Marine Stewardship Council (www.msc.org):

• PT Citraraja Ampat, Sorong pole and line Skipjack and Yellowfin Tuna certified November 2018 to November 2023.
• French Polynesia albacore and yellowfin longline fishery certified June 2018 to June 2023.
• American Samoa EEZ Albacore and Yellowfin Longline Fishery certified November 2017 to November 2022.
• SZLC CSFC & FZLC FSM EEZ Longline Yellowfin and Bigeye Tuna certified with component(s) in assessment October 2018 to October 2023.
• SZLC, CSFC & FZLC Cook Islands EEZ South Pacific albacore & yellowfin longline certified June 2015 to June 2020.
• PNA Western and Central Pacific skipjack and yellowfin tuna; for purse seine setting on unassociated/ non FAD free schools; from December 2011 to March 2023.
• Fiji Albacore and Yellowfin tuna longline certified December 2012 to January 2023.
• FZLC Cook Islands EEZ South Pacific albacore & yellowfin longline: certified June 2015 for 5 years.
• Walker Seafood Australia albacore, yellowfin tuna and swordfish; for pelagic mid-set longline; from August 2015 for 5 years.
• Tri Marine Western and Central Pacific Skipjack and Yellowfin Tuna: certified June 2016 to June 2021.
• Solomon Islands skipjack and yellowfin tuna purse seine and pole and line: certified July 2016 to July 2021.

Several other yellowfin fisheries are under assessment.

Friends of the Sea (www.friendofthesea.org)

• Friend of the Sea does not certify fisheries, but rather tuna fishing fleets, including some company fleets fishing for yellowfin and other tunas in the Asia-Pacific region. A list of currently certified fleets can be found through this link.

Several conservation and sustainable/fair food organizations also promote sustainable tuna campaigns, e.g., see the Pew Charitable Trusts Global Tuna Conservation campaign.

FISHERIES ASSESSMENTS

The status of yellowfin tuna stocks is difficult to assess because the species is harvested by many different fishing gears, over a wide geographic area with each gear type tending to catch fish of a different size range. Longline fishing mainly harvests adult yellowfin tuna whereas purse seines harvest a wide size range of yellowfin tuna, including many juveniles.

Fisheries catch data, which are essential to yellowfin tuna assessments, have several shortcomings. In particular, reporting of yellowfin tuna catches is inconsistent among fleets and gears. For some gear types, such as those used in artisanal fishing, reporting of catch and effort is limited, e.g., despite their importance, the catches of yellowfin tuna in Indonesia, Philippines, and Vietnam are not fully monitored. Yellowfin tuna catches are under-reported for several gear types, especially purse seines, because juvenile yellowfin tuna school are harvested with other tuna species of similar size, especially skipjack (MRAG Asia Pacific, 2016). Log sheets from purse seine fisheries tend to be biased towards recording most small tunas as skipjack. Illegal, unreported and unregulated (IUU) fishing was estimated for yellowfin to be around 15% of the estimated total catch on yellowfin tuna in the Western and Central Pacific Convention Area during 2014 (for sets associated with floating objects) (MRAG Asia Pacific, 2016). Much of this is driven by estimates of misreporting (non-reporting/under-reporting and mis-identifying) in the purse seine fishery which is subject to 100% observer coverage. Misreporting of juvenile yellowfin (and bigeye) tuna occurs both in the WCPO and the IO fisheries and the logbook estimates are adjusted using port - or sea - samples of fish to help reduce the bias.

Western and Central Pacific Ocean

For yellowfin tuna in the WCPO, stock assessment and data management services are provided by the Oceanic Fisheries Programme of the Secretariat of the Pacific Community (SPC) and reviewed by the Scientific Committee of the Western and Central Pacific Fisheries Council. Yellowfin tuna assessments are based on catch, effort, fish size and tagging data from the major component fisheries – longline and purse seine fleets - and defined fishing regions of the management area of the Western and Central Pacific Fisheries Commission (WCPFC). Corrections and adjustments are made in the assessment models to account for the estimates of catch composition by species and biases in the monitoring data. Increasing attention is being paid to analyses of data from the fisheries conducted in the intensively fished Indonesian and Philippine waters (Langley et al., 2011). The Scientific Advisory Committee of the ISSF takes into consideration the WCPFC stock assessments, plus other reliable information, in making its sustainability assessments of stock abundance, fishing mortality and environment (ISSF, 2018).

