Yellowfin tuna
Overview
 
The yellowfin tuna is a species of tuna
Tuna
Tuna is a salt water fish from the family Scombridae, mostly in the genus Thunnus. Tuna are fast swimmers, and some species are capable of speeds of . Unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red coloration derives from myoglobin, an...

 found in pelagic waters of tropical and subtropical ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

s worldwide.

Yellowfin is often marketed as ahi, from its Hawaiian
Hawaiian language
The Hawaiian language is a Polynesian language that takes its name from Hawaii, the largest island in the tropical North Pacific archipelago where it developed. Hawaiian, along with English, is an official language of the state of Hawaii...

 name ahi although the name ahi in Hawaiian
Hawaiian language
The Hawaiian language is a Polynesian language that takes its name from Hawaii, the largest island in the tropical North Pacific archipelago where it developed. Hawaiian, along with English, is an official language of the state of Hawaii...

 also refers to the closely related bigeye tuna
Bigeye tuna
The bigeye tuna, Thunnus obesus, is an important food fish and prized recreational game fish. It is a true tuna of the genus Thunnus, belonging to the wider mackerel family Scombridae....

. The species name, albacares ("white meat") can lead to confusion. The tuna known as albacore
Albacore
The albacore, Thunnus alalunga, is a type of tuna in the family Scombridae. This species is also called albacore fish, albacore tuna, albicore, longfin, albies, pigfish, tombo ahi, binnaga, Pacific albacore, German bonito , longfin tuna, longfin tunny, or even just tuna...

 in English, is a different species of tuna: Thunnus alalunga.
Encyclopedia
The yellowfin tuna is a species of tuna
Tuna
Tuna is a salt water fish from the family Scombridae, mostly in the genus Thunnus. Tuna are fast swimmers, and some species are capable of speeds of . Unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red coloration derives from myoglobin, an...

 found in pelagic waters of tropical and subtropical ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

s worldwide.

Yellowfin is often marketed as ahi, from its Hawaiian
Hawaiian language
The Hawaiian language is a Polynesian language that takes its name from Hawaii, the largest island in the tropical North Pacific archipelago where it developed. Hawaiian, along with English, is an official language of the state of Hawaii...

 name ahi although the name ahi in Hawaiian
Hawaiian language
The Hawaiian language is a Polynesian language that takes its name from Hawaii, the largest island in the tropical North Pacific archipelago where it developed. Hawaiian, along with English, is an official language of the state of Hawaii...

 also refers to the closely related bigeye tuna
Bigeye tuna
The bigeye tuna, Thunnus obesus, is an important food fish and prized recreational game fish. It is a true tuna of the genus Thunnus, belonging to the wider mackerel family Scombridae....

. The species name, albacares ("white meat") can lead to confusion. The tuna known as albacore
Albacore
The albacore, Thunnus alalunga, is a type of tuna in the family Scombridae. This species is also called albacore fish, albacore tuna, albicore, longfin, albies, pigfish, tombo ahi, binnaga, Pacific albacore, German bonito , longfin tuna, longfin tunny, or even just tuna...

 in English, is a different species of tuna: Thunnus alalunga. However, yellowfin tuna is officially designated albacore in French, and is referred to as albacora by Portuguese fishermen.

Description

The yellowfin tuna is one of the largest tuna species, reaching weights of over 300 pounds (136.1 kg), but is significantly smaller than the Atlantic
Northern bluefin tuna
The Northern bluefin tuna is a species of tuna in the Scombridae family. It is variously known as the Atlantic bluefin tuna, giant bluefin tuna and formerly as the tunny. Atlantic bluefin are native to both the western and eastern Atlantic Ocean, as well as the Mediterranean Sea...

 and Pacific bluefin
Pacific bluefin tuna
Pacific bluefin tuna, Thunnus orientalis are some of the biggest and fastest fish in the Pacific Ocean.They possess streamlined bodies to reduce water resistance and conserve energy for trans-Pacific migrations...

 tunas that can reach over 1000 pounds (453.6 kg) and slightly smaller than the bigeye tuna and the southern bluefin tuna
Southern bluefin tuna
The southern bluefin tuna, Thunnus maccoyii, is a tuna of the family Scombridae found in open southern hemisphere waters of all the world's oceans mainly between 30°S and 50°S, to nearly 60°S...

