An opaque reporting system for oil pollution in UK waters is masking the true state of ongoing oil pollution, according to Oceana UK’s latest report, Sea Slick: The true scale and impact of chronic oil pollution in UK seas.

The new analysis demonstrates that the extent of frequent, small-scale ‘chronic oiling’ in the North Sea has been grossly underestimated due to a combination of the oil industry’s failure to provide data and an “opaque and misleading” reporting system.

Oil companies must report both accidental oil spills and intentional discharges of so-called ‘produced water’ – a byproduct containing oil and other toxic chemicals – which can be released under permit. However, breaches of these permits, despite representing considerable oil contamination, have typically been excluded from external analysis and scrutiny.

As a result of this technicality, levels of oil pollution have typically been significantly underestimated. When ‘permit breaches’ are added to ‘accidental spills’, the total volume of oil spilt into UK waters since 2014 increases by 43%, and more than doubles the volume between 2021-2024, according to Oceana’s latest report.

This untransparent reporting system is compounded by the failure of oil corporations to accurately report, as nearly a third (32%) of the reports of permit breaches for ‘produced water’ failed to include the volume of oil discharged – meaning true level of pollution is likely to be even higher.

Overall, there was a 36% increase in the average concentration of oil in ‘produced water’ released into UK waters between 2016 and 2020. All of this points to an industry that is not being held to account for their ongoing actions and is putting precious marine wildlife at risk.

Hugo Tagholm, executive director of Oceana UK, said: “Our investigation reveals a shambles of opaque and incomplete reporting that is concealing the true scale of the toxic oil pollution causing devastation for UK seas and marine wildlife. I can’t know how a dolphin feels trying to hunt underwater with lung lesions, or a seabird that is drowning because its oiled feathers mean it cannot fly. But I do know it isn’t good enough. The oil industry has so far been allowed to mark its own homework on this with barely any oversight. The government can and must now chart a new course, holding the industry accountable and ensuring that our seas get the protection they deserve.”

Poor enforcement and regulation also plague the issue of toxic ‘produced water’. Since 2014, less than 2% of all oil discharge permit applications have been rejected. Of the permit breaches reported between January 2011- May 2024, less than 1% were investigated.

Spills are self-reported by oil companies, with little oversight. The Offshore Petroleum Regulator for Environment and Decommissioning (OPRED) only inspected 15% of oil and gas infrastructure in 2023, a new Freedom of Information request submitted by Oceana UK revealed, down from 25% in 2022.

There were only two recorded convictions or fines in the last five years. In 2020, BP was fined just £7,000 for violating the Offshore Petroleum Activities (Oil Pollution Prevention Control) Regulations for a spill that occurred in 2016. This fine amounts to 0.006% of their annual profits in the year of the spill.

Between January 2021 and May 2024, just five companies were responsible for almost 84% of all oil discharged in breach of permit. The worst offender for these permit breaches (as well as for chemical spills) was Repsol Resources, a company which owns the Piper Bravo rig,  near to where numerous slicks were identified in satellite images.

Commenting on the findings of Oceana’s report, Dr Rosie Williams, postdoctoral researcher at the ZSL’s Institute of Zoology, UK says: “A growing body of research now recognises that the steady release of oil and other toxins into marine environments poses a huge threat to marine life. Substances such as PAHs and heavy metals can accumulate in animals and act as carcinogens and negatively impact the immune and reproductive systems. This bioaccumulation of chemicals is also a major concern from a human health perspective, as they enter our own food system. We need the government to do more to hold oil companies to account. The under-reporting from the industry on what toxins are being released into our ocean is an issue that must be urgently addressed.”

Chronic oiling is linked to a wide range of harms to marine wildlife across the food chain, from cancer to impacts on immune systems and reproductive capacity.

The UK’s network of marine protected areas (MPAs), which are home to internationally important ocean life, suffered 248 spills from permit breaches between January 2021 and May 2024. Nearly half (49%) of the reports of these breaches failed to record the volume of oil discharged. Therefore, the reported volume of oil entering the UK’s most vulnerable and important habitats is likely to be vastly underestimated.

Over half of the UK public (58%) assume that oil and gas drilling is already banned in marine protected areas, Oceana’s polling shows. But in reality, over a third of the licences granted to oil companies in the recent 33rd Licensing Round overlap with MPAs.

In light of this, it is perhaps unsurprising that the majority of UK adults (71%) do not trust the regulator to ensure marine wildlife is protected from oil and gas drilling.