Atlantic bluefin tuna in the east Atlantic and Mediterranean is recovering from historically low levels. There remains concern for abundance, but not for fishing pressure.Atlantic bluefin tuna is managed and assessed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). The eastern stock was heavily fished from the 1950s until 1996, when management measures caused catches to drop from a peak of 60,000 tonnes to 10,00 tonnes. Recent catches have been around 30,000 tonnes. The last stock assessment was carried out in 2022, using data up to 2020. It is unclear when the next assessment will be carried out.Route 2 (data limited) scoring has been applied to this rating owing to the lack of reference points in stock assessments. Atlantic bluefin tuna is considered to have medium resilience to fishing pressure.The stock declined from the 1970s until 1991, coming close to stock collapse. It began to increase in the mid-2000s when a recovery plan was implemented. Assessments confirm a recent stock biomass increase, although the magnitude of the increase remains difficult to quantify. The assessment depends on recruitment estimates, which are highly unstable. It is also closely related to assumptions made about stock structure and migratory behaviour, which are poorly known. Given the levels of uncertainty, and that the stock is recovering from very low levels, MCS considers that there is still concern for the biomass.Fishing mortality (F) increased from the 1970s until the recovery plan was introduced, and then declined sharply. It has recently been increasing again, but remains below the target level. F in 2020 is estimated to be 81% of F0.1, which is a proxy for FMSY and has been set with the aim of maintaining the biomass at B0.1. This is an increase from the estimate of average F from 2015-2017, which was 42.6% of the target level. However, F remains below the target and therefore, there is no concern for fishing pressure.The outlook for this stock is highly uncertain because of the uncertainties in the data. However, it is projected that the spawning biomass will increase under the current TAC of 36,000t.The fattening and farming activities in the Mediterranean since 1997 have resulted in increasing but unknown catches of juveniles going into farms. There have been considerable improvements in data quality and quantity over the past few years but important gaps remain.It is unclear how much of the Eastern Atlantic stock mixes with and supports the Western Atlantic stock.Atlantic bluefin was listed as Endangered on the IUCN Red List until 2021, when it was moved to Least Concern. It is still listed as Endangered in the Mediterranean and Gulf of Mexico.
