Tuna, yellowfin

Thunnus albacares

Method of production — Caught at sea
Capture method — Longline
Capture area — Atlantic Ocean (FAO 21,27,31,34,41 and 47)
Stock area — Atlantic
Stock detail — All Areas
Picture of Tuna, yellowfin

Sustainability rating four info

Sustainability overview

Preliminary catch in 2016 was 127,777 t, above the recent average and above both Maximum Sustainable Yield (MSY, 126,304 t) and Total Allowable Catch (TAC, 110,000). The last stock assessment was carried out in 2016 and indicated the stock was most likely overfished but not being subjected to overfishing. The estimated MSY may be below what was achieved in past decades because overall selectivity has shifted to smaller fish. A TAC is in place but it does not include country specific limits and since 2012, the TAC has been exceeded in every year except one, and by increasing amounts (5% over in 2012, 27% over in 2017). It is possible that overfishing is now occurring and a new stock assessment has been recommended to be carried out in 2019. Projections suggested that maintaining catch levels at the current TAC of 110,000 t was expected to maintain healthy stock status through to 2024 with at least 68% probability, but if 2017 catch levels are maintained this probability drops to 30%. A multi-annual management programme has been in place for bigeye and yellowfin since 2012 and a closure and restrictions on the purse seine fishery exist off the west coast of Africa to reduce juvenile catches of bigeye and yellowfin, but this has had little impact. About 14% of the catch is taken in pelagic longline fisheries which can be associated with significant bycatch of other billfish and vulnerable species such as sharks, turtles and seabirds. Whilst some mitigation measures are in place, their effectiveness has not been evaluated and better data collection & reporting is needed. Observer coverage is 5% on large longliners, yet this is not being complied with by several countries and 20% coverage is recommended.

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.

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

Atlantic

Stock information

Yellowfin and other tuna stocks in the Atlantic are assessed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). Yellowfin tuna have been exploited by three major gears (longline, bait boat and purse seine fisheries) and by many countries throughout its range. Overall Atlantic catches declined by nearly half from their peak in 1990 (193,600 t) to 109,000 t estimated for 2013. 2017 catch was 139,316 t - above both Maximum Sustainable Yield (MSY, 126,304 t) and Total Allowable Catch (TAC, 110,000).

The last stock assessment was carried out in 2016. There are uncertainties in stock structure, natural mortality, and growth which could have important implications for the assessment; the ongoing Atlantic Ocean Tropical Tuna Tagging Programme (AOTTP), if fully successful, will help reduce these uncertainties. The assessment indicates that the stock was most likely overfished (Biomass, B, at 0.95Bmsy) but not being subjected to overfishing (Fishing mortality, F, at 0.77Fmsy). However, since 2012 the TAC has been exceeded in every year except one (5 year average catch is 124,200t), and by increasing amounts (5% over in 2012, 27% over in 2017): it is possible that overfishing is now occurring and a new stock assessment has been recommended to be carried out in 2019.

The estimated MSY is below what was achieved in past decades because overall selectivity has shifted to smaller fish, mainly through fishing on floating objects (FADs). The recent average weight in European purse seine catches, which represent the majority of landings, had declined to about half of the average weight of 1990. A declining trend in average weight and a corresponding increase in the catch of small yellowfin is also evident in eastern tropical bait boat catches. Projections suggest that maintaining catch levels at the current TAC of 110,000 t was expected to maintain healthy stock status (B>BMSY, F<FMSY) through to 2024 with at least 68% probability, but if 2017 catch levels are maintained this probability drops to 30%.

Management

Criterion score: 0.75 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 address 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 International Commission for the Conservation of Atlantic Tunas (ICCAT). 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. There remain large data deficiencies in most tuna and billfish fisheries, particularly with regards to fine scale spatial and temporal data for both target and especially for vulnerable bycatch species. For this reason, it is important to choose tuna that has been caught by vessels that are well regulated by their flag state.

The TAC (Total Allowable Catch) for yellowfin from 2012 onwards is 110,000 t, which is expected to maintain healthy stock status through to 2024. However, in recent years this has been exceeded by 17-37% and there are concerns that the stock is now subject to overfishing. In 2018 the scientific committee suggested that existing conservation and management measures appeared to be insufficient and needed to be strengthened.

The following measures are in place for bigeye, skipjack and yellowfin:
There is a tagging programme to improve stock assessments for tropical tunas and gauge effectiveness of management measures for these species. This has yet to deliver the needed data.
A multi-annual management programme has been in place for bigeye and yellowfin since 2012, and eastern skipjack since 2015. Fishing for these species using aggregation devices, including FADs, is prohibited from 1st January to 28th February in an area off the west African coast to reduce catches of juvenile bigeye and yellowfin. All vessels fishing during this period must have an observer on board. The scientific committee concluded that closures to date have not been effective at reducing the mortality of juvenile bigeye tuna, and any reduction in yellowfin tuna mortality was minimal, largely due to the redistribution of effort into areas adjacent to the moratorium area.
For the rest of the year, no more than 500 FADs may be active at any one time and countries must have FAD Management Plans that improve understanding of FADs and limit their impacts on the ecosystem.
ICCAT maintains a list of vessels over 20m authorised to fish for these species, although other vessels may retain them as bycatch as long as the country sets limits on this and doesn’t exceed its quota.
Countries are encouraged to reduce discards.

