Yellowfin tuna

Atlantic yellowfin tuna is not overfished and is not subject to overfishing. However, there is some uncertainty in this assessment, and recent catches have been above recommended levels, which could cause the stock to decline.Yellowfin tuna in the Atlantic is assessed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). The last stock assessment was carried out in 2024, using data up to 2022.Catches of yellowfin declined from their peak of 190,000 tonnes in 1990 to 100,000t in 2007, and subsequently rose to an average of 141,000 tonnes from 2020-2024. Biomass has continuously declined throughout the lifetime of the fishery, while fishing mortality has been increasing since the mid-2000s.In 2022, biomass (B) was 37% above biomass levels associated with Maximum Sustainable Yield (SSB MSY). Therefore, the stock is not in an overfished state.Fishing mortality (F) in 2022 was 89% of the fishing pressure levels associated with FMSY. Therefore, the stock is not subject to overfishing.The catch in 2024 was 140,300 tonnes. This is of concern to the scientific committee because it exceeds the adopted catch limit (110,000t) and has exceeded MSY (122,000t) every year since 2015. Projections indicate that catches above 120,000t would cause biomass to decline. At 140,000 tonnes, there is a 48% probability that the stock will be above BMSY and below FMSY by 2030.Some catches are on Fish Aggregating Devices (FADs), which tend to catch smaller tunas, including juveniles. The scientific committee has highlighted that increased catches of small yellowfin (and small bigeye, as they are caught together on FADs) will have negative effects on stock size and future harvest rates.

Few appropriate management measures are in place. Management is not effective at controlling fishing pressure on this stock. Catch limits have been exceeded in every year since 2015, at levels that are expected to cause the stock to decline.Tuna, marlin and swordfish are highly migratory species that occur both on the high seas and within the waters of multiple coastal states, making harmonised and effective management challenging. Regional Fisheries Management Organisations (RFMOs) are therefore responsible for the assessment, management and monitoring of these stocks on behalf of their member countries. However, the extent to which agreed measures are implemented, monitored and enforced varies considerably between countries.Atlantic yellowfin tuna is managed and assessed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). Core management measures include an overall Total Allowable Catch (TAC), restrictions on fishing capacity and gear, and controls on fishing practices, particularly the use of Fish Aggregating Devices (FADs).An overall TAC of 110,000 tonnes, unallocated by country, has been in place since 2012. Scientific advice indicates that maintaining catches at 120,000 tonnes or less would be expected to sustain the stock in a healthy condition through to 2033, suggesting that the TAC itself is broadly aligned with scientific advice. However, total catches have exceeded the TAC every year since 2015. Average reported catches between 2020 and 2024 were approximately 141,000 tonnes, a level expected to lead to stock decline. ICCAT’s scientific committee has consequently concluded that existing conservation and management measures are insufficient and require strengthening.Most yellowfin tuna catches are taken by purse seine fisheries, many of which deploy FADs. FADs aggregate tuna and other pelagic species, increasing fishing efficiency but also resulting in high catches of juvenile fish, which can negatively affect population growth. In European purse‑seine fleets, which account for the majority of landings, the average size of yellowfin has declined to around half of the average weight observed in 1990, at least partly due to increased fishing on FADs and the capture of smaller individuals.To address these impacts, ICCAT has implemented a multi‑annual management plan for tropical tunas, covering yellowfin and bigeye tuna since 2012, and eastern skipjack since 2015, with a strong focus on FAD management. Early measures included a two‑month FAD fishing ban in areas of high juvenile abundance and a limit of 500 FADs per vessel. As these measures did not sufficiently reduce juvenile mortality, additional restrictions were introduced. The number of operational FADs per vessel was reduced to 300 in 2021–2022, and a full‑area FAD closure lasting 72 days was implemented in 2022. For 2025, ICCAT has agreed a 45‑day closure (17 March–30 April) during which purse‑seine and baitboat vessels are prohibited from fishing on floating objects in both the high seas and EEZs, alongside a 15‑day pre‑closure ban on deploying drifting FADs.Further measures include limits on the number of FADs with operational buoys, set at 300 per vessel in 2025 and reducing to 288 in 2026 and 2027, with CPCs encouraged not to exceed their 2018 FAD fishing effort levels. CPCs with purse‑seine or baitboat fisheries are also required to submit annual FAD management plans. To reduce bycatch and environmental impacts, ICCAT requires that from 1 January 2025, all FADs deployed or redeployed must be non‑entangling, and has agreed a stepwise transition to biodegradable FADs between January 2025 and January 2028, excluding tracking buoys.Additional conservation measures include a ban on discarding skipjack, yellowfin and bigeye tuna, meaning all catches must be landed, and a tagging programme aimed at improving stock assessments and evaluating management effectiveness. This programme contributed to improvements in the 2019 yellowfin assessment.There is also a ban on drift nets (introduced by the EU in 2002 and by ICCAT in the Mediterranean in 2003), restrictions on at‑sea transhipment unless pre‑authorised and observer‑covered, and the maintenance of IUU vessel lists.Observer coverage requirements are 100% for purse‑seine vessels targeting tropical tunas and 10% for large longline vessels, although compliance remains uneven and falls short of the 20% coverage recommended by scientists for robust data collection. Vessel Monitoring Systems (VMS) are mandatory for all vessels over 24 metres, and work is ongoing to expand electronic monitoring systems.Despite this range of measures, persistent TAC overruns, continued high juvenile mortality, and uneven implementation and enforcement indicate that current management remains inadequate to ensure the long‑term sustainability of Atlantic yellowfin tuna.

