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Tuna, yellowfin

Thunnus albacares

Method of production - Caught at sea
Capture method - Purse seine (non FAD associated)
Capture area - Indian Ocean (FAO 51,57)
Stock area - Indian Ocean
Stock detail - All Areas
Certification -
Fish type - Oily fish

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This fish, caught by the methods and in the area listed above, is the least sustainable fish to eat and should be avoided. Click on the rating icon above to read more and on the alternatives tab below to find sustainable fish to eat.


Sustainability overview

In 2015, the Indian Ocean Tuna Commission (IOTC) undertook a much needed new stock assessment for Indian Ocean yellowfin tuna which confirmed that recent catches outside of the scientific advice have been excessive and have overfished the stock (Spawning biomass, SB, at 0.66SBmsy) and are unsustainable (Fishing mortality, F, at 1.34Fmsy). Catches need to be significantly reduced to rebuild the stock and scientists advise that a 20% reduction in catches could rebuild the stock (to Bmsy) by 2024 with 50% probability. Whilst agreements have been made to reduce catches by 10% and to reduce the number of FAD sets, this is less than recommended based on the current perception of the stock. However, a new expedited stock assessment is expected to be undertaken before the end of 2016.

Whilst the majority of the catch is taken by EU flagged purse seiners (mainly FAD sets from Spain then France), substantial catches are also take in longline, handline and gillnet fleets from various IOTC nations including Maldives (11%), Indonesia (10%), Iran (9%), Sri Lanka (9%), Yemen (8%) and India (8%).

The most selective methods include: handline, troll, pole and line, and then FAD free purse seine. Bycatch of vulnerable species is of serious concern in the gillnet fisheries which are largely unmanaged. Bycatch remains of concern in longline fisheries and to a lesser extent in purse seine fisheries. FAD associated purse seine sets in particular encounter a greater proportion of bycatch and juvenile fish compared with non-FAD purse seine sets, and it is unclear what other ecosystem impacts FADs may have. Monitoring and reporting of interactions with vulnerable bycatch species needs improvement across all fleets.

MCS recommends avoiding products from red rated tuna fisheries.

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
Indian Ocean

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Stock information
In 2015, the Indian Ocean Tuna Commission (IOTC) undertook a much needed new stock assessment for Indian Ocean yellowfin tuna. The last assessment before this was undertaken in 2012 and since that assessment, catches had increased considerably (over 100,000t) above recommended levels (300,000t) despite being within the upper limit of the estimated maximum sustainable yield (MSY). The 2014 catch of 430,327t is up again up from 407,633t in 2013 and 400,322t in 2012, in comparison to 329,184 t landed in 2011, 301,655 in 2010 and 266,848 t landed in 2009. The latest assessment confirms that recent catches have been excessive and have reduced the population size below that which can support MSY, indicating the stock is overfished (Spawning biomass, SB, at 0.66SBmsy) and subject to overfishing (Fishing mortality, F, at 1.34Fmsy). The spawning biomass is approximately 23% of unfished levels. It is expected that current levels of catch would exacerbate the decline of this stock in the short term. If the biomass is recovered to healthy levels, the maximum sustainable yield is estimated to be 421,000t

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

In 2014, large scale purse seiners, primarily from the European Union, were responsible for approximately 34.5% of the total Indian Ocean yellowfin catch. In recent years, the proportion of the purse seine catch taken on floating objects (Fish Aggregation Devices - FADs) has been increasing with the 2013 catch of 101,905t being the highest on record. The 2014 catch was a little lower at approximately 95,081t, but still about 40% greater than the 2006 to 2010 five year average and now represents 22% of the total catch. At the same time, purse seine catches on free schooling fish have reduced by over 20% and now accounts for 12.5% of the total catch.

Purse seines generally target smaller fish than longlining and often catch large numbers of juvenile fish. Yellowfin is often taken in purse seine sets targeting the smaller skipjack tuna. The IOTC scientific committee has noted that the increasing proportion of juvenile yellowfin being caught, particularly in FAD purse seine fisheries, has reduced the maximum sustainable yield.

Purse seines are associated with lower mortality rates of sharks, turtles and certainly birds, compared with longlining, however their widespread use means they may still have a significant impact on turtles, sharks and cetaceans. FAD associated purse seine fisheries catch a higher proportion of juvenile fish and non-target species compared with sets on free schooling tuna. There are measures employed to reduce bycatch such as sorting grids, yet improved monitoring is required to assess their effectiveness. Poorly designed FADs may also entangle sharks and turtles. The increasing use of FADs is of concern due to the unknown impacts such gear might have on natural migratory patterns, growth rates and predation rates of affected pelagic species. Research into this should be prioritised.

Recently, the IOTC have developed measures that require countries to develop FAD management plans which include more detailed specifications of catch reporting from FAD sets and the development of improved FAD designs to reduce the incidence of entanglement of non-target species. In 2015, the IOTC also imposed a maximum limit of 550 drifting FADs that can be used at any one time. Whilst a limit is certainly needed, this number will most likely not restrict current FAD usage significantly.

The IOTC have also recently introduced measures which prohibit knowingly setting purse seines around whale sharks or cetaceans, and should such species be unintentionally caught, every effort is to be made to ensure their safe release. Monitoring and reporting is deficient.

Regarding sharks, participating members are to develop conservation and management measures for vulnerable shark species which includes the prohibition to retain, tranship or land certain species and requires details of interactions with these species to be logged. This already applies to thresher sharks and, as in most tuna RFMOS, oceanic whitetip sharks. Monitoring of these measures is currently deficient and the effectiveness of these measures is to be reviewed in 2016. Several countries have failed to implement national plans for sharks, seabirds and turtles as required (although the shark plan is not binding in India as they have objected to the measure).

Click here to see which countries have and have not fully implemented plans and actions for seabirds, sharks and marine turtles http://www.iotc.org/sites/default/files/documents/2015/11/IOTC-2015-SC18-06E_-_Status_of_NPOAs.pdf

There is also ban on the discarding of bigeye, yellowfin and skipjack tunas by purse seine vessels under IOTC jurisdiction.

Read more about capture methods


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

IOTC, 2015. Compendium of Active Conservation and Management Measures for the Indian Ocean Tuna Commission. Available at http://www.iotc.org/cmms [Accessed Dec 2015].

IOTC, 2015. Report of the 18th Session of the IOTC, Scientific Committee. Bali, Indonesia, 23 to 27 November 2015. http://www.iotc.org/sites/default/files/documents/2015/12/IOTC-2015-SC18-RE_-_FINAL_DO_NOT_MODIFY.pdf [Accessed Dec 2015].

IOTC, 2015. Report of the 19th Session of the Indian Ocean Tuna Commission. Busan, Rep. of Korea, 27 April to 1 May 2015. Available at http://www.iotc.org/sites/default/files/documents/2015/06/IOTC-2015-S19-RE.pdf [Accessed Dec 2015].

IOTC, 2015. Status of development and implementation of national plans for seabirds and sharks, and implementation of FAO guidelines to reduce marine turtle mortality in fishing operations. Available at http://www.iotc.org/sites/default/files/documents/2015/11/IOTC-2015-SC18-06E_-_Status_of_NPOAs.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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