Increased harvests on FADs may have negative consequences for adult yellowfin and bigeye tuna, as well as other by-catch species. The increasing use of fish aggregation devices (FADs) in skipjack fisheries since the early 1990s, have changed the species composition of free schools. It is noted that, in fact, the free schools of mixed species were considerably more common prior to the introduction of FADs. Furthermore, the association with FADs may also have an impact on the biology (growth rate, plumpness of the fish) and on the ecology (distances, movement orientation) of skipjack and yellowfin (“ecological trap” concept). To increase long term sustainable yield, the scientific committee continues to recommend that effective measures be found to reduce FAD-related and other fishing mortality of small yellowfin tuna.

Other management measures of note include:
There is a mandatory level of observer coverage of 5%, which may not have been implemented by many fleets, although some fleets are currently implementing voluntary observer programmes that cover 100% of fishing trips. This is in spite of scientific committee recommendation of a minimum of 20% for accurate reporting of bycatch. Purse seine and longline vessels over 20m long are encouraged to increase their observer coverage from the required minimum. Vessel Monitoring Systems are required for all vessels over 24m.
In 2015 a working group was formed to look at ways to reduce juvenile catches of bigeye and yellowfin tuna caught in FAD fishing.
Drift nets are banned in the Mediterranean.
ICCAT maintains lists of vessels authorised to fish for tuna and tuna-like species in the ICCAT area, and those caught carrying out Illegal, Unreported or Unregulated activities.
At-sea transhipment is prohibited unless pre-authorised and the vessel has an observer on board.
In 2017 ICCAT banned the discarding of skipjack, yellowfin and bigeye.
In 2016 the Commission passed measures to strengthen and streamline its compliance assessment process and to develop a scheme of responses to non-compliance.

Capture Information

Criterion score: 0.75 info

Longline catches for yellowfin in the Atlantic have fluctuated since the 90s, but now account for about 11% of the total catch. The longline fishery generally catches medium to large yellowfin compared to the purse seine and pole and line fisheries which target smaller fish. Pelagic longlining is associated with the bycatch of vulnerable species, including sharks, sea turtles and seabirds.

ICCAT aims to take an ecosystem-based and precautionary approach to fisheries management. In order to protect juvenile swordfish, a closure period applies to longline vessels targeting Mediterranean albacore from 1 October to 30 November each year.

For sharks: Countries are required to develop and submit National Plans of Action for the conservation and management of sharks. Sharks must be fully utilised (e.g. no removal of fins). Sharks must be released wherever possible (if not being directly targeted) and countries must try to minimise bycatch of sharks (although no gear-specific measures are identified). Catching silky sharks, hammerheads, oceanic whitetips, and bigeye threshers is prohibited, and catching other thresher species is discouraged. Shortfin mako can be caught and retained, but as of 2017 the country’s law must require a minimum length of 180cm for males and 210cm for females, otherwise, shortfin makos caught alive must be released unharmed. This is expected to prevent the stock’s currently poor state from worsening, and a rebuilding plan will be developed for 2019. In 2016 additional measures for blue shark were introduced, mainly focussed on improved data recording, with potential to introduce Harvest Control Rules. A catch limit of 39,102 t was also introduced in the north Atlantic (but none for the south Atlantic): if exceeded the commission has committed to reviewing the effectiveness of its blue shark management measures. Preliminary catch in 2016 was 42,117 t. Porbeagle is overfished throughout the Atlantic, significantly so in the northwest, and for the north Atlantic overall it is predicted to take at least 30 years to recover if there was zero fishing mortality. The main porbeagle-directed fisheries (EU, Uruguay and Canada) have closed, and ICCAT have a recommendation to release live porbeagle unharmed, but it is still caught incidentally and discarded, and also landed by other fleets. Currently there is not enough data to properly assess the status of many pelagic sharks (no assessments have been carried out for the Mediterranean).

For seabirds: There are particular concerns over the status of albatross and petrels. South of 20 degrees South, vessels must use bird-scaring lines. Swordfish vessels are exempt from this if they fish at night and weight their hooks. South of 25 degrees South, vessels must use 2 of the three measures mentioned. In the Mediterranean, these measures are voluntary. However, recommended best practice is to use all three of the aforementioned measures for all longline vessels.

For turtles: Longliners must carry equipment and have training to enable them to safely release turtles that have been caught. Countries are required to research and trial circle hooks for longliners. The scientific committee recommends that longliners targeting swordfish and sharks must use either large circle hooks or finfish bait as mitigation, but this has not been implemented.

There is a mandatory level of observer coverage of 5%, which may not have been implemented by many fleets, in spite of scientific committee recommendation of a minimum of 20% for accurate reporting of bycatch. However, some fleets are currently implementing voluntary observer programmes that cover 100% of fishing trips.

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

ICCAT, 2018. Report of the Standing Committee on Research and Statistics (SCRS) of the International Commission for the Conservation of Atlantic Tunas, 1-5 October 2018, Madrid, Spain. 469 pp. Available at https://www.iccat.int/Documents/Meetings/Docs/2018/REPORTS/2018_SCRS_REP_ENG.pdf [Accessed on 22.11.2018].

ICCAT, 2018. Resolutions, Recommendations and other Decisions. Available at http://www.iccat.es/en/RecsRegs.asp [Accessed on 11.12.2018].

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].