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In recent years, international meetings on managing the Pacific bluefin tuna (Thunnus orientalis) and seafood auctions for this species have sparked headlines, such as those below, advocating urgent action to reduce overfishing or exclaiming at the astronomical prices for a single large fish.

The fishery for Pacific bluefin tuna is in serious trouble, more so than for any other tuna, even the other bluefin tuna stocks (for a summary, see the ISSF Status of the Stocks Report). The wild population of Pacific bluefin tuna is officially overfished, and overfishing is still going on.


AsiaPacific-FishWatch has produced an authoritative profile of Pacific bluefin tuna that will help you navigate the complex profile of this species. We cover its stock status, how it is produced from fishing, ranching and closed life-cycle aquaculture, what we know about who produces it, and how its eaten, as well as it basic biology and how it is affected by the environment and climate. The profile has been developed and reviewed by experts.

Here are some key facts from our Pacific bluefin tuna profile, although much remains to be understood about this species. Please visit the whole profile on this link:

  • Pacific bluefin tuna is economically and ecologically important due to its high market value and its role as a large predator in pelagic ecosystems. It is highly migratory and very widely distributed in the Pacific Ocean, seasonally inhabiting subarctic, temperate, and tropical waters in the North Pacific Ocean, and temperate waters in the south around Australia and New Zealand. It also undertakes large vertical movements.
  • Pacific bluefin tuna has only one stock and spawning has only been recorded in the north western Pacific Ocean. It is the second largest of all the tunas. Only the Atlantic bluefin tuna (Thunnus thynnus) is larger. Until 1999, Pacific and Atlantic Bluefin tuna were considered the same species.
  • About 14,000 tonnes is caught from the wild per year, most in the Western Pacific Ocean. Many of the smaller Pacific bluefin tuna are caught live in coastal waters, and taken to coastal cages in Japan and Mexico, and grown out, adding weight and value to the wild catch. In 2002 in Japan, the life cycle was closed in captivity and a small amount of production now comes from full aquaculture. Pacific bluefin tuna is caught both as targeted catch and as non-targeted bycatch, by many different fishing methods, including by several types of small-scale Japanese fisheries.
  • Pacific bluefin tuna is managed jointly by two tuna Regional Fisheries Management Organisations (RFMO), namely the Western and Central Pacific Fisheries Commission (WCPFC) and the Inter-American Tropical Tuna Commission (IATTC) and their country members. Given the concerns for the status of the stock and its fisheries, environmental non-government organizations have campaigned for much stronger catch restrictions.
  • The Pacific bluefin tuna stock is assessed as overfished and subject to overfishing. The 2016 stock assessment from the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean (ISC) estimated that the spawning stock biomass was 2.6% of its estimated unfished level.
  • Pacific bluefin tuna is a most prized commodity in the sashimi market.
  • Under global climate change predictions, the relative abundance, spatial distribution ranges, and predator-prey dynamics in food webs of Pacific bluefin tuna are expected to change in response to altered oceanographic regimes that govern life cycle and seasonal movements.

The profiles have been written by Victoria Jollands and peer reviewed by many experts. Information has been drawn from peer reviewed sources which are given for each page of the profile. See Contributors and Reviewers for details and acknowledgements.

Friday, 24 February 2017 05:52

Pacific bluefin tuna

This FAO image is for Thunnus thynnus (Atlantic bluefin tuna), a species that is difficult to distinguish from T. orientalis by external features alone.


This FAO image is for Thunnus thynnus (Atlantic bluefin tuna), a species that is difficult to distinguish from T. orientalis by external features alone (see BIOLOGY).

Scientific Name:
Thunnus orientalis

Temminck & Schlegel 1844

Common Name:
Pacific bluefin tuna

Sunday, 29 November 2015 23:34

Longtail Tuna

Scientific Name:
Thunnus tonggol

Bleeker 1851

Common Name:
Longtail Tuna

Saturday, 21 February 2015 05:55

Albacore Tuna

Scientific Name:
Thunnus alalunga

Bonnaterre 1788

Common Name:
Albacore Tuna

Monday, 14 April 2014 07:32

Bigeye Tuna

Scientific Name:
Thunnus obesus

Lowe, 1839

Common Name:
Bigeye Tuna

Thursday, 10 April 2014 18:36

Yellowfin Tuna

01-sco thu alb pri 2497 1 FAO

FAO Species Fact Sheet

Scientific Name:
Thunnus albacares

Bonnaterre 1788

Common Name:
Yellowfin Tuna

Monday, 30 September 2013 16:56




Available species and species in preparation:


Crustaceans (In preparation)

Molluscs (In preparation)

Echinoderms (In preparation)

Plants (In preparation)


Wednesday, 04 September 2013 20:13


The following organisations have been involved in different ways in planning and developing AsiaPacific-FishWatch. Detailed acknowledgments of all contributions and contributors are provided for each species presentation.


