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Tuna, Pacific bluefin

Thunnus orientalis

Method of production - Caught at sea
Capture method - All applicable methods
Capture area - Pacific (FAO 61,67,71,77,81,87)
Stock area - Pacific Ocean
Stock detail - All Areas
Certification -
Fish type - Oily fish

Sustainability rating Click for explaination of rating

This fish, caught by the methods and in the area listed above, is the least sustainable fish to eat and should be avoided. Click on the rating icon above to read more and on the alternatives tab below to find sustainable fish to eat.


Sustainability overview

Pacific bluefin is a relatively slow growing and long-lived predator that is both a very important commercial and artisanal species. The majority of the catch in the Pacific is taken by purse seiners with much of the catch now fattened in pens before being sold on the sashimi market. Approximately 90% of fish is captured before it has had a chance to breed and is seriously contributing to the overfishing on this Pacific-wide stock. The latest stock assessment was undertaken in 2014 and, similar to previous assessments, indicated that the stock is still heavily overfished the biomass is estimated to be at historical low levels, with the spawning biomass near historical low levels, and is also still subject to heavy overfishing. Recently bolstered catch and effort limits are a positive sign, yet it remains to be seen whether or not these will be sufficient to reduce fishing mortality to sustainable levels and to recover the biomass.

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

Stock area
Pacific Ocean

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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 has increased, and the effect of this fleet on the stock is currently greater than any of the other fishery groups. This is due to the very high proportion of juvenile bluefin caught in these purse seine fisheries. The latest stock assessment was carried out in 2016 (using data up to 2014) and used a substantially improved model from the 2014 assessment. It indicates that spawning stock biomass (SSB) fluctuated throughout the assessment period (1952-2014) but steadily declined from 1996 to 2010. The decline appears to have ceased since 2010, although the stock remains near the historic low. The stock is heavily overfished, with spawning biomass in 2014 at about 2.6% of unfished levels. This is a slight improvement on the 2012 figure of 2.1%, which was revised using the new 2016 methods. Fishing mortality from 2011-2013 appears to be lower than previous assessments (2009-2011 and 2002-2004), but still tends to exceed almost all calculated biological reference points (e.g. F is 1.63 Fmax). The provisional total Pacific Bluefin tuna catch in 2015 was 11,020 t in the North Pacific Ocean, which was a 36% decrease over 2014 and a 30% decrease over the average for 2010-2014 (15,640t).

IUCN Red List lists Pacific Bluefin tuna as Vulnerable.

Management

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). Bluefin tunas have 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 led to increased management measures, yet there remained concern that such measures were insufficient to have a positive impact on the stock, particularly if recruitment remained below average.

The provisional total Pacific Bluefin tuna catch in 2015 was 11,020 t in the North Pacific Ocean, which was a 36% decrease over 2014 and a 30% decrease over the average for 2010-2014 (15,640t). In 2014 additional measures were developed by the WCPFC, which were updated in 2016. IATTC have a adopted similar resolutions. These include a multiannual rebuilding plan for stock tuna starting in 2015, with the initial goal of rebuilding the spawning biomass (SB) to the historical median (40,994 t) within 10 years with at least 60% probability. An additional rebuilding target will be adopted in 2017 to achieve by 2030. Reference points and harvest control rules are to be developed in 2017. All WCPFC members are to ensure that: total fishing effort by their vessels fishing for Pacific bluefin tuna in the area north of 20 degrees N shall stay below the 2002 to 2004 annual average levels; all catches of Pacific bluefin tuna less than 30 kg shall be reduced to 50% of the 2002 to 2004 levels. WCPFC is looking to establish a catch documentation scheme as a matter of priority.

Similarly, the IATTC has further reduced its Total Allowable Catch (TAC) from: 5,600t in 2012; and 5,000t in 2014; down to 3,300t a year for 2015 and 2016 (Or a maximum total of 6,600t over the two years).

