Tuna, yellowfin

Thunnus albacares

Method of production — Caught at sea
Capture method — Longline
Capture area — Pacific, Eastern Central (FAO 77), South, East (FAO 87) and West (FAO 81)
Stock area — Eastern Pacific
Stock detail — All Areas
Picture of Tuna, yellowfin

Sustainability rating four info

Sustainability overview

Updated: November 2020

East Pacific yellowfin is better understood than other tropical tunas in the area, but further research is needed. While the stock is not thought to be overfished or subject to overfishing, fishing mortality is increasing and there are no catch limits. The primary measure has been effort limits on the purse seine fishery (responsible for 36% of catches). However, these controls are set to expire at the end of 2020 and have not been replaced, so yellowfin will become effectively unmanaged. Longline catches of yellowfin in the Eastern Pacific Ocean have been steadily decreasing and account for around 4% of the total retained catch. While longlining is unlikely to have habitat impacts, it can have a bycatch of highly vulnerable and Endangered species, including sharks, turtles, and seabirds. Some mitigation measures are in place, but they don’t follow scientific recommendations for best practice. The Eastern Pacific sub-population of leatherbacks is classified as Critically Endangered and at risk of extinction in the area. Bycatch and fishery interactions are the primary cause of the decline, and gillnets and longlines are the primary cause of bycatch - specifically in the southern and central Eastern Pacific (from Chile to Mexico). Better observer coverage and bycatch reduction in the next 5 years (by 2025) are critical.

Commercial buyers should establish what measures the flag state and fleet relating to their source is taking to reduce impacts to and improve reporting of interactions with vulnerable species. Large buyers should consider supporting such improvements. MCS also advocates specifying the need for supplying vessels, in particular purse seiners, to register on the ISSF Proactive Vessel Register.

There are some Marine Stewardship Council (MSC) certified fleets within this area which represent the best option. There are also Fisheries Improvement Projects (FIPs) for purse seine fleets operating in this fishery which are making good progress to address some key environmental issues and aim to achieve MSC certification. Further info abut these FIPs is available from fisheryprogress.org.

Biology

Tuna belong to the family Scombridae. They are large, oceanic fish and are seasonally migratory, some making trans-oceanic journeys. Yellowfin are found throughout the world’s tropical and subtropical seas, except the Mediterranean. They often form large, size specific schools, frequently associated with dolphins or floating objects. Yellowfin is a large fast growing species, reaching maximum sizes of 240cm in length, 200kg in weight and an age of 8 years. They mature when 2 to 5 years old and mainly spawn in summer. Smaller fish are mainly limited to surface waters, while larger fish are found in surface and deeper waters, but rarely below 250m. Yellowfin has medium resilience to fishing.

Stock information

Criterion score: 0 info

Yellowfin stocks in the Eastern Pacific Ocean (EPO) are not thought to be overfished or subject to overfishing.

This stock is managed and assessed by the Inter-American Tropical Tuna Commission (IATTC). Catches before 1985 were between 100,000t and 200,000t, increasing to around 300,000t from the late 1980s until 2005. From 2001-2003 there were peaks of over 400,000t. They have since declined to around 240,000t. In 2020, stock status indicators (SSIs) were developed for yellowfin. Some of them indicate that the stock is subject to increased fishing mortality and that there is a need for precautionary management. These indicators use average values from 2000-2019 as a reference point. The main fisheries were assessed separately: dolphin-associated purse seining, free-school purse seining, floating-object purse seining, and longlining. Trends in the floating object, or fish aggregating device (FAD) fishery, showed the most concerning results: Effort and catches are above the reference point, while catch per set and average length of the tuna caught is below the average. All models indicated a decline in biomass, although the extent of the decline is not clear.

The assessment concludes that at the beginning of 2020, the spawning biomass of yellowfin ranged from 49% to 219% of the level associated with Maximum Sustainable Yield (MSY). During 2017-2019 the fishing mortality (F) of yellowfin ranged from 40% to 168% of the level at MSY. There is a low probability of F being above FMSY (9%) and zero probability of it being above the limit reference point. The probability of the spawning biomass being below MSY is also low (12%), and again there is a zero probability of it being below its limit reference point. MCS has moved from Route 2 (data limited) to Route 1 scoring for stock status, as there is now an assessment against MSY-based reference points (although the actual values for F and B are not known). Recruitment of young fish into the stock appears to be declining, and has been below the long term average since 2000. There are occasional peaks, e.g. in the late 1990s and in 2020. These peaks may be influenced by El Nino events.

