This is now considered to be a separate species from Thunnus orientalis (Collette 1999).

This species has experienced declines in range and reported catch per unit effort since the 1960s. Although a number of uncertainties exist in the reported data, the best estimates from the most recent stock assessment indicate that there has been 63% decline in the past 20 years (1985-2005) which is approximately three generation lengths in the eastern Atlantic stock. This stock is listed as Endangered. However, given current fishing effort there is no current indication that these declines are slowing, and strict management measures should be enforced. Of equal importance, is the need to correct current inconsistencies and flaws in the data reported for this species.

The Atlantic bluefin tuna is present in the Mediterranean Sea and the southern Black Sea. In the Black Sea, bluefin tuna were well documented in ancient times and there was an annual migration from the Black Sea to the eastern Mediterranean spawning grounds. However, after World War II, environmental conditions in the Black Sea deteriorated and now bluefin tuna rarely occur in Black Sea waters.

Bluefin tuna have been fished in the Mediterranean for hundreds of years, and scientists and managers generally agree that the bluefin tuna is currently being overfished in the Mediterranean Sea. It is also generally agreed that the stock will continue to be overfished because of its high economic value and inadequate protection. However, because catch statistics are unreliable, assessment models are challenging. When reported catches from the eastern Atlantic and Mediterranean stock peaked in 1996 (at 50,807 t), managers and fisheries scientists decided it was overfished and a quota system was implemented. Subsequently, ranching of wild caught individuals became an important means to increase the biomass of exported tuna. Once caged, larger individuals can increase up to 25% in size while smaller ones can increase by 100% or more (A. Di Natale, pers. comm. 2008). All of this compounds the difficulties of interpreting the data. Based on the 2006 ICCAT report (International Commission for the Conservation of the Atlantic Tunas), the 2003-2004 fishing mortality rate (under the current overall fishing pattern) may be more than three times higher than that which would allow the stock to stabilize at the maximum sustainable yield, or MSY, level. Current fishing is expected to continue to drive the spawning biomass to a very low level.

In the eastern Atlantic and Mediterranean, annual catches during 2000-2004 ranged between 32,000 t and 35,000 t and the status of the stock is over-exploited (Majkowski 2007). The current quota system was predicated on a maximum sustainable yield (MSY) of 29,000 t, but current models put the MSY at 15,000 t (ICCAT SRCS 2006). The official estimate (ICCAT SCRS 2006) of the catch in the Mediterranean Sea that is caged after being caught is around 32,000 t, but the actual caged tonnage is probably closer to 39,000 t.

In the eastern Atlantic, age composition structure has changed over time (e.g. the population is now dominated by young age groups). Based on this trend of changing age structure and taking into account under reporting of catches (ICCAT SCRS 2009), spawning stock biomass has declined by 63% over the past 20 years (1985 to 2005) and spawning stock abundance has declined by approximately 32% (to a current population of 990,000 adults) (Y. Uozumi, pers. Comm. 2009). Based on a generation length of 6.5 years, this stock is considered as Endangered under IUCN Red List Criterion A2bd.

In the eastern Atlantic and in the Mediterranean Sea stock, age at first maturity is about 3 to 5 years (115-121 cm FL), with a longevity of 35 years or more (Corriero et al. 2003, Rooker 2007, Rooker 2008, Santamaria 2009). The average age of mature individuals (one generation length) is conservatively estimated to be 6.5 years in the eastern Atlantic.

There are several spawning grounds throughout the Mediterranean (Oray and Karakulak 2005). The eastern Atlantic stock spawns in the Mediterranean Sea from May to August at temperatures of 22.5-25.5°C. Maturity begins at age 3 and by age 5 all fish are fully mature. Females weighing between 270 and 300 kg produce as many as 10 million eggs per spawning season (Corriero et al. 2005). At 24°C, embryo development lasts about 32 hours and larval stages about 30 days. Egg size is 1.0 mm, and larval length at hatching is 2.8 mm. At early life stages (2.8-8 mm) larvae may grow 0.3 mm/day (Itoh et al. 2000, Miyashita et al. 2000, García-Rodriguez et al. 2006).

This is a highly valued species for the Japanese sashimi markets, which has led to severe overfishing in both the Eastern and Western Atlantic. It is also an important game fish particularly in the United States and Canada. The main gears are purse-seine, longline and traps. It is also used for commercial ranching (in the Mediterranean Sea).

