Capture method — Purse seine (FAD & Free School)
Capture area — Pacific, Eastern Central (FAO 77), South, East (FAO 87) and West (FAO 81)
Stock area — Eastern Pacific
Stock detail — All Areas
Updated: November 2019
The stock assessment for Eastern Pacific Ocean (EPO) yellowfin tuna is very uncertain, with conflicting trends (decreasing catch per unit effort but increasing average size of the fish). This could suggest changes in abundance, in the population structure, or in the fishery. A new assessment is planned for 2020. In the meantime, at limited scoring has been applied. It appears that there is not currently concern for fishing pressure or stock size.
Management measures include capacity limits for purse seiners, interim Harvest Control Rules, seasonal closures and restrictions on the number of floating objects the purse seine fishery can use. However, these have failed to limit fishing pressure on bigeye, skipjack and yellowfin tuna, and in 2019 indications are that fishing mortality is increasing on all three species. This is primarily owing to increases in purse seine fishing effort, specifically on floating objects.
Approximately 59% of the yellowfin catch in the EPO is made by purse seining on tuna-dolphin associations. This method has been employed for decades and makes use of the natural herding skills of the dolphins to keep the tuna in a tight ball which allows the seine to then encircle them. In the past, this has however resulted in large incidental catches and mortality of dolphins. During 2015, 96.4% of all sets made on tuna associated with dolphins were accomplished with no mortality or serious injury to the dolphins. Dolphin mortality is managed and closely monitored by AIDCP, with 100% observer coverage. The last dolphin surveys took place in 2006, and therefore the status of these populations is uncertain, although two of the three species are listed as depleted. Further efforts are needed to ensure dolphin mortality is reduced to zero as quickly as possible and MCS advises buyers to only source products which have been verified as ‘dolphin safe’ and carry the dolphin safe ecolabel.
A further 36% of the yellowfin catch in the EPO is made by non-dolphin-associated purse seining: 23% on floating objects including Fish Aggregation Devices (FADs) and 13% on free schooling tuna. The high volume of juveniles caught in the purse seine fisheries has substantially reduced the available sustainable yield of bigeye tuna, which is in an overfished state, with overfishing occurring: fishing morality needs to be reduced on this species. The proportion of bycatch of vulnerable species is low in purse seine fisheries in the EPO (less than 0.5% for sharks), yet the overall catch of sharks is still significant and better monitoring and reporting is needed. FADs can also entangle sharks and turtles, but FAD construction and overall management is improving. There is 100% observer coverage on large purse seiners, but small purse seiners have no observer requirement and data from them is very poor.
Longline catches of yellowfin in the Eastern Pacific Ocean have been steadily decreasing and account for around 4% of the total retained catch. Longlining targets larger, mature fish yet is often associated with the bycatch of vulnerable species such as seabirds, turtles and sharks. To address this, IATTC requires a number of mitigation measures and countries must develop national plans of action to address the bycatch of sharks, turtles and seabirds. There is particular concern for the waved albatross, because it is endemic to the EPO and nests only in the Galapagos Islands. There has been marked decline in the number of nesting female leatherback turtles (a Critically Endangered population), owing to bycatch in longlines and gillnets. In 2018, all forms of purse seining combined caught 505 tonnes of sharks. Longlining caught 13,680t. Only 5% observer coverage is required on longliners greater than 20m in length, although the scientific committee recommends 20% coverage and improved standards of data collection. Despite strong recommendations to increase coverage as part of the urgent measures to protect leatherback turtles, a new resolution on observer coverage in 2019 kept the minimum at 5%, although consideration of electronic monitoring systems is planned in 2020.
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. MCS also advocates specifying the need for supplying vessels, in particular purse seiners, to register on the ISSF Proactive Vessel Register.
There are some Marine Stewardship Council (MSC) certified fleets within this area which represent the best option. There are also Fisheries Improvement Projects (FIPs) for purse seine fleets operating in this fishery which are making good progress to address some key environmental issues and aim to achieve MSC certification. Further info abut these FIPs is available from fisheryprogress.org.
