Tuna, Atlantic bluefin
Method of production - Caught at sea
Capture method - All applicable methods
Capture area - Worldwide (FAO All Areas)
Stock area - East Atlantic & Mediterranean
Stock detail - All Areas
Fish type - Oily fish
Atlantic bluefin tuna is a large, slow growing and long lived species, making it vulnerable to overfishing. The stock has been significantly overfished since the 1970s, and illegal, unreported and unregulated (IUU) fishing has been a serious problem as individual fish can regularly be sold in excess of tens of thousands of pounds. Recent improvements in stock management, monitoring and enforcement under a recovery plan have had a positive effect on the stock. The 2014 assessment indicates that fishing mortality is now below the Maximum Sustainable Yield (Fmsy) and that the biomass is increasing. There remain large uncertainties in the assessment however, and it is not clear if the stock is still overfished. The East Atlantic component of the stock is likely important to the West Atlantic bluefin stock and the species remains listed as Endangered by the IUCN.
Tuna belong to the family Scombridae. They are large, oceanic fish and are seasonally migratory, some making trans-oceanic journeys. Able to tolerate both warm and cool temperatures, bluefin tuna range throughout the entire north Atlantic and adjacent seas, (primarily the Mediterranean Sea) and can frequent depths to 1000m. Despite this thermal tolerance, a recent analysis of present vs historical ranges concluded that Atlantic bluefin tuna has shown range contractions of 46% since 1960 ? more than any other pelagic species . Despite poorly understood movements from east to west, a distinction in populations is made between the two regions. Interestingly, life history characteristics differ greatly between them. In the Mediterranean, bluefin tuna is assumed to mature at approximately 25 kg (age 4), whereas in the Gulf of Mexico in the West Atlantic, maturity occurs at approximately 145 kg (age 9). Northern bluefin grow slowly compared with other tunas and billfish but can reach more than 450cm in length and 680kg in weight with a maximum age of approximately 40 years. Spawning occurs from April to June in the Gulf of Mexico and June to August in the Mediterranean.
East Atlantic & Mediterranean
The bluefin tuna stock in the East Atlantic and Mediterranean are assessed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). Reported catches in the East Atlantic and Mediterranean reached a peak of over 50,000 t in 1996 (With additional unreported catches possibly equal to that), severely overfishing the stock. Since then, reported catches have steadily decreased, stabilising according to Total allowable Catches (TACs) in the last few years. The 2013 reported catch of 13,333t is just under the TAC of 13,500t. reported catches since 2010 have averaged 11,200t which is nearly a third of the average annual reported catches in the period 2005 to 2009. The most recent stock assessment was carried out in 2014 and in spite of recent improvements in data collection, there remain important data limitations for this assessment, primarily as a result of the mis-reporting that took place until 2007. Despite this, results do clearly indicate that fishing mortality is well below the Maximum Sustainable Yield (F approximately at 0.4Fmsy proxy). The modelled state of the biomass however, is highly dependent on the historical productivity of the stock. Scenarios based on low, med and high historical productivities result in a current biomass that is either high (1.6Bmsy proxy) , medium (1.1Bmsy proxy) or low (0.67Bmsy proxy). It still remains unclear how much of the Eastern Atlantic stock mixes with and supports the Western Atlantic stock. The species is still listed as Endangered by the International Union for the Conservation of Nature (IUCN).
Tuna fisheries in the Atlantic are managed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). Bluefin tuna has been badly managed in the past with a lack of regulation and enforcement across its range. Contributing to this has been its extremely high market value. Information available has demonstrated that catches of bluefin tuna from the East Atlantic and Mediterranean were seriously under-reported between the mid-1990s through to 2007. The ICCAT scientific committee views this lack of compliance with TAC and under-reporting of the catch as a major cause of stock decline over that period. Bluefin is still reportedly captured in illegal gill net fisheries in Italy and is still officially permitted in Morocco. In recent years, ICCAT have implemented a range of management measures to reduce IUU fishing for bluefin and to aid the recovery of the stock. A stock rebuilding program has been in effect since 2006 which aims to recover (with over 60% probability) the stock to Bmsy by 2022. Adherence to the TACs and the rebuilding programme have had a positive effect on the stock, however there are still important knowledge gaps that need to be addressed. As bluefin is so valuable, there remains a strong incentive to increase fishing mortality beyond the rebuilding plan and for operators to under-report catches. ICCAT and participating coastal states must remain diligent in their management, monitoring and enforcement to avoid losing the important increases in abundance that have been observed in recent years.