In previous assessments conducted prior to 1996 (IUCN 2007), the eastern Atlantic stock was considered Endangered but the western Atlantic stock was considered Critically Endangered. The two stocks were considered Overexploited and Depleted, respectively by Majkowski (2007), seriously over-fished by Joseph (2009), and Critically Endangered by MacKenzie et al. (2009).

This is a highly valued species for the Japanese sashimi markets, which has led to severe overfishing in both the Eastern and Western Atlantic. It is also an important game fish particularly in the United States and Canada. It is also used for commercial ranching (in the Mediterranean Sea).

For European Union member states, driftnet fishing for tuna has been banned since 1 January 2002, while the ban entered into force in 2004 for all the other contracting parties to ICCAT, as well as the GFCM (General Fisheries Commission for the Mediterranean) member states, but a driftnet fishing activity is still officially permitted in Morocco. In 2002, ICCAT fixed the total allowable catch (TAC) for the East Atlantic and Mediterranean bluefin tuna at 32,000 t per year for the period 2003-2006. The most recent ICCAT Rec. [08-05] established decreasing TACs: 29,500 t in 2007, 28,500 t in 2008, 22,000 t in 2009, 19,950 t in 2010 and 18,500 t in 2011. However, Libya, Morocco and Tunisia were authorized to carry over into 2009 and 2010, their previous quota allocations that were not taken and Libya and Turkey disagreed with the allocation key accepted by other Contracting Parties to ICCAT and declared autonomous fishing quotas higher than their ICCAT allocation. The available information indicated that the 2007 fishing mortality rate was, under the 2004-2007 overall fishing pattern, more than three times the level which would permit the stock to stabilize at the maximum sustainable yield (MSY) level.

The intention of Rec. [06-05] and Rec. [08-05] are seen as a step in the right direction, but as previously noted, the ICCAT consider that it is unlikely to fully fulfil the objective of the plan to rebuild the stock to the MSY level by 2023. ICCAT is developing new strategies that would imply much lower catches during the next few years (on the order of 15,000t or less), but the long-term gain could lead to catches of about 50,000 t with substantial increases in spawning biomass. For a long lived species such as bluefin tuna, it will take some time (> 10 years) to realize the benefit. The ICCAT further believes that a time area closure could greatly facilitate the implementation and the monitoring of such rebuilding strategies. Clearly, an overall reduction in fishing effort and mortality, as stated in 2008, is needed to reverse current trends. The 2007 fishing capacity largely exceeds the 2007 TAC, but the 2008 catch capacity might be under 2008 TAC if illegal fishing did not occur. However, the potential catch capacity is clearly above TAC. Therefore, management actions need to be pursued to mitigate the impacts of overcapacity as well as to eliminate illegal fishing. Deferring effective management measures will likely result in even more stringent measures being necessary in the future to achieve the ICCAT objectives.

The Scientific, Technical and Economic Committee for Fisheries (STECF) agrees with the ICCAT-SCRS that the minimum catch size should be set at 25 kg in order to avoid misreporting and/or discarded catches of mature fish between 25 kg and 30 kg. There remains an urgent need to have more reliable and complete size frequency data (particularly, but not only, for early year-classes 1 to 3) for the period following the introduction of a TAC in the Mediterranean. Tagging programs, fishery independent surveys and mining of historical data will all contribute to a better understanding of the status of this species and should be encouraged (STECF 2009).

Although the results of the projections are highly dependent on estimated state of the stock in 2007 and future recruitment levels (both being uncertain), the overall evaluation of Rec. [06-05] is viewed by the Committee as unlikely to rebuild the stock in 15 years with 50% probability. Therefore, the Committee decided to contrast the above projections related to Rec. [06-05] with additional management strategies, i.e. (i) F0.1 or FMAX strategies (implying short-term yields at 15,000 t or less), (ii) a closure of the Mediterranean Sea in May-June-July together with a size limit at 25 kg (as recommended by the ICCAT SCRS in 2006) or (iii) a moratorium over the East Atlantic and Mediterranean Sea during 1, 3 or 5 years followed by an F0.1 strategy. The results clearly indicated that all these alternative management strategies would have a higher probability of rebuilding the stock by 2023 and a lower probability of stock collapse in the future than Rec.[ 06-05], regardless of the assumed productivity of the stock (ICCAT 2009).