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About IMO Numbers

The International Maritime Organization (IMO) number is one type of unique vessel identifier (UVI).

For a ship, the IMO number remains linked to the hull for its lifetime, regardless of changes in name, flag, or owner. IMO numbers help to improve maritime safety and security and reduce illegal fishing activities. IMO numbers are issued free of charge.

ISSF’s UVI/IMO Vessel List shows known IMO numbers for tuna fishing vessels that operate in various oceans. The information in this list has been compiled from a variety of sources, including:

IHS Register
Vessel registers maintained by IATTC, ICCAT, IOTC, WCPFC and FFA
Industry sources

IMO/UVI Vessel Data

IMO numbers have been validated against the IHS Register.

However, some fields — such as Flag or Vessel Type — do not seem to be updated in the IHS database as quickly as they are in the RFMO vessel records.

In such cases, the RFMO data have been used.

RELATED INFORMATION

Scientific Reports

ISSF 2025-09: A Snapshot of the Large-Scale Tropical Tuna Purse Seine Fishing Fleets as of June 2025*

Infographics

IMO Numbers & Transparency in the Fishing Industry

IMO/UVI Resources
IMO Number Registration Instructions [PDF]
ISSF UVI Application Form [Online]

Corrections & Additions

ISSF does not warrant that all information in the UVI/IMO Vessel List is accurate or complete. If you are aware of any errors or omissions, please notify us.

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