Yellowfin tuna

Yellowfin tuna in the Eastern Pacific Ocean is not thought to be overfished or subject to overfishing.The Eastern Pacific Ocean (EPO) yellowfin tuna stock is managed and assessed by the Inter-American Tropical Tuna Commission (IATTC). Catches of yellowfin tuna in this area increased from 100,000t in the 1980s to over 400,000t in the early 2000s. They have since declined to around 233,000t (the average for 2015-2019).The most recent stock assessment for EPO yellowfin was carried out in 2020. As part of this, a number of stock status indicators were developed. The actual values for fishing pressure and biomass are not known, but it does assess stock status using MSY-based reference points. The next assessment is expected in 2024.The assessment concluded that at the beginning of 2020, the spawning biomass of yellowfin ranged from 49% to 219% of the level associated with Maximum Sustainable Yield (MSY). this is a wide range of values, but the probability of the spawning biomass being below MSY is low (12%), and there is a zero probability of it being below its limit reference point. Therefore, the stock is not thought to be in an overfished state.Between 2017 and 2019, the fishing mortality (F) for yellowfin ranged from 40% to 168% of the level associated with MSY. Again, this is a wide range of values but there is a low probability of F being above FMSY (9%) and zero probability of it being above the limit reference point. Therefore, the stock is not thought to be subject to overfishing.Recruitment of young fish into the stock appears to be declining, and has been below the long term average since 2000. There are occasional peaks, which may be influenced by El Nino events.Tagging studies of yellowfin throughout the Pacific indicate that they tend to stay within 1,800 km of their release positions. This tendency to stay within the same area, along with variation in characteristics of yellowfin between areas, suggests that there might be multiple stocks of yellowfin throughout the Pacific Ocean. However, movement between these potential stocks cannot be estimated with currently-available tagging data. This is the main uncertainty in the current stock assessment.

Few appropriate management measures are in place. There are controls relating to which fishing gears can be used where and when. However, there are no catch limits. Regulations are insufficient to prevent catches from increasing further and potentially exceeding sustainable limits.Tuna 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. It is important that commercial buyers choose tuna that has been caught by vessels that are well regulated by their flag state.This stock is managed and assessed by the Inter-American Tropical Tuna Commission (IATTC). Some stocks overlap with the Western and Central Pacific Fisheries Commission (WCPFC). The IATTC and WCPFC endeavour to work together to promote compatibility between their respective conservation and management measures across the Pacific, but this is not always achieved.Management of tropical tunas (bigeye, yellowfin, and skipjack) in the Eastern Pacific is through Resolutions that last for 3 years at a time. The conservation measures for tropical tunas in the Eastern Pacific Ocean during 2022-2024 (C-21-04) include a number of controls relating to which fishing gears can be used where and when. The aim is to keep fishing mortality at or below the status quo (average during 2017-2019). However, it does not include catch limits for yellowfin or skipjack. Therefore, not all appropriate management measures are in place.In 2016, interim Harvest Control Rules (HCRs) were brought in for bigeye, skipjack and yellowfin purse seine fisheries (C-16-02). The HCRs set out targets and limits for fishing mortality, which should be used as a basis for other management measures. Skipjack and yellowfin stock assessments are too uncertain to produce actual estimates of fishing mortality, although they have concluded that it is likely to be below the target reference point. However, some indicators show that fishing mortality is increasing on all three species owing to increases in purse seine fishing effort, specifically on Fish Aggregating Devices (FADs). Fishing mortality on skipjack in 2021 was above the status quo. This suggests that management may not be controlling fishing pressure, although the IATTC scientific committee have not recommended any changes to the current approach. There is a limit on the number of FADs each fishing vessel can use (varying by vessel size). FADs catch high numbers of juvenile yellowfin and bigeye, and are the main cause of increasing fishing pressure on tropical tunas. FAD limits are therefore seen as one of the most important ways to control tuna fishing. The upper limit for the largest vessels is gradually reducing from 450 in 2018-2021 to 340 by 2024, which is a 25% reduction. Recommendations were for a 30% reduction.A Management Strategy Evaluation for tropical tunas is being carried out from 2021-2024, beginning with bigeye tuna. This should provide some clarity on whether current measures can achieve their targets.Other management includes:Bigeye catch limits for longliners (varying by country). The scientific committee advises that if adequate management is in place for bigeye, this should also protect the skipjack stock.A ban on large purse seiners fishing in areas and at times when catches of small bigeye tuna are high. The closed periods are longer for vessels with higher bigeye catches.A requirement to retain and land all bigeye, skipjack, and yellowfin tuna caught by purse seiners.There is 100% observer coverage on large purse seiners to monitor catches and effort. The scientific committee continues to recommend 20% observer coverage for small purse seiners in order to get better data on discards and bycatch. Since 2011 only 5% observer coverage has been required on large longliners, considered by the scientific committee to be too low for accurate data: a minimum of 20% coverage is recommended. In addition, data recorded by longliners is considered inadequate for scientific purposes and minimum data standards must be identified and introduced.To help address IUU, the IATTC maintains an IUU Vessel List, maintains a register of authorised fishing vessels, prohibits transhipments at sea for most vessels (some exemptions apply), and requires most other transhipments to be documented and observed. Countries are required to report annually on monitoring, control and compliance of management measures. IATTC was the last tuna RFMO to adopt Port State measures (in 2021) to strengthen work to tackle IUU. IATTC does not report on countries' compliance with management measures and does not have a framework for addressing non-compliance.

