As Europe moves towards climate neutrality by 2050 under the ambitious EU Green Deal, the shipping industry finds itself at the forefront of environmental regulation.
New frameworks such as FuelEU Maritime and the Mediterranean’s designation as an emission control area (ECA) from 1 May mark a turning point in the region’s regulatory landscape.
FuelEU mandates progressive reductions in the carbon intensity of ships, starting at 2% in 2025 and reaching up to 80% to 100% by 2050, while the Mediterranean ECA limits sulphur emissions to 0.1%, aligning with existing standards in the Baltic and North seas.
These developments, although vital for decarbonisation, may also bring unintended consequences. As compliance costs rise, some operators may seek less transparent routes to remain competitive.
In this context, increasing attention is turning to the so-called “shadow fleet”, a term used to describe a segment of older, obscurely operated vessels that often sail under flags of convenience and operate outside traditional regulatory and financial systems.
Estimates suggest that around 850 tankers may fall into this category globally, many of which are ageing and likely not equipped with modern emissions-reduction technologies.
In the Mediterranean and Black Sea regions, these vessels are believed to play a growing logistical role in oil trades, particularly from sanctioned jurisdictions, via ship-to-ship operations carried out in international waters.
While such transfers are not inherently illegal, the opacity of these movements raises important questions about transparency, oversight and potential environmental risks.
The European Union’s regulatory tightening, especially in terms of fuel standards and emissions monitoring, may inadvertently create incentives for vessels to avoid compliance by operating in regulatory grey zones.
For example, ships avoiding port calls or inspections may be less likely to be held accountable to ECA sulphur limits or FuelEU requirements.
This is particularly relevant in areas where AIS gaps, manual reporting or strategic routing allow vessels to minimise detection.
While most of the regulated fleet has shifted to low-sulphur fuels or scrubber-equipped systems, there are concerns that some vessels operating outside formal oversight may continue to use traditional high-sulphur fuel oils.
Given reduced global demand, such fuels may be available at discounted prices through informal or opaque supply chains.
The absence of consistent emissions monitoring on these ships makes it difficult to assess their environmental impact, but the potential for non-compliant fuel use cannot be ruled out.
The risk here is twofold.
First, environmental impact: vessels in this unofficial fleet are often powered by outdated engines and rely on high-sulphur fuels, making them significantly more polluting than their regulated counterparts.
Second, regulatory leakage: if a parallel maritime network continues to grow outside of the EU’s environmental governance, it could undermine the overall effectiveness of the Green Deal’s maritime pillar.
For countries with strong maritime sectors, this poses both a challenge and an opportunity.
Countries with active shipping communities, operating a significant share of the world fleet, are in a unique position to contribute to transparency, sustainability, and regulatory alignment. By leading in compliance and technology adoption, shipowners can help reinforce Europe’s green leadership at sea.
In the months ahead, policymakers and industry stakeholders alike may need to consider additional safeguards, from stronger flag-state accountability to more robust enforcement of emissions standards beyond port jurisdictions.
As global decarbonisation targets approach, ensuring that all vessels, regardless of ownership structure or operational model, are part of the solution will be key.
The shadow fleet may not yet be fully visible, but its implications are becoming harder to ignore.
Kelly Gerakoudi is an Associate Professor in Shipping Management at Deree — The American College of Greece