In light of the positive results of the 2014 stock assessment, TACs for the next three years have been increased from the 2014 level of 13,400t to: 15,821t, 18,911t, and 22,705t for 2015, 2016 and 2017 respectively. In addition to a TAC, the rebuilding plan also includes: Limits on capacity; Closed fishing seasons for longliners (six months), purse seiners (11 months), and for pole and line, pelagic trawl and sport fishing vessels (eight months each); Minimum sizes of 8 and 30 kg depending on the fishery; A register of authorized fishing vessels and authorized farming facilities; A requirement for weekly catch reports to national agencies and monthly catch reports to ICCAT; 100% observer coverage for purse seiners and for transfers to sea pens; VMS on every vessel over 15 m in length; and the prohibition of trade of bluefin not accompanied by valid catch documents.
ICCAT have developed an IUU vessel register and a register of vessels authorised to undertake transhipments at sea.
ICCAT generally requires 5% observer coverage on all purse seine, longline and pole and line vessels greater than 15m in length.
Approximately 44% of the bluefin in the East Atlantic and Mediterranean is caught in purse seine fisheries that target free schooling fish (as opposed to using Fish Aggregation Devices, FADs). These fish are live captured to then be transported to sea pens where they are held and fattened for later sale on the Asian sashimi market. Purse seining on free schools encounters less bycatch compared with FAD associated fisheries, though both still have interactions with vulnerable species. Approximately 21% of the catch is taken in pelagic longline fisheries. Pelagic longlining can encounter considerable bycatch of vulnerable species, including sharks, turtles and sea birds. There are a range of measures that can be employed to reduce bycatch including: circle and/or barbless hooks to prevent turtle capture; chemical, magnetic and rare earth metal shark deterrents; and weighted branchlines, bird scaring lines, underwater chutes and night setting to reduce the incidental capture of seabirds. ICCAT specify that at least two of these different measures should be employed yet their use is not well monitored or enforced in these fisheries. There is also a prohibition to retain at risk shark species including: bigeye thresher, oceanic whitetip, hammerhead and silky sharks. This has been in place for over four years, yet ICCAT has not received records of compliance from the majority of member states. Monitoring of bycatch is deficient in these fisheries. Porbeagle is significantly overfished, and whilst there is a zero EU TAC for porbeagle, it is still caught incidentally and discarded, and also landed by other fleets. Several species of albatross are threatened with extinction, and whilst there have been many advances in reducing interactions with longline fisheries, it is not clear how effective these have been.
Approximately 13% of the catch is taken in fixed net traps that reportedly have a low impact on non-target species.
Approximately 6% of the catch is taken in pole and line fisheries. This is a very selective method of fishing yet relies on significant amounts of baitfish. Assessment of these bait fish fisheries is generally needed.
To a lesser extent, bluefin is also captured in illegal gill net fisheries. For EU Member States, driftnet fishing for tuna has been banned since January 2002, yet remains a problem in some Italian fisheries and is still officially permitted in Morocco. Gill netting, especially offshore drift netting, encounters a very high proportion of bycatch.
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.
Froese, R. and Pauly, D. Editors, 2013. FishBase. World Wide Web electronic publication. Available at www.fishbase.org [Accessed Nov 2013].
ICCAT, 2014. Inter-sessional meeting of the sub-committee on ecosystems. Olhão, Portugal, 1 to 5 September 2014. Available at https://www.iccat.int/Documents/Meetings/Docs/2014_SCECO_Rep_ENG.pdf [Accessed Nov 2014].
ICCAT, 2014. Report of the Standing Committee on Research and Statistics (SCRS). Marid, Spain, 29 Sept to 3 Oct 2014. Available at https://www.iccat.int/Documents/Meetings/Docs/2014-SCRS-REP_ENG.pdf [Accessed Nov 2014].
ISSF, 2014. ISSF Tuna Stock Status Update, 2014: Status of the world fisheries for tuna. ISSF Technical Report 2014-09. International Seafood Sustainability Foundation, Washington, D.C., USA. Available at http://iss-foundation.org/wp-content/uploads/downloads/2014/09/ISSF-2014-09-Status-of-the-Stocks-Sept-11-BYCATCH-APPENDIX.pdf [Accessed Nov 2014].
IUCN, 2012. IUCN Red List of Threatened Species. Version 2012.2. Available at www.iucnredlist.org [Accessed December 2012].
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