Euthynnus pelamis, Katsuwonus pelamis
Capture method — Gill or fixed net
Capture area — Pacific, North West (FAO 61) and Central (FAO 71,77)
Stock area — Western and Central Pacific
Stock detail — All Areas
Updated: November 2020
The Western and Central Pacific Ocean (WCPO) skipjack stock supports the largest tuna fishery in the world, accounting for approximately 37% of worldwide tuna landings. It is not subject to overfishing, but the stock size is slightly below target levels and is projected to decline under current catch levels. A Harvest Control Rule is to be developed for skipjack. Until then, management measures are mainly aimed at limiting fishing effort by purse seiners, which is responsible for around 80% of the skipjack catch. There are also limits on the number of large longliners allowed to fish for skipjack. Observers, to verify catch and bycatch, are on 100% of purse seiners within the main fishing grounds, but coverage is low for other areas and gear types at just 5%. There is not enough data to be sure that countries are complying with the management measures. 12% of the skipjack catch is taken in artisanal ring and gill net fisheries with unconfirmed impacts to bycatch species. Gillnets used for catching tuna and tuna like species can be 7 km and are known for extremely high bycatch including endangered marine turtles, whales, dolphins and sharks. WCPFC bans the use of gillnets over 2.5km long, but monitoring is poor. A critical fail is applied to capture method impacts due to bycatch concerns, resulting in a default red rating.
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.
The Western and Central Pacific Ocean (WCPO) skipjack stock supports the largest tuna fishery in the world, accounting for approximately 37% of worldwide tuna landings. It is not subject to overfishing, but the stock size is slightly below target levels and is projected to decline under current catch levels.
This stock is managed and assessed by the Western and Central Pacific Fisheries Commission (WCPFC). The latest stock assessment was carried out in 2019 using data up to 2018. Skipjack tuna catches in the WCPO increased steadily from 1970 onwards, roughly doubling during the 1980s. After stabilising at around 1 million tonnes during the early 1990s, they increased to a record catch of around 2 million tonnes in 2014. Catches have since levelled off at around 1.75 million tonnes. Fishing mortality (F) has correspondingly increased, peaking in 2018 at 45% of levels associated with Maximum Sustainable Yield (MSY). There is zero probability that F exceeds FMSY, meaning that the stock is not subject to overfishing. Biomass has declined from about 90% of unfished levels in 1970 to 44% in 2018. There is a Target Reference Point of 50% of unfished levels. While this puts the stock below the target level, the stock assessment concludes that the stock is not overfished because it is above the Limit Reference Point of 20%. Spawning biomass is around 2.5 times the level associated with MSY (SBMSY), but fishing mortality is continuously increasing and SB has reached its lowest level on record. The scientific committee therefore recommends that management is implemented to keep the biomass fluctuating around the TRP, e.g. through a Harvest Control Rule.
The skipjack catch in 2018 (1,795,048t) was a 10% increase from 2017 and a 1% decrease from the 2013-2017 average. If 2012 purse seine effort levels (and 2012 catches for other gear types) are maintained, SB is projected to decrease to 42% of unfished levels. To keep the stock at between 44% and 50% of unfished levels, effort must be reduced from 2012 levels by 7-25%. This would lead to increases in spawning biomass of between 3% and 18%.
The scientific committee advises that tagging data is a critical component of the skipjack stock assessment and recommend regular large-scale tagging cruises and complementary tag recovery work continue to be undertaken in a way that provides the best possible data for stock assessment purposes.
The Western and Central Pacific Ocean (WCPO) skipjack stock supports the largest tuna fishery in the world, accounting for approximately 37% of worldwide tuna landings. It is not subject to overfishing, but the stock size is slightly below target levels and is projected to decline under current catch levels. A Harvest Control Rule is to be developed for skipjack. Until then, management measures are mainly aimed at limiting fishing effort by purse seiners, which is responsible for around 80% of the skipjack catch. Observers, to verify catch and bycatch, are on 100% of purse seiners within the main fishing grounds, but are low for other areas and gear types at just 5%. There is not enough data to be sure that countries are complying with the management measures.
Most tuna stocks range across and are accessed by numerous coastal states, making harmonised and effective management of these individual stocks very difficult. As a result, 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. The tuna fisheries in the Western and Central Pacific Ocean (WCPO) are managed by the Western and Central Pacific Fisheries Commission (WCPFC). 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. A significant proportion of West Pacific skipjack and yellowfin tuna is caught within the waters of the Parties to the Nauru Agreement (PNA). These South Pacific island nations have incorporated additional management measures, and pushed for improvements in the wider management of these stocks. In addition, around 50% of West Pacific purse-seine-caught skipjack and 70% of yellowfin is certified by the Marine Stewardship Council.
