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.

Most yellowfin tuna from the Atlantic is caught by purse seining. This method is associated with bycatch of species such as sharks, turtles and marine mammals.Purse‑seine fisheries account for approximately 66% of Atlantic yellowfin tuna catches. An estimated 18% of purse‑seine catches are taken on Fish Aggregating Devices (FADs), with the remaining 48% taken on free‑schooling tuna, although it is not always possible to reliably distinguish catches by fishing method.Purse‑seine fisheries are associated with the bycatch of sharks, sea turtles and marine mammals, although bycatch rates are generally lower than in longline fisheries. Bycatch levels are higher when FADs are used, as FADs aggregate a wide range of species in addition to target tuna. It is estimated that non‑target species account for around 7% of total catch by weight in FAD fisheries in the Atlantic, compared with approximately 1.8% in free‑schooling purse‑seine fisheries.FADs frequently incorporate hanging components such as ropes and netting, which increase the risk of entanglement of vulnerable species. Lost or abandoned FADs may continue to ghost fish and contribute to marine debris. A number of mitigation measures have been introduced to address these impacts. These include requirements for the use of non‑entangling FAD designs, the phasing‑out of non‑biodegradable FAD materials, and the submission of FAD Management Plans aimed at improving monitoring and limiting ecosystem impacts. In addition, 100% observer coverage is required on large purse‑seine vessels targeting tropical tunas, which improves bycatch data collection and supports compliance with management measures.Sharks represent the primary bycatch concern in these fisheries and are among the most threatened marine taxa globally. Sharks are both targeted and caught as bycatch in Atlantic tuna fisheries. Reported bycatch species include the Critically Endangered scalloped hammerhead (Sphyrna lewini), silky shark (Carcharhinus falciformis), and bigeye thresher (Alopias superciliosus), which is classified as Endangered in European and Mediterranean waters. Observer data from 2020 recorded 1,098 dead shark discards and 1,109 live shark discards. Given that observer coverage in longline fisheries is only 10%, these figures are likely to be substantial underestimates of total shark mortality.Some mitigation measures are in place for sharks, including a ban on shark finning. Retention of silky sharks, hammerheads, oceanic whitetip sharks and bigeye threshers is prohibited, while catches of other thresher shark species are discouraged. Shortfin mako sharks, which are heavily overfished, may be caught and retained, although measures were introduced in 2022 with the aim of ending overfishing of the species. Data limitations remain significant, and the status of many pelagic shark species cannot currently be fully assessed; no stock assessments have been conducted for the Mediterranean. Further research is also needed to understand the impacts of entanglement in FADs on shark populations.Sea turtles are also taken as bycatch in purse‑seine and longline fisheries, 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 reported 20 dead turtle discards, 1,308 live discards, and 20 discards of unknown status, although these figures are again likely to underestimate true mortality due to limited observer coverage. Estimated post‑release mortality ranges from 1-4%. Longline vessels are required to safely unhook and release turtles alive, and purse‑seine vessels must avoid encircling them; however, other scientifically recommended measures, such as the use of finfish bait and large circle hooks, are not mandatory.There are no specific management measures aimed at protecting marine mammals, including cetaceans, and ICCAT has not prioritised systematic data collection on marine mammal bycatch to date. Improved monitoring and mitigation are therefore required to better understand and reduce impacts on these species. The fishery is not currently considered a significant threat to seabirds.Beyond bycatch concerns, FAD use raises broader ecosystem issues, including potential impacts on the species composition of tuna schools, migration patterns, growth rates and predation dynamics. Purse‑seine fisheries catch juvenile yellowfin and bigeye tuna, and scientific advice recommends reducing these impacts to support stock sustainability.