Tuna, skipjack

Euthynnus pelamis, Katsuwonus pelamis

Method of production — Caught at sea
Capture method — Pole & line; Troll
Capture area — Atlantic, North (FAO 27), Central (FAO 34) and South (FAO 47) Eastern
Stock area — East Atlantic
Stock detail

All Areas


Picture of Tuna, skipjack

Sustainability rating three info

Sustainability overview

Skipjack stocks are difficult to assess. The last stock assessment was carried out in 2014, but no reliable estimate of the maximum sustainable yield (MSY) could be provided. MSY may be increasing, but more slowly than the growth rate of catches. It is unlikely that the eastern skipjack stock is overexploited or experiencing overshing, but a new stock assessment is needed. The Scientific Committee recommends that the catch and effort levels do not exceed the level of 2012-2013 catch or effort (around 218,434 t). The provisional catch in 2017 (242,289 t) exceeds this level by 11%. There is concern regarding the under reporting of skipjack catches in the Atlantic. There are no specific management measures for skipjack in the ICCAT area, but several time/area regulatory measures intended to protect juveniles of yellowfin and bigeye tuna exist. Approximately 15% of skipjack in the East Atlantic is caught in pole and line and, to a lesser extent troll fisheries. These methods are more labour intensive but are very selective and have minimal bycatch; though impacts to bait fish populations used in pole and line fisheries needs to be assessed. Whilst the scale of this is unlikely to overexploit stocks of these species, it could have implications for local availability.

Commercial buyers should establish what measures the flag state or fleet relating to their source is taking to improve data collection, research, monitoring and management of their fisheries and specify the need to see ongoing, demonstrable improvements. Large buyers should consider supporting such improvements.

Biology

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.

Stock information

Criterion score: 0.25 info

Stock Area

East Atlantic

Stock information

Skipjack and other tuna stocks in the east Atlantic are assessed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). Numerous changes have occurred in the skipjack fishery since the early 1990s (e.g. the progressive use of FADs and expansion of the fishing area), which has increased the proportion of the biomass exploited. Currently, the major fisheries are the purse seine fisheries, followed by the bait boat fisheries. Following the historic record in 2013 (255,730 t), the total catches of skipjack throughout the Atlantic Ocean (including catches of “faux poison” landed in Cote d’Ivoire) have remained high. This represents a very sharp rise compared to the average catches of the five years prior to 2010 (155,157 t), although it’s possible that catches from that period were under-reported. There has been a sharp increase in purse seine catch, particularly catches based around floating objects, in part due to piracy in the Indian Ocean displacing fleets into the Atlantic. Estimates of the unreported catches of these purse seiners have increased since 2006 and may have exceeded 20,000 t for the three main species of tropical tunas. The scientific committee expressed the need for the countries and the industry concerned in the region to cooperate to estimate and report these catches accurately to ICCAT. The amount of fish discarded, and the proportion of small skipjack (37 cm) landed as ‘faux poison’ are around 10,000 t per year. The Scientific Committee recommends that the catch and effort levels do not exceed the level of 2012-2013 catch or effort (around 218,434 t). The provisional catch in 2017 (242,289 t) exceeds this level by 11%.

In all the oceans, traditional stock assessment models are difficult to apply to skipjack because of their particular biological and fishery characteristics (on the one hand, continuous spawning, spatial variation in growth and on the other, discrimination of effort for free schools and FADs, transition between these two fishing methods which are difficult to quantify). In order to overcome these difficulties, several assessment methods have been applied to the two stocks of Atlantic skipjack. Smaller sub-units of stocks are being considered and it is expected that the five year Atlantic Tropical Tuna Tagging Programme (AOTTP), may improve understanding of skipjack stock structures and movement patterns. The last stock assessment for east Atlantic skipjack was carried out in 2014, but no reliable estimate of the maximum sustainable yield (MSY) could be provided. MSY may be increasing, but more slowly than the growth rate of catches. It is unlikely that the eastern skipjack stock is overexploited or experiencing overshing, but it is possible that current catches are at or even above MSY. There is no evidence of a fall in yield, or in the average weight of individuals captured. No projections are available to indicate the effect of current catches on this stock.