. Reported sizes in the literature have ranged as high as 239 centimetres (94.1 in) in length and 200 kilograms (440.9 lb) in weight. The International Game Fish Association
International Game Fish Association
The International Game Fish Association is the leading authority on angling pursuits and the keeper of the most current World Record fishing catches by fish categories. Fishermen who are sport fishers are careful to follow their stringent rules for fair play and line requirements in order to...

 (IGFA) record for this species stands at 388 pounds (176 kg). Angler Kurt Wiesenhutter boated this fish in 1977 near San Benedicto Island in the Pacific waters of Mexico. Two larger fish weighing 395 lb and 399.6 lb were boated in 1992 and 1993 respectively. These remarkable fish stand as the largest rod and reel yellowfin tuna captures thus far. On November 30, 2010, Mike Livingston of Sunland, California reeled in a 405.2 lb Yellowfin off the tip of the Baja peninsula aboard the vessel the Vagabond. Livingston's 86 inches (2,184.4 mm) catch, which had a girth of 61 inches (1,549.4 mm), is still pending verification by the International Game Fish Association to replace Wiesenhutter's 388 pounder as the new all-tackle World Record holder.

The second dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

 and the anal fin, as well as the finlets between those fins and the tail, are bright yellow, giving this fish its common name. The second dorsal and anal fins can be very long in mature specimens, reaching almost as far back as the tail and giving the appearance of sickle
Sickle
A sickle is a hand-held agricultural tool with a variously curved blade typically used for harvesting grain crops or cutting succulent forage chiefly for feeding livestock . Sickles have also been used as weapons, either in their original form or in various derivations.The diversity of sickles that...

s or scimitars. The pectoral fins are also longer than the related bluefin tuna, but not as long as those of the albacore
Albacore
The albacore, Thunnus alalunga, is a type of tuna in the family Scombridae. This species is also called albacore fish, albacore tuna, albicore, longfin, albies, pigfish, tombo ahi, binnaga, Pacific albacore, German bonito , longfin tuna, longfin tunny, or even just tuna...

. The main body is very dark metallic blue, changing to silver on the belly, which has about 20 vertical lines.

Habitat

Yellowfin tuna are epipelagic fish that inhabit the mixed surface layer of the ocean above the thermocline
Thermocline
A thermocline is a thin but distinct layer in a large body of fluid , in which temperature changes more rapidly with depth than it does in the layers above or below...

. Sonic tracking has found that although yellowfin tuna, unlike the related bigeye tuna
Bigeye tuna
The bigeye tuna, Thunnus obesus, is an important food fish and prized recreational game fish. It is a true tuna of the genus Thunnus, belonging to the wider mackerel family Scombridae....

, mostly range in the top 100 metres (328.1 ft) of the water column and penetrate 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 metres (246.1 ft) but was recorded as having made three dives to 578 m, 982 m and 1160 metres (3,805.8 ft).

Life history

Deeper diving and cruising seems to happen more often in the daytime, changing to shallower swimming at night, probably in response to the vertical movement of prey items in the deep scattering layer. They are normally a schooling fish and stay in their immediate school.
Although mainly found in deep offshore waters, yellowfin tuna may approach shore when suitable conditions exist. Mid-ocean islands such as the Hawaiian archipelago, other island groups in the Western Pacific, Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

 and Maldives islands Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

, as well as the volcanic islands
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 of the Atlantic such as Ascension Island
Ascension Island
Ascension Island is an isolated volcanic island in the equatorial waters of the South Atlantic Ocean, around from the coast of Africa and from the coast of South America, which is roughly midway between the horn of South America and Africa...

 often harbor yellowfin feeding on the baitfish these spots concentrate close to the shoreline. Yellowfin may venture well inshore of the continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...

 when water temperature and clarity are suitable and food is abundant.

