Albacore tuna

Albacore tuna in the north Pacific Ocean is not overfished and not subject to overfishing.North Pacific albacore is assessed by the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean (ISC) and jointly managed by the Inter-American Tropical Tuna Commission (IATTC) and the Western and Central Pacific Fishery Commission (WCPFC). Catches of this stock have fluctuated, peaking at 130,000 tonnes in 1976, dropping to 40,000t in 1991 and then increasing to 120,000t in 1999. They have since declined again, reaching around 43,000t in recent years. The last stock assessment was carried out in 2023, using data up to 2021. Assessments should be conducted every 3 years according to the North Pacific albacore harvest strategy, so the next one is expected in 2026.WCPFC and IATTC have set a target reference point for fishing intensity of F45%SPR, which is the fishing intensity (F) that results in the stock producing a spawning potential ratio (SPR) of approximately 45%. There is also a target to keep fishing effort below the average level from 2002-2004. The threshold and limit reference points for the spawning stock biomass (SSB) to be at 30% and 14% respectively of unfished levels (SSBcurrent, F=0). SSBcurrent, F=0 fluctuates with changes in recruitment.Spawning biomass declined until 2004, fluctuated until 2018, and has since increased to historically high levels. Estimates for recent biomass are uncertain, but SSB has never been below the threshold of 30%. In 2021, it was 70,229 tonnes, which equates to 54% SSBcurrent, F=0. Estimates range from 40-68%, but remaining above the 30% threshold. Therefore, the stock is not in an overfished state. The stock is 303% of SSB at MSY.Fishing intensity (F) fluctuated around the target level between 1998 and 2007, exceeding it several times. It has since declined. Average F from 2018 to 2020 was estimated to be 59%SPR, resulting in a population with an SPR of approximately 59%. This indicates that F was below the target of 45%, and therefore the stock is not subject to overfishing. Effort is below the 2002-2004 average.Projections indicate that if recent fishing intensity (2018-2020) is maintained, the stock is expected to remain around 54% SSBcurrent, F=0.Juveniles aged 2-4 are the largest components of north Pacific albacore catch owing to the size of surface fisheries (primarily troll and pole-and-line), which mainly remove juveniles.There remains high uncertainty in this stock assessment, owing to uncertainty around recruitment values.

Some appropriate management measures are in place to control fishing activity. However, most catches are immature albacore, which could have implications for the stock in future. Observer coverage in most fisheries targeting albacore is too low and needs to be improved.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.North Pacific albacore is assessed by the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean (ISC) and jointly managed by the Inter-American Tropical Tuna Commission (IATTC) and the Western and Central Pacific Fishery Commission (WCPFC). The impact of fisheries in the WCPFC area (70% of catches) on north Pacific albacore tuna are far greater than that of fisheries in the IATTC area, and so management measures by WCPFC are considered to be of greater importance. However, management must be comparable and properly implemented across the entire range of the stock in order for it to be effective. The IATTC and WCPFC endeavour to work together to promote compatibility between their respective conservation and management measures across the Pacific. However, this is not always achieved.In 2022, both IATTC and WCPFC adopted a new harvest strategy for North Pacific albacore. It is based on a management strategy evaluation (MSE) in 2021 and sets the parameters for making management decisions. It includes a target to keep fishing intensity at F45%, which would result in the stock producing a spawning potential ratio (SPR) of 45%. There is also a target to keep fishing effort below the average level from 2002-2004. If spawning stock biomass falls below 30% of the unfished biomass, additional management measures would be triggered. The limit at which a rebuilding plan would be triggered is 14% of unfished biomass. The biomass should be above the limit with at least 80% probability.A Harvest Control Rule (HCR) was adopted by both RFMOs in 2023. It sets out how fishing pressure should be adjusted based on the stock status in relation to the above reference points. It does not include an option for closing the fishery at low stock levels, and instead includes a minimum allowable fishing intensity of F87%. It is unclear what mechanism will be used to achieve the required fishing intensity. The MSE advised that mixed controls, on both effort and catches, would be most effective in keeping the biomass at stable levels.Other management measures by both IATTC and WCPFC include a freeze on fishing effort to 2002-2004 levels. Effort in eastern Pacific Ocean has been below the 2002-2004 average since 2011. Equivalent figures have not been provided by WCPFC to assess the effectiveness of this measure. However, total catches for both east and west from 2002-2004 averaged 93,470, and catches have been below this since then. The 2018-2022 average is around 50,000t.Most catches are juvenile albacore, as the fishery consists primarily of surface fisheries (e.g. troll and pole-and-line) which catch smaller fish. This could have implications for the stock in future.Monitoring of the fisheries is not high enough for some fleets with most requirements relating to the tropical tuna fisheries. Both RFMOs have 100% observer coverage on large purse seiners (for WCPFC this is on the high seas, or on vessels fishing in multiple countries' waters, or all vessels fishing between 20N and 20S). Albacore is mainly caught by longline, pole and line, and troll. Only 5% observer coverage is required on pole & line vessels and large longliners, considered too low for accurate data:. A minimum of 20% coverage is recommended. In addition, data recorded by longliners in the IATTC area is considered inadequate for scientific purposes and minimum data standards must be identified and introduced.To help address illegal, unregulated and unreported fishing, WCPFC and IATTC maintain an IUU Vessel List; a register of authorised large longliners; and prohibit transhipments at sea for large purse seiners, and most other transhipments must 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. However, improvements are needed on compliance processes in both RFMOs.