Management

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 address 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 International Commission for the Conservation of Atlantic Tunas (ICCAT). 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. There remain large data deficiencies in most tuna and billfish fisheries, particularly with regards to fine scale spatial and temporal data for both target and especially for vulnerable bycatch species. For this reason, it is important to choose tuna that has been caught by vessels that are well regulated by their flag state.

Despite the absence of evidence that the eastern stock is overexploited, but considering the lack of quantitative findings for the eastern stock assessment, and pending the submission of additional data (including on FADs and on the ongoing tagging programme) which are necessary to improve the stock assessment, the scientific committee recommends that the catch and effort levels do not exceed the level of 2012-2013 catch or effort. In addition, increasing harvests and fishing effort for skipjack could lead to involuntary consequences for other species that are caught in combination with skipjack in certain fisheries (particularly juveniles of yellowfin and bigeye). For the West Atlantic, catches should not be allowed to exceed the MSY. There is concern regarding uncertainties which the underreporting of skipjack catches may have on the perception of the state of the stocks - estimates of the unreported catches of some purse seiners have increased since 2006 and may have exceeded 20,000 t for the three main species of tropical tunas. In spite of this advice, and attempts by the scientific committee to develop a Harvest Control Rule (HCR) for the eastern stock, no TAC (Total Allowable Catch) or HCR is in place for skipjack.

The following measures are in place for bigeye, skipjack and yellowfin:
There is a tagging programme to improve stock assessments for tropical tunas and gauge effectiveness of management measures for these species. This has yet to deliver the needed data.
A multi-annual management programme has been in place for bigeye and yellowfin since 2012, and eastern skipjack since 2015. Fishing for these species using aggregation devices, including FADs, is prohibited from 1st January to 28th February in an area off the west African coast to reduce catches of juvenile bigeye and yellowfin. All vessels fishing during this period must have an observer on board. The scientific committee concluded that closures to date have not been effective at reducing the mortality of juvenile bigeye tuna, and any reduction in yellowfin tuna mortality was minimal, largely due to the redistribution of effort into areas adjacent to the moratorium area.
For the rest of the year, no more than 500 FADs may be active at any one time and countries must have FAD Management Plans that improve understanding of FADs and limit their impacts on the ecosystem.
ICCAT maintains a list of vessels over 20m authorised to fish for these species, although other vessels may retain them as bycatch as long as the country sets limits on this and doesn’t exceed its quota.
Performance indicators and evaluations of the projected impact of current management measures are expected in 2017, with adjustments to management following in 2018.
Countries are encouraged to reduce discards.
The increasing use of fish aggregation devices (FADs) in skipjack fisheries since the early 1990s have changed the species composition of free schools. It is noted that, in fact, the free schools of mixed species were considerably more common prior to the introduction of FADs. Furthermore, the association with FADs may also have an impact on the biology (growth rate, plumpness of the fish) and on the ecology (distances, movement orientation) of skipjack and yellowfin (“ecological trap” concept).

Other management measures of note include:
There is a mandatory level of observer coverage of 5%, which may not have been implemented by many fleets, although some fleets are currently implementing voluntary observer programmes that cover 100% of fishing trips. This is in spite of scientific committee recommendation of a minimum of 20% for accurate reporting of bycatch. Purse seine and longline vessels over 20m long are encouraged to increase their observer coverage from the required minimum. Vessel Monitoring Systems are required for all vessels over 24m.
In 2015 a working group was formed to look at ways to reduce juvenile catches of bigeye and yellowfin tuna caught in FAD fishing.
are banned in the Mediterranean.
ICCAT maintains lists of vessels authorised to fish for tuna and tuna-like species in the ICCAT area, and those caught carrying out Illegal, Unreported or Unregulated activities.
At-sea transhipment is prohibited unless pre-authorised and the vessel has an observer on board.
In 2017 ICCAT banned the discarding of skipjack, yellowfin and bigeye.
In 2016 the Commission passed measures to strengthen and streamline its compliance assessment process and to develop a scheme of responses to non-compliance.

