Just 474 out of more than 90,000 oil slicks from ships worldwide were reported to authorities between 2014 and 2019, according to data obtained by Lloyd’s List and shared with the Guardian and Watershed Investigations. The figure was compared against a scientific study that used satellite imagery to count slicks over the same period.
New research by Florida State University found that all oil slicks visible by satellite exceed pollution limits by at least three orders of magnitude, making them illegal. Many slicks result from ships deliberately discharging bilge water containing oil to maintain stability.
Dr Elizabeth Atwood of Plymouth Marine Laboratory said: “The level of under-reporting of pollution is a huge unknown.” Hugo Tagholm, executive director of Oceana UK, called it “appalling” and highlighted “the frankly mind-bending under-reporting of the situation.”
Analysis of hundreds of thousands of satellite images showed that 20% of slicks (90,411) originated from ships, covering an area roughly the size of Italy. In contrast, 2% came from oil platforms, 6% from natural seeps, and the rest from land or unidentified sources.
Despite these figures, few incidents faced sanctions under the International Convention for the Prevention of Pollution from Ships (Marpol). In European waters, enforcement remains uneven, with EU countries checking fewer than half of possible spills detected by satellite, confirming pollution in only 7% of cases, according to a March audit by the European Court of Auditors.
Experts warn that chronic spills threaten marine life. A study off six West African countries found 16% of slicks were from ships, yet no incidents were recorded by authorities in those nations during the study period.
