Across the waters of West Africa, commercial fishing vessels vanish along international boundary lines.
No signal. No location. Hours — sometimes days, and even weeks — pass.
Then, they suddenly reappear.
In a bizarre plot twist, new FIU research reveals 11 ships account for the majority of these dark journeys — 73% to be exact.
That startling concentration is at the heart of a new study published in Applied Geography by FIU criminologists Stephen Pires and Emilie Christiansen along with Georgia Southern University researcher Dylan Spencer. They analyzed thousands of instances in which commercial fishing vessels appeared to intentionally disable their automatic identification systems (AIS) off the coast of West Africa.
What they uncovered suggests the vessels aren't simply disappearing at random. The same ships are going dark again and again, often in very particular places. They are also sailing under what the researchers call "flags of convenience." Rather than flying under their country of origin's flag, these ships are often registered in another country, which can provide economic or regulatory advantages if the registered county has weaker enforcement and oversight. The practice itself is legal, and neither a flag of convenience nor an AIS gap proves a vessel is fishing illegally. But both have been associated with increased risk of illegal, unreported and unregulated fishing, according to Pires, who is associate chair of the Department of Criminology & Criminal Justice in the Steven J. Green School of International & Public Affairs and a researcher in FIU's Institute of Environment.
The researchers wanted to know whether the disappearances left behind patterns that could help authorities identify where illegal fishing is most likely to occur. From the data, patterns did emerge.
"You don't need to track down and board every fishing vessel flying a flag of convenience or going dark," Pires said. "You need to identify the most chronic offenders in your waters — which in this case amounted to only 11 vessels over three years — and board those ships to ask good questions, request documentation and check whether they are also committing other crimes, such as labor abuse or trafficking illicit products."
If illegal behavior is identified, the vessels can be removed from these waters, which Pires said can lead to significant reduction in illegal activity.
"Illegal fishing is one of the biggest threats to ocean health," said Mike Heithaus, marine biologist and FIU's vice provost of Environment and Environmental Resilience. "This kind of work can help fisheries can remain healthy and ensure their operations remain sustainable."
Using publicly available data from Global Fishing Watch, the researchers examined more than 3,600 dark journeys recorded over a three-year period off the coasts of 23 West African countries. About 1,058 involve vessels flying flags of convenience.
The team applied crime science, which is typically reserved for the study of street crime, to the open ocean. Criminologists have long known that crime tends to cluster in particular places where opportunity is high and the risk of getting caught is low. The research team found a similar pattern at sea. By observing their movement patterns, they can see where ships are going dark and where they come back online.
Dark activity was concentrated in specific areas, particularly around the Gulf of Guinea and near the outer edges of countries' exclusive economic zones (EEZs). Along those boundaries, enforcement responsibilities shift, patrol resources are limited and vessels remain close to productive fishing grounds. Nearly half of the dark journeys involving convenience-flagged vessels began or ended beyond an EEZ boundary.
"If a fishing vessel turns off its AIS signal near the EEZ boundary, disappears for hours or even days, and then resumes its signal just outside that same boundary, that is very suspicious," said Christiansen, a Ph.D. candidate studying international crime. "It could potentially indicate that the vessel entered those waters to evade detection while engaging in illegal fishing activities."
There can be legitimate reasons for AIS gaps, including technical or operational issues, Christiansen said. But convenience-flagged vessels were nearly twice as likely to begin or end a dark journey beyond an EEZ and averaged about five times as many dark journeys per vessel as their non-convenience-flagged counterparts.
For countries with thousands of miles of ocean to monitor and limited enforcement resources, the researchers say authorities could use patterns in vessel behavior to focus surveillance on particular boundary areas and vessels that repeatedly disappear from tracking systems.
Pires suggests vessel confiscation and loss of insurance coverage as potential deterrents. The latter can be devastating to companies because it would deprive them of access to many ports around the world, he said.
"These countries would benefit from the implementation of geofencing technologies that monitor vessel movements in and out of designated high-risk zones," Pires said. "Such systems could trigger alerts when AIS transmissions are disabled, vessels enter predefined high-risk areas, fishing vessels engage in potential ship-to-ship encounters, or vessels visit known ports of convenience."
The findings show that disappearing from a tracking system doesn't necessarily mean disappearing without a trace. The ocean may provide plenty of places for ships to hide. But even in the dark, patterns can reveal themselves.
FIU conducts similar research and continually monitors illegal fishing activity in the eastern Pacific Ocean off South America and Mexico. The work comes out of the university's National Security Research Hub as illicit fishing is recognized as having negative effects on economic and political stability in the region in addition to devastating natural resources.