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: 0.25 info
Yellowfin stocks in the Eastern Pacific Ocean (EPO) are managed and assessed by the Inter-American Tropical Tuna Commission (IATTC). There is uncertainty about the historical patterns of this stock, with possibly three distinct periods since 1975: below average recruitment until 1982, mostly above average from 1983 to 2002, and then mostly below average until 2014. Levels of maximum sustainable yield (MSY) and the biomasses corresponding to the MSY may differ in the different periods.
The stock assessment for EPO yellowfin is very uncertain, with conflicting trends (decreasing catch per unit effort but increasing average size of the fish). This could suggest changes in abundance, in the population structure, or in the fishery. A new assessment is planned for 2020. Catches have remained relatively stable since 2008, fluctuating between 200,000 tonnes and 250,000t. Overall fleet capacity has increased since 2015, and effort on purse seines on floating objects (around 20% of catches) has more than doubled since the early 2000s. Effort in other areas, however, e.g. dolphin-associated purse seines (60% of catches), has stayed steady or declined. There is no management advice available based on the current data, but it appears that there is not currently concern for fishing pressure or stock size. Yellowfin tuna has a medium resilience to fishing pressure.
Tagging studies suggest that there could be multiple stocks of yellowfin in the EPO and throughout the Pacific Ocean, but movement between these potential stocks is not fully understood.
Criterion score: 0.5 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 achieve 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 Inter-American Tropical Tuna Commission (IATTC). 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.
In 2016 interim Harvest Control Rules were brought in for bigeye, skipjack and yellowfin purse seine fisheries, with the aim of preventing fishing effort from exceeding FMSY for the species that requires the strictest management. For other fisheries, management measures will be as consistent as possible with those for the purse seine fishery. Further evaluation of this HCR and alternatives will be conducted, so that a permanent HCR can be adopted. In 2002, purse seine fleet capacity (defined by the well volume of the boats) was frozen. In 2017, it was acknowledged that the commission had failed since 2013 to reduce fishing mortality of yellowfin and bigeye (adjusted for capacity) to a level not exceeding MSY: fleet capacity in 2017 was estimated to be about 6.7% greater than the previous three-year average. Management measures were updated accordingly, in line with recommendations: the 62-day closure for large purse seiners was extended to 72 days annually until 2020. The scientific committee considers it essential that fleet capacity does not increase further. In 2019, skipjack, yellowfin and bigeye assessments were too uncertain to produce values for fishing mortality, and stock status indicators were used instead. Indications are that fishing mortality is increasing on all three species owing to increases in purse seine fishing effort, specifically on floating objects. There are per-vessel limits on the number of FADs that can be active at any one time (between 70 and 450, depending on vessel size) and regular reporting on FAD activity is required. However, it is considered to be impractical to limit FAD purse seining alone, as accurate real-time monitoring of FAD versus non-FAD sets is challenging. Instead the combined number of purse seine sets (FAD and non-FAD) is recommended to be limited to 2015-2017 average numbers (a 13% decrease on 2018 levels), with only dolphin-associated sets allowed once this limit is reached. In addition, the current FAD limits are considered to be arbitrary and too high, and should be reduced by 30%.
Until 2020, there is a 30-day closure of an area known as the “Corralito” (west of the Galapagos Islands, where catch rates of small bigeye are high) to the purse-seine fishery for yellowfin, bigeye, and skipjack tuna.
A requirement to retain and land all bigeye, skipjack, and yellowfin tuna caught by purse seine has been extended until 2020, although the degree of enforcement regime may vary depending on the country or authority.
There is 100% observer coverage on large purse seiners. The scientific committee continues to recommend 20% observer coverage for small purse seiners, to obtain better data on discards and bycatch, as well as investigations into an electronic monitoring system on all purse seiners for better data on species, sizes, and quantities of target and bycatch species. Since 2011 only 5% observer coverage has been required on large longliners, considered by the scientific committee to be too low for accurate data: a minimum of 20% coverage is recommended. In addition, data recorded by longliners is considered inadequate for scientific purposes and minimum data standards must be identified and introduced.