Tagging studies of yellowfin throughout the Pacific indicate that they tend to stay within 1,800 km of their release positions. This tendency to stay within the same area, along with variation in characteristics of yellowfin between areas, suggests that there might be multiple stocks of yellowfin throughout the Pacific Ocean. However, movement between these potential stocks cannot be estimated with currently-available tagging data. This is the main uncertainty in the current stock assessment.

Management

Criterion score: 0.75 info

East Pacific yellowfin is better understood than other tropical tunas in the area, but further research is needed. While the stock is not thought to be overfished or subject to overfishing, fishing mortality is increasing and there are no catch limits. The primary measure has been effort limits on the purse seine fishery (responsible for 80% of catches).

Most tuna stocks range across and are accessed by numerous coastal states, making harmonised and effective management of these individual stocks very difficult. To try and achieve this, Intergovernmental Regional Fisheries Management Organisations (RFMOs) have been established. There are five main tuna RFMOs worldwide and it is their responsibility to carry out data collection, scientific monitoring and management of these fisheries. This stock is managed and assessed by the Inter-American Tropical Tuna Commission (IATTC). Whilst the RFMOs are responsible for the development of management and conservation measures, the degree to which they are implemented, monitored and enforced still varies significantly between coastal states. For this reason, it is important to choose tuna that has been caught by vessels that are well regulated by their flag state.

Management of tropical tunas (bigeye, yellowfin, and skipjack) in the Eastern Pacific is based on measures that last for three years. The current measures run from 2017-2020. At the 2020 IATTC commission meeting, the planned rollover of these measures to 2021 was blocked by one country, although a subsequent emergency meeting has resulted in them being extended until the end of 2021. Measures include:
A 30-day closure to large purse seiners of an area known as the “Corralito” (west of the Galapagos Islands, where catch rates of small bigeye are high) in October-November. Either before or after this, an additional 72-day closure in the whole IATTC area.
A limit on Fish Aggregating Devices, which catch high numbers of juvenile yellowfin and bigeye and are the main cause of increasing fishing pressure on all three tropical tunas. Limits per vessel range from 70 to 450, depending on vessel size. There were concerns about practicality of these limits, as accurate real-time monitoring of FAD versus non-FAD sets is challenging. It was recommended instead that the combined number of purse seine sets (FAD and non-FAD) should be limited to 2015-2017 average numbers (a 13% decrease on 2018 levels), with only dolphin-associated sets allowed once this limit is reached. In addition, the FAD limits were considered to be arbitrary and too high, and should be reduced by 30%.
Bigeye catch limits for longliners (varying by country). The scientific committee advises that if adequate management is in place for bigeye, this should also protect the skipjack stock.
A requirement to retain and land all bigeye, skipjack, and yellowfin tuna caught by purse seiners.
These measures represent the primary controls on catches and fishing effort for tropical tunas, and without them these fisheries will be effectively unregulated. Information on additional management measures is below.

In 2016, interim Harvest Control Rules were brought in for bigeye, skipjack and yellowfin purse seine fisheries, with the aim of preventing fishing effort from exceeding FMSY for the species that requires the strictest management. For other fisheries, management measures will be as consistent as possible with those for the purse seine fishery. Skipjack, yellowfin and bigeye stock assessments are too uncertain to produce values for fishing mortality, and stock status indicators and risk assessments are used instead. Indications are that fishing mortality is increasing on all three species owing to increases in purse seine fishing effort, specifically on floating objects. However, it is thought that yellowfin tuna is not overfished and not subject to overfishing. There are plans to evaluate this HCR and assess alternatives, so that a permanent HCR can be adopted.

The scientific committee considers it essential that fleet capacity does not increase beyond current levels. In 2002, regulations were implemented to freeze purse seine fleet capacity, but this has not been successful. Fleet capacity in 2017 was estimated to be about 6.7% greater than the previous three-year average. In 2017, it was acknowledged that the commission had failed since 2013 to reduce fishing mortality of yellowfin and bigeye (adjusted for capacity) to a level not exceeding MSY.

There is 100% observer coverage on large purse seiners. The scientific committee continues to recommend 20% observer coverage for small purse seiners, to obtain better data on discards and bycatch, as well as investigations into an electronic monitoring system on all purse seiners for better data on species, sizes, and quantities of target and bycatch species. Since 2011 only 5% observer coverage has been required on large longliners, considered by the scientific committee to be too low for accurate data: a minimum of 20% coverage is recommended. In addition, data recorded by longliners is considered inadequate for scientific purposes and minimum data standards must be identified and introduced.

To help address IUU, the IATTC maintains an IUU Vessel List; maintains a register of authorised fishing vessels; and prohibits transhipments at sea for most vessels (some exemptions apply) and requires most other transhipments to be documented and observed as part of the regional observer programme. Countries are required to report annually on monitoring, control and compliance of management measures. However, IATTC is the only tuna RFMO not to have adopted Port State measures to strengthen work to tackle IUU. IATTC does not report on countries’ compliance with management measures and does not have a framework for addressing non-compliance.