WCPFC is looking to establish harvest strategies for key fisheries and stocks but has not yet completed this work and so a bridging measure is in force to manage bigeye, yellowfin and skipjack. It lasts from 2018 until harvest strategies are in place, or February 2021. There is a limit reference point for the spawning biomass of bigeye, skipjack, and yellowfin tuna of 20% of unfished levels (SB/SBF0 = 0.2), below which the stock should not fall. Skipjack also has an interim target reference point of 50% of unfished levels, while bigeye and yellowfin are to be maintained at recent levels (the average from 2012-2015). Skipjack is slightly below the target, at 44%, and is projected to decline under current catch levels. Recent effort levels in terms of numbers of sets in the tropical purse seine fishery have been 87% (2015-2018 average) and 98% (2019 levels) of those in 2012.
An evaluation of the bridging measure in 2019 found that it would achieve its targets if bigeye recruitment remains high, but if that declines, fishing mortality will double to above FMSY and biomass has a 20% chance of dropping below the limit reference point. For yellowfin, the measure will marginally fail its aims as SB will experience a small decrease. The bridging measure includes a number of new measures and consolidates some pre-existing ones. It isn’t clear how well they have been implemented, especially given the ongoing increases in total catch of skipjack. The scientific committee recommends more comprehensive data collection relating to FADs. It also recommends reducing fishing mortality on juveniles by preventing increases in overall fishing mortality. In the tropical region, between 20 degrees North and 20 degrees South, the following applies:
FADs are banned for 5 months of the year (3 months for Kiribati and the Philippines). VMS polling frequency increases to every 30 minutes during the FAD closure.
Effort limits (in vessel days) apply to purse seining on the high seas (excluding Small Island Developing States, SIDS). Limits vary by country. Effort shouldn’t be transferred into areas outside of the bridging measure. Large purse seine and longline vessel numbers and capacity are frozen to 2016 levels (excluding SIDs and Indonesia).
Purse seiners must retain and land all bigeye, skipjack, and yellowfin tuna. This is intended to incentivise reductions in bycatch of juvenile fish.
100% observer coverage is required for purse seine vessels. Outside of the areas covered by the bridging measure, observer coverage on purse seiners is poor. Only 5% coverage is required on longliners greater than 20m in length. 20% is considered to be the minimum to be effective.
Other measures that apply to tuna in the wider convention area:
Each purse seine vessel is limited to 350 drifting FADs at a time. Countries should have FAD management plans, with strategies to implement closures and other measures for reducing mortality of juvenile bigeye.
Catch and/or effort limits apply to purse seining within national waters (it varies by country). For bigeye, there are country-specific limits on longline catch. By 2020, limits for bigeye and a framework to allocate them amongst countries should be developed. Catches by other fisheries for bigeye, yellowfin or skipjack tuna (except those taking less than 2,000 tonnes) are frozen to either the average level for 2001-2004 or the level of 2004.
To help address IUU, the WCPFC maintains an IUU Vessel List, prohibits transhipments at sea between purse seiners (some exemptions apply) and requires all other transhipments to be documented and 100% observed as part of the regional observer programme.
In 2017 a Compliance Monitoring Scheme was introduced to assess and improve compliance with obligations, and penalise non-compliance.
Criterion score: Critical Fail info
12% of the skipjack catch is taken in artisanal ring and gill net fisheries with unconfirmed impacts to bycatch species. Gillnets used for catching tuna and tuna like species can be 7 km and are known for extremely high bycatch including endangered marine turtles, whales, dolphins and sharks. WCPFC bans the use of gillnets over 2.5km long, but monitoring is poor.
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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WCPFC, 2020. Stock Status and Management Advice: Skipjack Tuna (Katsuwonus pelamis). Available at https://www.wcpfc.int/doc/03/skipjack-tuna [Accessed on 10.12.2020].
WCPFC, 2020. Summary Report of the Sixteenth Regular Session of the Scientific Committee of the WCPFC, 12-19 August 2020 (Reconvened on 10 September 2020), Online. Available at https://www.wcpfc.int/file/568072/download?token=hcPeql6u [Accessed on 10.12.2020].
WCPFC, 2020. Conservation and Management Measures of the Western and Central Pacific Fisheries Commission. Compiled 2 Nov 2020 - 09:46. Available at https://www.wcpfc.int/system/files/booklets/31/CMM%20and%20Resolutions.pdf [Accessed on 10.12.2020].