Capture Information

Criterion score: 0.25 info

Approximately 15% of skipjack in the East Atlantic is caught in pole and line and, to a lesser extent troll fisheries. These methods are more labour intensive but are very selective and have minimal bycatch; though impacts to bait fish populations used in pole and line fisheries needs to be assessed. The nominal effort of bait boats has remained stable for over 20 years.

ICCAT aims to take an ecosystem-based and precautionary approach to fisheries management.

For sharks: Countries are required to develop and submit National Plans of Action for the conservation and management of sharks. Sharks must be fully utilised (e.g. no removal of fins). Sharks must be released wherever possible (if not being directly targeted) and countries must try to minimise bycatch of sharks (although no gear-specific measures are identified). Catching silky sharks, hammerheads, oceanic whitetips, and bigeye threshers is prohibited, and catching other thresher species is discouraged. Shortfin mako can be caught and retained, but as of 2017 the country’s law must require a minimum length of 180cm for males and 210cm for females, otherwise, shortfin makos caught alive must be released unharmed. This is expected to prevent the stock’s currently poor state from worsening, and a rebuilding plan will be developed for 2019. In 2016 additional measures for blue shark were introduced, mainly focussed on improved data recording, with potential to introduce Harvest Control Rules. A catch limit of 39,102 t was also introduced in the north Atlantic (but none for the south Atlantic): if exceeded the commission has committed to reviewing the effectiveness of its blue shark management measures. Preliminary catch in 2016 was 42,117 t. Porbeagle is overfished throughout the Atlantic, significantly so in the northwest, and for the north Atlantic overall it is predicted to take at least 30 years to recover if there was zero fishing mortality. The main porbeagle-directed fisheries (EU, Uruguay and Canada) have closed, and ICCAT have a recommendation to release live porbeagle unharmed, but it is still caught incidentally and discarded, and also landed by other fleets. Currently there is not enough data to properly assess the status of many pelagic sharks (no assessments have been carried out for the Mediterranean).

There is a mandatory level of observer coverage of 5%, which may not have been implemented by many fleets, in spite of scientific committee recommendation of a minimum of 20% for accurate reporting of bycatch. However, some fleets are currently implementing voluntary observer programmes that cover 100% of fishing trips.

Alternatives

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
Arctic char
Herring or sild
Salmon, Atlantic (Farmed)
Salmon, Chinook, King Salmon
Salmon, Chum, Keta, Calico or Dog salmon
Salmon, Coho , Silver, White
Salmon, Pink, Spring , humpback
Salmon, Sockeye , Red Salmon, Bluebacks, Redfish
Sprat, whitebait
Swordfish
Trout, Rainbow
Tuna, albacore
Tuna, bigeye
Tuna, skipjack
Tuna, yellowfin

References

ICCAT, 2018. Report of the Standing Committee on Research and Statistics (SCRS) of the International Commission for the Conservation of Atlantic Tunas, 1-5 October 2018, Madrid, Spain. 469 pp. Available at https://www.iccat.int/Documents/Meetings/Docs/2018/REPORTS/2018_SCRS_REP_ENG.pdf [Accessed on 22.11.2018].

ICCAT, 2018. Resolutions, Recommendations and other Decisions. Available at http://www.iccat.es/en/RecsRegs.asp [Accessed on 11.12.2018].

IPNLF, 2012. Ensuring sustainability of live bait fish, International Pole and Line Foundation, London, 57 pp.

ISSF, 2018. Status of the world fisheries for tuna: October 2018. ISSF Technical Report 2018-21. International Seafood Sustainability Foundation, Washington, D.C., USA. 103 pp. Available at: https://iss-foundation.org/about-tuna/status-of-the-stocks/ [Accessed on 06.12.2018].