Euthynnus pelamis, Katsuwonus pelamis
Capture method — Pole & line; Troll
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
Skipjack tuna is a notoriously difficult species to assess, as its high and variable productivity makes it difficult to detect the effect of fishing on the population. This is compounded in the Eastern Pacific Ocean (EPO) by a lack of data, which is being addressed through a tagging study from 2019-2023. Data limited scoring has been applied for assessing stock status. The scientific committee advises that if a levelling off of catch or Cath Per Unit Effort (CPUE) occur, it may indicate that the exploitation rate is near or above the level associated with MSY. However, there is a significant amount of uncertainy surrounding all possible indicators relating to the level of fishing pressure. There is no concern for the biomass, as according to the scientific committee, the indicators have yet to detect any adverse impacts of the fishery. Therefore, MCS considers that there is curently no concern for fishing pressure or biomass.
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.
Less than 1% of EPO skipjack catch is taken by troll, and pole and line boats. These fisheries are labour intensive yet very selective and low impact to the marine ecosystem. Pole and line fisheries depend on significant quantities of bait fish to attract the tuna. Whilst these bait fish are usually small, resilient species, some basic monitoring and management measures need to be developed.
99% of the skipjack landings in the Eastern Pacific Ocean (EPO) are from purse seining: 70% on floating objects including Fish Aggregation Devices (FADs), and 29% on free schooling fish. FAD-associated purse seining generally encounters higher bycatch rates than sets on free-schools, and higher proportions of juvenile tuna. Most bigeye tuna purse-seine catch is from the FAD skipjack fishery: bigeye tuna is in an overfished state, with overfishing occurring, and 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.
Commercial buyers should establish what measures the flag state and fleet relating to their source is taking to improve the management of FADs and status of bycatch and other tuna species caught with skipjack. 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 some Fisheries Improvement Projects (FIPs) for purse seine fleets operating in this area which are making good progress to address some key environmental issues and aim to achieve MSC certification. Further information about 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. Skipjack tuna are found throughout the world’s tropical and warm temperate waters. During the day they school on the surface (often with birds, drifting objects, sharks, whales etc.) but at night can descend to depths of 260m. Skipjack tuna are a very fast growing species, maturing at 2 to 3 years old (40cm in length) and living for up to 12 years. They can grow up to 100cm and 34kg in weight but are rarely found larger than 80cm and 10kg. They spawn all year round and have a medium to high resilience to fishing.
Criterion score: 0.25 info
The skipjack stock in the Eastern Pacific Ocean (EPO) is assessed by the Inter-American Tropical Tuna Commission (IATTC). Skipjack tuna is a notoriously difficult species to assess. Due to its high and variable productivity, it is difficult to detect the effect of fishing on the population with standard methods. This is particularly true for the stock of the EPO, where there is a lack of data. Therefore, data limited scoring has been applied to assess stock status. Skipjack has medium resilience to fishing pressure, and there appears to be no concern for fishing pressure or biomass.
According to the scientific committee, of primary concern for this stock is the constantly increasing exploitation rate, but this appears to have levelled off in recent years and consequences have not emerged. While biomass and recruitment appear to have been increasing over the past 20 years, this is based on unreliable and probably optimistic Catch per Unit Effort (CPUE) data, and therefore is probably an inflated estimate. However, there is no concern for the biomass, as according to the scientific committee, the stock indicators have yet to detect any adverse impacts of the fishery.
The scientific committee state that it is unknown if the current fishing mortality levels are appropriate because there is no reference point, but that a levelling off of catch or Catch per Unit of Effort (CPUE) may indicate that the exploitation rate is near or above the level associated with MSY. With regard to catches: following record high levels (342,500t in 2016), catches have declined to around 288,000t in 2018, below the 5 year average (311,000t) and close to the recent 10-year average (279,000t). With regard to CPUE: this is measured as Catch per Days Fished, which has generally increased but declined in the last 2-3 years. However, Catch per Days Fished is probably overestimated, because there has been an increase in the number of floating-object purse seine sets that have been put out per day. Catch per set (which would be another way to measure CPUE) has fallen.
The average weight of skipjack has been declining since 2000, reaching levels last seen in the early 1980s. In 2015 and 2016 it was below the lower reference level (although this is likely due to large recruitments in 2015 and 2016), increased in 2017 but fell again in 2018. The long-term pattern of reduced average weight is probably due to increasing fishing mortality, resulting from the increasing number of purse seine sets. Any continued decline in average length is a concern.
This stock assessment presents a number of uncertainties. Overall, considering that there is no concern for biomass, that skipjack is less susceptible to overfishing that other tropical tunas, and that the scientific assessment cannot provide clear indications of overfishing, MCS considers that there is currently no concern for biomass or fishing pressure.
As skipjack and bigeye tuna stocks have similar characteristics, skipjack status can be inferred from bigeye status, as long as bigeye fishing mortality is below the MSY level. The 2018 assessment of bigeye indicates that the stock is subject to overfishing, so skipjack status cannot be inferred from bigeye status. The large-scale tagging program in the EPO, which began in 2019 and will run until 2023, is critical to obtain an assessment of this stock.
Discards of skipjack at sea have decreased each year, from 8% in 2004 to a low of less than 1% in 2017, averaging about 3% of the total catch of the species.
Criterion score: 0.75 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 info
A very minor part - less than 1% - of the Eastern Pacific Ocean skipjack catch is taken by troll, and pole and line boats.
These fisheries are labour intensive yet very selective and low impact to the marine ecosystem. Pole and line fisheries depend on significant quantities of bait fish to attract the tuna. Whilst these bait fish are usually small, resilient species, some basic monitoring and management measures need to be developed. The scientific committee 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.
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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