Capture method — Pole & line
Capture area — Indian Ocean: Western (FAO 51), Eastern ( FAO 57)
Stock area — Indian Ocean
Stock detail — All Areas
Updated: November 2020
Yellowfin tuna in the Indian Ocean is in an overfished state, and subject to overfishing. Recent catches have been above the catch limits and this lack of compliance by the fishery is concerning. If catches continue to increase it could lead to the stock crashing by 2027. There are significant issues with monitoring and compliance in most fisheries that are overseen by the Indian Ocean Tuna Commission (IOTC). This reduces the accuracy of stock assessments, the effectiveness of management measures, and the likelihood of maintaining the fisheries at a sustainable level. Observer coverage, which could improve monitoring, is very low, at just 5%. Recommendations are for 20%. Therefore, MCS considers Indian Ocean tuna and swordfish fisheries to be poorly managed and requiring considerable improvement. Around 4% of Indian Ocean yellowfin catches are from pole and line fisheries. This method of fishing targets fish near the surface, and so rarely touches the seabed and doesn’t have habitat impacts. It is labour-intensive and very selective, meaning there are low levels of bycatch of vulnerable species. Pole and line fishing can use large quantities of live fish for bait, which could have impacts on baitfish populations. However, most of that catch in this fishery comes from the Maldives, which monitors livebait catches and has a management plan for them.
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 and to recover the yellowfin stock. Large buyers should consider supporting such improvements.
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.
Criterion score: 0.75 info
Indian Ocean yellowfin tuna has been overfished and subject to overfishing since 2015, and recent catches have been some way above recommended limits.
This stock is managed by the Indian Ocean Tuna Commission (IOTC). Catches of Indian Ocean yellowfin tuna peaked in 2004 at over 500,000 t, dropped to around 250,000 t in 2009 and in recent years have stabilised at around 400,000 t. A stock assessment was carried out in 2018, indicating that the stock was overfished and subject to overfishing. Spawning Biomass, SB, was estimated to be at 83% of levels associated with Maximum Sustainable Yield (0.83 SBMSY). Fishing mortality, F, was at 120% of levels associated with MSY (1.2 FMSY). There is some uncertainty in these estimates and a workplan is underway to address these uncertainties, although no new advice could be provided in 2019. Discussions were not progressed in 2020, owing to Covid disruption, but a special meeting is scheduled for March 2021 to plan a new stock assessment and improve management.
Provisional catch in 2019 was 427,240 tonnes, taking the 2015-2019 average catch to 424,103t. This is higher than the estimated Maximum Sustainable Yield, which is 403,000t. Projections indicated that if catches were maintained at 410,000t there would be a 90-94% probability of the stock exceeding its limits by 2027, meaning that SSB would be less than 0.4 SSBMSY and F would be above 1.4 FMSY. If catches were maintained at 450,000t, it is projected by 2027, the stock would either crash, or at least one fishery wouldn’t be able to take its catch due to absence of fish. Reductions in catch to around 327,000 t would be needed to see the stock recovering to sustainable levels by 2027 with 50% probability.
The stock status has been driven by unsustainable catches of yellowfin tuna taken over the last five years, and the relatively low recruitment levels in recent years.
It is possible that the stock area does not match management areas, as the boundary between the Atlantic Ocean and Indian Ocean stock is not clear, but genetic analysis suggests that more of the South African catch is from the Indian Ocean stock, while it is currently reported as Atlantic stock.
Criterion score: 0.75 info
Yellowfin tuna in the Indian Ocean is in an overfished state, and subject to overfishing. Recent catches have been above the catch limits and this lack of compliance by the fishery is concerning. If catches continue to increase it could lead to the stock crashing by 2027. There are significant issues with monitoring and compliance in most fisheries that are overseen by the Indian Ocean Tuna Commission (IOTC). This reduces the accuracy of stock assessments, the effectiveness of management measures, and the likelihood of maintaining the fisheries at a sustainable level. Observer coverage, which could improve monitoring, is very low, at just 5%. Recommendations are for 20%. Therefore, MCS considers Indian Ocean tuna and swordfish fisheries to be poorly managed and requiring considerable improvement.
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.
