Tuna, Pacific bluefin

Thunnus orientalis

Method of production — Caught at sea
Capture method — All applicable methods
Capture area — Pacific Ocean (FAO 61,67,71,77,81,87)
Stock area — Pacific Ocean
Stock detail

All Areas


Picture of Tuna, Pacific bluefin

Sustainability rating five info

Sustainability overview

The latest stock assessment was carried out in 2018 and whilst more optimistic than previous assessments, indicated that the stock was still heavily overfished and likely subject to overfishing with fishing mortality above possible proxies for maximum sustainable yield. Catch in 2017 was 14,707t, an 11% increase from 2016 and a 9% increase from the average 2012-2016. Among the primary management measures, there is a rebuilding plan for the stock which started in 2015, with the initial goal of rebuilding the spawning biomass to about 7% of unfished levels by 2024 with at least 60% probability, which would still be considered a heavily overfished state. A second rebuilding target was agreed in 2018, which is SSB at 20% of unfished levels within 10 years after achieving the initial management target (or by 2034, whichever is earlier) and there is a high probability of achieving this under current management, however MCS does not consider either target ambitious enough and is concerned over increasing catches. To reduce the impact on juveniles, catches of tuna below 30kg must be reduced to 50% of overall catch or less, but it is noted that juvenile bluefin can weigh up to 85kg. Catch limits have been imposed but vary depending on jurisdiction. Due to the state of the stock, a critical fail is triggered and a default red rating applies to all gear types.

Biology

Tuna belong to the family Scombridae. They are large, oceanic fish and are seasonally migratory, some making trans-oceanic journeys. Bluefin tuna are the largest of the tuna species, reaching upwards of 680 kg. There are three species in each of the Pacific, Atlantic and Southern Oceans. In all oceans bluefins are known for their impressive migrations, routinely crossing ocean basins. Pacific bluefin tuna are generally smaller than their Atlantic cousins, reaching a maximum length of 3m and a maximum weight of 540kg. Not only do they have a hydrodynamic shape, their pectoral (side) fins can be retracted and, unlike other fish, their eyes are set flush to their body. Pacific bluefin tuna is capable of swimming at speeds of 12 to 18 miles per hour (20-30 km per hour) for brief periods. In the Pacific, tagging studies indicate there is only one stock with a spawning ground off southern Japan. Pacific bluefin tuna spawn between Okinawa (Japan) and the Philippines, in April and August, then migrate over 6,000 nautical miles to the eastern Pacific, eventually returning to their birth waters to spawn. They reach reproductive maturity at around 5 years and 60kg.

Stock information

Criterion score: Default red rating info

Stock Area

Pacific Ocean

Stock information

Pacific bluefin tuna (Thunnus orientalis) has a single Pacific-wide stock managed by both the Western and Central Pacific Fisheries Commission (WCPFC) and the Inter-American Tropical Tuna Commission (IATTC). Pacific bluefin is assessed by the International Scientific Committee for Tuna and Tuna-like species in the North Pacific (ISC).

Historical Pacific bluefin tuna (PBF) catch records are scant, yet landing records from coastal Japan date back to as early as 1804 and to the early 1900s for U.S. fisheries. Catches appear to have peaked before WWII at about 59,000t, after which they fluctuated widely, peaking at 40,383 t in 1956 and reaching a low of 8,653 t in 1990. Since the early 1990s the impact of the Western Pacific Ocean purse seine fleet on the stock has increased, and the effect of this fleet is currently greater than any of the other fishery groups, due to the very high proportion of juvenile bluefin caught in these purse seine fisheries.

A new stock assessment was carried out in 2018 using data up to 2016, and was more optimistic than the previous assessment in 2016, mainly due to the inclusion of the relatively good recruitment in 2016. The stock is heavily overfished. WCPFC has set a lower limit for the spawning stock biomass (SSB) at 20% of unfished levels: SSB in 2016 was 3.3% of unfished levels (an improvement from 2.6% in 2014). The stock remains subject to overfishing relative to most of the common fishing intensity-based reference points. Under the current WCPFC and IATC management measures, and assuming a low recruitment scenario, there is a 98% probability of rebuilding SSB to 6.7% of unfished levels by 2024, which is the initial management target. There is a 96% probability of achieving the second rebuilding target, which is SSB at 20% of unfished levels within 10 years after achieving the initial management target (or by 2034, whichever is earlier). These projection results are strongly influenced by the inclusion of the relatively high, but uncertain recruitment estimate for 2016. Catch in 2017 was 14,707t, an 11% increase from 2016 (13,175t) and a 9% increase from the average 2012-2016 (13,526t). Scientific advice is that while the most precautionary approach is to maintain the catch limits, some increases are possible without posing a danger to the rebuilding of the stock. Any increase in catch limits would need to consider the desired rebuilding rate and the distribution of catch between small and large bluefin.