Some yellowfin tuna in the Atlantic are caught by longlining. While longlining is unlikely to have habitat impacts, it can have a bycatch of highly vulnerable species such as sharks, turtles, and seabirds.Longline fisheries targeting Atlantic yellowfin tuna have shown considerable variability in catches since the 1990s and currently account for approximately 14% of total Atlantic yellowfin catches.Monitoring and reporting of bycatch in ICCAT‑managed fisheries remain inadequate. Most bycatch data are derived from scientific observer programmes. Scientific guidance indicates that 20% observer coverage is required to generate reliable data, yet ICCAT mandates only 5% coverage, increasing to 10% from 2022, and many fleets fail to meet even these minimum requirements. As a result, the impacts of these fisheries on vulnerable species are poorly quantified and likely underestimated.Both longline and purse‑seine fisheries catch sea turtles, including loggerhead, leatherback and olive ridley turtles. According to the IUCN Red List, loggerhead turtles are Endangered in the northeast Atlantic, while leatherback turtles are Endangered in the northwest Atlantic and Critically Endangered in the southwest Atlantic. Observer data from 2020 recorded 20 dead turtle discards, 1,308 live discards, and 20 discards of unknown fate, though these figures are almost certainly underestimates due to limited observer coverage. Estimated post‑release mortality is 1-4%. Longline vessels are required to safely unhook and release live turtles, while purse‑seine vessels must avoid encircling turtles. However, other scientifically recommended measures, such as the use of finfish bait and large circle hooks, are not mandatory.Seabird bycatch, particularly of albatrosses and large petrels, is a significant concern in longline fisheries and represents one of the leading threats to these groups globally. In the Atlantic, bycatch risk is highest south of 25°S, which overlaps with the highest densities of these species. Observer data for 2020 recorded 195 dead seabirds, 21 live discards, and 2 discards of unknown status, including species such as wandering albatross, Endangered sooty albatross, and black‑browed albatross. Given low observer coverage, actual mortality is likely much higher. An assessment estimated that 30,000-40,000 seabirds were killed annually by longlining across the Southern Hemisphere (including the South Atlantic) between 2012 and 2016.Mitigation requirements do not fully align with best‑practice recommendations from the Agreement on the Conservation of Albatrosses and Petrels (ACAP). ICCAT requires vessels to adopt one or more mitigation measures, such as weighted branch lines, bird‑scaring lines or night setting, depending on area and gear type. ACAP, however, recommends simultaneous use of all three measures, or alternatively the use of hook‑shielding or underwater bait‑setting devices. In the Mediterranean, the use of all seabird mitigation measures remains voluntary.