---
title: "Mass Dolphin Deaths in the Black Sea: Scientists Link the Tragedy to Russia’s War"
language: en
content_profile: environmental_analysis
section: ""
structure_profile: "unclassified"
archive_status: "active"
hub: ""
ai_mode: "include"
canonical: "https://zeleniy-list.od.ua/en/mass-dolphin-deaths-black-sea-2026/"
translations: "[]"
published: "2026-06-18 06:07:48"
modified: "2026-09-16 09:00:36"
---

# Mass Dolphin Deaths in the Black Sea: Scientists Link the Tragedy to Russia’s War

## Summary

Mass dolphin deaths in the Black Sea reached an unprecedented scale in spring 2026. In just a few days, dozens of dead cetaceans were found along the coast of Tuzly Estuaries National Nature Park. Scientists link the tragedy to the combined impact of Russia’s war against Ukraine — acoustic pollution, chemical contamination of the marine environment, and eco…

## Full analysis

Mass dolphin deaths in the Black Sea reached an unprecedented scale in spring 2026. In just a few days, dozens of dead cetaceans were found along the coast of Tuzly Estuaries National Nature Park. Scientists link the tragedy to the combined impact of Russia’s war against Ukraine — acoustic pollution, chemical contamination of the marine environment, and ecosystem destruction.

Unprecedented loss of cetaceans

Since the start of Russia’s full-scale invasion, Ukrainian scientists have regularly documented cetacean deaths along the Black Sea coast. As early as spring 2022, environmentalists began finding an extraordinarily large number of dead dolphins washed ashore with all their fins intact. This indicated that the animals had not died after becoming entangled in fishing nets (fishermen cut off dolphins’ fins to remove them from nets). The situation was especially alarming in Tuzly Estuaries National Nature Park. Since spring 2022, park staff together with border guards have systematically documented marine mammal deaths. It became clear that this could be directly linked to the active hostilities in the Black Sea that began on February 24, 2022.

According to Ivan Rusev, Doctor of Biological Sciences and head of the research department at Tuzly Estuaries National Nature Park, at least 50,000 animals died from war-related factors in the Black Sea during the first year of the full-scale invasion.

Ivan Rusev shows the skeleton of a dolphin found on the Black Sea coast. Photo by Mariana Verbovska, NGL.media

In spring 2026, the problem flared up again. During May and the first half of June alone, dozens of new cases of dead dolphins washing ashore were recorded. The first days of June were the most tragic.

“We have never recorded so many dead dolphins in three days during the entire war. On June 5–7, 2026, the sea washed a horrifying number of dead cetaceans onto the coast of Tuzly Estuaries National Nature Park — 39 animals: 37 harbour porpoises, one bottlenose dolphin and one common dolphin. We surveyed only 37 kilometres of the national park’s coastline,” wrote Ivan Rusev on Facebook on June 9. The scientist described the number of dead animals as unprecedented. According to him, the dolphins had died more than a month earlier and were only now being washed ashore. The scientists surveyed only 25 kilometres of coastline. The true scale of the die-off at sea may therefore be many times greater — thousands of killed mammals simply sink into the depths.

Most of the cetaceans found were in various stages of decomposition. This indicates that they died at sea and were later carried ashore by currents and storms. In some cases, scientists noted extreme emaciation, insufficient fat reserves and other signs of prolonged stress.

 Dolphins are dying in occupied territories too

The situation for dolphins in the Sea of Azov is even worse, says Pavlo Goldin, a leading researcher at the I. I. Schmalhausen Institute of Zoology of the National Academy of Sciences of Ukraine, Doctor of Biological Sciences and a specialist in Black Sea marine mammals. The population of the Azov harbour porpoise — an endemic subspecies that lives exclusively in the Sea of Azov — is at risk of complete extinction because of Russian activities and the consequences of occupation, the zoologist said.

The main drivers of decline include deaths in fishing nets, poaching, disruption of water exchange caused by the Kerch Bridge, underwater noise, and the impossibility of effective conservation oversight under occupation. While there were 10,000–15,000 Azov harbour porpoises in 2001, only a few thousand remain today. “This could eventually lead to the complete extinction of the Azov harbour porpoise,” the scientist warns.

