Tuna, yellowfin

Thunnus albacares

Method of production — Caught at sea
Capture method — Purse seine (Dolphin-associated)
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 three 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. Approximately 71% of the yellowfin catch in the EPO is made by purse seining on tuna-dolphin associations. In the past this has caused very high dolphin mortality, but this has been greatly reduced over the years. However, in recent years the number has stopped decreasing and further efforts are needed to ensure dolphin mortality is reduced to zero as quickly as possible.

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: 0.75 info

Approximately 71% of the yellowfin catch in the EPO is made by purse seining on tuna-dolphin associations. In the past this has caused very high dolphin mortality, but this has been greatly reduced over the years. However, in recent years the number has stopped decreasing and further efforts are needed to ensure dolphin mortality is reduced to zero as quickly as possible.

This method has been employed for decades and makes use of the natural herding skills of the dolphins to keep the tuna in a tight ball which allows the seine to then encircle them. In the past, this has however resulted in large incidental catches and mortality of dolphins. The Agreement on the International Dolphin Conservation Program (AIDCP) aims to reduce incidental dolphin mortalities in the purse-seine fishery in the eastern Pacific Ocean to levels approaching zero. AIDCP sets a dolphin mortality limit (DML) for the international fleet, which is divided between vessels. In 2019 the total limit was 5,000 animals. The total mortality of dolphins in the fishery has been reduced from about 132,000 in 1986 to a low of 688 in 2017, which has since risen to 778 in 2019. On average from 2015-2019, 750 dolphins were killed annually. This equates to between 0.01% and 0.03% of the various dolphin populations. However, the last dolphin surveys took place in 2006, and therefore the current status of these populations is uncertain. The IATTC, in collaboration with the government of Mexico, the Pacific Alliance for Sustainable Tuna (PAST), and the Centre for Research into Ecological and Environmental Modelling (CREEM) at the University of St Andrews in Scotland is undertaking a project to survey the dolphin populations in the EPO.

The Tuna Tracking System established under the AIDCP tracks the tuna caught in each set from the time it is captured until it is unloaded. Tuna caught in sets in which dolphins are not killed or seriously injured is defined as “dolphin-safe”. During 2019, 96% of sets made on tuna associated with dolphins were accomplished with no mortality or serious injury to the dolphins. Dolphin mortality is managed and closely monitored by AIDCP, with 100% observer coverage.

Purse seining can be associated with bycatch of other vulnerable species, although less so in tuna-dolphin associated fishing. Some sharks and rays are caught, and the scientific committee 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.

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].

AIDCP, 2020. Report on the International Dolphin Conservation Program. AIDCP-41-02 presented to the Agreement on the International Dolphin Conservation Program, 41st Meeting of the Parties, 30 November 2020, Online. Available at https://www.iattc.org/Meetings/Meetings2020/IATTC-95/AIDCP-41/_English/AIDCP-41-02-MTG_Report%20on%20International%20Dolphin%20Conservation%20Program.pdf [Accessed on 15.12.2020].

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].