Background Information
- Stock condition
Yellowfin tuna is assessed and managed as a single stock across the Western and Central Pacific Ocean (WCPO). This reflects the species’ wide-ranging distribution and higher levels of mixing compared to skipjack. The WCPO stock is distinct from yellowfin in the Eastern Pacific Ocean (EPO), which is managed separately by the Inter-American Tropical Tuna Commission (IATTC), with coordination in areas where fisheries overlap.
This basin-wide approach recognizes that yellowfin is targeted by a diversity of fleets and gears, from industrial purse seine and longline vessels to small-scale fisheries in Southeast Asia. Environmental conditions such as El Niño and La Niña events influence catch patterns, with larger fish more common in El Niño years. Most yellowfin catches in the WCPO occur within Pacific Island EEZs, making regional management essential to balance conservation, small island state development aspirations, and the needs of distant-water fishing nations.
- Current Fishery Status
Yellowfin tuna is one of the cornerstone species of the Western and Central Pacific Ocean (WCPO) fishery. In 2024, the catch was estimated at around 678,000 metric tonnes, representing just over one-fifth of the region’s total tuna harvest. This catch comes from a mix of fisheries. Industrial purse seine vessels dominate the harvest, taking more than 330,000 tonnes, while longline fleets contribute about 80,000 tonnes. In addition, small-scale and artisanal fisheries in Southeast Asia, particularly in Indonesia, the Philippines, and Vietnam, make a major contribution, though reporting from these sectors is often incomplete. See the page on West Pacific East Asia (WPEA) to understand how WCPFC is supporting strengthened data collection in these countries.
The structure of fleets has shifted over time. Purse seine fleets based in Pacific Island countries such as Papua New Guinea, Kiribati, the Federated States of Micronesia, and the Marshall Islands have expanded, reflecting domestic development objectives. In contrast, distant-water fleets from Japan, Korea, Chinese Taipei, and the United States have declined in vessel numbers since the 1990s. Catches also vary depending on ocean conditions. During El Niño years, larger yellowfin tend to dominate the catch, while La Niña years are characterized by smaller fish.
- Importance of the Fishery
Yellowfin tuna is economically and socially significant. In 2024, it generated an estimated landed value of USD 1.6 billion, underlining its importance to both coastal and distant-water fishing economies. The species is central to export markets: purse seine catches supply global canneries, while longline fisheries provide fresh and frozen product to the high-value sashimi market. For many Pacific Island countries and territories, as well as Southeast Asian coastal states, yellowfin is also a key source of food security and livelihoods. Because yellowfin is caught alongside skipjack and bigeye in mixed tropical tuna fisheries, its management is inherently linked to the broader sustainability of WCPO tuna fisheries.
Science
- Stock status – latest assessment
Scientific assessments indicate that the yellowfin tuna stock in the WCPO is in a healthy condition. The 2023 stock assessment concluded that the stock is not overfished and is not subject to overfishing. Spawning biomass is well above the limit reference point of 20 percent of unfished levels, meaning that the population is capable of replenishing itself under current conditions.
However, stock-wide status can obscure localized problems. In some areas, particularly in equatorial purse seine fisheries, there is evidence of localized depletion of larger yellowfin. This highlights the importance of looking not only at basin-wide averages but also at regional patterns in abundance and fishing pressure. In addition, the reliability of assessments depends on the quality of the underlying data. Incomplete reporting, especially from small-scale fisheries in Indonesia and the Philippines, introduces uncertainty. Biological assumptions about growth, maturity, and reproductive capacity also carry some uncertainty, which is being addressed through new research.
- Scientific advice to managers
The advice from scientists has been consistent. Current levels of fishing mortality appear sustainable, but there should be no increase in pressure. Managers are advised to continue close monitoring of the fishery, particularly in regions of high effort. Improved data collection in Southeast Asia is a high priority, as are better records of size composition and effort levels. Research under a project designed by the Scientific Committee, which focuses on the reproductive biology of yellowfin, is producing valuable new insights on maturity schedules, fecundity, and spawning frequency. Incorporating this new information into future stock assessments will strengthen confidence in results and reduce uncertainty in management decisions.
How does the WCPFC manage the yellowfin fishery?
- Current management framework
Yellowfin tuna is managed under CMM 2023-01, the WCPFC’s Tropical Tuna Conservation and Management Measure. This measure also applies to skipjack and bigeye tuna, reflecting the fact that these species are caught together in the same fisheries. The measure sets an interim objective of maintaining the spawning biomass ratio at or above the average level observed between 2012 and 2015. This objective serves as a short-term guide until formal harvest strategies are agreed.
To achieve this, a number of controls are in place. Purse seine vessels are subject to seasonal closures on the use of drifting fish aggregating devices (FADs), with a 1.5-month closure across the WCPO and an additional one-month closure on the high seas. There are also limits on the number of active instrumented buoys (currently capped at 350 per vessel) and requirements for the use of non-entangling, biodegradable FAD designs. Longline fisheries are subject to catch and effort limits, often applied on a zone or flag-state basis. Importantly, the measure requires compatibility between high seas and exclusive economic zone (EEZ) measures to ensure consistent application across the stock.
- Management issues
Despite this framework, several challenges remain. Because yellowfin is part of a mixed fishery, efforts to control its harvest can affect skipjack and bigeye catches, and vice versa, making it difficult to design effective species-specific measures. Data gaps in Southeast Asia continue to limit the precision of assessments and complicate management decisions. Questions of equity also play a role: Pacific Island countries seek to maximize economic returns from their tuna resources while ensuring sustainability, which must be balanced against the interests of distant-water fishing nations. Another concern is “effort creep,” where advances in fishing technology, particularly electronic FADs, increase the effective fishing power of fleets and risk undermining the intent of effort limits.
- Improving Future Management
Looking ahead, the WCPFC is moving toward a harvest strategy approach for yellowfin tuna. This involves setting a clear target reference point and developing harvest control rules that would automatically adjust management in response to changes in stock status. Improved monitoring and compliance, including the use of electronic monitoring and stronger observer coverage, will be critical to ensure accurate data collection. Incorporating new biological findings supported by ongoing scientific research will help reduce uncertainty in future stock assessments. Management discussions are also likely to consider spatial measures to address localized depletion, ensuring that pressure is more evenly distributed across the fishery. Finally, climate change poses a longer-term challenge, as shifts in ocean temperature and productivity are expected to alter the distribution and abundance of yellowfin, requiring adaptive management approaches.
Take-home: Yellowfin tuna in the WCPO is currently in good condition and supports one of the most valuable fisheries in the world. At the same time, localized pressures, data uncertainties, and questions of equity mean that management must continue to evolve. The adoption of harvest strategies, stronger monitoring, and integration of new science will be key steps in ensuring that yellowfin tuna remains both a sustainable resource and a foundation for economic development and food security in the Pacific region.