Background information
Stock condition
Albacore tuna (Thunnus alalunga) is a single species, but fisheries scientists treat the North Pacific and South Pacific populations as two separate management “stocks” because distinct oceanographic barriers, migration patterns, and minimal mixing create functionally self-contained units. By incorporating each stock’s unique biology into their assessments, such as growth rates, spawning seasons, and movement corridors, managers can build more accurate population models and design tailored harvest strategies that keep both stocks sustainable.
Responsibility for managing albacore in the North Pacific Ocean is coordinated across regional fisheries management organizations (RFMOs). The Inter-American Tropical Tuna Commission (IATTC) also manages albacore in the North Pacific Ocean and relies on the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean (ISC) for stock assessment.
Current fishery status
The North Pacific albacore fishery operates across both the Western and Central Pacific Ocean (WCPO) and the Eastern Pacific Ocean (EPO), involving several national fleets and fishing gear types. Troll fisheries, particularly from the United States and Japan, target juvenile albacore and make up the bulk of the directed fishing activity. Longline fisheries, predominantly operated by Japan, target sub-adult and adult albacore and represent a secondary component of the fishery. In recent years, catches have declined from historical levels, with the U.S. troll fleet reporting a catch of approximately 1,626 metric tons in 2022, down from the 3,000 to 4,000 metric tons typical of earlier periods. These trends reflect potential shifts in stock distribution, market demand, and operational decisions rather than a biological concern.
Importance of the fishery
The North Pacific albacore (NPO ALB) fishery remains an economically and strategically important multi-national fishery for several countries and territories in the Pacific, supporting both commercial and artisanal operations. It contributes to livelihoods, especially among small-scale trolling operations in coastal communities. Additionally, the fishery holds strategic value for Small Island Developing States (SIDS) in the region, who may wish to expand domestic participation in the future. Given its transboundary nature and the multiple jurisdictions involved, the fishery also serves as a platform for international cooperation between regional fisheries management organizations (RFMOs) such as the WCPFC and IATTC.
Science
Stock assessment by the ISC
The most recent stock assessment of North Pacific albacore was completed in July 2023 by the ISC’s Albacore Working Group using data through 2020 (with breeding-stock estimates out to 2022). They ran an age-structured model, which tracked males and females at each age, using data from both catch records and independent survey indicators. To judge health, they compared current spawning biomass against a precautionary “limit” set at 20% of the unfished stock. The result: today’s spawning stock is 3.44 times that limit. In other words, there are more than three times as many adult, breeding-age albacore in the ocean as the minimum level scientists consider safe. The stock assessment also measured fishing pressure and found it to be just 44% of the level that would produce the maximum sustainable yield. Taken together, these findings tell us the albacore population in the North Pacific Ocean is well above minimum safety levels and is being fished at a deliberately conservative rate.
Stock status and advice
The ISC found that North Pacific albacore populations are healthy, but they pointed out that the number of new, young fish entering the stock can fluctuate widely with changing ocean conditions. This variability matters especially for troll fisheries, which rely heavily on catching juvenile albacore. To guard against unexpected downturns, the ISC advised keeping fishing pressure at current levels and investing in improved data collection, particularly on juvenile abundance and how different gears select for albacore, to ensure managers can detect and respond to recruitment shifts in a timely manner.
How does the WCPFC manage North Pacific albacore?
Current management system
Management of North Pacific albacore within the WCPFC Convention Area is currently governed by Conservation and Management Measure (CMM) 2019-03. This measure maintains fishing effort at or below levels observed during the 2002–2004 period, as reported by each CCM. The measure requires CCMs to report annual catch and effort data by gear type and mandates that the Northern Committee monitor the stock in coordination with the ISC and the WCPFC Scientific Committee. The measure also encourages collaboration with the IATTC to ensure consistent management approaches across the range of the stock. It provides allowances for SIDS to develop their fisheries without violating the spirit of the effort limitation, provided such development is domestically driven.
Management issues
While the current management framework has proven effective in preventing overfishing, several challenges persist. Effort-based controls, while precautionary, can be difficult to monitor and enforce, particularly for fleets with variable fishing patterns. There are gaps in data reporting, especially regarding gear-specific effort and catch composition. Furthermore, the differing management approaches of WCPFC and IATTC can lead to inconsistencies in implementation and enforcement. Finally, as climate change alters ocean conditions, albacore distribution and productivity may shift in ways that undermine current assumptions embedded in the management framework.
Improving future management
To strengthen management, the ISC and Northern Committee have recommended advancing the development of harvest strategies, including the establishment of target reference points, harvest control rules, and management strategy evaluation (MSE) frameworks. Such tools would enable more adaptive and transparent decision-making. Improved data collection, particularly on juvenile catch and longline selectivity, is needed to support robust scientific assessments. Harmonization of measures between the WCPFC and IATTC would help eliminate discrepancies and improve compliance. Lastly, integrating environmental indicators into management strategies could provide a more responsive approach to the effects of climate change on stock dynamics.