Yellowfin tuna often travel in schools with similarly sized companions. They sometimes school with other tuna species and mixed schools of small yellowfin and skipjack tuna
Skipjack tuna
The skipjack tuna, Katsuwonus pelamis, is a medium-sized perciform fish in the tuna family, Scombridae. It is otherwise known as the aku, arctic bonito, mushmouth, oceanic bonito, striped tuna, or victor fish...

, in particular, are commonplace. They are often associated with various species of dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...

s or porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...

s, as well as with larger marine creatures such as whale
Whale
Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...

s and whale shark
Whale shark
The whale shark, Rhincodon typus, is a slow-moving filter feeding shark, the largest extant fish species. The largest confirmed individual had a length of and a weight of more than , but unconfirmed claims report considerably larger whale sharks...

s. They also associate with drifting flotsam such as logs and pallets, and sonic-tagging indicates that some follow moving vessels. Hawaiian yellowfin associate with anchored fish aggregation devices (FADs) and with certain sections of the 50-fathom curve.

Diet and predation

Yellowfin tuna prey include other fish, pelagic crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, and squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...

. Like all tunas their body shape is evolved for speed, enabling them to pursue and capture fast-moving baitfish such as flying fish, saury
Saury
Sauries are fish of the family Scomberesocidae. There are two genera, each containing two species. The name Scomberesocidae is derived from the Greek, skombros = tuna/mackerel, and esox = nursery of salmon....

 and mackerel
Mackerel
Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. They may be found in all tropical and temperate seas. Most live offshore in the oceanic environment but a few, like the Spanish mackerel , enter bays and can be...

. Schooling species such as myctophids or lanternfish
Lanternfish
Cooper Lanternfishes are small mesopelagic fish of the large family Myctophidae. One of two families in the order Myctophiformes, the Myctophidae are represented by 246 species in 33 genera, and are found in oceans worldwide. They are aptly named after their conspicuous use of bioluminescence...

 and similar pelagic driftfish, anchovies
Anchovy
Anchovies are a family of small, common salt-water forage fish. There are 144 species in 17 genera, found in the Atlantic, Indian, and Pacific Oceans. Anchovies are usually classified as an oily fish.-Description:...

 and sardine
Sardine
Sardines, or pilchards, are several types of small, oily fish related to herrings, family Clupeidae. Sardines are named after the Mediterranean island of Sardinia, around which they were once abundant....

s are frequently taken. Large yellowfin prey on smaller members of the tuna family such as frigate mackerel and skipjack tuna
Skipjack tuna
The skipjack tuna, Katsuwonus pelamis, is a medium-sized perciform fish in the tuna family, Scombridae. It is otherwise known as the aku, arctic bonito, mushmouth, oceanic bonito, striped tuna, or victor fish...

.

In turn, yellowfin are preyed upon when young by other pelagic hunters, including larger tuna, seabirds and predatory fishes such as wahoo
Wahoo
The wahoo is a scombrid fish found worldwide in tropical and subtropical seas. It is best known to sports fishermen, as its speed and high-quality flesh make it a prize game fish...

, shark and billfish
Billfish
The term billfish is applied to a number of different large, predatory fish characterised by their large size and their long, sword-like bill. Billfish include the sailfish and marlin, which make up the family Istiophoridae, and the swordfish, sole member of the family Xiphiidae...