The IATTC and WCPFC endeavour to work together to promote compatibility between their respective conservation and management measures across the Pacific.

Capture Information

Criterion score: 1 info

Longline catches of yellowfin in the Eastern Pacific Ocean have been steadily decreasing and accounts for around 4% of the total retained catch. While longlining is unlikely to have habitat impacts, it can have a bycatch of highly vulnerable and Endangered species, including sharks, turtles, and seabirds. Some mitigation measures are in place, but they don’t follow scientific recommendations for best practice. Mandatory observer coverage is very low, at just 5%. In general, 20% is scientifically recommended to ensure adequate monitoring of catch and bycatch. In the south-east Pacific, where part of this fishery takes place, longlining is one of the main contributors to the decline of leatherback turtle.

To address bycatch of vulnerable species, IATTC requires some mitigation measures Countries must develop national plans of action to address the bycatch of seabirds, turtles and sharks. Longlining for swordfish and albacore tuna usually happens in shallower waters than other tuna species, making it more accessible to some species such as seabirds.

Seabirds: Feeding opportunities for some seabird species are dependent on the presence of tuna schools feeding near the surface. Some seabirds, especially albatrosses (waved (Phoebastria irrorata), black-footed (P. nigripes), Laysan (P. immutabilis), and black-browed (Thalassarche melanophrys)) and petrels, are susceptible to being caught on baited hooks in pelagic longline fisheries. There is particular concern for the waved albatross, because it is endemic to the EPO and nests only in the Galapagos Islands. Longliners must use one or more seabird bycatch mitigation measures from a set list of options, depending on vessel size and fishing location, including weighted branch line, bird scaring lines, and night setting. However, recommended best practice is for those three measures to be applied simultaneously. IATTC’s scientific committee has recommended stricter requirements for seabird mitigation techniques and proof of effectiveness before new techniques are introduced.

Turtles: IATTC note that tuna fisheries in the Eastern Pacific are having an adverse effect on sea turtle populations, and there is particular concern over the marked decline in the number of nesting female leatherback turtles (3,000 in 1990; 300 in 2015). The Eastern Pacific sub-population of leatherbacks is classified as Critically Endangered and at risk of extinction in the area. Bycatch and fishery interactions are the primary cause of the decline, and gillnets and longlines are the primary cause of bycatch - specifically in the southern and central Eastern Pacific (from Chile to Mexico). Better observer coverage and bycatch reduction in the next 5 years (by 2025) are critical. IATTC have noted that mortality rates of turtles due to longlining are possibly greater for those that set their lines at shallower depths at night for albacore and swordfish. In addition, there is a sizeable fleet of artisanal longline vessels from coastal nations that also impact sea turtles. Vessels must carry line cutters and de-hookers to promptly release turtles or to foster to recovery any sick or comatose turtles captured. All interactions with sea turtles must be recorded. In 2019 additional measures were brought in for shallow-set longliners: one of the following mitigation measures must be used: large circle hooks, or only finfish for bait, or other measures if and when they are approved by the Commission.

Sharks: In 2018, all forms of purse seining combined caught 505 tonnes of sharks. Longlining caught 13,680t. Permissible sharks are to be fully utilized and no more than 5% of fins to total shark weight can be retained. There is a prohibition to land oceanic whitetips, silky sharks, and mobula rays. Shark lines are prohibited. For fisheries specifically targeting sharks, countries are required to develop management plans, demonstrating how they intend to avoid or reduce catches of highly depleted shark species. Any shark (whether alive or dead) caught that is not retained must be promptly released unharmed, following safe release requirements. There are special measures to protect silky sharks, including a limit on bycatch of silky sharks to a maximum of 20% of the total catch by fishing trip in weight and for surface longliners, no more than 20% of the silk shark catch can be individuals below 100cm. This is an interim measure, to be replaced when there is enough data for a stock assessment of the species. Fishing in silky shark pupping areas is prohibited, although these areas do not appear to have been clearly defined. In 2016 IATTC introduced stricter monitoring and reporting of catches of shark species, but the scientific committee continues to advise that shark data collection is inadequate and must be improved - it is currently not possible to assess the state of most sharks and mobulid ray species. The scientific committee also recommends that experiments be conducted on mitigating bycatches of sharks, especially in longline fisheries, and on the survival of sharks and mobulid rays captured by all gear types, with priority given to those gears with significant catches.

