Tuna, yellowfin

Thunnus albacares

Method of production — Caught at sea
Capture method — Purse seine (FAD & Free School)
Capture area — Pacific, North West (FAO 61) and Central (FAO 71,77)
Stock area — Western and Central Pacific
Stock detail — All Areas
Picture of Tuna, yellowfin

Sustainability rating three info

Sustainability overview

The latest stock assessment was carried out in 2017 and is similar to that from 2014 and indicating that overfishing is not occurring and the stock is not considered to be in an overfished state. Maximum Sustainable Yield (MSY) has been revised upwards in the new assessment to 670,800 t (it was 586,400t in 2014). The scientific committee continues to recommend measures to reduce fishing mortality on juveniles and maintain current spawning biomass levels. Total yellowfin catch in 2017 was a record for the second year running, at 670,890 t, a 4% increase from 2016 and a 12% increase from the average 2012-2016, due to purse seine catch increasing (all other gears decreased). There is no TAC or harvest control rule established. As of January 2018, a bridging measure is in force to manage bigeye, yellowfin and skipjack - all caught together. As part of this, spawning biomass depletion ratios for bigeye and yellowfin are to be maintained at recent levels (the average from 2012-2015) and skipjack at 50 percent of unfished levels. The bridging measure includes a number of new measures and consolidates some pre-existing ones and includes limits on vessel days and 5months of closures for purse seine sets on Fish Aggregation Devices (FADs). About 62% of the yellowfin catch from the WCPO is taken in purse seine fisheries: 23% that set gear on floating objects (FADs), and 39% on free-schooling tuna. These fisheries target smaller tuna that aggregate closer to the surface whereas the longliners target larger fish that inhabit deeper waters. Many juvenile fish are often caught in purse seine fisheries and the method is also associated with bycatch of vulnerable species including sharks, turtles and other billfish. The proportion of this bycatch is higher in FAD-associated fisheries, which can also entangle species. Whilst the proportion of this bycatch compared with the total catch is low, the high volume of tuna that is caught means that even a low proportion of this can still be relatively high in terms of total volume or individuals. Redistribution of effort from FADs to free schools has resulted in substantial reductions in estimated catches of silky shark (by 83%) and oceanic whitetip shark (by 57%). Observer coverage is 100% for purse seiners on the High Seas and between 20 N and S unless fishing exclusively in their national waters.

Commercial buyers should establish what measures the flag state and fleet relating to their source is taking to reduce impacts to vulnerable species. Large buyers should consider supporting such improvements. There is a Fishery Improvement Project (FIP) in place for some purse seine fleets in this area which is making good progress at improving elements of the fishery. More info is available here

MCS also advocates specifying the need for supplying vessels, in particular purse seiners, to register on the ISSF Proactive Vessel Register.

There are Marine Stewardship Council (MSC) certified fleets within the scope of this assessment which represent the best choice.

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

Stock Area

Western and Central Pacific

Stock information

The yellowfin tuna fishery in the Western and Central Pacific Ocean (WCPO) is the second largest after skipjack, and is assessed and managed by the Western and Central Pacific Fisheries Commission (WCPFC).

A new stock assessment was carried out in 2017 and is similar to that from 2014, now including data up to the end of 2015. There is a 96% probability that overfishing is not occurring (F at 0.74Fmsy) and a 92% probability that the stock is not in an overfished state (spawning biomass levels (SB) 33% of unfished levels and median spawning biomass levels, SB, at 1.39SBMSY). Maximum Sustainable Yield (MSY) has been revised upwards from 586,400t in 2014 to 670,800t in the new assessment. Total yellowfin catch in the WCPO has slowly increased over time but jumped to a new level in 1998, with annual catches regularly exceeding 500,000t ever since. Total yellowfin catch in 2017 was a record for the second year running, as 670,890 t, a 4% increase from 2016 and a 12% increase from the average 2012-2016 - due to purse seine catch increasing (all other gears decreased).

The stock has been continuously declining for about 50 years, since the late 1960’s. Levels of fishing mortality and depletion differ between regions, and fishery impact is highest in the tropical region, mainly due to the purse seine fisheries in the equatorial Pacific and the “other” fisheries within the Western Pacific. Both juvenile and adult fishing mortality show a steady increase since the 1970s, but while juvenile fishing mortality has stabilized since the late 1990s, adult fishing mortality has increased continuously. The scientific committee continues to recommend measures to reduce fishing mortality on juveniles and maintain current spawning biomass levels.

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. 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 tuna fisheries in the Western and Central Pacific Ocean (WCPO) are 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.

WCPFC has put in place a lower limit for the spawning biomass of bigeye, skipjack, and yellowfin tuna of 20 percent of unfished levels (SB/SBF=0, aka spawning biomass depletion ratio), below which the stock should not fall. For skipjack there is also an interim target of 50 percent of unfished levels, which was adopted in 2015 and has been reached. The scientific committee recommends reducing fishing mortality on juvenile bigeye and yellowfin in the tropics, through preventing increases in overall fishing mortality, until targets for these two stocks can be agreed. The commission is looking to establish harvest strategies for key fisheries and stocks but has not yet completed this work and so, as of January 2018, a bridging measure is in force to manage bigeye, yellowfin and skipjack - the measure lasts until harvest strategies are in place or until February 2021. As part of this, spawning biomass depletion ratios for bigeye and yellowfin are to be maintained at recent levels (the average from 2012-2015) and skipjack at 50 percent. The bridging measure includes a number of new measures and consolidates some pre-existing ones, and is outlined below.

