Skipjack tuna

West Atlantic skipjack tuna is abundant and not subject to overfishing.Skipjack stocks in the Atlantic are assessed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). A new stock assessment was carried out in 2022, the first since 2014. It uses data up to 2020. It is unclear when the next assessment is expected. West Atlantic skipjack catches peaked in 1985 at 40,000 tonnes. They have since declined, reaching around 18,800t in 2020.The biomass (B) of the stock was fairly constant until 1980, when it declined but fluctuated above the level associated with Maximum Sustainable Yield (B MSY). In 2020, B was 160% of BMSY. Therefore the stock is not in an overfished state.Fishing mortality (F) was low the 1960s, but increased and has fluctuated around 40% of FMSY since then. In 2020, F was 41% of FMSY. Therefore, the stock is not subject to overfishing.Projections indicate that future constant catches of 20,000 t, close to the current catch (19,951 t in 2021) are expected to maintain the stock above BMSY and below FMSY through to 2028. Catches at MSY (35,277t) would result in a less than 1% probability of the stock being below Blim (20% of BMSY) in 2028.

Few appropriate management measures are in place for this stock. There are no catch limits and few fishing controls.Tuna, marlin, and swordfish are highly migratory species, found on the high seas and in numerous countries' waters. This makes harmonised and effective management challenging. Regional Fisheries Management Organisations (RFMOs) are responsible for monitoring and managing these stocks on behalf of the countries that access them. However, the degree to which management is implemented, monitored and enforced by each country varies significantly.West Atlantic skipjack tuna is managed and assessed by the International Commission for the Conservation of Atlantic Tunas (ICCAT).There is no catch limit (Total Allowable Catch, TAC) or Harvest Control Rule (HCR) in place for this stock. The primary management measure is a limit on Fish Aggregating Devices (FADs), but this does not affect the west Atlantic stock.A new stock assessment for Atlantic skipjack was carried out in 2022. This was a significant improvement in the understanding of the stock, as there had not been an assessment since 2014.The new assessment indicates that the stock is in a healthy state and that a constant catch at MSY (35,277t) would result in a less than 1% probability of the stock being below Blim (20% of BMSY) in 2028. Recent catches (2017-2021) have been below MSY, averaging 21,250 tonnes. However, there is no catch limit to ensure they stay at this level.Most tropical tuna management focuses purse seine nets, many of which use Fish Aggregating Devices (FADs). FADs are floating objects that attract tuna and other species, making it easier to set nets around them to catch them. Many juvenile fish are caught in these fisheries, which can have implications for future population growth. Therefore, there is a ban on using FADs throughout the Atlantic (ICCAT convention area) for 72 days in January to mid-March. This is intended to reduce fishing pressure on bigeye and yellowfin tuna. In 2022, the scientific committee concluded that it also may have reduced skipjack catches in the east Atlantic. However, in 2022 the scientific committee noted that no fleets were targeting west Atlantic skipjack using FADs, so the measure has had minimal effect on this stock.Most western skipjack tuna catches are by bait boats, or pole and line. However, there are few management measures to control this fishery. Therefore, few appropriate management measures are in place. Work is underway in 2023 to develop management objectives. Management measures also include:Countries must calculate the fishing capacity needed to deliver their set quotas, and reduce current capacity, e.g. by reducing licenses or vessel sizes, if it is too high. An analysis in 2022 estimated that in total there are 72 purse seine vessels actively fishing in the area, with a higher capacity (fish-hold volume) than needed. There were 99 vessels licensed to fish in the area, so there is also excess latent capacity.Countries are 'encouraged' not increase fishing effort above the 2018 level.Countries must submit FAD management plans to improve knowledge about FADs being used, manage deployment and recovery, and reduce ecosystem impacts.In 2021 the number of permitted support vessels, which help to increase the efficiency of purse seiners, was frozen.A requirement for 100% observer coverage on large purse seiners targeting tropical tunas all year round. The requirement for longline is only 10% and many fleets are not reaching this level. There does not appear to be a set level for baitboats. Scientific recommendations are 20% for accurate data.There is a ban on discarding skipjack, yellowfin and bigeye tuna: all fish caught must be landed. There is also a tagging programme to improve stock assessments for tropical tunas and gauge effectiveness of management measures.In terms of monitoring and surveillance, other management by ICCAT includes:A ban on drift nets by the EU in 2002 and by ICCAT in the Mediterranean in 2003.A list of vessels authorised to fish for this species, and a list of vessels caught carrying out Illegal, Unreported or Unregulated activities. At-sea transhipment is prohibited unless pre-authorised and the vessel has an observer on board.Work is underway to improve electronic monitoring. Vessel Monitoring Systems are required for all vessels over 24m.

Most skipjack tuna in the west Atlantic are caught by pole & line. This is a generally low-impact method.Pole & line accounted for nearly 80% of the total skipjack catch in the west Atlantic in 2021, at around 15,500 tonnes. This method targets fish near the surface, and so rarely touches the seabed, reducing the risk of habitat impacts. It is labour-intensive and very selective, meaning there are low levels of bycatch of vulnerable species. It involves fishing with rods, using live bait to attract the tuna. The baitfish, usually small pelagic species such as sardines or anchovy, are caught and stored alive nearby or on the boats.In this area, most of the fishing is by Brazilian boats using sardines as bait. The fishery is responsible for only a small proportion (less than 5%) of the total catch of Brazilian sardines. The Brazilian sardine fishery collapsed in the 1990s owing to excess fishing pressure and adverse environmental conditions. Management measures were subsequently brought in, and now include a closed season, closed areas, a requirement for tuna vessels to catch their own bait, and restrictions on fishing close to the beach. There is a recognized need to reduce overall sardine fishing effort, especially during periods of low sardine abundance, but primarily by the targeted purse seine fishery.Surface fisheries tend to catch smaller and younger tunas than those fishing in deeper waters. This could be of concern, as the scientific committee has highlighted that increased catches of small yellowfin will have negative effects on stock size and future harvest rates. Therefore, effective measures should be introduced to reduce fishing mortality on small yellowfin tunas.