IUCN Red List lists Pacific Bluefin tuna as Vulnerable.

Management

Criterion score: Default red rating info

Pacific bluefin tuna has a single Pacific-wide stock managed by both the Western and Central Pacific Fisheries Commission (WCPFC) and the Inter-American Tropical Tuna Commission (IATTC). This stock has been badly managed in the past with a lack of regulation and enforcement across their range. Contributing to this has been its extremely high market value adding plenty of incentive for Illegal, Unreported and Unregulated (IUU) fisheries. In recent years, decreased catches and fish sizes and concerns over the stock status (the stock is now at 3.3% of unfished levels) have led to increased management measures. Catch in 2017 was 14,707t, an 11% increase from 2016 (13,175t) and a 9% increase from the average 2012-2016 (13,526t).

The impact of fisheries in the WCPFC convention area on Pacific bluefin tuna are far greater than that of fisheries in the IATTC area, and so management measures by WCPFC are considered to be of greater importance. However, management must be comparable and properly implemented across the entire range of the stock in order for it to be effective. Therefore, both have implemented the following a rebuilding plan for the stock, starting in 2015, with the initial goal of rebuilding the spawning biomass (SB) to the historical median (40,994 t, based on the period 1952-2014) by 2024 with at least 60% probability. This would take the SB to about 7% of unfished levels. IATTC adopted a second rebuilding target in 2018, consistent with the recommendation that it be for SB to reach 20% of unfished levels within 10 years of reaching the initial target, or by 2034, whichever is sooner, with at least 60% probability. Current management measures are on track to achieve both targets with greater than 96% probability. A Northern Committee working group comprising IATTC, WCPFC and others was established in 2016 to support joint working on Pacific bluefin tuna and has recommended that the interim rebuilding target be supported by an interim harvest control rule, whereby if probability of achieving the target drops to less than 60%, catches of fish below 30kg are reduced, and if probability rises to above 75% overall catches are allowed to increase (with some restrictions). This has not yet been adopted into management measures, although reference points and harvest control rules are to be developed by 2020. The commissions require (WCPFC) or encourage (IATTC) small bluefin (under 30kg) to be 50% of total catch or less. In WCPFC fishing effort (north of 20 degrees N) and all catches are limited to the 2002-2004 average. Countries can use part of the catch limit for Pacific bluefin tuna smaller than 30 kg to catch Pacific bluefin tuna 30 kg or larger in the same year (the implications of this measure on the stock are to be reviewed by ISC in 2020). In IATTC total catches are limited to 6,200 t in 2019 and 2020 combined (reduced from 6,600t for 2017 and 2018 combined). Individual countries are limited to 600t for 2019 and 2020 combined. In both cases, if a country goes over its catch limit the amount of the overage will be deducted from the following year’s catch. IATTC’s scientific committee has recommended that WCPFC do more to limit catches of adult bluefin. While reductions in catch limits apply to fish smaller than 30kg, juvenile Pacific bluefin tuna can weigh up to 85kg, and so this measure does not limit catches on all juveniles.
A catch documentation scheme (CDS) is to be developed by 2020 to help combat IUU.
WCPFC requires countries to, wherever possible, take measures necessary to prevent commercial transaction of Pacific bluefin tuna and its products that undermine the effectiveness of the management measures.