Monitoring and compliance with management measures in the IOTC region is generally poor, and MCS is particularly concerned about the impact this is having on a number of species. Some countries repeatedly fail to report catch data to the commission annually. In 2018 IOTC introduced a new measure aimed at improving reporting on catch and bycatch, including prohibiting a country from retaining a species if they fail to report catches for it. However, in 2020 the scientific committee reported that data reporting issues persist.
The 2018 stock assessment indicated that the yellowfin stock remains overfished and subject to overfishing, and the scientific committee continues to recommend that catches should be reduced by 20% from to 2014 levels to around 330,000 tonnes. A yellowfin tuna rebuilding plan has been in place since 2016, mainly focussed on reducing catches. Countries whose 2014 catches exceeded certain thresholds (5000t for all gears except gillnet, which is 2000t) should reduce their catches by a certain amount compared to 2014 levels (purse seine by 15%, gillnet and longline by 10%, other gears by 5%). Countries can determine their own methods for achieving these reductions. If they exceed their catch limits, the excess is deducted from the following two years’ allowance. In addition, the number of supply vessels (which increase fishing capacity) is limited to 50% of the number of purse seine vessels in 2018-2019 and 40% in 2020-2022. The plan also ‘encourages’ countries to fast-track phasing out of gillnets, to set them at 2m deep to mitigate ecological impacts, and increase observer coverage on gillnetters to 10%. It is generally considered to be ineffective, as the measures are estimated to achieve only a 10% reduction from 2014 levels, and some countries may have inaccurately reported their 2014 catches as being below certain thresholds to escape the measures. Some countries, particularly the longline fleets, have achieved the required decreases, which is to be applauded. The Maldives, which are heavily dependent on healthy tuna stocks, decommissioned their longline yellowfin tuna fleet in 2019 (which was catching roughly 3,000 tons per year), to contribute rebuilding of Indian Ocean yellowfin tuna stocks. However, these efforts have been offset by significant increases elsewhere, especially in the gillnet fleets. Overall catches have increased by 7% from 2014 levels and are now 30% above the recommended limit of 330,000t. Provisional catch in 2019 was 427,240 tonnes, taking the 2015-2019 average catch to 424,103t. There is a 100% probability of the stock falling below safe limits by 2027, and it could crash, if fishing pressure is not adequately reduced. The scientific committee has also suggested that the rebuilding plan has displaced activity onto purse seines with fish aggregating devices, which has led to an associated increase in catches of skipjack tuna and juvenile yellowfin and bigeye.
MCS is very concerned by this lack of control and enforcement, which undermines the ability of the IOTC to keep the stock at sustainable levels. Over the years, widespread concern has been expressed about the state of the stock and lack of progress to rebuild it. A number of major UK supermarkets and seafood suppliers have written to the IOTC to raise concerns, and in 2020 some made commitments to stop sourcing it unless improvements were made at the IOTC meeting at the end of the year. Owing to Covid disruption, the 2020 IOTC meeting was shortened and did not discuss yellowfin tuna. Instead, a special session to discuss this stock is planned for March 2021. While catch reductions are crucial, particular focus should be on reducing catches of juvenile yellowfin. Some gears, such as purse seining on FADs, have a higher proportion of juveniles and may need further restrictions. The Iranian gillnet fishery in the Sea of Oman, responsible for around 40,000t and increasing, is almost exclusively taking juveniles. It is also crucial to improve monitoring and compliance with management measures. Any rebuilding or management plan appears highly unlikely to rebuild this stock without significant changes to ensure that catch limits are being complied with.
Additional management measures for yellowfin include:
On average from 2015-2019, purse seining accounted for around 35% of skipjack catches: 23% using Fish Aggregating Devices (FADs) and 10% on free-schooling fish. The maximum number of drifting FADs that can be in use at any one time by each purse seiner has been steadily reduced from 550 in 2015 to 300 in 2019, and the maximum that can be acquired each year reduced from 1100 in 2015, to 500 in 2019. Countries that use FADs must report regularly to the Commission and submit FAD management plans outlining how they will minimise mortality of juvenile yellowfin and bigeye tuna and vulnerable non-target species such as sharks, turtles and rays.