Fishing mortality on both adults and juvenile fish has increased in recent years however are estimated to be below maximum sustainable yield (MSY) levels indicating that overfishing is not occurring. The geographic patterns of exploitation, however, are of concern (Tremblay-Boyer et al., 2017). Most of the catch is taken in western equatorial areas, with declines in both purse-seine and longline catch towards the east (Tremblay-Boyer et al., 2017). In the western equatorial Pacific part, the fishery is at least fully exploited with no potential for a substantial increase in catches to be sustainable (ISSF, 2018). Historical analyses indicate that MSY has been reduced to approximately 60% of its levels prior to 1970 through increased harvesting of juveniles (WCPFC, 2012). Most of the increase in juvenile harvesting is from the Philippines and Indonesian surface fisheries (purse seine, troll and various artisanal gears) (Tremblay-Boyer et al., 2017). The spawning biomass in Philippine and Indonesian waters appears to have declined to about 31% of the unexploited level (WCPFC, 2012). If mortality of juveniles were reduced, MSY levels would increase (WCPFC, 2012).

The purse-seine fishery on tuna schools associated with floating objects (including FADs) and the Philippines and Indonesian domestic fisheries have the greatest effect on yellowfin tuna stocks. These fisheries are conducted in western equatorial waters, including Indonesia, Philippines, the Federated States of Micronesia (FSM), the Republic of the Marshall Islands (RMI), Palau and the Solomon Islands. The purse-seine fishery on unassociated schools has a moderate effect. These western equatorial fisheries also influence yellowfintuna fisheries in all other parts of the WCPO (WCPFC, 2012).

Although tagging data indicate that yellowfin tuna in the WCPO are a single stock, sub-regional biological differences are recognised. For stock modelling, the WCPO area has been disaggregated into regions so as to describe spatial processes and fishing mortality within regions (Tremblay-Boyer et al., 2017). The biological characteristics of yellowfin tuna in the Western equatorial region need further investigation as growth rates, spawning and maturity schedules may differ from those elsewhere in the region (Tremblay-Boyer et al., 2017).

Indian Ocean

For yellowfin tuna in the IO, the stock is assessed by the Scientific Committee of the Indian Ocean Tuna Commission (IOTC). The Scientific Advisory Committee of the ISSF takes the IOTC stock assessments, plus other reliable information, to make their sustainability assessments of stock abundance, fishing mortality and environmental impact (ISSF, 2018). In the IO, tagging data support the assumption that yellowfin comprises a single stock (Langley, et al, 2009). Yellowfin tuna assessments are based on catch, effort, fish size and tagging data. Stock estimates for the IO are compromised by the lack of detailed catch statistics from some coastal fisheries, the gillnet fishery of Pakistan and some industrial longline fleets (e.g. from India).

For the five years 2013-2017, the average catch has been about 400,000 tonnes, a decline since the peak of about 500,000 tonnes between 2003 and 2006 (IOTC, 2018a). The decrease in longline and purse seine effort has substantially lowered the pressure on the IO yellowfin stock. However, if the security situation in the western IO were to improve, a rapid reversal in fleet activity in this region may lead to an increase in effort which the stock might not be able to sustain. Catches would then be likely to exceed MSY levels (IOTC, 2013a). The increase in catches in recent years has substantially increased the pressure on the Indian Ocean stock, resulting in fishing mortality exceeding the MSY-related levels (IOTC, 2018a).

The yellowfin tuna stock is determined to remain overfished and subject to overfishing. The decline in stock status to below MSY reference level is not well understood due to various uncertainties (IOTC, 2018a).

FISHERIES MANAGEMENT

The yellowfin tuna fisheries are managed by regional tuna fisheries management organizations (RFMOs) and by national governments. Reaching agreement on management measures is difficult due to competing interests of countries and fleets and preferences for different types of management choices, e.g., total allowable catch limits, vessel day limits, and restricting access to fishing areas.

As for the stock assessments, the management of the yellowfin tuna fisheries is complicated by the mix of gears and fleets exploiting the stocks in both oceans, and problems in misreporting of catches of yellowfin (and bigeye), especially in purse seine fisheries.

Industrial tuna fisheries are managed by the IOTC and the WCPFC. The Inter-American Tropical Tuna Commission (IATTC) management area encompasses the Eastern Pacific, with some overlap with the WCPFC Convention Area. The RFMOs meet annually to consider and endorse recommended management actions. [See Slide Show for convention area maps].

