a variety of , such as seafood, often raw, and vegetables. Styles of sushi and its presentation vary widely, but the one key ingredient is " ...

and

sashimi is a Japanese delicacy consisting of fresh raw fish or meat sliced into thin pieces and often eaten with soy sauce. Origin The word ''sashimi'' means "pierced body", i.e. "刺身" = ''sashimi'', where 刺し = ''sashi'' (pierced, stuck) ...

, coupled with increasing population growth, has resulted in global stocks of the species being overfished and bluefin is the most endangered and considered "a serious conservation concern". Complicating the efforts for sustainable management of bluefin fish stocks within national exclusive economic zones ( EEZ) is bluefin migrate long distances and hunt in the midocean that is not part of any country's EEZ, so have been vulnerable to overfishing by multiple countries' fishing fleets. International agreements and conventions are good-faith agreements and are difficult to monitor or enforce. Though this fish has been farmed in captivity by the Japanese and by the Australians with the help of the Japanese, yields are lower than other farmed fish due to the slow growth rate of bluefin tuna, therefore keeping prices high. On December 30, 2012, a bluefin tuna caught off northeastern Japan, was sold at the

Tsukiji fish market is a major tourist attraction for both domestic and overseas visitors in Tokyo. The area contains retail markets, restaurants, and associated restaurant supply stores. Before 2018, it was the largest wholesale fish and seafood market in the wor ...

Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, with an estimated 37.468 ...

for a record 155.4 million yen ($1.76 million) – a unit price of JP¥ 1.274 million/kg (US$3,600/lb).

References

External links

*
Nutritional benefits of tuna

The International Commission for the Conservation of Atlantic Tunas
{{Authority control Marine fish genera Extant Cenozoic first appearances

Taxonomy

Species

Overfishing

References

Further reading

External links