Additional measures implemented by both IATTC and WCPFC: There is 100% observer coverage on large purse seiners (for WCPFC this is on the high seas, or on vessels fishing in multiple countries’ waters, or all vessels fishing between 20N and 20S).
Only 5% observer coverage is required on large longliners, considered by IATTC’s scientific committee to be too low for accurate data: a minimum of 20% coverage is recommended. In addition, data recorded by longliners in the IATTC area is considered inadequate for scientific purposes and minimum data standards must be identified and introduced.
To help address IUU, WCPFC and IATTC maintain an IUU Vessel List; a register of authorised large longliners; and prohibit transhipments at sea for large purse seiners, and most other transhipments must be documented and observed as part of the regional observer programme. Countries are required to report annually on monitoring, control and compliance of management measures. The IATTC and WCPFC endeavour to work together to promote compatibility between their respective conservation and management measures across the Pacific.

IATTC report 40% catch reductions in their area since 2012 through resolutions and voluntary measures.

Capture Information

Criterion score: Default red rating info

Approximately 66% of Pacific bluefin is captured in purse seine fisheries that target free schooling fish, 9% by longlining, 6% by trolling ad 12% by set nets. During recent years, most of the catches have been transported to holding pens, where the fish are held for fattening and later sale to sashimi markets. These fisheries catch a very high proportion of juvenile fish (although recent juvenile fishing mortality has been lower than in previous years).

Purse seining is commonly an industrial scale fishery used to catch tuna destined for canneries. These fisheries target smaller fish that aggregate close to the surface, whereas longliners target larger fish that inhabit deeper waters. Many juvenile fish are often caught in purse seine fisheries and the method is also associated with bycatch of species such as sharks, turtles and marine mammals. Longlining targets larger, mature fish yet is often associated with the bycatch of vulnerable species such as seabirds, turtles and sharks. Whilst bycatch may comprise a small proportion of the total catch, the high volume of tuna that is caught means that it can still be significant for these vulnerable species.

To address this, both the IATTC and the WCPFC require a number of mitigation measures.
Purse seiners must not put out sets around whale sharks, turtles or cetaceans, and WCPFC has introduced some measures to limit the number of FADs and require their design to be non-entangling.
Seabirds: Longliners must use one or more seabird bycatch mitigation measures from a set list of options, depending on vessel size and fishing location, including weighted branch line, bird scaring lines, and night setting. However, recommended best practice is for those three measures to be applied simultaneously.
Turtles: vessels must carry line cutters and de-hookers to promptly release turtles or to foster to recovery any sick or comatose turtles captured. WCPFC also requires the use of circle hooks for shallow set gear for swordfish to reduce turtle capture, however a study in 2017 noted that less than 1% of Western and Central Pacific Ocean (WCPO) longline effort is subject to mitigation, even though approximately 20% of the WCPO longline effort consists of shallow sets. IATTC have noted that mortality rates of turtles due to longlining are possibly greater for those that set their lines at shallower depths at night for albacore and swordfish, although WCPFC notes that there are significantly more deep sets than shallow sets and a lower chance of live release from deep sets.
Sharks: permissible sharks are to be fully utilized and no more than 5% of fins to total shark weight can be retained; there is a prohibition to land oceanic whitetips and silky sharks (and mobula rays in IATTC area); and countries must develop national plans of action to address the bycatch of sharks, turtles and seabirds. Shark lines are prohibited. For fisheries specifically targeting sharks, countries are required to develop management plans, demonstrating how they intend to avoid or reduce catches of highly depleted shark species. For the IATTC, any shark (whether alive or dead) caught that is not retained must be promptly released unharmed, following safe release requirements. There are special measures to protect silky sharks, including a limit on bycatch of silky sharks to a maximum of 20% of the total catch by fishing trip in weight. In 2016, WCPFC adopted measures to improve recording of manta and mobula rays discarded and released, and to treat these species as key shark species for assessment and research. The scientific committee has noted that target and limit reference points have not yet been established for pelagic sharks by WCPFC.
Monitoring and reporting is deficient in many fisheries, and the effectiveness of these measures has not been evaluated. In 2016 IATTC introduced stricter monitoring and reporting of catches of shark species, but the scientific committee continues to advise that shark data collection is inadequate and must be improved. The scientific committee has also recommended stricter requirements for seabird mitigation techniques and proof of effectiveness before new techniques are introduced.
There is 100% observer coverage on large purse seiners in the EPO so the data coming from these fleets should be useful and of high quality. Only 5% observer coverage is required on longliners greater than 20m in length, although the scientific committee recommends 20% coverage and improved standards of data collection.

