Good Fish Guide
Tuna, Atlantic bluefin (Caught at sea)
Method of production - Caught at sea
Capture method - All applicable methods
Capture area - North East Atlantic, Mediterranean and Black Sea (FAO 27,37)
Stock area - East Atlantic & Mediterranean
Stock detail - All Areas
Certification - None
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 Globally and in the Mediterranean, and Near Threatened in Europe.
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 2015 reported catch of 16,201t was just over the 2015 TAC of 16,142 t and is the highest in the past 5 years (average 12,681t). The stock status for 2015 indicated little change in the current levels of fishing mortality and spawning stock biomass compared to 2013. In spite of recent improvements in data collection, there remain important data limitations for this assessment, primarily as a result of the misreporting 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, medium and high historical productivities result in a current biomass that is either high (1.60Bmsy proxy) , medium (1.10Bmsy 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 listed as Endangered by the International Union for the Conservation of Nature (IUCN) Globally and in the Mediterranean, but listed as Near Threatened in Europe.
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: 16,142t, 19,296t, and 23,155t for 2015, 2016 and 2017 respectively. The updated projections in 2016 are consistent with previous projections in that they indicate the goal of achieving BMSY (through 2022) with at least 60% probability might already have been reached or will soon be reached. The committee recommends adding a new phase to the current recovery plan. 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 has noted that the current mandatory level of observer coverage of 5% has not been implemented by many of the fleets and in 2016, updated their recommendation for a minimum of 5% observer coverage of fishing effort in each of the pelagic longline, purse seine, bait boat, traps, gillnet and trawl fisheries.
Approximately 62% 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 14% 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 are available and required to be employed to reduce bycatch and mortality of these species including: circle and/or barbless hooks to prevent turtle capture; chemical, magnetic and rare earth metal shark deterrents; and bird scaring lines for vessels south of 20 degrees S. South of 25 degrees S, longline vessels must use at least two of the following: night setting, bird-scaring lines or line weighting. In the Mediterranean, seabird mitigation measures are voluntary. There is also a prohibition to retain at risk shark species including: bigeye thresher, oceanic whitetip, hammerhead, silky and porbeagle 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 and the scientific committee strongly recommends improvements in data collection. 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. In 2016 additional measures for blue shark were introduced, mainly focussed on improved data recording, with potential to introduce Harvest Control Rules. 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 19% of the catch is taken in fixed net traps that reportedly have a low impact on non-target species.
Approximately 2% 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. 2% is also taken in recreational sports fisheries.
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.
In 2016, work was begun to improve ICCAT's understanding of the trophic ecology of pelagic ecosystems that are important and unique for species managed in this area. ICCAT also introduced a number of recommendations, to improve compliance and reporting. ICCAT has noted that the current mandatory level of observer coverage of 5% has not been implemented by many of the fleets and in 2016, updated their recommendation for a minimum of 5% observer coverage of fishing effort in each of the pelagic longline, purse seine, bait boat, traps, gillnet and trawl fisheries.
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.
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