Regional associations, such as the Pacific Islands Forum Fisheries Agency (FFA) and the Parties to the Nauru Agreement (PNA) are increasingly influential in tuna fisheries management. Individual island countries also manage their tuna resources, through national tuna management plans.

Each of the tuna RFMOs has a scientific committee that advises the RFMO management on stock status, monitoring and management advice and implications using their own and additional scientific advice provided by specialist organizations and individual national experts. The scientific committees also maintain databases for the catch, effort, size frequency, tagging, biological data, observer, sampling and other data.

In the European Union countries, which are important tuna markets, regulations against illegal, unreported and unregulated (IUU) fishing vessels (Council Regulation (EC) No. 1005/2008 and Commission Regulation (EU) No 468/2010) act, in effect, as management drivers. Campaigns by international environment organizations, such as Greenpeace, the Pew Environment Group and the World Wide Fund for Nature (WWF), advocate against the catch of juvenile yellowfin (and bigeye) tuna, especially by purse seiners in association with drifting FADs. These campaigns have led to some marketing chains (in Australia, UK, USA) imposing bans or foreshadowing bans on canned tuna harvested around FADs

Western and Central Pacific Ocean

Western and Central Pacific Convention Area conservation and management measures have the objective of ensuring that the fishing mortality rate of yellowfin tuna is not greater than F_msy, i.e. F/F_msy ≤ 1. Specific measures include port and at-sea inspections, an observer programme for purse seine and longline vessels, positive vessel list (vessels authorised to fish in flag States of RFMO member countries), IUU vessel lists, release tool for sea turtles, fishery closures, total allowable catch and effort, “freezing” vessel capacity, reducing excess fleet capacity, reducing “trading” of fishing effort, and obligatory carrying of satellite-linked tracking devices (http://www.wcpfc.int/conservation-and-management-measures/).

A Harvest Strategy and interim objective was developed for yellowfin under CMM 2018. A limit reference point of 20% of the estimated recent average spawning biomass in the absence of fishing is established for yellowfin tuna. Pending agreement on a target reference point the spawning biomass depletion ratio (SB/SBF=0) is to be maintained at or above the average SB/SBF=0 for 2012-2015 (CMM2018-01).

Regional inter-governmental and industry organizations concerned with tuna in the WCPO are:

• Pacific Islands Forum Fisheries Agency (FFA) - (member countries: Australia, Cook Islands, Federated States of Micronesia, Fiji, Kiribati, Marshall Islands, Nauru, New Zealand, Niue, Palau, Papua New Guinea, Samoa, Solomon Islands, Tokelau, Tonga, Tuvalu and Vanuatu)
• Parties to the Nauru Agreement (PNA) (http://www.pnatuna.com/) - (member countries: Federated States of Micronesia, Kiribati, Marshall Islands, Nauru, Palau, Papua New Guinea, Solomon Islands and Tuvalu). The influence of the PNA in tuna management in the WCPF Convention Area has been significant because, as a group, the zones of the member countries host significant yellowfin tuna resources.
• TeVaka Moana Arrangement (TVMA) (http://www.tevakamoana.org/) - (member countries: Cook Islands, New Zealand, Niue, Samoa, Tokelau and Tonga).
• Pacific Islands Tuna Industry Association (PITIA) - (member countries: Cook Islands, Federated States of Micronesia, Fiji, Kiribati, Marshall Islands, Nauru, Niue, Palau, Papua New Guinea, Solomon Islands, Tonga, Tuvalu and Vanuatu).

Indian Ocean

IOTC conservation and management measures include port inspections, an observer programme, a FAD management plan, transshipment controls, use of vessel monitoring system (for vessels greater than 15 m and fishing on the high seas), limitations on fishing capacity, gear and area closures, retention polices, electronic logbooks for purse-seiners, a vessel registry, positive vessel list, IUU vessel list, required use of a release tool for sea turtles, and other conservation measures for sea birds and sharks (http://www.iotc.org/cmms).

In 2018, the IOTC developed a rebuilding plan for yellowfin tuna (Resolution 18/01, IOTC, 2018b).

AQUACULTURE

Yellowfin tuna is not produced in aquaculture. It has been spawned in captivity in Panama and also in Bali but larval rearing has proven difficult so far (Hutchinson et al., 2012).

A GUIDE TO FURTHER READING

Note: Details of all sources are given in References below.