The IATTC require 100% regional observer coverage on large purse seiners. In the WCPFC 100% coverage is required for all purse seine vessels fishing on the high seas and in waters under the jurisdiction of one or more coastal States, or vessels fishing in waters under the jurisdiction of two or more coastal States during the same trip; and on all purse seiners fishing between 20N and 20S. Both the IATTC and WCPFC require 5% observer coverage on longline vessels over 20m in length.

To help address IUU, both the IATTC and the WCPFC maintain an IUU Vessel list as well as a register of large longliners that are authorised to target Pacific bluefin tuna; it is also prohibited to undertake transhipments at sea between purse seiners (some exemptions apply) and all other transhipments need to be documented and 100% observed as part of the regional observer programme.

Management (if fully implemented) is on target to achieve conservation objectives with 69% probability. This would be improved by an additional 10% reduction in catch limit, and the greatest effect would be achieved by limiting catches of small fish. Potential effects resulting from the measures of the WCPFC and IATTC starting in 2015 or by other voluntary measures are not yet reflected in the data used in the most recent assessment. In 2016, the Scientific Committee expressed the need for urgent coordinated actions between WCPFC and IATTC in reviewing the current rebuilding plan, establishing the emergency rule, and considering and developing reference points and Harvest Control Rules for the long term management of Pacific bluefin tuna.

Capture information

Approximately 68% of Pacific bluefin is captured in purse seine fisheries that target free schooling fish. 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. Approximately 90% of the total catch is made on juvenile fish, aged 0-3yr. The ISC recommend that fishing effort be reduced, particularly for juvenile fish. Lesser amounts of bluefin are caught via trolling, gillnet, trap, pole-and-line and longline gear.

In 2016 IATTC adopted a resolution to prohibit retention, transshipment, landing or storing of silky sharks caught by purse seine vessels. They also introduced stricter monitoring and reporting of catches of shark species. There is 100% observer coverage on large purse seiners in the EPO so the data coming from these fleets should be very useful and of high quality. Also 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.

Read more about capture methods


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 2016].

Froese, R. and D. Pauly. Editors. 2016. FishBase. Available at www.fishbase.org [Accessed Dec 2016].

IATTC, 2016. Active IATTC and AIDCP resolutions and recommendations. Available at http://www.iattc.org/ResolutionsActiveENG.htm [Accessed Dec 2016].

ISC, 2016. 2016 Pacific bluefin tuna stock assessment: report of the Pacific bluefin tuna working group. International scientific committee for tuna and tuna-like species in the North Pacific Ocean. Sapporo, Hokkaido, Japan, 13-18 July 2016. Available at http://isc.fra.go.jp/reports/isc/isc16_reports.html [Accessed Dec 2016].

ISC, 2016. Report of the sixteenth meeting of the international scientific committee for tuna and tuna-like species in the North Pacific Ocean: plenary session. Sapporo, Hokkaido, Japan, 13-18 July 2016. Available at http://isc.fra.go.jp/reports/isc/isc16_reports.html [Accessed Dec 2016].

ISSF, 2016. ISSF Tuna stock status update, 2016: Status of the world fisheries for tuna. ISSF Technical Report 2016-05B. International Seafood Sustainability Foundation, Washington, D.C., USA. Available at http://iss-foundation.org/knowledge-tools/technical-and-meeting-reports/download-info/issf-2016-05b-status-of-the-world-fisheries-for-tuna-nov-2016/ [Accessed Nov 2016].

ISSF, 2016. Status of the world fisheries for tuna: Management of tuna stocks and fisheries, 2016. ISSF Technical Report 2016-14.International Seafood Sustainability Foundation, Washington, D.C., USA. Available at http://iss-foundation.org/downloads/13305/ [Accessed Nov 2016].

WCPFC, 2016. Scientific committee meeting: summary report. Twelfth regular session. Bali, Indonesia, 3-11 August 2016. Available at https://www.wcpfc.int/meetings/sc12 [Accessed Dec 2016].

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