. As they increase in size and speed, yellowfin become able to escape most of their predators. Adults are threatened only by the largest and fastest hunters, such as toothed whale
Toothed whale
The toothed whales form a suborder of the cetaceans, including sperm whales, beaked whales, dolphins, and others. As the name suggests, the suborder is characterized by the presence of teeth rather than the baleen of other whales.-Anatomy:Toothed whales have a single blowhole on the top of the head...

s, particularly the false killer whale
False Killer Whale
The False Killer Whale is a cetacean, and the third largest member of the oceanic dolphin family . It lives in temperate and tropical waters throughout the world. As its name implies, the False Killer Whale shares characteristics, such as appearance, with the more widely known Orca...

, pelagic sharks such as the mako
Isurus
Isurus is a genus of mackerel sharks in the family Lamnidae, commonly known as the mako sharks. There are two living species, the common shortfin mako shark and the rare longfin mako shark , and several extinct species known from fossils. They range in length from 9 to 15 feet, and have an...

 and great white
Great white shark
The great white shark, scientific name Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a large lamniform shark found in coastal surface waters in all major oceans. It is known for its size, with the largest individuals known to have approached...

, and large blue marlin
Blue marlin
Blue marlin may refer to:* Atlantic blue marlin, Makaira nigricans* Indo-Pacific blue marlin, Makaira mazara, whether or not it is a separate species from Makaira nigricans is currently debated* MV Blue Marlin, a heavy transport ship...

and black marlin
Black marlin
The black marlin is a species of marlin found in tropical and subtropical Indo-Pacific oceans not far from the surface. It is a large commercial game fish with a maximum published weight of , but greater weights than this have been recorded. It is one of the largest marlins and bony fish...

. The main source of mortality, however, is industrial tuna fisheries.

The commercial fishery

Modern commercial fisheries catch yellowfin tuna with encircling nets (purse seines), and by industrial longlines.

Pole and line

Formerly, much of the commercial catch was made by pole and line fishing, using live bait such as anchovy to attract schools of tuna close to the fishing vessel that were then taken with baited jigs on sturdy bamboo
Bamboo
Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....

 or fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

 poles or on handlines. This fishery, which targeted skipjack and occasionally albacore, as well as yellowfin, for canning, reached its heyday between World War I and the 1950s before declining. The most well-known fleet of pole and line boats sailed from San Diego in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 and exploited abundant stocks in Mexican waters, as well as further south to Panama
Panama
Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...

, Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....

 and the Galapagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...

. Interviews with fishery participants as well as video footage preserve the memory of this fishery and the boats and men that pursued it.

Pole and line fishing is still carried out today in areas such as the Maldives
Maldives
The Maldives , , officially Republic of Maldives , also referred to as the Maldive Islands, is an island nation in the Indian Ocean formed by a double chain of twenty-six atolls oriented north-south off India's Lakshadweep islands, between Minicoy Island and...

, Ghana
Ghana
Ghana , officially the Republic of Ghana, is a country located in West Africa. It is bordered by Côte d'Ivoire to the west, Burkina Faso to the north, Togo to the east, and the Gulf of Guinea to the south...

, and by a small number of boats fishing out of the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...

, Madeira
Madeira
Madeira is a Portuguese archipelago that lies between and , just under 400 km north of Tenerife, Canary Islands, in the north Atlantic Ocean and an outermost region of the European Union...

 and the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...

. Few pole and line boats now specifically target yellowfin and the contribution that these fisheries make to the total commercial catch is incidental to the total take. In the Maldives, for instance, the catch is a mix of skipjack tuna and small yellowfin that often associate with them.

Purse seining

Purse seining largely took over commercial tuna fisheries in the 1960s and 1970s. Today, purse seines account for more of the commercial catch than any other method. The purse seine fishery primarily operates in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, in the historic tuna grounds of the San Diego tuna fleet in the eastern Pacific, and in the islands of the western Pacific, where many US tuna canneries relocated in the 1980s; but significant purse-seine catches are also made in the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and in the tropical Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

, especially in the Gulf of Guinea
Gulf of Guinea
The Gulf of Guinea is the northeasternmost part of the tropical Atlantic Ocean between Cape Lopez in Gabon, north and west to Cape Palmas in Liberia. The intersection of the Equator and Prime Meridian is in the gulf....

 by French and Spanish vessels.