Monitoring and reporting is deficient in many fisheries, and the effectiveness of these measures has not been evaluated. Only 5% observer coverage is required on longliners greater than 20m in length, although the scientific committee recommends 20% coverage and improved standards of data collection. Despite strong recommendations to increase coverage as part of the urgent measures to protect leatherback turtles, a new resolution on observer coverage in 2019 kept the minimum at 5%.

References

ACAP, 2019. ACAP Review and Best Practice Advice for Reducing the Impact of Pelagic Longline Fisheries on Seabirds, Reviewed at the Eleventh Meeting of the Advisory Committee of the Agreement on the Conservation of Albatrosses and Petrels, 13 - 17 May 2019, Florianopolis, Brazil. Available at https://www.acap.aq/en/bycatch-mitigation/mitigation-advice/3498-acap-2019-review-and-best-practice-advice-for-reducing-the-impact-of-pelagic-longline-fisheries-on-seabirds/file [Accessed on 29.11.2019].

Dias, M. P., Martin. R., Pearmain, E., J., Burfield, I. J., Small, C., Phillips, R. A., Yates, O., Lascelles, B., Garcia Borboroglu, P. and Croxall, J. P., 2019. Threats to seabirds: A global assessment. Biol. Cons. 237, pp 525-537. https://doi.org/10.1016/j.biocon.2019.06.033 [Accessed on 29.11.2019].

Griffiths, S. and Fuller, L., 2019. Ecosystem considerations. Document SAC-10-14 presented to the Inter-American Tropical Tuna Commission Scientific Advisory Committee Tenth Meeting, 13-17 May 2019, San Diego, California, USA. Available at https://www.iattc.org/Meetings/Meetings2019/SAC-10/Docs/_English/SAC-10-14_Ecosystem%20considerations.pdf [Accessed on 03.12.2019].

IATTC, 2020. Inter-American Tropical Tuna Commission: Active IATTC and AIDCP Resolutions and Recommendations. Available at https://www.iattc.org/ResolutionsActiveENG.htm [Accessed on 14.12.2020].

IATTC, 2020. Report On The Tuna Fishery, Stocks, And Ecosystem In The Eastern Pacific Ocean In 2019. IATTC-95-05 presented to the Inter-American Tropical Tuna Commission 95th Meeting, 30 November - 4 December 2020, Online. Available at https://www.iattc.org/Meetings/Meetings2020/IATTC-95/Docs/_English/IATTC-95-05_The%20fishery%20and%20status%20of%20the%20stocks%202019.pdf [Accessed on 14.12.2020].

IATTC, 2020. Staff Recommendations for Management and Data Collection, 2020. IATTC-95-01 presented to the Inter-American Tropical Tuna Commission 95th Meeting, 30 November - 4 December 2020, Online. Available at https://www.iattc.org/Meetings/Meetings2020/IATTC-95/Docs/_English/IATTC-95-01-MTG_Conservation%20recommendations%20by%20the%20Commission%20staff.pdf [Accessed on 14.12.2020].

ISSF, 2020. Position Statement 2020-02: IATTC. presented to the Inter-American Tropical Tuna Commission 95th Meeting, 30 November - 4 December 2020, Online. Available at https://iss-foundation.org/downloads/21177/ [Accessed on 15.12.2020].

ISSF, 2020. Status of the world fisheries for tuna. Nov. 2020. ISSF Technical Report 2020-16. International Seafood Sustainability Foundation, Washington, D.C., USA. Available at https://iss-foundation.org/knowledge-tools/technical-and-meeting-reports/download-info/issf-2020-16-status-of-the-world-fisheries-for-tuna-november-2020/ [Accessed on 10.12.2020].

Lopez, J., Lennert-Cody, C., Maunder, M., and Aires-da-Silva, A., 2019. Adjusting current fad limits to meet 2019 staff recommendations for tropical tuna management in the Eastern Pacific Ocean. Document FAD-04-01 presented to the Inter-American Tropical Tuna Commission Ad-Hoc Permanent Working Group on Fads Fourth Meeting, 19 July 2019, Bilbao, Spain. Available at https://www.iattc.org/Meetings/Meetings2019/IATTC-94/Docs/_English/FAD-04-01_Active%20FAD%20limits.pdf [Accessed on 03.12.2019].

Wallace, B., 2019. A call for collaboration between IAC and IATTC to save Eastern Pacific leatherbacks. Presented to the Inter-American Tropical Tuna Commission Scientific Advisory Committee Tenth Meeting, 13-17 May 2019, San Diego, California, USA. Available at https://www.iattc.org/Meetings/Meetings2019/SAC-10/BYC-09/Presentations/BYC-09-PRES_A%20call%20for%20collaboration%20between%20IAC%20and%20IATTC%20to%20save%20Eastern%20Pacific%20leatherbacks.pdf [Accessed on 02.12.2019].