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Tuna, yellowfin

Thunnus albacares

Method of production - Caught at sea
Capture method - Longline
Capture area - Eastern Pacific - EPO (FAO 77,81,87)
Stock area - Eastern Pacific Ocean
Stock detail - All Areas
Certification -
Fish type - Oily fish

Sustainability rating Click for explaination of rating

This fish, caught by the methods and in the area listed above, is not a good choice of sustainable fish to eat and should be only eaten very occasionally. Click on the rating icon above to read more and on the alternatives tab below to find more sustainable fish to eat.


Sustainability overview

In 2015, the IATTC updated their 2013 stock assessment which indicated the population had slightly improved since the last assessment . The results indicate that the spawning biomass has improved a little in recent years and at the start of 2015 was slightly overfished, but not subject to overfishing. The is considerable uncertainty in this assessment and it is suggested that the stock may now be moving from a regime of high productivity to an intermediate one and it is recommended that fishing mortality not be increased. Purse seines set on free schooling tuna as opposed to being associated with Fish Aggregation Devices (FADs) or dolphins represent the most selective fisheries.

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. This is particularly important for the dolphin associated purse seine fishery which needs to increase efforts to reduce dolphin mortality to zero as soon as possible. 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.

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

Stock area
Eastern Pacific Ocean

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Stock information
Yellowfin stocks in the Eastern Pacific Ocean (EPO) are managed and assessed by the Inter-American Tropical Tuna Commission (IATTC). In 2014, catches were approximately 233,566t which is roughly equal to the previous five year average of 234,178t and below the estimated Maximum Sustainable Yield (MSY) of 275,258t. In 2015, the IATTC updated their 2013 stock assessment and indicated that both spawning biomass and fishing mortality had slightly improved since the last assessment, yet uncertainty remained about recent and future levels of recruitment and biomass. The scientific committee note that there have been two, and possibly three different productivity regimes, and the MSY levels and the biomasses corresponding to the MSY may differ among the regimes. The population may have switched in the last ten years from a high to an intermediate productivity regime. The results indicate that the spawning biomass has improved a little in recent years and at the start of 2015 is slightly below that which would produce MSY (0.99Bmsy) and is therefore slightly overfished. Recent fishing mortality (2012-2014) was below Fmsy (0.86Fmsy) indicating that the stock is not being subject to overfishing. It is noted though that if a stock-recruitment relationship is assumed, the outlook is more pessimistic, and current effort would be estimated to be above the MSY level. It is also noted that MSY could be increased by reducing fishing mortality in fisheries which take juveniles.

Management

Most tuna stocks range across and are accessed by numerous coastal states, making harmonised and effective management of these individual stocks very difficult. As a result, 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. The yellowfin tuna fishery in the Western and Central Pacific Ocean (WCPO) is managed by the Western and Central Pacific Fisheries Commission (WCPFC). 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. There is a WWF coordinated Fisheries Improvement Project (FIP) for some local handline fleets in the Philippines - the Partnership Project Towards Sustainable Tuna (PPTST). The project aims to get the fishery to MSC application by 2017, and is working on numerous aspects including monitoring and reporting.

Whilst the stock at last assessment was not overfished nor being subject to overfishing, recent catches are slightly over the Maximum Sustainable Yield (MSY) and increased fishing mortality in the equatorial regions is likely to increase depletion of the biomass. The scientific committee recommend implementing measures to maintain the current spawning biomass levels and that a spatial management approach should be considered to reduce fishing mortality, particularly on juveniles.

Established management and conservation measures of note include: maximum limits for days at sea and a requirement by members to prevent days at sea increasing beyond specified levels; complimentary requirements across fisheries and regions to ensure fishing mortality on bigeye, yellowfin and skipjack tuna stocks are maintained at or reduced to Fmsy in a addition to a purse seine landing obligation for these species between 20??N and 20??S; and there was recent agreement by coastal states to take measures to not increase catches of yellowfin from their vessels.

For the FAD fisheries: there is a 3-month closure of fishing on FADs in EEZ waters and on the High Seas between 20degrees N and 20degrees S; plus, in 2015 and 2016, each member shall choose between extending this FAD closure to five months, or limit the number of FAD sets to less than the number of sets made by its vessels in a prescribed reference period. In 2017, a prohibition on FAD sets on the high seas will apply, except for vessels purse seine flagged to Kiribati. Additionally there is a requirement to submit FAD management plans, including information on strategies used to implement the closure and other measures for reducing mortality of juvenile bigeye. It isn't clear how successfully these measures have been implemented yet, especially given the ongoing increases in total catch of skipjack and bigeye.

There is also a limit between 20N and 20S in the number of purse seine vessels with freezing capacity.

100% regional observer coverage is required for all purse seine vessels fishing on the high seas and in waters under the jurisdiction of one or more coastal States, or vessels fishing in waters under the jurisdiction of two or more coastal States during the same trip; and on all purse seiners fishing between 20N and 20S.

To help address IUU, the WCPFC maintains an IUU Vessel List; prohibits transhipments at sea between purse seiners (Some exemptions apply) and requires all other transhipments to be documented and 100% observed as part of the regional observer programme.

Capture information

Longline catches of yellowfin in the Eastern Pacific Ocean have been steadily decreasing and in roughly represent 4% of the total retained catch. Longlining targets larger, mature fish yet is often associated with the bycatch of vulnerable species such as seabirds, turtles and sharks. To help address this, the IATTC require: that longliners over 20m in length use at least two prescribed seabird mitigation measures (e.g. tori line, dyed bait, weighted branch line, night setting, underwater setting chute); for vessels to carry line cutters and de-hookers to promptly release turtles or to foster to recovery any sick or comatose turtles captured; permissible sharks are to be fully utilized and no more than 5% of fins to total shark weight can be retained with a prohibition to land oceanic whitetip sharks; and countries to develop national plans of action to address the bycatch of sharks, turtles and seabirds. Monitoring and reporting is deficient in many fisheries however, and the effectiveness of these various measures has not been evaluated. The IATTC requires 5% observer coverage on longliners greater than 20m in length.

Monitoring and reporting of interactions with vulnerable species in particular needs to be improved.

Read more about capture methods


References
Froese, R. and Pauly, D. Editors, 2015. FishBase. Available at www.fishbase.org [Accessed Dec 2015].

IATTC, 2015. Active IATTC and AIDCP Resolutions and Recommendations. Available at http://www.iattc.org/ResolutionsActiveENG.htm [Accessed Dec 2015].

IATTC, 2015. Status of yellowfin tuna in the Eastern Pacific Ocean in 2014 and outlook for the future. Available at http://www.iattc.org/Meetings/Meetings2015/6SAC/PDFs/SAC-06-06-YFT-assessment-2014.pdf [Accessed Dec 2015].

ISSF, 2015. Status of the world fisheries for tuna: management of tuna stocks and fisheries. Nov 2015 Update. Available at http://iss-foundation.org/knowledge-tools/reports/technical-reports/download-info/issf-technical-report-2015-03-a-status-of-the-world-fisheries-for-tuna-november-2015/ [Accessed Dec 2015].

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