Institutional sponsor

Asia Fisheries Society -

Institutions and Roles

Commonwealth Scientific and Industrial Research Organisation (Australia) – provider of content -

Food and Agriculture Organization of the United Nations – provider of content -

Forum Fisheries Agency – initial planning meeting -

Indian Ocean Tuna Commission – provider of content -

International Seafood Sustainability Foundation – funding support for tuna presentations, Scientific Advisory Committee review -

Ministry of Marine Affairs and Fisheries (Indonesia) – initial planning meeting support -

National Atmospheric and Oceanic Authority (United States of America) – funding support for initial planning meeting, initial planning meeting -

Network of Aquaculture Centres in Asia-Pacific – initial planning meeting -

Secretariat for the Pacific Community – initial planning meeting, species reviewers, provider of images -

Shanghai Ocean University (China) – initial planning meeting -

Southeast Asian Fisheries Development Center – initial planning meeting -

University Putra Malaysia (Malaysia) – initial planning meeting, secretariat support to AsiaPacificFishWatch project and Asian Fisheries Society -

Meryl J Williams – conceptual developer, initiator and director This email address is being protected from spambots. You need JavaScript enabled to view it.

Sunday, 18 August 2013 16:02

Skipjack Tuna

Scientific Name:
Katsuwonus pelamis

Linnaeus 1758

Common Name:
Skipjack Tuna

Sunday, 18 August 2013 08:37


This Glossary has been prepared to provide simple meanings for some technical terms in the text which may not be easily understood especially by non-technical minded visitors of the AsiaPacific-FishWatch website. The definitions for the words were derived from definitions in existing glossaries which were modified for the present purpose. The main reference sources were the FAO glossary websites for fisheries and aquaculture ( - and the NOAA FishWatch Glossary ( Other sources, such as and were also referred to.


The total weight of a group or stock of living organisms (e.g. fish, plankton etc.) or of some defined fraction of it (e.g. spawners) in an area at a particular time.


The unintentional catch of other creatures living near thetarget species. Such creatures may include other fish species, marine mammals, turtles, or even seabirds. Fishermen try to avoid bycatch because it takes time and energy away from catching their target species. Managers try to reduce bycatch and its impacts in a number of ways, such as working with fishermen to develop gear that is more efficient in catching the target species and closing areas to fishing where or when the probability of bycatch is high.


In general, the extent to which a stock is susceptible to fishing. In fisheries modelling, the fraction of a fish stock which is caught by a defined unit of the fishing effort, also called the catchability coefficient (q).

Distant water fishing

Catching of fish by vessels outside their own country’s waters under special access agreements, i.e. in all FAO major fishing areas other than those adjacent to the flag State.

Dolphin-safe tuna

A number of labels which denote that the tuna was caught in compliance with various laws or policies designed to minimize fatalities of dolphins during fishing. Some labels impose stricter requirements than others.


The quantity of fishing gear of a specific type used on the fishing grounds over a given unit of time, e.g. hours trawled per day, number of hooks set per day or number of hauls of a beach seine per day. When two or more kinds of gear are used, the respective efforts must be adjusted to some standard type before being added.

Exclusive Economic Zone (EEZ)

A zone under national jurisdiction (up to 200-nautical miles wide) declared in line with the provisions of the 1982 United Nations Convention on the Law of the Sea, within which the coastal State has the right to explore and exploit, and the responsibility to conserve and manage, the living and non-living resources.

Fecund, fecundity

Fecundity refers to the potential reproductive capacity of an organism or population expressed as the number of eggs (or offspring) produced during each reproductive cycle. Fecundity usually increases with age and size. A highly fecund organism is thus one which produces a large number of eggs or offspring.

Fish aggregating (or aggregation) devices (FADs)

Man-made or natural floating objects placed on the ocean surface, often anchored to the bottom, to attract schooling pelagic fish species such as tuna, marlin and dolphin fish, thus increasing their catchability. They usually consist of buoys or floats tethered to the ocean floor with concrete blocks.


