Tuna, yellowfin

Thunnus albacares

Method of production — Caught at sea
Capture method — Purse seine (FAD & Free School)
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

The 2018 stock assessment indicates that whilst the stock is not overfished, it is subject to slight overfishing and there is concern that fishing capacity of the purse seine fishery continues to increase. In 2016 interim Harvest Control Rules were brought in for bigeye, skipjack and yellowfin purse seine fisheries - as these species are caught together - with the aim of preventing fishing effort from exceeding MSY for the species that requires the strictest management; for other fisheries, management measures will be as consistent as possible with the purse seine fishery. 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. 34% of the yellowfin catch in the EPO is made by purse seining (excluding tuna-dolphin shots): 21% on floating objects including Fish Aggregation Devices (FADs) and 13% on free schooling tuna. The high volume of juveniles caught in the purse seine fisheries has substantially reduced the available sustainable yield of bigeye. The proportion of bycatch of vulnerable species is low in purse seine fisheries in the EPO (less than 0.5% for sharks), yet the overall catch of sharks is still significant and better monitoring and reporting is needed from the smaller purse seiners. FADs can also entangle sharks and turtles, but FAD construction and overall management is improving. There is 100% observer coverage on large purse seiners, but small purse seiners have no observer requirement and data from them is very poor.

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: 0.25 info

Stock Area

Eastern Pacific

Stock information

Yellowfin stocks in the Eastern Pacific Ocean (EPO) are managed and assessed by the Inter-American Tropical Tuna Commission (IATTC). There is uncertainty about the historical patterns of this stock, with possibly three different productivity regimes since 1975: below average recruitment until 1982, mostly above average from 1983 to 2002, and then mostly below average until 2014. Levels of maximum sustainable yield (MSY) and the biomasses corresponding to the MSY may differ among the regimes. Annual recruitments for 2015 to 2017 were estimated to be at or above average, but this is uncertain. The spawning biomass ratio (SBR) has been average or below average since 2005, except during 2008-2010, coinciding with strong and weak La Nina events respectively.

The assessment method of yellowfin tuna in the eastern Pacific Ocean in 2018 is similar to the previous assessment, with the addition of new and updated data. The provisional 2017 catch of 211,899 t is lower than in previous years (2012-2016 average is 238,558 t) and below MSY (264,283 t). The stock is subject to overfishing: recent fishing mortality, F, is slightly above MSY (F multiplier = 0.99 or F=1.01 FMSY). Although F is only just above FMSY, fishing capacity of the purse seine fishery continues to increase, which is a concern. The stock is not overfished, with the ratio of spawning biomass (S) to SMSY estimated to be 1.08. The recent biomass ratio of fish aged 3 quarters and older, however, is higher, at 1.35, because of the large recent recruitments.

Under the current (2015-2017 average) fishing mortality, the SBR is predicted to increase in the next two years because of the large recent recruitments, and level off at about MSY level if recruitment is average. Catches are predicted to increase in the near future, but these interpretations are uncertain, and highly sensitive to the assumptions made about the stock-recruitment relationship, the average size of the oldest fish, and the assumed levels of natural mortality . The results are more pessimistic if different values are assigned to these factors. According to the scientific committee, moderate changes in the long-term levels of effort will change long-term catches only marginally, while changing biomass considerably. Maintaining the fishing mortality below the MSY level would result in only a marginal decrease in the long-term average yield, with the benefit of a relatively large increase in the spawning biomass. Increasing the average weight of the yellowfin caught could increase the MSY.

Management

Criterion score: 0.5 info

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.

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. Further evaluation of this HCR and alternatives will be conducted, so that a permanent HCR can be adopted.

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: fleet capacity in 2017 was estimated to be about 6.7% greater than the previous three-year average. Management measures were updated accordingly, in line with recommendations: the 62-day closure for large purse seiners was extended to 72 days annually until 2020. However, in 2018 a new bigeye stock assessment indicated that the stock was now subject to overfishing, and while the assessment was too uncertain to recommend further extensions of the closure, indications are that current measures remain insufficient to prevent overfishing of bigeye. Scientific recommendations are for the total number of purse seine sets (FAD and non-FAD) to be limited to 14,895 in 2019 and 14,498 in 2020, with only dolphin-associated sets allowed once this limit is reached. These have yet to be adopted by the commission, although there are per-vessel limits on the number of FADs that can be active at any one time (between 70 and 450, depending on vessel size) and regular reporting on FAD activity is required.

Until 2020, there is a 30-day closure of an area known as the “Corralito” (west of the Galapagos Islands, where catch rates of small bigeye are high) to the purse-seine fishery for yellowfin, bigeye, and skipjack tuna.

A requirement to retain and land all bigeye, skipjack, and yellowfin tuna caught by purse seine has been extended until 2020, although the degree of enforcement regime may vary depending on the country or authority.

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. 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

34% of the yellowfin catch in the EPO is made by purse seining: 21% on floating objects including Fish Aggregation Devices (FADs) and 13% on free schooling tuna.