“The examined cetaceans showed signs of severe intoxication and gastrointestinal damage: seizures, severe pain, loss of coordination, emaciation and dehydration, rapid shallow breathing, and critical liver and pancreatic dysfunction (hepatitis, acute pancreatitis), confirmed by blood tests and ultrasound,” Rusev cites the conclusions of environmentalists in Russia, where many dead and concussed dolphins washed ashore in May 2026 near Novorossiysk and in the waters off occupied Crimea.

Documenting cetacean deaths in occupied territories is a major challenge, forcing Ukrainian scientists to rely on reports from social media. In Ukraine, by contrast, every disturbing find is documented with photographs, coordinates and a description of the condition of the animals.

A documented dolphin death is not only a conservation warning but also an important element in recording the environmental consequences of the war. That is why Ukrainian scientists continue systematic coastal monitoring, collecting evidence for future assessments of environmental damage and efforts to hold those responsible accountable. The data collected form an evidence base for further scientific research and criminal investigations.

Ivan Rusev (left) and a journalist from the German television channel ZDF film a grim discovery in Tuzly Estuaries National Nature Park. Photo: Ivan Rusev’s Facebook page

Why dolphins are dying

The scientific community does not currently point to a single cause of Black Sea dolphin deaths. Instead, a growing body of research indicates the combined impact of several factors. Back in 2022, Rusev proposed a hypothesis about the cause of dolphin deaths. Sonar systems used by Russian military vessels can inflict acoustic trauma on dolphins. This can impair their ability to navigate and hunt fish, weaken immunity, and contribute to viral infections and epizootics.

Pavlo Goldin stresses the importance of a comprehensive approach to studying the causes of these deaths. He noted that scientists are considering several possible groups of causes: infectious diseases, acute intoxication from pollutants entering the sea as a result of hostilities, and acoustic trauma caused by sonar from Russian warships and submarines.

Powerful explosions, military vessel operations and the use of active sonar can disrupt dolphins’ echolocation. For animals that navigate and hunt by sound, this means losing the ability to find food, avoid danger and maintain normal behaviour.

A second factor is chemical pollution of the marine environment. Over the years of war, the Black Sea has been exposed to numerous accidental releases of petroleum products, fuels, lubricants and other pollutants. In just the past six months, there have been two major sunflower oil spills into marine waters. In both cases, the cause was Russian strikes on port infrastructure in Odesa region. Ship accidents and destruction of coastal infrastructure have created additional risks. Heavy metals, petroleum products, sunflower oil, explosives, chemical compounds, fragments of various munitions and drones, bombed ships, aircraft and missiles enter the sea. Most military devices contain fuel, lubricants, heavy metals, polymers and other hazardous materials.

The destruction of the food base is no less important. Changes in marine ecosystem structure affect the abundance of fish on which cetaceans feed. As a result, dolphins have to spend more energy searching for food, leading to exhaustion and higher mortality.

Criminal investigation: Ukraine documents ecocide

At the beginning of the full-scale invasion, the Specialized Environmental Prosecutor’s Office of the Odesa Regional Prosecutor’s Office opened criminal proceedings over the mass destruction of wildlife — dolphins including harbour porpoises, bottlenose dolphins, common dolphins and others — as a result of Russia’s armed aggression against Ukraine. The case was opened under Article 441 of the Criminal Code of Ukraine — ecocide.

The probable cause of their mass deaths was identified as the use of sonar by vessels of the aggressor state, including submarines and surface ships, producing powerful sounds that adversely affect animal health. At the prosecutor’s initiative, examinations and necropsies were carried out on cetaceans — harbour porpoises and common dolphins — found dead on the coast. During the necropsies, specialists collected organ and tissue samples for laboratory analysis of pathologies and to establish the causes of death of the marine mammals.