A type of fishing gear which causes the fish to be gilled, entangled or enmeshed in the netting. The nets can be used alone or, as is more common, in large numbers placed in line. They may be used to fish on the surface, in midwater or on the bottom.


Bony or cartilaginous processes that project from the gill arch of fish and which filter tiny prey as food. They are not to be confused with the gill filaments that make up the bony part of the gill. Rakers are usually present in two rows, projecting from both the anterior and posterior side of each gill arch.

Gonadosomatic index (GSI)

The ratio of gonad weight to total body weight, expressed as a percentage. The GSI is helpful in identifying seasons of spawning, as the ovaries of gravid females rapidly increase in size just prior to spawning.

Growth overfishing

Occurs when too many small fish are being harvested too early, through excessive fishing effort and poor selectivity (e.g. too small mesh sizes) and the fish are not given enough time to grow to the size at which the maximum yield-per-recruit from the stock would be obtained. A reduction of fishing mortality on juveniles, or their outright protection, would lead to an increase in yield from the fishery.

Illegal, unreported and unregulated (IUU) fishing

Fishing that violates national or international law or rules, that hasn’t been reported where reporting is required, or that is inconsistent with relevant international laws or rules. Either the fishing activities are not regulated or the fishing vessels involved are not able to be regulated. Illegal activities can include fishing without a licence or quota for certain species, unauthorized transshipments to cargo vessels, failing to report catches or making false reports, keeping undersized fish that are otherwise protected by regulations, fishing in closed areas or during closed seasons, and using prohibited fishing gear. By dodging conservation and management measures, those engaging in IUU fishing can cut corners and lower their operating costs. As a result, their illegally-caught products provide unfair competition to law-abiding seafood industries in the marketplace.

IUCN Red List

Compiled by the World Conservation Monitoring Centre, the IUCN Red List is the world's most comprehensive inventory of the global conservation status of biological species. Among others, it includes more than 6,000 animal species known to be threatened with extinction.

Long line

Fishing method in which short lines carrying hooks are attached to a longer main line at regular intervals. The horizontal mainline is connected to the surface by floats. The main lines can be as long as 150 km and have several thousand baited hooks (such as in tuna fishing).

Pole and line

A fishing technique in which surface schooling fish, such as yellowfin and skipjack tuna, are attracted to the vessel and driven into a feeding frenzy by throwing live or dead bait into the water and spraying water onto the sea surface to simulate the escape behaviour of small prey. The fish are lured with a line and a hook attached to a pole and pulled off the water by manual or powered devices.

Purse seine

Net characterized by the use of a purse line at the bottom of the net which enables the net to be closed like a purse and retain all the fish caught. Purse seines, which may be very large, are operated by one or two boats.


The process by which fish join the exploitable stock in the fishing area each year, through a process of growth (i.e. the fish grows to size at which it is catchable by the fishing methods being used) or migration (i.e. the fish moves into the fishing area). The process may be short or longer than a year, depending on the biology of the species and the fishing method and gear.

Ring net

Net operated by surrounding a shoal of pelagic fish with a “wall” of netting, often operated by two boats.


Japanese term for sliced fish (especially tuna) and shellfish (scallop, abalone, lobster, squid, or octopus) served raw as a delicacy.


Ability to persist in the long-term.

Swim bladder

A buoyancy organ possessed by most bony fish which enables the fish to stay at a particular water depth without having to waste energy in swimming. Located in the body cavity, it is derived from an out pocketing of the digestive tube. Also called gas bladder, fish maw or air bladder.

Total allowable catch (TAC)

Total annual catch allowed to be taken from a resource in a specified period (usually a year) that, if exceeded, will terminate the fishery for that year. The TAC may be allocated to stakeholders in the form of quotas as specific quantities or proportions.

Troll lines, trolling

Simple lines, provided with natural or artificial bait, trailed near the surface or at a certain depth by a vessel at a speed of 2-10 knots. Several lines are usually towed at the same time, by using outriggers. Trolling is used to catch tuna and tuna-like fish.


Layer below the surface layer of the sea or certain lakes, where the temperature gradient increases abruptly compared to the warmer layer above and the colder layer below (i.e. where temperature decreases rapidly with increasing depth). It is usually an ecological barrier and its oscillations have significant consequences on fish stocks distribution and ocean productivity. Factors that affect the depth and thickness of a thermocline include seasonal weather variations, latitude and longitude, and local environmental conditions.

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