Purse seining is commonly an industrial scale fishery used to catch tuna destined for canneries. These fisheries target smaller fish that aggregate close to the surface, whereas longliners target larger fish that inhabit deeper waters. Many juvenile fish are often caught in purse seine fisheries and the method can also be associated with bycatch of vulnerable species, in particular sharks. In the EPO, the bycatch of sharks comprises a small proportion of the total catch of tuna, but as the volume of tuna caught is high, the catch of sharks is still significant.

FAD-associated purse seining generally encounters higher bycatch rates compared with sets on free-schools, and higher proportions of juvenile tuna. It’s unknown if the widespread use of FADs has other impacts such as on the natural species composition of tuna schools, migratory patterns, growth rates and predation rates of affected pelagic species. The 2018 assessment of yellowfin tuna, often caught with bigeye, indicates that the stock is subject to overfishing. Poorly designed FADs can also entangle animals like sharks and turtles.

Bycatch mitigation measures such as sorting grids are in place to reduce mortality of turtles, sharks and non-target species in general. From Jan 2015, all purse seiners using FADs in the EPO must record and report to the authorities details relating to the FAD design, deployment, catch and bycatch summaries for each set. Additionally, FAD design is required to be non-entangling so as to minimise interaction with turtles and sharks and is encouraged to be made from biodegradable materials. Further restrictions to reduce the entanglement of sharks, sea turtles or any other species come into force in January 2019. Vessels are prohibited from knowingly setting a purse seine around tuna schools associated with a live whale shark and if a whale shark is incidentally encircled, all reasonable steps must be taken to ensure its safe release. Details of the interaction are to be recorded, as are details of any interactions with sharks and turtles. Permissible sharks are to be fully utilized and no more than 5% of fins to total shark weight can be retained; landing oceanic whitetip, silky sharks and mobula rays is prohibited and vessels must not fish in silky shark pupping areas. 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. There is 100% observer coverage on large purse seiners in the EPO so the data coming from these fleets should be useful and of high quality. It has been recommended that an observer programme be established for small purse seiners as well.

Alternatives

Based on method of production, fish type, and consumer rating: only fish rated 2 and below are included as an alternative in the list below. Click on a name to show the sustainable options available.

Anchovy, anchovies
Arctic char
Herring or sild
Salmon, Atlantic (Farmed)
Salmon, Chinook, King Salmon
Salmon, Chum, Keta, Calico or Dog salmon
Salmon, Coho , Silver, White
Salmon, Pink, Spring , humpback
Salmon, Sockeye , Red Salmon, Bluebacks, Redfish
Sprat, whitebait
Swordfish
Trout, Rainbow
Tuna, albacore
Tuna, bigeye
Tuna, skipjack
Tuna, yellowfin

References

Fishery Progress, 2018. Fishery Improvement Project Directory. Available at https://fisheryprogress.org/ [Accessed on 05.12.2018].

IATTC, 2018. Inter-American Tropical Tuna Commission: Active IATTC and AIDCP Resolutions and Recommendations. Available at https://www.iattc.org/ResolutionsActiveENG.htm [Accessed on 05.12.2018].

IATTC, 2018. Ecosystem considerations. Document SAC-09-1 for the Inter-American Tropical Tuna Commission Scientific Advisory Committee, Ninth Meeting, 14-18 May 2018, La Jolla, California, USA, 15 pp.

IATTC, 2018. Staff recommendations for management and data collection. Document SAC-09-15 Rev 2 for the Inter-American Tropical Tuna Commission Scientific Advisory Committee, Ninth Meeting, 14-18 May 2018, La Jolla, California, USA, 15 pp. Available at https://www.iattc.org/Meetings/Meetings2018/SAC-09/9th-Meeting-Scientific-Advisory-Committee.htm [Accessed on 05.12.2018].

IATTC, 2018. Tunas, Billfishes and Other Pelagic Species in the Eastern Pacific Ocean in 2017. Document IATTC-93-01 for the Inter-American Tropical Tuna Commission 93rd meeting, 24 and 27-30 August 2018, San Diego, California. 115 pp. Available at https://www.iattc.org/Meetings/Meetings2018/IATTC-93/IATTC-AIDCP-Annual-Meetings-AUG2018ENG.htm [accessed on 05.12.2018].

ISSF, 2018. Status of the world fisheries for tuna: October 2018. ISSF Technical Report 2018-21. International Seafood Sustainability Foundation, Washington, D.C., USA. 103 pp. Available at: https://iss-foundation.org/about-tuna/status-of-the-stocks/ [Accessed on 06.12.2018].

Restrepo, V., Dagorn, L., Itano D., Justel-Rubio A., Forget F. and Moreno, G., 2017. A summary of bycatch issues and ISSF mitigation initiatives to-date in purse seine fisheries, with emphasis on FADs. ISSF Technical Report 2017-06. International Seafood Sustainability Foundation, Washington, D.C., USA.