FIU criminologists trace 73% of dark fishing journeys off West Africa to 11 vessels
FIU criminologists found that 11 vessels account for 73% of the AIS-off "dark" fishing journeys they analyzed off West Africa over three years. The authors say inspectors can focus on those repeat vessels, though the base for the 73% is left open.
The Scientist · Science desk
Key figures: if the 73% is of all dark journeys, the 11 vessels made at least about 240 dark journeys each; if it is of convenience-flagged journeys, they averaged about 70 each. The study covered more than 3,600 dark journeys, about 1,058 of them convenience-flagged.
| Figure | Value | Note | Claim |
|---|---|---|---|
| Per vessel if 73% is of all journeys, at least about | 240 dark journeys | 15 | |
| Per vessel if base is convenience-flagged, about | 70 dark journeys | average dark journeys each | 16 |
| Dark journeys, more than | 3,600 journeys | 2 | |
| Convenience-flagged, about | 1,058 journeys | 3 |
What happened
- The team used public Global Fishing Watch records covering more than 3,600 dark journeys over three years off the coasts of 23 West African countries.
- About 1,058 of those journeys involved vessels flying flags of convenience.
- Dark activity concentrated around the Gulf of Guinea and near the outer edges of exclusive economic zones, where enforcement responsibilities shift and patrol resources are limited.
- Compared with other vessels, ships under flags of convenience started or finished a dark journey outside an EEZ at close to twice the rate, and each one made roughly five times as many dark journeys on average.
Why it matters
- decision Agencies with thin patrol resources face a choice between screening every convenience-flagged ship and boarding a short list of chronic ones; the authors argue for the list.
- constraint A gap does not prove illegal fishing, so a list built this way buys inspectors a reason to ask questions and request documents; any finding has to come from the inspection.
- capability The inputs are public Global Fishing Watch records, so a coastal agency can repeat the same screen for its own waters.
The 73% needs a denominator, and the phys.org write-up of the study leaves it open. It says 11 ships account for 73% of "these dark journeys" [14]. That could mean all of the more than 3,600 journeys, or only the roughly 1,058 flown under convenience flags [2][3].
The two readings imply different things. Against the full set, the 11 would have made at least about 240 dark journeys each over three years [15], and they could not all be convenience-flagged, because 73% of 3,600 is about 2,630 journeys and the convenience-flagged total is about 1,058 [17]. Against the convenience subset, the 11 would average about 70 journeys each [16] and would account for no more than about 21% of all dark journeys [18]. The write-up does not say which reading holds, or how many vessels in all produced the journeys.
Pires, Christiansen and Georgia Southern's Dylan Spencer published the work in Applied Geography [1]. They applied crime science, usually reserved for street crime, to the open ocean [10]. Criminologists have long known that crime clusters where opportunity is high and the risk of getting caught is low [13], so the team logged where ships went dark and where they came back online. The design rules out random disappearance: the same ships go dark again and again, often in very particular places [11]. Nearly half of the dark journeys by convenience-flagged vessels began or ended beyond an EEZ boundary [5].
"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 [8]. She also said there can be legitimate reasons for a gap, including technical or operational issues [9]. The team's count covers instances in which vessels appeared to disable the signal on purpose [12].
Pires drew the enforcement conclusion. "You don't need to track down and board every fishing vessel flying a flag of convenience or going dark," he said [19]. The boardings he has in mind are meant to "ask good questions, request documentation and check whether they are also committing other crimes, such as labor abuse or trafficking illicit products" [21].
The thing this doesn't tell you is whether any of the 11 were fishing illegally. Pires says a flag of convenience is legal, that neither it nor an AIS gap proves illegal fishing, and that both have been associated with increased risk [7]. His view that removing offending vessels can lead to a significant reduction in illegal activity [20] is a projection. The analysis described counted dark journeys, so the effect of removing vessels is untested here.
In our view the repeat-vessel pattern is the sturdy result, and the list it produces depends on the base. Under the full-set reading the list includes ships that do not fly convenience flags [17]. Under the convenience-subset reading it holds only convenience-flagged ships and covers about a fifth of all dark journeys [18].
What to watch
- Whether the authors report the base for the 73% and how many of the 11 vessels fly flags of convenience.
- What inspectors find if coastal states board vessels flagged by this method, including any labor abuse or trafficking.
- Whether the same vessels keep going dark at EEZ edges in later years of Global Fishing Watch data.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence45
- Adoption
- Insufficient
- Hype gap+20
- Incentives
- Insufficient
- Confidence50
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
The study was published in Applied Geography by FIU criminologists Stephen Pires and Emilie Christiansen along with Georgia Southern University researcher Dylan Spencer.
- [2]
Using publicly available Global Fishing Watch data, the researchers examined more than 3,600 dark journeys recorded over a three-year period off the coasts of 23 West African countries.
- [3]
About 1,058 of the dark journeys involved vessels flying flags of convenience.
- [4]
Dark activity was concentrated in specific areas, particularly around the Gulf of Guinea and near the outer edges of countries' exclusive economic zones, where enforcement responsibilities shift, patrol resources are limited and vessels remain close to productive fishing grounds.
- [5]
Nearly half of the dark journeys involving convenience-flagged vessels began or ended beyond an EEZ boundary.
- [6]
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.
- [7]
Flags of convenience are 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.
- [8]
"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.
- [9]
Christiansen said there can be legitimate reasons for AIS gaps, including technical or operational issues.
- [10]
The team applied crime science, which is typically reserved for the study of street crime, to the open ocean.
- [11]
The vessels are not simply disappearing at random: the same ships go dark again and again, often in very particular places.
- [12]
The researchers analyzed instances in which commercial fishing vessels appeared to intentionally disable their automatic identification systems off the coast of West Africa.
- [13]
Criminologists have long known that crime tends to cluster in particular places where opportunity is high and the risk of getting caught is low.
- [14]
FIU research reveals that 11 ships account for the majority of the dark journeys studied, 73% of them.
- [15]
If the 73% is measured against all dark journeys, the 11 vessels made at least about 240 dark journeys each over three years.
- [16]
If the 73% is measured against only the convenience-flagged journeys, the 11 vessels averaged about 70 dark journeys each.
- [17]
If the 73% is measured against all dark journeys, the 11 vessels account for about 2,630 journeys, more than the roughly 1,058 convenience-flagged journeys in total, so they cannot all be convenience-flagged.
- [18]
If the 73% is measured against only the convenience-flagged journeys, the 11 vessels account for no more than about 21% of all dark journeys.
- [19]
"You don't need to track down and board every fishing vessel flying a flag of convenience or going dark," Pires said.
- [20]
Pires said that if illegal behavior is identified and vessels are removed from these waters, it can lead to a significant reduction in illegal activity.
- [21]
Pires said the aim of boarding the most chronic offenders is to "ask good questions, request documentation and check whether they are also committing other crimes, such as labor abuse or trafficking illicit products."
Get this ledger inside ChatGPT. Ask about any of our stories and the answer brings its figure, each claim’s verdict and the sources. Free, no account.
Sources
1 independent publisher whose own reporting we read for this story.
- phys.orgNow you see them: Researchers uncover patterns in vessels that vanish at sea
1 article · October 14, 2026
Topics and entities
Follow any of these and your For You feed starts watching them — no settings page required.