Purse seine vessels locate tuna via onboard lookouts, as was done in the pole and line fishery, but they also employ sophisticated onboard electronics, sea-surface temperature and other satellite data, and from helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

s overhead. Once a school is located, the net is set around it. A single set may yield 100 tonnes (98.4 LT). Modern tuna seiners have a capacity of up to 2000 metric tons (1,968.4 LT) reach speeds of over 17 knots (9.3 m/s) and carry multiple spotting helicopters.

Purse seining for yellowfin tuna became highly controversial in the late 1970s when it became apparent that the eastern Pacific fishery was killing many spinner dolphin
Spinner Dolphin
The Spinner Dolphin is a small dolphin found in off-shore tropical waters around the world. It is famous for its acrobatic displays in which they spin longitudinally along their axis as they leap through the air.-Taxonomy:...

, pantropical spotted dolphin
Pantropical Spotted Dolphin
The Pantropical Spotted Dolphin is a species of dolphin found in all the world's temperate and tropical oceans. The species was beginning to come under threat due to the killing of millions of individuals in tuna purse seines...

 and other cetacea
Cetacea
The order Cetacea includes the marine mammals commonly known as whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek , meaning "whale" or "any huge fish or sea...

ns (often referred to as 'porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...

' by the tuna fleet) that accompany the fish. This association has been long-recognized by commercial tuna fishermen.

Since the introduction of "dolphin-friendly" labeling, an increasing number of purse seine sets are now made on "free schools" unassociated with dolphins, as well as schools that associate with floating objects—another long-understood association that has grown in importance in tuna fisheries. The latter practice in particular has a major ecological impact because of the high proportion of bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...

, including manta rays, sea turtles, pelagic sharks, billfish
Billfish
The term billfish is applied to a number of different large, predatory fish characterised by their large size and their long, sword-like bill. Billfish include the sailfish and marlin, which make up the family Istiophoridae, and the swordfish, sole member of the family Xiphiidae...

 and other threatened marine species taken by setting nets around logs and other floating objects. Such tuna are often significantly smaller than the larger adult tuna associated with dolphins. The removal of huge numbers of juvenile yellowfin and bigeye tuna that have yet to reach breeding age has major potential consequences for tuna stocks worldwide.

Longline

Most of the commercial catch is canned, but the sashimi
Sashimi
Sashimi is a Japanese delicacy. It consists of very fresh raw meat, most commonly fish, sliced into thin pieces.-Origin:The word sashimi means "pierced body", i.e...

 marketplace adds significant demand for high-quality fish. This market is primarily supplied by industrial tuna longline vessels.

Industrial longlining was primarily perfected by Japanese fishermen who expanded into new grounds in the Western Pacific, Indian and Atlantic oceans in the late 1950s and early 1960s. Longlining has since been adopted by other fishermen, most notably South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...

, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

, and the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

Tuna longlining targets larger sashimi-grade fish of around 25 kilograms (55.1 lb) and up that swim deeper in the water column. In tropical and warm temperate areas, the more valuable bigeye is often the main target, but significant effort is also directed towards larger yellowfin. Longlining seeks areas of higher ocean productivity indicated by temperature and chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...

 fronts formed by upwellings, ocean current eddies and major bathymetric
Bathymetry
Bathymetry is the study of underwater depth of lake or ocean floors. In other words, bathymetry is the underwater equivalent to hypsometry. The name comes from Greek βαθύς , "deep", and μέτρον , "measure"...

 features. Satellite imaging technology is the primary tool for locating these dynamic and constantly changing ocean areas.

