Study Tracks Repeat AIS Gaps Among Fishing Vessels Off West Africa
Researchers analyzed thousands of cases where commercial fishing vessels appeared to switch off their automatic identification systems off West Africa. They found that 11 ships accounted for 73% of these dark journeys, often near international boundaries and under flags of convenience. The study notes that while such gaps are legal, they are linked to a higher risk of illegal, unreported, and unregulated fishing.
FIU criminologists Stephen Pires and Emilie Christiansen, working with Georgia Southern's Dylan Spencer, drew on Global Fishing Watch records covering 23 West African nations between 2017 and 2019. Of roughly 3,600 dark journeys logged, about 1,058 involved convenience-flagged ships, and the team mapped where these gaps began and ended, finding clusters along maritime borders.
The authors argue enforcement resources are finite, so targeting the small number of repeat offenders — boarding them, requesting paperwork, and checking for related crimes like labor abuse — may curb illicit activity more efficiently than broad screening.
Concentrating inspections on a handful of repeat offenders could ease the burden on stretched maritime authorities, potentially reducing illegal catches that threaten food security and coastal livelihoods in West Africa. Clearer patterns may also help insurers, seafood buyers and port officials flag risky voyages. Yet AIS gaps remain lawful and inconclusive on their own, so any enforcement response may raise questions about fairness for crews and operators who have done nothing wrong.