New Fusion of Global Datasets Advances Understanding of Vessel Identity and Activity

Novel research provides new tool to improve global fisheries oversight

Illegal, unreported and unregulated (IUU) fishing accounts for up to $23.5 billion every year and is enabled by vessels frequently changing their name, flag State or owner. New research , led by Global Fishing Watch and published in Science Advances , uses big data processing and a compilation of global datasets to track and analyze vessels to reveal their changing identities and reflagging patterns.

This novel research and first-of-its-kind public dataset can complement existing international efforts to address the global scope of potential IUU fishing and enable authorities to improve oversight and enforcement. We sat down with two of the study’s authors, Jaeyoon Park and Jenn Van Osdel .

Q: What kind of data was analyzed in this study and how did you make sense of it? 

Jaeyoon : We combined two datasets in this study–vessel registry data and vessel tracking data–processing more than 100 billion GPS positions with consolidated identification information for about 200,000 vessels. 

For identification data, we gathered, cleaned and combined vessel identity information from over 40 public registries. These include regional fisheries management organization (RFMO) registries, national registries, and lists compiled by researchers. Each of those lists have been maintained since early 2019 and were coupled with historical data where available. 

The resulting database includes vessel identity characteristics, such as name, call sign, and International Maritime Organization (IMO) number; physical attributes, like ship dimensions and tonnage; the name and nationality of the vessel owner; and fishing authorization details. Since many data sources do not keep historical data, this database will serve as an important archive for vessel identity information that will continue to develop. 

For vessel tracking data, we used information from the automatic identification system, or AIS—a transponder designed for safety at sea. These data include the majority of commercial fishing vessels and their GPS positions, allowing us to use Global Fishing Watch’s machine learning-based technology to identify when and where a fishing vessel is likely engaged in fishing and visiting ports. 

We then used a technique known as “fuzzy matching” to link these two databases together. This machine learning technology determines how similar two words are to one another, allowing us to compare identity information–like ship names and call signs–between what is broadcast on AIS and what we’ve collected from the registries. Linking this information powered the paper’s analysis. It allowed us to track vessels throughout their lifetime, reconstruct vessel history to map patterns of reflagging and reveal fishing that was potentially unauthorized—or at least not publicly authorized.


Q: The study finds that almost 20 percent of fishing that occurs on the high seas is conducted by vessels that are internationally unregulated or not publicly authorized. What’s the significance of this?

Jaeyoon : Our analysis defines unauthorized fishing as any fishing that takes place within an RFMO by a vessel that is not included on a public authorization list. But it’s important to note that this only means it’s potentially unauthorized, as public records may be incomplete, outdated or simply not available. 

When fishing takes place in international waters, outside the jurisdiction of RFMOs, we consider it internationally unregulated in our analysis. While vessels operating on the high seas may be authorized by the relevant national authorities, stringent and transparent management measures at the international level are needed to reduce the risk of IUU fishing activities continuing undetected. 

Jenn : In this context, our analysis revealed that about 20 percent of high seas fishing can be categorized as internationally unregulated or not publicly authorized. As our results are based on the analysis of AIS tracking data, which can be subject to spoofing and manipulation—coupled with the absence of a global mandate requiring all fishing vessels to broadcast AIS—the true amount of such fishing in international waters may vary. Concentrations of this activity appear to be particularly high in the west Indian Ocean and the southwest Atlantic Ocean, which corresponds to areas in which nongovernmental organizations have recommended regional governance systems .And while AIS is not suited to inform compliance as a standalone tool, we do hope our analysis helps inform authorities of vessel behavior as part of a broader risk assessment process used to monitor areas for IUU fishing and prioritize enforcement resources.

Q: The study highlights areas in the world where foreign-owned vessels are most active. What are the implications of the operations of foreign ownership?

Jenn : Foreign-owned vessels are those that are owned by an individual or company in one country but operate under the flag of another. When properly regulated and monitored, this is not a cause for alarm. But in some cases, vessel owners may deliberately register their vessels in another country to one with which they have no link to reduce the oversight of their operations. This can suggest a potential risk of IUU fishing. 