Forensic specialists perform necropsies on dead dolphins. Photo: Odesa Regional Prosecutor’s Office

At an information event in Odesa in April 2023, Volodymyr Frantsevych, head of the Odesa Regional Environmental Prosecutor’s Office, spoke about the investigation under Article 441 of the Criminal Code of Ukraine into Russia’s armed aggression that caused the mass deaths of Black Sea dolphins.

According to him, 117 cetacean deaths were documented along Ukraine’s Black Sea coast, in Odesa, Mykolaiv and Kherson regions and temporarily occupied Crimea. The data were collected, among other sources, from media and social media reports. In 15 cases, according to the Institute of Zoology, the deaths were caused by acoustic trauma. Six necropsies were carried out during the investigation, and biological materials were collected for further research. Forensic veterinary examination proved difficult because Ukraine lacks an official methodology for establishing a causal link between acoustic exposure and cetacean health. Ukraine, however, is a party to ACCOBAMS — the Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and Contiguous Atlantic Area. The samples were therefore sent to specialists in EU countries: the University of Padua in Italy and the University of Veterinary Medicine Hannover in Germany. The prosecutor’s office also sent requests for international legal assistance to Bulgaria, Türkiye and Romania to identify similar dolphin deaths.

“The dolphin killers already have names,” Frantsevych said. Military intelligence identified Russian service members involved in the crimes. Satellite imagery showed that since the beginning of the full-scale invasion, more than 30 Russian surface ships and submarines equipped with sonar systems had operated in the Black Sea. More than 500 missiles were also launched from the Black Sea at Ukrainian territory, affecting marine life as well. Based on the research findings, the Odesa prosecutor’s office plans first to bring Russian service members to criminal responsibility at the national level. This could then help hold the aggressor state accountable before the International Criminal Court.

The current procedural status of the case is not being disclosed, but environmentalists continue documenting dolphin deaths and submitting the evidence to investigators to strengthen the case.

The problem extends beyond Ukraine

The Black Sea is a shared ecosystem for six coastal states. Populations of harbour porpoises, common dolphins and bottlenose dolphins constantly migrate between the territorial waters of different countries. The consequences of marine environmental degradation therefore are not confined to Ukraine’s coastline.

The tragedy of declining dolphin populations is transboundary in nature and has affected virtually the entire Black Sea.

In spring 2026, numerous dead dolphins were recorded washing ashore along Bulgaria’s Black Sea coast. Dolphin carcasses were found in the areas of Varna, Burgas and Balchik and on beaches at Sunny Beach resort. Dozens of reports of stranded animals were registered in the Varna and Balchik areas alone. Most of the dead animals were harbour porpoises ( Phocoena phocoena) — a species that tends to remain closer to shore. Reports had been coming in since at least early May 2026. In particular, Bulgarian media reported dead dolphins on the coast on May 3–4, 2026.

Ivan Rusev believes that dolphin deaths in Bulgaria in late May and early June 2026 were part of a single broader catastrophe caused by the war.

After dead dolphins began appearing on Bulgaria’s coast in May 2022, Dimitar Popov of the Bulgarian organization Green Balkans, in an interview with BNR Burgas, said: “The war is increasing noise pollution in the northern Black Sea, which is one of the priority habitats for cetaceans. This is where the continental shelf is widest and most productive for their ecosystem, which explains their higher density in this part of the Black Sea. Deteriorating environmental conditions due to increased noise pollution make it harder for them to find prey and cause disorientation. Naturally, this forces them to seek quieter areas farther south. Loud sounds can also cause acoustic trauma and, consequently, more cases of disoriented dolphins along the Black Sea coast.”

Romania’s coastline has also been affected by the catastrophe. Dolphin deaths and carcasses washing ashore were recorded on the Romanian coast during the same period — late May to early June 2026.

Dolphins in the Black Sea ecosystem

The mass deaths of dolphins point to deeper processes taking place in the Black Sea ecosystem. Their loss affects the Black Sea itself, Goldin stresses . Dolphins are a key species in the Black Sea. As apex predators, they help stabilize the entire ecosystem: they regulate fish abundance, which in turn affects zooplankton, phytoplankton and crustaceans.

