# Shadow Fleets: A Growing Challenge in Global
## 4 Approaches to Detecting Dark and Gray Fleet Characteristics
### Disabled AIS Transmitters  
One of the most telling signs of a vessel's attempt to operate under the radar is the manipulation or complete disabling of its Automatic Identification System (AIS) transmitter. The AIS is a crucial tool in maritime safety, designed to provide real-time tracking and identification information about ships to other vessels and to coastal authorities. It transmits data including the ship's identity, position, speed, and course [30].  
Dark and gray fleet vessels often disable their AIS transmitters to vanish from radars and avoid detection by authorities. This tactic is particularly common in areas where illicit activities, such as smuggling, illegal fishing, or unauthorized transshipment of sanctioned goods, are conducted. By going 'dark,' these vessels can operate without revealing their location, making it challenging for enforcement agencies to track their movements and ascertain their activities [31; 32]. The deliberate disabling of AIS transmitters not only poses significant risks to maritime safety, as it increases the likelihood of collisions at sea, but it also complicates the task of monitoring international waters for illegal activities. This behavior necessitates the development and deployment of alternative tracking technologiesand methodologies that can detect and monitor vessels even when they attempt to hide their presence [33; 34].  
The waters off West Africa have emerged as a hotspot for AIS spoofing and other deceptive practices, highlighting the global nature of these evasion tactics. Investigations have revealed sophisticated operations involving multiple vessels and coordinated AIS manipulation. For instance, tankers have been observed using falsified coordinates while conducting ship-to-ship transfers in the Mediterranean, demonstrating the lengths to which operators will go to conceal their activities [35]. One particularly concerning development has been the manipulation of AIS data. In some cases, 'ghost ships' have been created, with AIS signals showing nonexistent vessels or falsified positions, complicating efforts to track the movement of sanctioned oil [36; 37].  
The economic impact of these deceptive practices is substantial. Estimates suggest that USD 8 billion worth of oil exports have been facilitated through AIS spoofing and other evasion tactics, undermining the effectiveness of sanctions regimes [38].  
Case Study: The Crude Carrier Network. Recent investigations have revealed sophisticated networks of crude carriers operating in a shadow fleet. The PABLO, (ex-Mockinbird, ex-Helios, ex-Adisa, ex-Siro 1, ex-Hudara, ex-S Spirit, ex-Olympic Spirit II; IMO: 9133587), a 2003-built crude oil tanker flagged in Gabon, exemplifies the complexity of these operations [39]. After changing ownership in late 2022, the vessel  
* Switched off its AIS for extended periods in the Mediterranean;
* Conducted multiple ship-to-ship transfers in the Black Sea;
* Changed its flag twice within six months;
* Operated without proper insurance documentation.  
Systematic satellite surveillance between May and November 2024 has documented patterns of potentially illicit maritime operations in specific geographic regions. In waters approximately 70 km offshore of Eastern Johor, up to eight simultaneous ship-to-ship transfers have been observed in a single day, often involving aging vessels that compound environmental and safety risks. These operations frequently coincide with oil slick detections, demonstrating how operational patterns exploit gaps in maritime surveillance while increasing risks to marine ecosystems.  
The scale and regularity of these activities suggest an industrialized approach to sanctions evasion, with established operational patterns that exploit gaps in maritime surveillance and enforcement capabilities. The combination of AIS manipulation, aging vessels, and unsafe transfer practices observed in these waters exemplifies the complex challenges facing regulatory authorities and underscores the need for enhanced monitoring and enforcement mechanisms.