Most yellowfin tuna in the eastern pacific Ocean is caught by purse seining on tuna-dolphin associations. This can cause dolphin deaths, and while mortality has reduced, it is still too high.Approximately 65% of the yellowfin catch in the EPO is made by purse seining on tuna-dolphin associations. This method has been employed for decades. Tuna boats follow dolphins, which often swim alongside tuna and are easier to spot because they surface to breathe. The nets are set around both dolphins and tuna, and the dolphins are then released.In the past this has caused very high dolphin mortality, peaking at about 132,000 deaths in 1986. This has been greatly reduced over the years and now averages around 735 deaths. Mortality has been around this level since 2015.The La Jolla agreement for the conservation of dolphins came into force in 1993. It was followed by the Agreement on the International Dolphin Conservation Program (AIDCP) in 1999. AIDCP is a legally-binding multilateral agreement. Signatories include Mexico, Venezuela, Ecuador, Panama and Colombia. The agreement aims to reduce incidental dolphin mortalities in the purse-seine fishery in the eastern Pacific Ocean to levels approaching zero. As mortality has changed very little since the first agreement in 1993, further efforts are needed to keep reducing mortality.Most deaths are eastern spinner dolphins, southern spotted dolphins, whitebelly spinner dolphins and northeastern spotted dolphins. Mortality rates in 2021 equated to 0.01-0.02% of the various populations. However, the last dolphin surveys took place in 2006, and therefore the current status of these populations is uncertain. Work began in 2019 to survey the dolphin populations in the EPO. This data should provide greater confidence in the impact of this fishery on local dolphin populations.AIDCP sets a dolphin mortality limit (DML) for the international fleet, which is divided between vessels. A limit of 5,000 animals appears to have been in place since 1999. As this is well above current death rates, it does not appear to be controlling the fishery.The Tuna Tracking System established under the AIDCP tracks the tuna caught in each set from the time it is captured until it is unloaded. Tuna caught in sets in which dolphins are not killed or seriously injured is defined as "dolphin-safe". Since 2014, 96% of sets have been accomplished with no mortality or serious injury to the dolphins. Dolphin mortality is closely monitored by AIDCP, with 100% observer coverage. There were exemptions during the pandemic, applied March 2020-December 2022. During 2021, 94% of fishing trips were observed.Purse seining can be associated with bycatch of other vulnerable species, such as sharks and rays, although less so in tuna-dolphin associated fishing. The scientific committee recommends that experiments be conducted on mitigating bycatches of sharks, and on the survival of sharks and mobulid rays captured by all gear types, with priority given to those gears with significant catches.

AIDCP, 2022. Report on the International Dolphin Conservation Program. AIDCP-45-01 REV. Agreement on the International Dolphin Conservation Program, 45th Meeting of the Parties. 18-19 October 2022, La Jolla, California, USA. Available at https://www.iattc.org/GetAttachment/e52757e7-0dfe-4629-8514-914209358cf3/AIDCP-45-01_Report-on-International-Dolphin-Conservation-Program.pdf [Accessed on 19.12.2022].IATTC, 2021. Recommendations of the Scientific Advisory Committee (SAC) to the Commission (corrigendum). IATTC-97-01 presented to the 97th Meeting (Extraordinary) of the Inter-American Tropical Tuna Commission. Available at https://www.iattc.org/Meetings/Meetings2021/IATTC-97/Docs/_English/IATTC-97-01_Recommendations%20of%20the%20Scientific%20Advisory%20Committee%20(SAC)%20to%20the%20Commission%20(corrigendum).pdf [Accessed on 09.12.2021].IATTC, 2022. Inter-American Tropical Tuna Commission: IATTC Resolutions. Available at https://www.iattc.org/en-US/Resolution/Type/IATTC [Accessed on 13.12.2022].IATTC, 2022. Staff recommendations for management and data collection, 2022. IATTC-100-04. Inter-American Tropical Tuna Commission 100th Meeting. 1-5 August 2022. Phoenix, Arizona, USA. Available at https://www.iattc.org/GetAttachment/481b159a-a831-424a-ad4d-b18092cd88fa/IATTC-100-04_Staff-recommendations-to-the-Commission.pdf [Accessed on 19.12.2022].IATTC, 2022. Report on the tuna fishery, stocks, and ecosystem in the Eastern Pacific Ocean in 2021. Available at https://www.iattc.org/GetAttachment/99dc87b3-cf5f-4b7b-8e6e-f5aa9cab0fce/No-20-2022_Tunas,-stocks-and-ecosystem-in-the-eastern-Pacific-Ocean-in-2021.pdf [Accessed on 13.12.2022].IATTC, 2022. Vulnerability assessment of sharks caught in eastern Pacific Ocean pelagic fisheries using the EASI-fish approach. SAC-13-11. Inter-American Tropical Tuna Commission Scientific Advisory Committee 13th Meeting. 16-20 May 2022. Online. Available at https://www.iattc.org/GetAttachment/57b58325-ecdd-4133-acd0-84f0959f332b/SAC-13-11%20-%20Vulnerability%20status%20for%20sharks%20in%20the%20EPO%20EASI-fish%20assessment [Accessed on 03.01.2023].