Sea turtle
Sea turtle
Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...

 and seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

 bycatch is a major environmental issue in the longline fishery, as is the mortality that longline fishing inflicts on species that are incidentally captured, such as billfishes, sea turtles and pelagic sharks.

Artisanal fisheries

Besides the large-scale industrial purse seine and longline fisheries, yellowfin tuna also support smaller-scale artisanal fisheries that have often supplied local domestic markets for generations. Artisanal fisheries now also often fish for the lucrative sashimi market in many locations where international air shipment is possible.

Artisanal fishermen tend to employ assorted hook and line gear such as trolling lines, surface and deep handlines and longlines.

By far the largest fishery using artisanal methods exists in Philippine and Indonesian waters where thousands of fishermen target yellowfin tuna around fish aggregation devices or payaos, although this fishery far exceeds the artisanal scale in terms of tonnage caught and the numbers of partipants involved and should more properly be considered a commercial handline fishery. General Santos City
General Santos City
The City of General Santos is the southernmost port city of the Philippines. Being a highly urbanized first class city, GenSan is one of the most populous urban centers in the country with a population of 679,588 as per census data of 2010...

 is the most important Philippine port for the landing and transhipment of catches. Catches that qualify as sashimi-grade are mostly shipped to the Japanese sashimi market; those that do not meet the grade are sold locally or canned. Elsewhere in the Pacific, small boat fishers in Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

, Tahiti
Tahiti
Tahiti is the largest island in the Windward group of French Polynesia, located in the archipelago of the Society Islands in the southern Pacific Ocean. It is the economic, cultural and political centre of French Polynesia. The island was formed from volcanic activity and is high and mountainous...

 and other Pacific islands supply local and in some cases foreign markets with fresh yellowfin.

Handline-caught yellowfin tuna is one of the few exports of the economy of St Helena.

Sport fishing

Yellowfin tuna are a popular sport fish in many parts of their range and are prized for their speed and strength when fought on rod and reel. Many anglers believe that large yellowfin are, pound for pound, the fastest and strongest of all big game tunas: renowned American author S. Kip Farrington, who fished the classic giant bluefin tuna fisheries of Bimini
Bimini
Bimini is the westernmost district of the Bahamas composed of a chain of islands located about 53 miles due east of Miami, Florida. Bimini is the closest point in the Bahamas to the mainland United States and approximately 137 miles west-northwest of Nassau...

 and Cat Cay in the Bahamas as well as Wedgeport
Wedgeport
Wedgeport is a rural French Acadian fishing community located in Yarmouth County, Nova Scotia, Canada.- History :Wedgeport was settled in 1767 by returning Acadians that were deported from Nova Scotia to the Boston area. The village of Wedgeport was formally called Tusket Wedge, it was also at one...

 in Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, in their heyday, rated the yellowfin tuna of Hawaii as equal to a bluefin 'twice his weight'. Sport fishermen also prize the yellowfin tuna for its culinary qualities.
Yellowfin tuna probably first came to the attention of sports fishermen when they appeared on the tuna grounds of Catalina Island
Santa Catalina Island, California
Santa Catalina Island, often called Catalina Island, or just Catalina, is a rocky island off the coast of the U.S. state of California. The island is long and across at its greatest width. The island is located about south-southwest of Los Angeles, California. The highest point on the island is...

, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, only a few years after pioneering fishermen invented the sport, targeting the Pacific bluefin tuna
Pacific bluefin tuna
Pacific bluefin tuna, Thunnus orientalis are some of the biggest and fastest fish in the Pacific Ocean.They possess streamlined bodies to reduce water resistance and conserve energy for trans-Pacific migrations...

. These tuna were of the same species caught by commercial fishermen in Japan and the western Pacific, but the reason for their appearance was not known at the time. Later it was discovered that warmer water species such as yellowfin tuna, dorado and striped marlin
Striped marlin
The striped marlin, Tetrapturus audax, is a species of marlin found in tropical to temperate Indo-Pacific oceans not far from the surface. It is a large commercial game fish with a record weight of 190 kg, and a maximum length of 420 cm. The striped marlin is a predator that hunts during the day...

 enter southern California waters in seasons having favorable ocean conditions, particularly during the El Niño phenomenon, which brings warmer water up North America's western coast.