To help address IUU, the IATTC maintains an IUU Vessel List; maintains a register of authorised fishing vessels; and prohibits transhipments at sea for most vessels (some exemptions apply) and requires most other transhipments to be documented and observed as part of the regional observer programme. Countries are required to report annually on monitoring, control and compliance of management measures. The IATTC and WCPFC endeavour to work together to promote compatibility between their respective conservation and management measures across the Pacific.
Criterion score: 0.75 info
36% of the yellowfin catch in the EPO is made by purse seining: 23% on floating objects including Fish Aggregation Devices (FADs) and 13% on free schooling tuna.
Purse seining is commonly an industrial scale fishery used to catch tuna destined for canneries. These fisheries target smaller fish that aggregate close to the surface, whereas longliners target larger fish that inhabit deeper waters. Many juvenile fish are often caught in purse seine fisheries and the method can also be associated with bycatch of vulnerable species, in particular sharks. In the EPO, the bycatch of sharks comprises a small proportion of the total catch of tuna, but as the volume of tuna caught is high, the catch of sharks is still significant.
FAD-associated purse seining generally encounters higher bycatch rates compared with sets on free-schools, and higher proportions of juvenile tuna. It’s unknown if the widespread use of FADs has other impacts such as on the natural species composition of tuna schools, migratory patterns, growth rates and predation rates of affected pelagic species. Poorly designed FADs can also entangle animals like sharks and turtles.
Bycatch mitigation measures such as sorting grids are in place to reduce mortality of turtles, sharks and non-target species in general. From Jan 2015, all purse seiners using FADs in the EPO must record and report to the authorities details relating to the FAD design, deployment, catch and bycatch summaries for each set. Additionally, FAD design is required to be non-entangling so as to minimise interaction with turtles and sharks and is encouraged to be made from biodegradable materials. Further restrictions to reduce the entanglement of sharks, sea turtles or any other species come into force in January 2019. Vessels are prohibited from knowingly setting a purse seine around tuna schools associated with a live whale shark and if a whale shark is incidentally encircled, all reasonable steps must be taken to ensure its safe release. Details of the interaction are to be recorded, as are details of any interactions with sharks and turtles. Permissible sharks are to be fully utilized and no more than 5% of fins to total shark weight can be retained; landing oceanic whitetip, silky sharks and mobula rays is prohibited and vessels must not fish in silky shark pupping areas. In 2016 IATTC introduced stricter monitoring and reporting of catches of shark species, but the scientific committee continues to advise that shark data collection is inadequate and must be improved - it is currently not possible to assess the state of most sharks and mobulid ray species. Mobulid rays are among the bycatches of the tropical tuna purse-seine fishery, and are of special concern because of their low reproductive rates. Purse seining in the eastern Pacific Ocean catches an average of 1,500 mobula rays per year, mostly in dolphin and free-schooling sets. For other shark species, mainly silky, oceanic whitetip, hammerhead, and mako, catches are generally greatest in sets on floating objects, followed by unassociated sets and, at a much lower level, dolphin sets. In 2018, all forms of purse seining caught 505 tonnes of sharks combined. Longlining caught 13,680t. The scientific committee also recommends that experiments be conducted on mitigating bycatches of sharks, especially in longline fisheries, and on the survival of sharks and mobulid rays captured by all gear types, with priority given to those gears with significant catches. There is 100% observer coverage on large purse seiners in the EPO so the data coming from these fleets should be useful and of high quality. It has been recommended that an observer programme be established for small purse seiners as well.
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
Herring or sild
Salmon, Atlantic (Farmed)
Salmon, Chum, Keta, Calico or Dog salmon
Salmon, Pink, Spring , humpback
Salmon, Sockeye , Red Salmon, Bluebacks, Redfish
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