While neither uncommon nor unlawful, the complex nature of foreign ownership can obscure where catch and funds are going and make it difficult to properly investigate IUU fishing. Our analysis revealed that fishing by foreign-owned vessels is concentrated in certain regions, many of which have had calls for improved oversight and enforcement. Understanding these hotspots enables authorities to focus their risk assessment and oversight efforts. To make things more interesting, a 2018 studyshows that targeted regulation of foreign-owned vessels may enable flag States to address IUU fishing in a way that allows fish stocks to recover while also limiting impacts to domestic fisheries. Greater transparency of ownership is needed to understand who is profiting–and who is ultimately responsible for–commercial fishing activities. 

Q: How does this research complement existing registries or tools? 

Jaeyoon : Our analysis and data aims to complement existing public registries such as the Global Record of Fishing Vessels, Refrigerated Transport Vessels and Supply Vessels , commonly referred to as the Global Record—an ongoing initiative of the Food and Agriculture Organization of the United Nations ( FAO). The FAO describes the Global Record as a single access point for information on vessels used for fishing and fishing-related activities with the primary objective being to combat IUU fishing by enhancing transparency and traceability. 

We fully support this aim. While the Global Record continues to be developed and populated with vessel identity information, our dataset can act as an important stopgap. It will also serve as a companion dataset for the future that can be used to validate and enhance the full knowledge of vessels in the public domain. 

The International Maritime Organization also has a ship identification number scheme—an initiative introduced in 1987 to prevent maritime fraud. Under this scheme, a unique seven-digit number is assigned to a vessel, which remains with it until scrapping, regardless of changes in registration, name, country or ownership. Currently, there is no global mandate for the use of IMO numbers. Instead, a patchwork of requirements from flag and coastal States, RFMOs and industry groups mean that only a subset of industrial fishing vessels have obtained the number. Our data fills this gap and provides a temporary unique identifier for a vessel that does not have an IMO number, or is not eligible to obtain one. 

Q: What does it mean when a vessel is ‘reflagged’ and why is it important to examine patterns surrounding this practice?

Jenn: Reflagging occurs when a vessel is registered to and operates under a different State than it had previously, therefore changing its flag. It is important for authorities to be able to identify and track these kinds of changes, as unscrupulous operators may use reflagging as a tactic to avoid detection when conducting IUU activities. 

Abusive reflagging, combined with a lack of comprehensive public records, allows such vessel operators to simply switch flags and keep working while under sanction or investigation. A change of flag can also be used for financial or tax benefits. Problems can arise when vessels switch to a flag State where regulations for environmental pollution or labor protection are lax, raising concerns about the effectiveness of such regulations across States. Vessels that repeatedly reflag to States with limited capacity or lack of political will to implement their responsibilities may need to be more thoroughly vetted by fishing authorities. 

Our study found that reflagging occurs in just a few ports primarily by fleets with high foreign ownership, providing information about geographic patterns and dynamics of reflagging practices. 

Q: What do you hope to see happen as a result of this data now being available? 

Jaeyoon : Research like this can help flag States manage their vessels as outlined in the FAO Voluntary Guidelines for Flag State Performance . Our data can complement a State’s vessel monitoring system, which may get less frequent updates on a vessel’s position or may not cover foreign-flagged vessels. 

Our data are critical for port States, too. Under the FAO’s Agreement on Port State Measures, over 70 States and the European Union are required to collect and cross-check information on vessels requesting port entry, ensuring compliance with relevant conservation and management measures. Our data can also inform State efforts to prioritize actions such as contacting the flag State for further information, inspecting a vessel or denying a vessel entry into port. 

Public information can be limited, fragmented and inconsistent, but by piecing it together and cross-checking sources we can improve data quality, fill existing data gaps and help create a single reference for vessel history. We envision that easy access to robust vessel identity data will help inform authorities’ IUU fishing risk assessments and monitoring processes and also assist the global ocean community in holding flag States accountable. In this way, transparency can drive greater ocean governance, which Global Fishing Watch remains dedicated to supporting.

Jaeyoon Park is a senior data scientist at Global Fishing Watch. Jenn Van Osdel is a data scientist at Global Fishing Watch. 

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