Nature conservation | Greece: disturbing the peace for whales

Cuvier's beaked whales hunt for food in the deep waters of the Hellenic Trench. Photo: IMAGO/blickwinkel The search for oil and gas is increasingly shifting to the sea. According to the Global Energy Monitor, ten offshore fields accounted for 85 percent of the expected production volume of newly discovered oil and gas reserves worldwide in 2024. Ecological damage caused by oil and gas projects at sea occurs long before any production takes place. Seismic investigations are already used when searching for suitable deposits.

Such investigations into the search for natural gas off Greece are scheduled to begin in 2026: The US energy company Chevron and the partially state-owned Greek energy company Helleniq Energy have received concessions for four offshore blocks south of the Peloponnese peninsula and Crete. Chevron has a 70 percent stake in the project and assumes the role of operator, Helleniq Energy has a 30 percent stake. The concession areas cover approximately 47,000 square kilometers.

The planned studies concern an area in the Mediterranean that is of particular importance for marine mammals. Critically endangered sperm whales and Cuvier's beaked whales live in the Hellenic Trench, a deep-sea channel between the Ionian Sea and Rhodes. There are different estimates of how large the sperm whale population is in the eastern Mediterranean: Ocean Care said around 200 to 250 animals in 2022, and the Pelagos Cetacean Research Institute said it was 110 to 150.

While the sound cannons were active, 70 percent fewer fin whale calls were recorded than during quieter periods.

The Hellenic Trench is an important feeding area for sperm whales. The animals typically dive to depths of several hundred to 2,000 meters to hunt squid and squid. As the largest toothed whales in the world, they orientate themselves using clicking sounds, which they also use to search for food. Characteristic click sequences, so-called codas, also serve for communication. A 2023 study found genetic differences between sperm whales in the Mediterranean and those in the North Atlantic. Because the population is small and independent and the Hellenic Rift is a central habitat for the animals, further losses can be particularly serious.

Cuvier's beaked whales also use the area's deep waters. Its classification as an Important Marine Mammal Area (IMMA) underlines the importance of the habitat for marine mammals.

WWF Greece describes the area as a refuge for whales and dolphins. “Here, marine mammals still find suitable habitat in an increasingly polluted Mediterranean,” says George Chasiotis, senior legal advisor to the organization. It is therefore essential to protect marine mammals from oil and gas drilling, seismic surveys and pollution "in order to preserve these vulnerable populations and support the recovery of marine ecosystems in Greek waters."

But the planned seismic surveys will expose the whales to a specific burden: underwater noise. Research ships use so-called sound cannons (English: airguns). These emit strong sound pulses at short intervals that penetrate the seabed and are reflected by the rock layers. This can then be used to create images of the geological structures beneath the seabed.

Since whales primarily communicate through sound, these sound pulses can have far-reaching effects on their orientation and foraging. "The most serious consequences include temporary or permanent hearing damage, which can affect the animals' ability to communicate, navigate, avoid danger and detect prey," explains WWF's Chasiotis. “Exposure to seismic noise can also trigger significant behavioral changes and disrupt, for example, food intake, resting phases, diving processes and migration patterns.”

Studies from other ocean regions show the effects on whales. A study published in the journal “Scientific Reports” in 2026 evaluated 63 days of underwater recordings from a seismic measurement campaign off northwest Spain. While the sound cannons were active, an average of 70 percent fewer fin whale calls were recorded than during quieter periods. Even after correcting for calls that may have been masked by the noise, the decrease was 52 percent. It remained unclear whether the animals called less or avoided the area.

A 2023 report prepared by Ocean Care for the UN Convention for the Protection of Migratory Species (CMS) puts the nominal source level of seismic sound cannons, i.e. the sound intensity in the immediate vicinity, at around 260 decibels. For comparison: When ramming offshore wind power foundations, around 237 decibels are given for a hydraulic hammer with 1000 kilojoules of impact energy, and 192 decibels in a certain frequency range for a cargo ship. However, the values ​​can only be compared to a limited extent due to different sound properties, according to the authors. Above all, ships generate persistent noise, while sound cannons and pile driving work generate recurring impulses. The extent to which marine mammals are exposed depends, among other things, on frequency, duration, repetition and distance to the source.

In addition to the possible consequences for the animals, there is the question of whether the environmental assessments for such projects meet the legal requirements. Francesco Maletto, lawyer at the environmental rights organization Client Earth, criticizes that environmental assessments for previous oil and gas projects in Greece were partly based on outdated data. During seismic investigations, the tests required under EU law were not carried out sufficiently. Together with WWF Greece and Greenpeace Greece, Client Earth therefore filed a complaint with the European Commission in 2023. This is still pending. It is not directed against the new Chevron concessions, but the structural problems highlighted therein could also be relevant to other approval processes, said Maletto.

Upon request, Chevron will refer to its general corporate principles. “Wherever Chevron operates, protecting our employees, communities, the environment and our facilities is our priority,” explains a company spokeswoman when asked. “It is company policy to comply with all applicable official requirements and approval requirements.” The statement does not indicate what specific measures are planned to protect marine mammals, such as acoustic monitoring or an interruption of investigations when whales are sighted.

A study published in April 2026 in the journal “Ethics in Science and Environmental Politics” provides an idea of ​​what risks could arise for wildlife. The researchers analyzed controversial case studies from the Mediterranean in which proven protective measures to reduce harmful effects on the marine megafauna native there - including whales, dolphins, seals and sea turtles - were not adhered to. Their conclusion: "Even if these failures do not clearly represent a violation of legal obligations, they demonstrate unethical behavior."

Nikos Mantzaris from the think tank The Green Tank also sees the planned gas projects in conflict with Greece's climate goals. In line with EU goals, Greece has committed to becoming climate neutral by 2050. Even if the planned seismic investigations were to detect commercially usable gas reserves, gas production would not be expected until the 2030s at the earliest, according to Mantzaris. Planned gas fields are often designed for an operating period of 20 to 30 years. The result: “Any new funding would extend well beyond 2050,” he warns.

The government of Prime Minister Kyriakos Mitsotakis, on the other hand, justifies the search for new deposits with the aim of making the energy supply more independent. The Greek Hydrocarbons and Energy Resources Management Company estimated the potential of gas reserves in the Greek maritime area to be around 680 billion cubic meters in 2024 - mathematically enough for around 100 years of the current consumption of around six billion cubic meters annually.

According to Mantzaris, it remains to be seen whether the gas would actually benefit Greece's energy supply. "According to the lease agreements, the gas belongs to the companies, which can sell it at market prices to any buyer at home or abroad," he says. The Greek state only receives production royalties, but has no right to the gas being used in its own country. "Greek consumers would still have to pay European market prices."

Mantzaris is also critical of gas production in terms of climate policy. Gas power plants are “already responsible for almost 60 percent of emissions in the electricity sector.” The expert sees this as the “main reason why the sector is exceeding its CO2 budget set out in the national climate protection law.” The new gas fields could continue to operate long after 2050 - with consequences for the habitat of marine mammals and Greece's goal of climate neutrality.

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