In the tropical region, between 20 degrees North and 20 degrees South, the following applies:
The use and deployment of FADs is prohibited for 5 months of the year (3 months for Kiribati and the Philippines). VMS polling frequency increases to every 30 minutes during the FAD closure.
Effort limits (in vessel days) apply to purse seining on the high seas (excluding Small Island Developing States, SIDS): limits vary by country. In order not to undermine the effectiveness of this, countries cannot transfer effort into areas outside of this region.
To create an incentive to reduce the non-intentional capture of juvenile fish, to discourage waste and to encourage an efficient utilization of fishery resources, purse seiners must retain on board and then land or transship at port all bigeye, skipjack, and yellowfin tuna (also applies to national waters).
All purse seine vessels operating on the high seas or within national waters in this region must carry an observer. This also applies to purse seiners anywhere in the convention area fishing in waters under multiple countries’ jurisdiction or moving between the high seas and national waters.
The number and capacity of large (over 24m) purse seiners and longliners (with freezing capacity and ice-chilled) operating in this area is frozen to 2016 levels (excluding SIDs and Indonesia).

Other measures that apply to the wider convention area:
The number of drifting FADs with activated instrumented buoys deployed at any one time is limited to 350 per purse seine vessel.
Catch and/or effort limits apply for purse seining within national waters (both the type of limit and the amount vary by country).
There are country-specific limits on longline bigeye catch, and by 2020 hard limits for bigeye and a framework to allocate them amongst countries shall be developed.
Catches by other commercial tuna fisheries for bigeye, yellowfin or skipjack tuna (excluding those taking less than 2,000 tonnes) shall not exceed either the average level for the period 2001-2004 or the level of 2004.

More generally:
There is a requirement to submit FAD management plans, including information on strategies used to implement closures and other measures for reducing mortality of juvenile bigeye. A number of aspects in the bridging measure have been brought forward from previous management measures, and it isn’t clear how well they have been implemented, especially given the ongoing increases in total catch of skipjack. The scientific committee recommends more comprehensive data collection relating to FADs.
Observer coverage on purse seiners is poor in areas not specified in the bridging measure and only 5% coverage is required on longliners greater than 20m in length. 20% is considered to be the minimum to be effective.
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.
In 2017 a Compliance Monitoring Scheme was introduced to assess and improve compliance with obligations, and penalise non-compliance.

Capture Information

Criterion score: 0.75 info

Purse seining is commonly an industrial scale fishery used to catch tuna destined for canneries. Purse seining on floating objects and Fish Aggregation Devices (FADs) to attract schools of fish accounts for about 23% of WCPO yellowfin, and purse seining on free schools accounts for about 39%. Many juvenile fish are often caught in purse seine fisheries and the method is also associated with bycatch of sharks, turtles and dolphins (more so in FAD-associated fisheries, which can also entangle species). Whilst the proportion of this bycatch compared with the total catch is relatively low, the high volume of tuna that is caught means that even a low proportion of this can still be relatively high in terms of total volume or individuals. The widespread use of FADs is also of concern due to the unknown impacts such gear might have on natural species composition of tuna schools, migratory patterns, growth rates and predation rates of affected pelagic species. The scientific committee recommends more comprehensive data collection relating to FADs.

To reduce the entanglement of sharks, marine turtles or any other species, and reduce the amount of synthetic marine debris, countries are encouraged to use non-entangling, natural and biodegradable design and materials for FADs, in line with scientific advice. Stricter (i.e. binding) measures may be adopted in 2018. Vessels are prohibited from knowingly setting a purse seine around tuna schools associated with a live whale shark, marine mammal or turtle, and all reasonable steps are required to be taken to ensure the safe release of these animals and details of the interaction are to be recorded if accidentally encircled. In 2016, catches of silky sharks in the longline fishery were around three times higher than in the purse seine fishery. Redistribution of effort from FADs to free schools has resulted in substantial reductions in estimated catches of silky shark (by 83%) and oceanic whitetip shark (by 57%). Shark measures include: full utilisation of permissible sharks and retention of no more than 5% of fins to total shark weight; a prohibition to land silky and oceanic whitetip sharks; a prohibition on the use of shark lines. The effectiveness of these measures are difficult to evaluate owing to lack of data. As of 2014, shark management plans are required where sharks are being targeted, although to date only 2 countries have developed them. There are measures to improve recording of manta and mobula rays discarded and released, and to treat these species as key shark species for assessment and research. In 2017 the scientific committee recommended guidelines for safe release of manta and mobulid rays, which were adopted by the WCPFC. The commission is also looking to develop guidelines for other rays and sharks, especially silky shark and oceanic whitetips, as well as develop stronger and more comprehensive management measures for sharks, but there is no stated deadline for this. It is recommended that target and limit reference points are established for pelagic sharks.

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].

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.

WCPFC, 2018. Conservation and Management Measures of the Western and Central Pacific Fisheries Commission. Available at https://www.wcpfc.int/conservation-and-management-measures [Accessed on 06.12.2018].

WCPFC, 2018. Summary Report of the Fourteenth Regular Session of the Scientific Committee of the Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, 8-16 August 2018, Busan, Republic of Korea. 34 pp. Available at https://www.wcpfc.int/meetings/14th-regular-session-scientific-committee [Accessed on 06.12.2018].