Vessel capacity and tonnage was frozen to 2007 levels for vessels over 24m, or vessels under this length operating in international waters. This measure expired in 2018, and IOTC reverted to previous legislation which froze capacity and tonnage to 2003 levels. This legislation is very generic, applying across all fleets, and would be better replaced by spatial and temporal closures and quota allocation. There also appear to be concerns that the freeze has not been well enforced thus far.
In 2016 IOTC introduced a number of resolutions to improve the poor compliance with existing management measures, e.g. observer coverage, catch and effort reporting, support for countries to implement measures. However, mandatory observer coverage is very low, at just 5% for all vessels over 24m or under 24m and fishing outside of their Exclusive Economic Zone (EEZ). A number of countries fail to meet the 5% threshold. In general, 20% is scientifically recommended to ensure adequate monitoring of catch and bycatch. In 2019 a proposal was put forward to increase coverage to at least 20%, but consensus could not be reached.
Other IOTC conservation and management measures of note include:
A ban on the discarding of bigeye, yellowfin and skipjack tunas by purse seine vessels which from 2018 will extend to non-target species such as other tunas and billfish.
A ban on the use of aircraft and unmanned aerial vehicles as fishing aids, which significantly contribute to fishing effort by helping to detect fish.
A ban on surface or submerged artificial lights for the purpose of aggregating tuna and tuna-like species beyond territorial waters.
In 2012 IOTC banned the use of driftnets on the high seas. In 2022 this will be extended to the entire IOTC area (i.e. within countries’ EEZs as well).
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 they are pre-approved, monitored by an observer and the vessel uses a Vessel Monitoring System (VMS).
Criterion score: 0.25 info
Around 4% of Indian Ocean yellowfin catches are from pole and line fisheries. This method of fishing targets fish near the surface, and so rarely touches the seabed and doesn’t have habitat impacts. It is labour-intensive and very selective, meaning there are low levels of bycatch of vulnerable species. Pole and line fishing can use large quantities of live fish for bait, which could have impacts on baitfish populations. However, most of that catch in this fishery comes from the Maldives, which monitors livebait catches and has a management plan for them.
Pole and line fishing consists of a bamboo or plastic pole, 10 to 15 feet in length, with a line and a feathered barbless hook attached to the smaller end of the pole, capable of handling a fish weighing below 23kg. It can use large quantities of live fish for bait, which could have impacts on baitfish populations. Much of the catch is from the Maldives and India, and it is often caught alongside skipjack. In the Maldives the main baitfish species being used is silver sprat, as well as small amounts of blue sprat, anchovy, fusiliers and cardinalfish. This is a fairly well-monitored fishery, with baitfish catches being recorded in logbooks, unlike in many other pole and line fisheries. The Maldives also has a livebait management plan. In the Maldivian skipjack fishery, which is MSC-certified and therefore has more scrutiny, it is not thought that any of the baitfish species are being put at risk by the fishery. It is estimated that between 3.5 and 7.7kg of sprat are used to catch 100kg of skipjack.
The proportion of yellowfin catches from artisanal fisheries (handline, gillnet, and pole and line) has increased from around 30% in 2000 to nearly 50% in recent years. Artisanal fisheries present more challenges with regard to reporting of catch data, so this increase raises concerns for the effectiveness of monitoring the fishery, and the accuracy of stock assessments, as fishing mortality might not be fully accounted for.
Pole and line fishing effort in the Maldives increased significantly from the 1970s, and there was an increase in boat size and power and the use of anchored Fish Aggregation Devices (FADs) from 1981. FADs can be associated with bycatch, for example by entangling vulnerable species, although this is more of a concern with drifting FADs than anchored ones. The Maldives has also set limits on yellowfin catches, although it is not clear what actions will be taken when the limits are reached. It has also limited the number of FADs, all of which are anchored, to 50. It is taking steps to encourage pole and line fishing on free schools instead of FADs, to further reduce risks of bycatch. Shark catches reported for the pole and line fisheries of Maldives and India are very low: the extent of shark catches taken by these fisheries, if any, is not thought to be significant.
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, European anchovy
Anchovy, Peruvian anchovy
Herring or sild
Horse Mackerel, Scad
Salmon, Chum, Keta, Calico or Dog salmon
Salmon, Pink, Spring , humpback
Salmon, Sockeye , Red Salmon, Bluebacks, Redfish
Sardine, European pilchard, sardines
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