Datasets and Code: Vessel Identity
Transparency plays a central role in promoting the sustainability of marine resources and advancing ocean governance. Reliable information about vessel identity is a fundamental pillar of ocean transparency. However, such data is often fragmented, incomplete or inconsistent across multiple sources — and in many cases, it is not publicly available at all.
Sources of identity information
Registries
Global Fishing Watch collects vessel identity information from over 30 public registries, including national registries, regional fisheries management organizations and intergovernmental bodies. We supplement these records with commercial, partner and internal datasets, as well as vessel lists compiled through expert feedback and manually validated by Global Fishing Watch. We regularly integrate data from these sources to keep vessel information as accurate and up to date as possible.
These records are automatically matched against vessel identity information transmitted through the automatic identification system, or AIS. The matching algorithm evaluates the similarity of key identity fields across sources, including vessel name, international radio call sign, International Maritime Organization (IMO) number, flag state and Maritime Mobile Service Identity (MMSI) — the primary identifier in AIS. A match generally requires agreement across multiple identity fields, with no major conflicts in other information.
Once matched to AIS data, registry records are aggregated to produce a consolidated identity record for each vessel. We refer to vessels identified through registry records as “known” fishing vessels.
AIS self-reported information
When classifying vessels, we also consider the content of their AIS messages. The shiptype field is a two-digit number corresponding to the vessel’s reported type of activity. A full list of these codes is available from Marine Traffic.
When vessels report that they are fishing, we refer to them as “self-reported” fishing vessels. Although this information can be useful, it is not always accurate. AIS identity information must be entered manually, creating opportunities for human error. Some vessels may report an incorrect ship type, while others may identify themselves as fishing vessels even when they are not, or fail to identify themselves as fishing vessels when they are.
While AIS devices are meant to correspond to vessels, many fishing vessels attach AIS devices to fishing gear. We identify thousands of MMSI in AIS data likely representing gear instead of vessels by examining the shipname field of an MMSI’s AIS messages. These names often contain values like “NET MARK,” “BUOY,” and “FISHING NET.” We refer to these MMSI as “likely_gear.”
Vessel classes
Understanding the different types of vessels operating at sea is essential for monitoring human activity and assessing its environmental and social impacts. Cargo ships, for example, have different implications from fishing vessels. The impacts of fishing vessels can also vary depending on their gear type, such as trawlers and drifting longliners. Global Fishing Watch classifies vessels into 40 categories, 16 of which represent types of fishing vessels.
Our vessel classification system uses registry records and information transmitted through AIS to train two AI models that estimate vessel type and fishing gear types worldwide. We are able to infer the vessel class and dimensions of tens of thousands of vessels in the AIS data for which we have no other information.
Details on model methodology, product impacts and caveats are available in the documentation.
Limitations and caveats
Vessel registry information is not globally representative
The quantity and quality of registry data available to Global Fishing Watch vary by flag State, resulting in uneven coverage of vessel identity information. For example, our information about some Asian fleets is less complete because fewer flag States in the region make their vessel registries publicly available than their European counterparts.
This lack of information, however, is complemented by other types of data, such as self-reported AIS data and our vessel characterization model. We aim to continually find more public sources of information, as an increasing number of initiatives help make more vessel identity data publicly available.
Limited information on smaller vessels
Our vessel identity data tends to include larger vessels — particularly those greater than 24 meters long — since they are more likely to be registered in regional or global public vessel registries. Apart from a handful of national-level registries that include small vessels, few registries provide comprehensive identity information for smaller vessels, particularly those shorter than 15 meters.
Small vessels are also less likely to use AIS in part because they may not be required to do so under applicable regulations. This limits the identity information we can derive from AIS data.
We work with partners to bring greater transparency to smaller vessels by encouraging broader use of AIS worldwide, assisting nations in opening up their vessel monitoring system data, and supporting initiatives that help small-scale fishery vessels become trackable.
Defining a vessel is challenging
In our data, a vessel is generally identified by an MMSI number associated with a vessel identity. Most vessels, particularly fishing vessels, use the same MMSI throughout the period covered by our data, which extends from 2012 to the present. However, the identity associated with a physical vessel can change over time, such as when its name or flag State changes or it comes under new ownership or management.
Such changes can be tracked through IMO numbers, permanent unique identifiers that follow a vessel from construction to scrapping. For vessels without IMO numbers, however, reconstructing a complete history of identity changes remains challenging because the necessary information is not always publicly available. Global Fishing Watch is working to establish links between different identities associated with the same vessel hull, with the aim of making this information available in the future.
A small number of vessels engage in behaviors that make their AIS data unreliable, such as simultaneously broadcasting the same MMSI as another vessel, commonly referred to as “identity spoofing.” To avoid presenting misleading information, our map and downloadable datasets exclude vessels identified as exhibiting these behaviors. We continue to develop methods to identify and correct these issues in our data.
License
Global Fishing Watch data is licensed for non-commercial use only. The site and its services are provided for non-commercial use only in accordance with the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license. If you would like to use the site and/or its services for commercial purposes, please contact us at [email protected].
Access our data
Data on vessel identity is available through several Global Fishing Watch tools:
- Global Fishing Watch map: Explore vessel identity information, including flag State, gear type, and vessel characteristics such as length, tonnage, and engine power.
- APIs and packages: Access vessel identity data programmatically through the Global Fishing Watch Vessels API, as well as the gfwr package for R users and the Global Fishing Watch Python package. This is the same data available through the map.
- Data Download Portal: Download a complete static dataset and supporting documentation, including vessel identity attributes. Unlike the continuously updated map and APIs, data available through the portal represents periodic static snapshots.
Each platform offers access to different components of the vessel identity dataset. To determine which tool best fits your needs, refer to our data availability guide.