Atlantic bluefin tuna

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.

Management has been effective at supporting stock recovery. However, there remains a lot of uncertainty about whether the stock has reached sustainable levels yet. Additionally, some illegal fishing is taking place.Tuna, marlin, and swordfish are highly migratory species, found on the high seas and in numerous countries' waters. This makes harmonised and effective management challenging. Regional Fisheries Management Organisations (RFMOs) are responsible for monitoring and managing these stocks on behalf of the countries that access them. However, the degree to which management is implemented, monitored and enforced by each country varies significantly.Atlantic bluefin tuna is managed and assessed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). After the eastern stock came close to collapse in the early 2000s, a rebuilding plan was introduced. It ran from 2007-2017, and included catch reductions and increases in minimum landing size. Although it is not known if the stock has reached target levels (Biomass at levels associated with Maximum Sustainable Yield), fishing pressure (F) was brought below FMSY. These measures are thought to have contributed to the subsequent rapid stock increase.During 2022, a number of management options were tested. Based on this, a new management procedure was introduced in 2023 that covers both east and west Atlantic bluefin tuna. It will be reviewed every 6 years. It includes harvest control rules that form the basis for setting catch limits (Total Allowable Catches, TACs) on a 3-yearly basis. Stocks must have a 60% or greater probability of not being overfished or subject to overfishing, and a less than 15% probability of being below Blim. Annual changes in TAC can be up to 20% increase or 35% decrease.TAC for 2023-2025 is 40,570t, split between the various catching countries. This is an increase from the 2020-2022 TAC of 36,000t. The stock assessment projected that catches of 36,000 tonnes would allow the stock to increase, but it is unclear what the expected impact of 40,000t would be. It is also unclear how management will ensure that biomass is above target thresholds with 60% probability when assessments have been unable to indicate the biomass. However, it appears that management is following the available scientific advice and has been effective at recovering the stock to date.Average catch from 2017-2021 was 30,500 tonnes - below the TAC. However, the Scientific Committee has been informed of unquantified illegal catches of unknown magnitude. Given the high levels of uncertainty around the status of the stock, this is of concern.Most of the catch is by purse seiners, mostly on juveniles, which are taken alive to tuna farms for fattening. While there is no data in the latest stock assessment relating to ages and sizes of tuna caught, a high catch of juveniles would be very concerning for the long-term growth of the stock.Management measures also include:To protect spawning grounds (the precise location of which are still being identified), there are open seasons, varying depending on gear and location.Annual fishing and farming plans must be submitted by each country, to include quotas and fishing seasons for each gear type.Countries must calculate the fishing capacity needed to deliver their set quotas, and reduce current capacity, e.g. by reducing licenses or vessel sizes, if it is too high. The allowed number of baitboats and trolls is frozen to 2006 levelsThere is a minimum size of 30kg or 115cm, although there are some exceptions, e.g. baitboats and trolls.Aerial vehicles cannot be used to help vessels find bluefin tuna.As of 2006, catch of Atlantic bluefin by longliners from the central Atlantic is frozen to levels caught in 1999/2000 as mixing of eastern and western stocks in this area is not well understood.Minimum observer coverage is higher than for other stocks and varies by gear: 20% for longliners, pelagic trawlers, and bait boats over 15m; 100% for purse seiners, towing vessels, and harvesting operations from traps.Countries must keep a list of vessels and traps authorised to fish for, and facilities authorised to farm, this species. Transhipment at sea is prohibited, and may only take place in designated ports with prior authorisation. Vessels over 15m must have Vessel Monitoring Systems. There is a catch documentation scheme, which since 2018 is fully electronic to improve tracking of bluefin from catch to farm to export.A small amount of bluefin tuna (less than 500 tonnes) is caught in Marine Stewardship Council-certified fisheries. Certifications are conditional improving the understanding of the stock and the fishery, and better monitoring of impacts on other species. This rating covers these certified fleets as well as uncertified fleets.

Some eastern Atlantic bluefin catches are by fixed traps, also known as 'almadraba'. These traps have low levels of bycatch, and are unlikely to have significant habitat impacts.About 15% of the eastern Atlantic bluefin catches are by fixed traps (around 5,500 tonnes in 2021). Tuna trapping is a traditional fishing method that has been practiced for over a thousand years. Most catches now are by Spain, Morocco and Portugal, with some by Italy. Traps are set up parallel to the coastline in areas that the tuna pass through when they migrate to or from their Mediterranean spawning grounds, e.g. the Straits of Gibraltar. They consist of a series of net chambers, which the tuna instinctively swim through, leading to a final pen. The pen has a net floor which is raised and the tuna are then harvested. Trapping is seasonal, and most traps are set facing westward, so that they catch adult tuna when they are returning from the spawning ground after spawning.The nets are anchored to the seabed, so depending on where the traps are set, there could be seabed impacts. Traps tend to be set on soft sediments, which are more robust than sensitive habitats like rocky or biogenic reefs.The mesh used for these nets is large, and so most species are able to escape. Those that are caught tend to have commercial value, with less than 1% of the catch being discarded. Other species caught can include small tunas, bigeye tuna, and swordfish. Atlantic bigeye and Mediterranean swordfish were estimated to be overfished and subject to overfishing in 2017, but trapping is not listed as one of the main capture methods for either stock. The small tunas are data limited, with some at high risk, but the main concern for these species is bycatch in the purse seine and longline fisheries. A 2012 review of bycatch management in RFMOs indicated that while sharks and rays can be caught in traps in some areas, this is not a concern in ICCAT fisheries. 100% of trap fisheries must have an observer, under ICCAT regulations, which should result in accurate bycatch records.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 and would receive a default red rating from MCS.