Press release

New study shows devastating impacts of oil and gas surveying on Mediterranean sea life

27.04.26

A new study lays bare the severe threats posed to much-loved marine mammals by oil and gas activities near Marine Protected Areas (MPAs) in Greek waters.

 

The article was commissioned by ClientEarth and published last week in Ethics in Science and Environmental Politics by world-renowned marine biologists. It evidences that impacts on marine ‘megafauna’ (particularly whales and dolphins) range from physical injuries such as hearing damage, chronic stress and hormonal changes, to behavioural changes such as altered feeding and resting patterns, and potentially strandings and mortalities.

 

Navigation and communication are impaired too, as the sound pollution interferes with vocalisation signals over large distances, whilst habitat displacement also presents major issues, with species such as beaked whales avoiding noisy areas for days.

In particular, the study spotlights the effects of seismic surveys, which are used to map the seabed in advance of oil and gas extraction. The process uses airguns, producing extremely loud low-frequency sounds, with a range of up to 4000 km. Airgun use is among the most harmful activities for marine life – they are one of the loudest sounds in the ocean, louder than any known biological sound. 

Two of the article’s three case studies analyse the subject matter of an ongoing legal action brought by ClientEarth, WWF Greece and Greenpeace Greece. The NGOs filed a formal complaint with the European Commission in 2023, raising concerns that oil and gas projects in the Hellenic Trench – in close proximity to protected sites - were being approved despite the clear dangers they posed to marine species, in blatant violation of EU nature conservation laws.

Francesco Maletto, Oceans Lawyer at ClientEarth said: “The widespread destruction that fossil fuels cause to our climate is well known, especially in Greece. But this new study reveals the extent to which the industry wreaks havoc on ecosystems at every level. The Hellenic Trench is one of the most biodiverse areas in the Mediterranean. Yet a cacophony of noise from oil and gas exploration is devastating its much-loved whales and dolphins. Will the Commission let this continue in a clear breach of EU law, or step in to protect some of Europe’s most endangered marine wildlife?”

Anna Vafeiadou, Legal sector leader at WWF Greece said: “Greek seas are still among the healthiest in Europe, precisely thanks to the absence of destructive activities, such as oil and gas drilling. We are sleepwalking into an environmental disaster, in case these new plans for petroleum drilling go ahead. The published scientific article presented today highlights the serious threats posed to Greece's clean seas and marine life by oil and gas activities. The scientific evidence is clear; there are limitations to the mitigation measures to hydrocarbon exploration in the unique ecosystem of the Hellenic Trench. We urge the European Commission to step in and ensure that EU law is upheld before irreversible harm occurs”

Costas Kaloudis, climate and energy campaigner at Greenpeace Greece, said: "With 20% of Greece’s marine areas conceded for hydrocarbon exploration and with an extremely weak institutional framework for marine protection, the future of the marine mammals that we strive to see protected seems bleak. The promises of the Greek government for thorough procedures that would prevent environmental harm and ensure that marine mammals would not be negatively affected by hydrocarbon exploration and drilling appear to be empty. It is time for the European Commission to step up its pressure on the Greek authorities: future generations should also enjoy a thriving biodiversity in the Greek seas. 

EU nature laws require Greek authorities to fully assess the impact that such activities will have on threatened marine life in protected areas, before giving them the green light. The scientific study validates the arguments raised in the complaint - that the assessments for the projects approved in the Mediterranean were conducted inappropriately, and not based on the best available science - as required under EU law.

The paper confirms suspicions about the validity of the results which led to the approval of the projects, identifying the use of outdated, incomplete and inaccurate data. It also found that the assessments downplayed serious risks of activities like seismic surveys for endangered species such as fin whales, instead relying on the assumption that animals could simply “move away” from noise.

In light of this latest study, the NGOs are renewing their call for the European Commission to take action against widespread violations of EU nature conservation law in the region.

ENDS

Notes to editors:

The scientific paper: 

  • Titled Impacts of hydrocarbon-related activities on marine megafauna: case studies from the Mediterranean Sea, the study was published in the latest issue of the peer-reviewed journal Ethics in Science and Environmental Policies.

  • The paper references research which demonstrated that low-frequency sound from seismic surveys can ensonify entire ocean basins, and reach distances of up to 4,000 km (Castellote et al. 2012, Nieukirk et al. 2012). 

  • Flawed mitigation measures: The paper also showed that a number of insufficient mitigation measures were taken. This includes the decision to conduct seismic surveys during winter to avoid affecting the ‘breeding processes’ of cetaceans. However, the report found that, despite these measures, there was a significant stranding of three goose-beaked whales during the surveying processes, within 10 km of the Ionian sea block, which were not mentioned in the environmental assessment.

Biodiversity and local context:

  • The Hellenic Trench and adjacent Ionian Archipelago are biodiversity hotspots, and a core habitat for many endangered and protected whale species (including goose-beaked whales and the endangered Mediterranean sperm whale), as well as loggerhead turtles and Mediterranean monk seals. For these reasons, they were designated as Important Marine Mammal Areas (“IMMAs”) by the IUCN. 

  • Anthropogenic noise has been linked to numerous beaked whale strandings and mortalities in the past.The paper references seven known mass strandings in the 1990s, and three goose-beaked whales that were stranded on Corfu in February 2022, an unusual event that occurred when seismic surveys were underway.

  • Noise from seismic surveys is not the only threat posed to marine megafauna in the Mediterranean by the oil and gas industry. From increased shipping noise and traffic, to drilling activities, chronic toxic pollution, infrastructure installation and decommissioning, these activities are contributing to chronic, cumulative, multi-layered stressors, and worsening the pre-existing impacts of overfishing, climate change and pollutants. The paper argues that the impact of seismic surveying must be considered in this wider context.

The legal complaint:

  • ClientEarth, WWF Greece and Greenpeace Greece originally wrote to the European Commission in December 2023 demanding the start of an infringement procedure against Greece. After an initial threat to close the case, the European Commission confirmed at the end of 2024 that they would pursue an investigation.

  • See the map regarding the new potential drilling areas here. 

  • In the latest exchange with the Commission (April 2026), the NGOs highlighted the implications of the study’s publication regarding the inadequacy of the impact assessments and compliance measures, and, also in light of ongoing expansion  of offshore oil and gas activities in the region, reiterated the need for the Commission to take enforcement actions against these systemic breaches of EU law by Greek authorities.

  • Contracts for four new concession blocks located in the south of Peloponnese and the south of Crete have now been ratified by the Hellenic Parliament by virtue of Law No. 5287/2026. The paper’s findings of flawed impact assessment conduct raise further concerns amongst the Complainants that the new activities will be conducted in the same flawed manner as those covered in their Complaint.

  • International fossil fuel giant Chevron and national company HELLENiQ Energy have both expressed formal interest in having further areas opened up for oil and gas activity and the Greek Ministry of Environment and Energy has accepted – starting the process for official licensing. Chevron is the world’s second biggest private hydrocarbons company, based in the USA and active in more than 180 countries.

About ClientEarth

ClientEarth works in over 60 countries across Africa, the Americas, Asia-Pacific and Europe. We shape, implement and enforce the law, to build a future for our planet in which people and nature can thrive. 

We are tackling climate change, protecting nature and stopping pollution, with partners and citizens around the globe. We hold industry and governments to account and defend everyone’s right to a healthy world.