Alternatives

Based on method of production, fish type, and consumer rating: only fish rated 2 and below are included as an alternative in the list below. Click on a name to show the sustainable options available.

Anchovy, anchovies
Arctic char
Herring or sild
Salmon, Atlantic (Farmed)
Salmon, Chinook, King Salmon
Salmon, Chum, Keta, Calico or Dog salmon
Salmon, Coho , Silver, White
Salmon, Pink, Spring , humpback
Salmon, Sockeye , Red Salmon, Bluebacks, Redfish
Sprat, whitebait
Swordfish
Trout, Rainbow
Tuna, albacore
Tuna, bigeye
Tuna, skipjack
Tuna, yellowfin

References

Collette, B., Fox, W., Juan Jorda, M., Nelson, R., Pollard, D., Suzuki, N. & Teo, S., 2014. Thunnus orientalis. The IUCN Red List of Threatened Species 2014: e.T170341A65166749. Available at http://dx.doi.org/10.2305/IUCN.UK.2014-3.RLTS.T170341A65166749.en [Accessed on 13.12.2018].

DiNardo, G., 2017. Summary report of the Pacific bluefin tuna international stakeholders meeting, hosted by the International Scientific Committee for Tuna and Tuna-Like Species in the North Pacific Ocean (ISC), 25-27 April 2017, Tokyo, Japan. 23pp. Available at http://isc.fra.go.jp/reports/isc/isc17_reports.html [Accessed on 13.11.2017].

IATTC, 2018. Inter-American Tropical Tuna Commission: Active IATTC and AIDCP Resolutions and Recommendations. Available at https://www.iattc.org/ResolutionsActiveENG.htm [Accessed on 05.12.2018].

IATTC, 2018. Staff recommendations for management and data collection. Document SAC-09-15 Rev 2 for the Inter-American Tropical Tuna Commission Scientific Advisory Committee, Ninth Meeting, 14-18 May 2018, La Jolla, California, USA, 15 pp. Available at https://www.iattc.org/Meetings/Meetings2018/SAC-09/9th-Meeting-Scientific-Advisory-Committee.htm [Accessed on 05.12.2018].

IATTC, 2018. Tunas, Billfishes and Other Pelagic Species in the Eastern Pacific Ocean in 2017. Document IATTC-93-01 for the Inter-American Tropical Tuna Commission 93rd meeting, 24 and 27-30 August 2018, San Diego, California. 115 pp. Available at https://www.iattc.org/Meetings/Meetings2018/IATTC-93/IATTC-AIDCP-Annual-Meetings-AUG2018ENG.htm [accessed on 05.12.2018].

ISC, 2017. Report of the Pacific bluefin tuna working group intersessional workshop for the International Scientific Committee for Tuna and Tuna-Like Species in the North Pacific Ocean (ISC), 15-20 February 2017, Shimizu, Shizuoka, Japan. Available at http://isc.fra.go.jp/reports/isc/isc17_reports.html [Accessed on 13.11.2017].

ISC, 2018. Report of the eighteenth meeting of the International Scientific Committee for Tuna and Tuna-Like Species in the North Pacific Ocean, Plenary Session, 11-16 July 2018, Yeosu, Republic of Korea. 93pp. http://isc.fra.go.jp/reports/isc/isc18_reports.html [Accessed on 05.12.2018].

ISSF, 2018. Status of the world fisheries for tuna: October 2018. ISSF Technical Report 2018-21. International Seafood Sustainability Foundation, Washington, D.C., USA. 103 pp. Available at: https://iss-foundation.org/about-tuna/status-of-the-stocks/ [Accessed on 06.12.2018].

WCPFC, 2018. Conservation and Management Measures of the Western and Central Pacific Fisheries Commission. Available at https://www.wcpfc.int/conservation-and-management-measures [Accessed on 06.12.2018].

WCPFC, 2018. Summary Report of the Fourteenth Regular Session of the Scientific Committee of the Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, 8-16 August 2018, Busan, Republic of Korea. 34 pp. Available at https://www.wcpfc.int/meetings/14th-regular-session-scientific-committee [Accessed on 06.12.2018].