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
Indian Ocean yellowfin was last assessed in 2012, using data to 2011. At the time, the stock was considered to be in a healthy state and not subject to overfishing, yet since then, catches have been significantly (100,000t) above recommended levels. This along with stock projections, suggest that overfishing could now be occurring, but a new stock assessment is needed to establish this with certainty. If catches continue to increase, the rating for this fishery will deteriorate. Better management and country specific quotas are needed to cap and reduce catches, particularly in the Fish Aggregation Device (FAD) purse seine and handline fisheries which have both increased significantly in recent years. Yellowfin is caught by a wide range of gears in the Indian Ocean. The most selective methods include: handline, troll and pole and line, and FAD free purse seine. Bycatch of vulnerable species is of concern in the gillnet and longline fisheries and to a lesser extent in purse seine fisheries. FAD associated purse seine sets 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 and poor catch reporting has been noted for a number of countries so it is important to only source from fisheries that are well regulated by their flag state. Yellowfin from the Maldives pole and line fishery is now certified by the Marine Stewardship Council and represents a good option. Commercial buyers should specify the need for catches to be reduced in line with scientific advice and establish what measures the flag state and fleet relating to their source is taking to reduces impacts on vulnerable species and to improve data collection, research and monitoring of their fisheries and specify the need to see ongoing, demonstrable improvements. Large buyers should consider supporting such improvements. MCS also advocates specifying the need for supplying vessels, in particular purse seiners, to register on the ISSF Proactive Vessel Register.
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 Dec 2012, the Indian Ocean Tuna Commission (IOTC) updated their 2011 assessment of the Indian Ocean yellowfin tuna stock. The last assessment was undertaken in 2012, using data up to 2011. That assessment indicated that the stock was not overfished (Spawning biomass, SB, 1.24 or 1.35Bmsy depending on model) nor being subject to overfishing (Fishing mortality, F, at 0.69 or 0.61Fmsy depending on model), however scientific advice following that assessment noted that significantly increased catches would likely reduce the biomass, and that catches should be limited to the lower MSY estimate of 300,000t. Catches have significantly exceeded this advice in the last 3years, with catches in 2011 being 327,000t; and catches in both 2012 and 2013 being approximately 400,000t. This is far in excess of the advice and over 50,000t above the median MSY estimate of 344,000t (with a range from 283,000 to 453,000t). Without a new stock assessment, it is difficult to know with certainty if the stock is now being subject to overfishing. However, stock projections developed for the 2012 assessment suggested that catches of 386,000t would result in exceeding Fmsy in 2013 and reduce the biomass to below sustainable levels by 2020 with 100% probability. Therefore, whilst it is possible that current catches of 400,000t could be sustained in the short term, it seems highly unlikely that they could be sustained in the long term. It is also noted that potential yields from the fishery have also declined in recent years as a result of an increased proportion of the catch being comprised of smaller fish, primarily from the FAD purse seine fishery.
A new stock assessment in 2015 will provide a more current and accurate picture of stock status.
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.
There is no harvest control rule that has been developed for Indian Ocean yellowfin 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 and hand line fisheries are of concern. Whilst there is an IOTC requirement for coastal states to limit and gradually reduce fishing capacity from 2006 levels, this does not apply to vessels under 24m in length which fish exclusively within their national waters. This means that capacity, particularly from coastal fisheries could well exceed 2006 levels. Management of small scale fisheries will need to improve considerably if they are to sustainably gain access to a larger proportion of the stock. This has been recently recognised by the IOTC and reflected in a new resolution which requires coastal states to establish national quotas for yellowfin and bigeye, and to advise on the best reporting requirement for artisanal tuna fisheries and to implement an appropriate data collection system.
A ban on the discarding of bigeye, yellowfin and skipjack tunas by purse seine vessels is in place.
The IOTC requires 5% regional observer coverage on 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 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.
Large scale purse seiners, primarily from the European Union, are responsible for approximately 34% 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. This represents 25% of the total catch. At the same time, purse seine catches on free schooling fish have reduced, with the 2013 catch of 34,458t (8.6% of total) representing the second lowest on record.
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 small 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.
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 RAMOS, 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).
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, 2013. FishBase. World Wide Web electronic publication. Available at www.fishbase.org [Accessed Nov 2013].
IOTC, 2014. Compendium of Active Conservation and Management Measures for the Indian Ocean Tuna Commission. Available at http://www.iotc.org/cmms [Accessed Dec 2014].
IOTC, 2014. Report of the Seventeenth Session of the IOTC Scientific Committee. Seychelles, 8-12 December 2014. Available at http://www.iotc.org/documents/report-17th-session-iotc-scientific-committee [Accessed Dec 2014].
IUCN, 2012. IUCN Red List of Threatened Species. Version 2012.2. Available at www.iucnredlist.org [Accessed December 2013].
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