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 north Pacific albacore tuna are caught by trolling. This is a low-impact method of fishing.Around 26% of north Pacific albacore catches are by troll fisheries. This method of fishing targets fish at the surface, and so rarely touches the seabed and doesn't have habitat impacts. It is labour-intensive and very selective. There can be some instances of seabird bycatch. There is no recent data on this but occurrences are thought to be very low.Trolling involves a number of fishing lines, attached to large poles or rods at the back of a boat, being slowly towed along near the surface. Artificial bait or lures can be used. Handlining and trolling can have small amounts of shark bycatch, although the main gears of concern for sharks are gillnet and longlines.Mandatory observer coverage is very low, at just 5%. In general, 20% is scientifically recommended to ensure adequate monitoring of catch and bycatch.