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
Fish type - Oily fish
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 there are several management measures in place, these have not been effective at preventing increases in catch and effort yet in recent years. It is very much hoped that at the upcoming May meeting, the IOTC can agree on strict measures to achieve a 20% reduction in total catches. To achieve this, strong leadership will be needed from the countries with the greatest catches.
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.
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.
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
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 achieve this, Intergovernmental Regional Fisheries Management Organisations (RFMOs) have been established; for this stock it is the Indian Ocean Tuna Commission (IOTC). There are five main tuna RFMOs worldwide and it is their responsibility to carry out data collection, scientific monitoring and management of these fisheries. 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. Retained yellowfin catch and/or effort data is poor or unknown for the following countries/fisheries including: many coastal fisheries, notably those from Indonesia, Sri Lanka, Yemen, and Madagascar; the gillnet fisheries of Iran and Pakistan; longliners of India; the fresh-tuna longline fishery of Indonesia; the gillnet and longline fishery of Sri Lanka; and other non-reporting industrial purse seine and longline vessels.
Catches need to be significantly reduced to rebuild the stock. A 20% reduction in catches is estimated to rebuild the stock (to Bmsy) by 2024 with 50% probability, however no harvest control rule has been developed for the fishery, and management of the catch and effort does not appear to be effective as catches have far exceeded scientific advice in recent years. Large catch increases, particularly in FAD associated purse seine, hand line and gill net fisheries are of concern. There are IOTC resolutions requiring coastal states to limit fishing capacity and to develop quota allocation systems or other relevant measures to limit fishing mortality in line with advice from the IOTC scientific committee, yet implementation of these important resolutions has stalled.
A ban on the discarding of bigeye, yellowfin and skipjack tunas by purse seine vessels is in place.
Regarding the use of Fish Aggregation Devices (FADs): In 2015, a maximum limit of 550 drifting Fish Aggregation Devices (dFADs) that can be in use at any one time by each purse seiner was implemented. A maximum of 1100 can be acquired each year. Whilst a limit is certainly needed, this number will most likely not restrict current FAD usage significantly. Greater reporting requirements are now also required by both vessels using FADs and countries that have FAD fishing vessels. Countries must submit FAD management plans that outline how they are to minimise mortality of juvenile yellowfin and bigeye tuna and vulnerable non-target species such as sharks, turtles and rays. From 2016, each FAD is also to be marked with a unique identification number.
5% regional observer coverage is required for all vessels over 24m and for vessels under 24m fishing outside of their Exclusive Economic Zone (EEZ).
To help address IUU, the IOTC maintains an active vessel register and an IUU Vessel List and prohibits transhipments for large scale vessels at sea unless part of the Programme to Monitor Transhipments at Sea, which requires a list of approved and authorised vessels to undertake transhipments to be maintained. Additionally, the programme requires all transhipments at sea to be monitored by an IOTC observer.
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.
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.
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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