Without dolphins, fish populations can expand unchecked and consume zooplankton, allowing microalgae to proliferate. Their toxins kill living organisms, including zooplankton and fish. The sea can turn into an algae-filled body of water where little else survives.

If these negative trends continue, the consequences may affect not only cetacean populations but the overall ecological resilience of the marine basin.

How international organizations are responding to ecocide in the Black Sea

International conservation organizations increasingly view the war as a major driver of the current crisis affecting Black Sea cetacean populations.

The Bulgarian conservation organization Green Balkans was among the first to respond to the mass deaths of marine mammals in the northern Black Sea. In March 2026, its Wildlife Rescue Centre team was mobilized after an extremely alarming report of mass mortality in the Shabla and Durankulak area. Nine marine mammal carcasses were found — representing all three Black Sea cetacean species: harbour porpoises, common dolphins and bottlenose dolphins — along with more than 300 Mediterranean shearwaters. The Green Balkans team transported some of the dead animals for a series of necropsies and analyses. The aim was to determine why so many protected species had died within such a short period. Green Balkans emphasized that the case was of exceptional importance for Bulgaria’s ecosystem because these species are strictly protected at both national and international levels.

A Bulgarian conservationist with the body of a dolphin that was found. Photo: Green Balkans 

One of the world’s leading cetacean conservation organizations, Whale and Dolphin Conservation (WDC), has actively documented the impact of the war on Black Sea dolphins since 2022.

WDC considers Black Sea species to be at risk of extinction. All three Black Sea cetacean species — harbour porpoise, bottlenose dolphin and common dolphin — are listed on the IUCN Red List: the harbour porpoise and bottlenose dolphin as Endangered and the common dolphin as Vulnerable. Before the war, scientists identified Important Marine Mammal Areas (IMMAs) — ocean areas of particular importance to marine mammals. Six such areas along Ukraine’s coast, including the Kerch Strait and the Sea of Azov, are now directly affected by military activity: warships, explosions, missiles and mines. WDC stresses that missile explosions and low-frequency ship sonar can kill dolphins directly or drive them from their normal habitats into dangerous areas. Dolphins rely on echolocation, and excessive noise disrupts their navigation. At the beginning of the war, WDC reported an unusually high number of dead dolphins on the western coast of Türkiye — more than 80 common dolphins — and more than 50 dead harbour porpoises caught in fishing nets in Bulgaria.

The situation of cetaceans in the Black Sea is also closely monitored by ACCOBAMS (Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and Contiguous Atlantic Area), a regional international agreement aimed at cetacean conservation. It brings together 23 countries, including all Black Sea coastal states.

Experts propose a plan to save dolphins

In the report of the 16th Meeting of the Scientific Committee (2025), ACCOBAMS identified priority areas of work for 2026–2028. In particular, it adopted a Post-War Plan for Black Sea Cetaceans. The plan sets out a comprehensive approach to mitigating all impacts of military activities on cetaceans, their habitats and prey. It covers not only noise pollution but also chemical pollution, eutrophication, increased infection risks, biological invasions by non-native species, and indirect military impacts such as construction work or changes to shipping routes.

The plan provides for:

Impact assessment — comprehensive monitoring of noise, chemical pollution and biological stress indicators, as well as necropsies of dead animals and long-term archiving of tissue samples.

Assessment of losses and recovery — the use of remote sensing methods, assessment of impacts on the distribution and abundance of dolphin prey, and evaluation of bycatch risks in fishing nets.

Practical measures — demining marine waters, creating new marine protected areas, including transboundary reserves, strengthening response to strandings, developing bycatch mitigation measures and running educational campaigns. The plan stresses that some measures can be implemented now regardless of the military situation, while specialized regional workshops involving experts are planned to develop a roadmap. The final stage should be a post-war aerial survey to update data on population status.

Yet even the best plan will not work if the aggression continues. Dolphins are a key species that stabilize the entire marine ecosystem. Ecocide can be stopped only by ending the war and holding those responsible accountable.

Featured photo by Ivan Rusev.