For IUCN Red List, see Bruce Collette and colleagues (2011) and https://www.iucnredlist.org/species/21857/9327139.

For stock status information, see the IOTC Report of the Twenty-first Session of the Indian Ocean Tuna Commission (IOTC, 2018a), Tremblay-Boyer and colleagues (2017) and WCPFC Scientific Committee summary report (WCPFC, 2012; WCPFC, 2018).

For environmental issues, see IOTC Report of the Twenty-first Session of the Indian Ocean Tuna Commission (IOTC, 2018a), and SC Summary Report (Western and Central Pacific Fisheries Commission, 2018).

For fisheries management information, see IOTC and WCPFC Working Papers, CMMs, Resolutions and Summary Reports. WCPFC CMM link: http://www.wcpfc.int/conservation-and-management-measures, IOTC Resolutions link: http://www.iotc.org/cmms.

REFERENCES

• Collette, B, A Acero, AF Amorim, A Boustany, C Canales Ramirez, G Cardenas, KE Carpenter, S-K Chang, N de Oliveira Leite Jr.,  A Di Natale, D Die, W Fox, FL Fredou, J Graves, A Guzman-Mora, FH Viera Hazin, M Hinton, M Juan Jorda, C Minte Vera, N Miyabe, R Montano Cruz, E Masuti, R Nelson, H Oxenford, V Restrepo, E Salas, K Schaefer, J Schratwieser, R Serra, C Sun, RP Teixeira Lessa, PE Pires Ferreira Travassos, Y Uozumi & E Yanez. 2011. Thunnus albacares. The IUCN Red List of Threatened Species 2011: http://www.iucnredlist.org/details/21857/0
  
• Hutchinson, W, G Partridge & J Hutapea. 2012. Achieving consistent spawning of captive yellowfin tuna (Thunnus albacares) at Gondol Research Institute of Mariculture, Bali, Indonesia. Final report, ACIAR project number FIS/2006/140. 31p.
• IOTC (Indian Ocean Tuna Commission). 2018a. Report of the Twenty-first Session of the Indian Ocean Tuna Commission. Seychelles, 3–7 December, 2018. IOTC–2018–S21–R[E]. 250p.
• IOTC (Indian Ocean Tuna Commission). 2018b. Report of the 22nd Session of the Indian Ocean Tuna Commission. Bangkok, Thailand, 21-25 May, 2018. IOTC–2018–S22–R[E]. 144p.
• ISSF (International Seafood Sustainability Foundation). 2018. Status of the world fisheries for tuna: October 2018. ISSF Technical Report 2018-21. 103p. https://iss-foundation.org/about-tuna/status-of-the-stocks/
• Langley, A, M Herrera, J-P Hallier & J Million. 2009. Stock assessment of yellowfin tuna in the Indian Ocean using MULTIFAN-CL. Indian Ocean Tuna Commission, 11^th Session of the Working Party on Tropical Tunas, 10-23 October 2009, Kenya. Working paper 10. 66p.
• Langley, A, S Hoyle, & J Hampton. 2011. Stock assessment of yellowfin tuna in the Western Central Pacific Ocean. Western & Central Pacific Fisheries Commission 7^th Scientific Committee Regular Session, 9-17 August 2011, Pohnpei, Federated States of Micronesia, Paper SA-WP-03 (Revision 1–03 August 2011). 135p.
• MRAG Asia Pacific. 2016. Towards the Quantification of Illegal, Unreported and Unregulated (IUU) Fishing in the Pacific Islands Region. MRAG Asia Pacific , 101p.
• Tremblay-Boyer, L, S McKechnie, G Pilling & J Hampton. 2017. Stock assessment of yellowfin tuna in the western and central Pacific Ocean. Western & Central Pacific Fisheries Commission 13th Scientific Committee Regular Session, 9-17 August 2017, Rarotonga, Cook Islands, Paper WCPFC-SC13-2017/SA-WP-WP-06 (Revision 1 – 04 August 2017). 125p.
• WCPFC (Western and Central Pacific Fisheries Commission), 2012. Summary Report of the Scientific Committee, the Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean. 7^th Regular Session, 9-17 August 2011, Kolonia, Pohnpei, Federated States of Micronesia. 211p.
• WCPFC (Western and Central Pacific Fisheries Commission), 2018. Summary Report of the Scientific Committee, the Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean. 14th Regular Session, 8-16 August 2018, Busan, South Korea. 307p.