The International Seafood Sustainability Foundation (ISSF) has released its report A Snapshot of the Large-Scale Tropical Tuna Purse Seine Fishing Fleets as of August 2026, continuing a unique global assessment that has tracked changes in the size, composition, and fishing capacity of the tropical-tuna purse-seine fleet since 2012. Because no single organization maintains a complete global database on tropical-tuna purse seiners, ISSF’s annually compiles vessel information from all five tuna Regional Fisheries Management Organizations (RFMOs) and other sources to provide a consistent, year-over-year view of global fleet size and capacity.
The 2026 analysis estimates that 693 large-scale purse-seine (LSPS) vessels are fishing for tropical tuna species, up from 675 in 2025. These vessels have a combined fish hold volume (FHV) of approximately 895,000 m3 (cubic meters), compared with approximately 865,000 m3 last year. Both the number of vessels and their combined FHV have increased by about 3% over the past year.
The report also expands its analysis of vessel participation in ISSF transparency tools, linking fleet-wide data with vessel-level information to provide additional insight into fishing capacity, vessel transparency, and participation in sustainable-fishing initiatives.
Of the 693 large-scale purse-seine vessels targeting tropical tunas, 505 — representing 73% of vessels and 83% of FHV — are listed on ISSF’s ProActive Vessel Register (PVR). Vessels on the PVR are tracked on sustainable-fishing best practices and independently audited for compliance with select ISSF Conservation Measures. For the first time, the report also includes data from ISSF’s Vessels in Other Sustainability Initiatives (VOSI), which identifies tuna vessels that have made public commitments to sustainable fishing beyond those reflected on the PVR. The analysis found that 402 LSPS vessels are listed on VOSI, representing 58% of vessels and 69% of FHV.
“Understanding changes in the global tuna fleet requires looking beyond vessel counts at a single point in time,” said Dr. Victor Restrepo, ISSF Vice President of Science. “By bringing together information from all five tuna RFMOs and other sources, and analyzing it annually, ISSF provides a comprehensive view of global fleet size and capacity that would not otherwise exist. These data can help RFMOs, governments, scientists, industry, and other stakeholders better understand changes in fishing capacity — and support more informed fisheries management and greater transparency.”
The ISSF analysis relies primarily on authorized vessel records maintained by the five tuna RFMOs, supplemented by other sources. It also highlights gaps or inconsistencies in available vessel information (e.g., vessel capacity values).
LSPS vessels are defined in the report as vessels with at least 335 m³ in FHV that target tropical tuna species — skipjack, yellowfin, and bigeye.
View the new A Snapshot of the Large-Scale Tropical Tuna Purse Seine Fishing Fleets as of August 2026 report here and the related infographic here.
Key Findings from the 2026 Snapshot
- New Vessel Additions: Twenty-four LSPS vessels built after 2012 were added to RFMO authorized vessel records since the June 2025 Snapshot report, including 10 vessels built in 2025 and three built in 2026.
- Fleet Turnover: Nineteen LSPS vessels were removed because they were scrapped, sank, or no longer appeared in RFMO authorized vessel records. An additional 19 vessels changed name and/or flag.
- Global Purse-Seine Fleet Growth: The estimated total number of tuna purse-seine vessels worldwide increased by 2%, from 2,106 in 2025 to 2,148 in 2026.
- Cross-Regional Authorization: Approximately 12% of LSPS vessels targeting tropical tunas are authorized to fish in more than one RFMO region — an important consideration in assessing and managing fishing capacity at the regional level.
These year-to-year changes illustrate why consistent global vessel data matter for fisheries management. Information on fleet size, FHV, vessel construction and retirement, flagging, and cross-RFMO authorization can inform research and policy discussions related to fishing capacity, authorized vessel lists, vessel registration and identification, fishing quotas, and compliance. More complete and consistent vessel information can also strengthen vessel traceability and efforts to prevent illegal, unreported, and unregulated (IUU) fishing.
Recommendations to Strengthen Vessel Data and Transparency
The report also identifies opportunities for vessel owners and tuna RFMOs to improve the quality, completeness, and transparency of vessel information, including:
- Expand IMO Number Use: Adoption of International Maritime Organization (IMO) numbers among LSPS vessels has grown substantially, from 12% in 2011 to 99% today. ISSF recommends expanding IMO number use across additional vessel types and sizes.
- Keep Vessel Information Current: Owners of vessels with IMO numbers should communicate changes in vessel details to IHS Maritime to ensure profiles are accurate and up to date.
- Improve RFMO Vessel Data Quality: Although the quality of RFMO vessel records has improved in recent years, the annual snapshot report continues to identify substantial changes and data gaps. Vessels may disappear from authorized vessel records, previously unlisted vessels may appear, and new vessel information can lead to changes in vessel classifications. Continued quality control and more complete reporting would strengthen the reliability of these records.
- Track Active Fishing Capacity: RFMOs should maintain not only lists of vessels authorized to fish but also records that identify the vessels actively fishing each year, providing a clearer picture of operational fishing capacity.
Expanding Global Capacity Analysis to Tuna Longline Fleets
ISSF’s longstanding purse-seine research is complemented this year by its first global analysis of tuna longline fleets. Published in July 2026, Characteristics of Longline Fleets Registered in Tuna Regional Fisheries Management Organizations as of June 2026 was modeled on the global approach ISSF has developed in its purse-seine snapshot series. The longline report harmonized vessel registry information from all five tuna RFMOs into a single dataset comprising 7,288 unique longline vessels.
Purse-seine and longline fishing account for approximately 66% and 9%, respectively — or three-quarters — of the global tuna catch. Together, these ISSF reports provide stakeholders with a broader picture of fleet composition, distribution, and fishing capacity across the two gear types responsible for the majority of global tuna production.
Both reports also demonstrate why assessing fishing capacity requires looking beyond vessel numbers alone. FHV can provide a more informative picture of operational fleet capacity. In the longline analysis, for example, 2,283 vessels measuring 24 meters or longer represented approximately 31% of registered longline vessels but accounted for approximately 86% of estimated longline FHV.
By identifying both fleet trends and gaps in vessel information, the two ISSF reports can support more data-driven fisheries research, policy development, monitoring, and compliance — while highlighting ways to improve the completeness, consistency, traceability, and transparency of the vessel data on which effective fisheries management depends.
