The catch of tropical tunas in the Eastern Pacific Ocean (EPO).

 

Approximately 13 percent of the world’s tuna production comes from the Eastern Pacific Ocean (EPO)–FAO Major Fishing Areas 67, 77 and 87. In 2023, catches of skipjack tuna, yellowfin tuna and bigeye tuna totaled around 761 800 tonnes, reflecting a 15 percent increase from 2022. The catch of tropical tunas in the EPO steadily increased since 1990s, reaching a record high of 800 000 tonnes in 2003. Total catches then declined until 2007 but have again been rising since, reaching the second-highest level in the entire time series in 2023 (FIGURE E.1.7). Catches of Pacific albacore tuna and Pacific bluefin tuna also occur in the EPO; however, these stocks are covered in the Western and Central Pacific Ocean section, as they are distributed there too. Average annual tropical tuna catches for the last five-year period (2019–2023) totalled 683 100 tonnes. During this recent period, skipjack tuna accounted for 49 percent of the catches by weight, followed by yellowfin tuna (39 percent) and bigeye tuna (12 percent). Purse-seine vessels took 95 percent of the total catch, followed by longliners (5 percent). During this time the skipjack tuna catch continuously increased to peak at around 390 000 tonnes in 2023, the highest level on record. Meanwhile, the yellowfin tuna catch reached its highest level in 2002, with a total of about 410 000 tonnes, and decreased to around 230 000 tonnes in 2020, before increasing to 300 000 tonnes in 2023 (FIGURE E.1.7). However, bigeye tuna followed a different trend, with catches peaking at approximately 140 000 tonnes in 2000 and declining since then to 70 000 tonnes in 2023, the lowest catch since 1984.

BIGEYE TUNA

 Bigeye tuna catches in 2023 were about 67 000 tonnes, a 2 percent decrease from 2022. Longline fishing dominated the catches in weight until the mid-1990s. However, in recent years purse-seine fishing accounts for a majority of the catch (71 percent), while longlining accounts for 29 percent (FIGURE E.1.8). Bigeye catches in the EPO by other gears are negligible. 

YELLOWFIN TUNA 

The yellowfin tuna fishery started at the beginning of the 1920s. Until about 1960, fishing was dominated by pole-and-line vessels; however, in the early 1960s pole-and-line vessels were converted into purse seiners, which have been the main gear since then (96 percent of the catch). The recent catches by purse seiners were about 70 percent (300 000 tonnes) of the record high caught in 2002 of 412 000 tonnes (FIGURE E.1.8). Catches from longline vessels, although smaller in magnitude, have also declined substantially in recent years. 

SKIPJACK TUNA 

In 2023, skipjack tuna catches were about 388 800 tonnes, a 31 percent increase from 2022. Skipjack tuna catches in the EPO are notoriously variable (FIGURE E.1.8). Purse-seine fishing dominates the catches, accounting for nearly 100 percent of the total.

BIGEYE TUNA In 2024, to evaluate stock status, the IATTC conducted a benchmark assessment that continues to use a risk analysis approach (Xu et al., 2024). The risk analysis encompasses three hypotheses structured hierarchically to address the main uncertainties, resulting in a total of 33 different models. The results of the assessment and risk analysis indicate that bigeye is not overfished and is likely fluctuating around the target level of SSBMSY, and that it is likely being exploited below the target level of FMSY, indicating that overfishing is not occurring (TABLE E.1.2 and FIGURE E.1.9).

 YELLOWFIN TUNA In 2024, the IATTC attempted to conduct a stock assessment (Minte-Vera et al., 2024), but the staff deemed that the model results were not sufficiently reliable to provide management advice. The results of the previous assessment (Minte-Vera et al., 2020) and risk analysis in 2020 (Aires-da-Silva et al., 2020) indicated the stock was not overfished and overfishing was not occurring. However, the model-weighted average of MSY across all models was estimated to be 288 000 tonnes, and current catches (306 000 tonnes in 2023) are above the estimated MSY. 