Yellowfin tuna were subsequently discovered by sport fishermen in Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...

, the Bahamas, Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

 and many other parts of their range. Larger adult fish which had developed distinctively long sickle fins were initially thought to be a different species and were known as Allison tuna (a name first given by the then curator of the Bermuda Aquarium, Louis Mowbray, in 1920). Such destinations as Hawaii and Bermuda became famed for their catches of these beautiful fish. In Hawaii, various styles of feather lures served as bait, but in Bermuda, chumming
Chumming
Chumming is the practice of luring animals, usually fish or sharks, by throwing "chum" into the water. Chum often consists of fish parts and blood, which attract fish, particularly sharks due to their keen sense of smell....

 techniques from boats anchored on productive banks were evolved to target not only Allison tuna but also wahoo and the smaller blackfin tuna
Blackfin tuna
Blackfin tuna is the smallest tuna species in the Thunnus genus, generally growing to a maximum of in length and weighing 21 kg . Blackfin have oval shaped bodies, black backs with a slight yellow on the finlets, and have yellow on the sides of their body...

. Bermudian experts developed techniques to take all these fish on light tackle
Fishing tackle
Fishing tackle, is a general term that refers to the equipment used by fishermen when fishing. Almost any equipment or gear used for fishing can be called fishing tackle. Some examples are hooks, lines, sinkers, floats, rods, reels, baits, lures, spears, nets, gaffs, traps, waders and tackle...

 and for many years the International Game Fish Association
International Game Fish Association
The International Game Fish Association is the leading authority on angling pursuits and the keeper of the most current World Record fishing catches by fish categories. Fishermen who are sport fishers are careful to follow their stringent rules for fair play and line requirements in order to...

 records for yellowfin tuna were dominated by entries from Bermuda in the lighter line classes, with fish in the 200 pounds (90.7 kg) and larger class from Hawaii taking most of the heavier line class records.

Today, yellowfin tuna are a major sport fish pursued by sports fishermen in many parts of the world. Thousands of anglers fish for yellowfin tuna along the eastern seaboard of the United States, particularly in North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

 and New England
New England
New England is a region in the northeastern corner of the United States consisting of the six states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut...

. Yellowfin are also a popular gamefish amongst anglers fishing from US Gulf Coast ports and also from San Diego and other ports of southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. Larger "long range" boats in the San Diego fleet also fish in Mexican waters, searching for yellowfin tuna in many of the grounds that the San Diego pole and line tuna clippers used to fish. The yellowfin tuna is also a highly prized catch in the offshore sport fisheries of South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. Sport fishing for yellowfin tuna exists on a smaller scale in many other parts of the world.

Cuisine

According to the Hawaii Seafood Buyers Guide, yellowfin tuna is widely used in raw fish dishes, especially sashimi
Sashimi
Sashimi is a Japanese delicacy. It consists of very fresh raw meat, most commonly fish, sliced into thin pieces.-Origin:The word sashimi means "pierced body", i.e...

. This fish is also excellent for grilling. Yellowfin is often served seared rare.

Yellowfin buyers recognize two grades, "sashimi grade" and "other", although there are variations in the quality of "other" grades.

Yellowfin is becoming a popular replacement for the severely depleted supplies of southern bluefin tuna
Southern bluefin tuna
The southern bluefin tuna, Thunnus maccoyii, is a tuna of the family Scombridae found in open southern hemisphere waters of all the world's oceans mainly between 30°S and 50°S, to nearly 60°S...

.

In 2010, Greenpeace International added the yellowfin tuna to its seafood red list.
"The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."

External links

Listed as Near Threatened (v3.1).
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