Some albacore catches in the north Pacific Ocean are by longlining. While longlining is unlikely to have habitat impacts, it can have a bycatch of highly vulnerable and endangered species, including sharks, turtles, and seabirds.Around 50% of north Pacific albacore catches are by longlining.Data on bycatch in longline fisheries is very poor because there are not enough scientific observers on vessels. Observer coverage is only required to be 5%, and scientific recommendations are for at least 20%. Both WCPFC and IATTC report that the 5% target is not currently being achieved, and the situation has been exacerbated by ongoing Covid impacts. In 2022, coverage in the WCPFC area was 4%. WCPFC scientists advise that observer coverage has been particularly poor in the northwest Pacific, and for all WCPFC bycatch data, trends are more reliable than magnitudes.In the WCPFC and IATTC areas, there are regulations for sharks and rays, turtles, seabirds and cetaceans. Most highlight the need for better data. Some bycatch mitigation measures are in place, but they often don't follow scientific recommendations for best practice, and their effectiveness has not been evaluated.Longlining for swordfish and albacore tuna usually happens in shallower waters than other tuna species, making it more accessible to species such as seabirds and increasing the risk of bycatch.Sharks are both bycaught and targeted in longline fisheries in the Pacific. In the western Pacific in 2021, an estimated 1.1 million sharks were caught as bycatch. In the eastern Pacific in 2021, over 9,000 tonnes of sharks were caught by longlining, including targeted blue shark. IATTC reports that almost all interactions resulted in mortalities. In both areas, bycatch species include bigeye thresher, shortfin mako, and silky shark. There are also some catches of the critically endangered oceanic whitetip and scalloped hammerhead, and the endangered pelagic thresher and mako species. A WCPFC stock assessment of oceanic whitetip in 2019 indicated it is at just 4% of unfished levels, although fishing pressure has been reduced and there were very slight signs of recent recovery. The greatest impact on this species is bycatch from longline fisheries, with lesser impacts from purse seining. Further catch mitigation and improved handling and release practices are required. Mobula rays, which includes a number of endangered species, are also bycaught.There are some mitigation measures, including restrictions on finning, a ban on landing silkies and oceanic whitetips, and restrictions on the use of shark lines (which increase bycatch in longlining). The effectiveness of these measures is difficult to evaluate owing to lack of data. As of 2014, shark management plans are required where sharks are being targeted, although few countries have developed them.Seabird bycatch is also a concern. Albatrosses and petrels are attracted to the baited hooks on longlines. There were at least 340 seabird deaths from EPO longlining in 2021, which is a minimum estimate given the significant data gaps. Species include the white-chinned petrel, wandering albatross, and black-browed albatross. In the WCPO, modelling has estimated that between 13,000 and 19,000 seabirds were killed annually in longline and purse seine fisheries from 2015 to 2018. Two thirds of the mortalities were by longline fisheries north of 20 degrees N.The required mitigation measures do not follow recommended best practice by ACAP (the Agreement on the Conservation of Albatrosses and Petrels). IATTC and WCPFC require one or more measures (depending on location) from a set list of options, including weighted branch lines, bird scaring lines and night setting. ACAP recommends the simultaneous use of all three, or hook-shielding or underwater bait setting devices.The five marine turtle species in the Pacific (green, hawksbill, leatherback, loggerhead and olive ridley) are vulnerable, endangered, or critically endangered. A 2023 review estimated that turtles represented 0.1% of WCPFC longline catch from 2003-2019, and around 13,000 individuals in 2021. Around 15% of turtle catches were loggerhead, which can be found in the north Pacific and therefore overlaps with this swordfish fishery. 52% were olive ridley and 13% green, both of which are more commonly found in the tropics. NOAA lists the North Pacific loggerhead population as endangered, with fisheries bycatch being the primary threat. IATTC does not have enough data to assess longline turtle bycatch in the east Pacific, although it reports that new rules in 2019 may lead to better data availability. Only 8 turtle deaths were reported in 2021, which is not representative of impacts.There are some mitigation measures, including requirements for safe handling and release. In the west, shallow-set swordfish longliners, used for swordfish and albacore, must use circle hooks and whole finfish bait (with some exemptions), but this covers less than 1% of WCPO longline effort, even though approximately 20% of the WCPO longline effort consists of shallow sets. The remaining 80% of longlining, which is deeper-set, has no mitigation requirements. In the east, shallow longliners must use circle hooks or finfish bait. Turtle interaction rates are thought to be higher in shallow-set longlines, but mortality rates are higher in deeper sets because sea turtles have a higher probability of asphyxiation.Interactions between marine mammals and longliners have been recorded, but data is very poor They can be attracted by the fish caught on the line. Species have included false killer whales and other cetaceans. A 2023 review estimated that mammals represented 0.01% of WCPFC longline catch from 2003-2019, and around 1,500 individuals in 2021. IATTC does not have enough data to assess longline mammal bycatch in the east Pacific. There were 11 reported deaths in 2021, which is a minimum estimate, given the data gaps.