SKIPJACK TUNA In 2024, IATTC staff conducted a benchmark stock assessment (Bi et al., 2024) using an integrated age-structured catch-at-length model and concluded that the stock is most likely not overfished and overfishing is not occurring (TABLE E.1.2).

In 2024, the IATTC updated the stock status indicators that serve as supplemental information to monitor the stocks of bigeye, yellowfin and skipjack tuna. Most fish aggregating device (FAD) fishery indicators suggest that the stocks for all three tropical tuna species have potentially been subject to increased fishing mortality, mainly due to the increase in the number of sets in the FAD fishery. The number of sets on floating objects in 2022 reached the highest value since 2000. The catch of yellowfin tuna and skipjack tuna on floating object sets were the highest in the time-series. However, for bigeye, both catch in weight and catch-per-set on floating-object sets are at the lowest level since 2000, which may partly be a result of the introduction of the bigeye catch threshold scheme per vessel in 2021 (Resolution C-24-01). An evaluation of the impact of this scheme confirmed that it likely had a positive effect on reducing bigeye tuna catches in 2022 and 2023.

There is an ongoing strategy evaluation (MSE) process for tropical tunas at the IATTC, adopted through Resolution C-19-07. This process has included introductory workshops for the fishing industry, managers and other stakeholders, as well as technical developments to refine the MSE framework and improve simulation models. In 2016, the IATTC adopted a harvest control rule (HCR) for the tropical tuna purse-seine fishery, based on interim target and limit reference points established in 2014 (Resolution C-16-02, later amended by C-23-06). The HCR aims to prevent fishing mortality from exceeding the MSY level for the tropical tuna stock (bigeye, yellowfin or skipjack tuna) that requires the strictest management. Additionally, if fishing mortality or spawning biomass approaches or exceeds the corresponding limit reference point–with an estimated probability of 10 percent or greater–the HCR triggers the implementation of additional management measures to reduce fishing mortality and support stock rebuilding.

There is an ongoing strategy evaluation (MSE) process for tropical tunas at the IATTC, adopted through Resolution C-19-07. This process has included introductory workshops for the fishing industry, managers and other stakeholders, as well as technical developments to refine the MSE framework and improve simulation models. In 2016, the IATTC adopted a harvest control rule (HCR) for the tropical tuna purse-seine fishery, based on interim target and limit reference points established in 2014 (Resolution C-16-02, later amended by C-23-06). The HCR aims to prevent fishing mortality from exceeding the MSY level for the tropical tuna stock (bigeye, yellowfin or skipjack tuna) that requires the strictest management. Additionally, if fishing mortality or spawning biomass approaches or exceeds the corresponding limit reference point–with an estimated probability of 10 percent or greater–the HCR triggers the implementation of additional management measures to reduce fishing mortality and support stock rebuilding.

The main conservation measure established by the IATTC for bigeye, yellowfin and skipjack tuna is Resolution C-24-01, which establishes a multi-annual management measure for tropical tunas in the Eastern Pacific Ocean during 2025–2026. 

This measure calls for: 

„ An annual 72-day closure for purse seiners greater than 182 tonnes capacity through January 2027. 

„ Additional 13 to 22 days of closure for vessels exceeding a particular annual bigeye tuna catch limit in a previous year. „ A seasonal closure of the purse seine fishery in an area known as “El Corralito”. 

„ A full retention requirement for all purse seine vessels regarding bigeye, skipjack and yellowfin tunas. 

„ Bigeye tuna catch limits for the main longline fishing nations. 

„ Limits on the number of active FADs from 50 FADs/vessel for the smallest to 340 FADs/vessel for Class 6 vessels (1 200 m3 capacity) in the 2025–2026 period. 

„ No deployment of FADs 15 days before the selected closure period. 

„ Provision of daily information on all active FADs (position and echosounder biomass data) as well as Vessel Monitoring System (VMS) data to the Secretariat.