“russia Distorts Nature”: A Marine Mammal Expert on How the War Affects Dolphins and How We Can Save Them Now

The Black and Azov Seas are home to three species of dolphins, each suffering in its own way due to russian aggression. What do we already know about how military actions affect them, and how can we help nature endure? Pavlo Holdin, a zoologist, ecologist, and expert on modern and extinct marine mammals, sheds light on these issues.

Currently, there are many conflicting reports regarding the number of dolphins killed since the full-scale invasion began. Some say 50,000, others mention 60,000 or more, while some believe these numbers are exaggerated. What do you think?

Any number mentioned right now—whether it is 10 dolphins or 100,000—has no scientific basis whatsoever. In 2019, Ukrainian researchers conducted an extensive aerial survey of the Black Sea. After the war, after our victory, we can fly again and cover all our waters, including those around Crimea. That will give us an idea of where dolphin populations have increased or decreased and how many remain in total, and then we can assess how many may have died. 

Until then, I believe it is premature to draw definitive conclusions. For now, the figures we [the Institute of Zoology of the National Academy of Sciences of Ukraine and the Ukrainian Scientific Center of Ecology of Sea] provide relate to the bodies of animals found onshore. Of course, this assessment can and should be supplemented in the future with ecological modeling and extrapolated to estimate total losses.

So, what confirmed data do we have?

In 2022, more than 900 cases of dolphin deaths were recorded in the Black Sea region. This includes Ukraine, Romania, Bulgaria, Turkey, and Georgia. Naturally, this does not cover all the incidents, but it is a starting point for analysis and modeling. 

It is also important to note that we only work with verified photos and video recordings of deceased dolphins. Whenever we receive such materials, we verify them to ensure they are not fake, as media reports have sometimes falsely claimed sightings of dead dolphins that turned out to be from different locations or times.

Can I assume that such disinformation, especially if coming from russians, aims to undermine and discredit ecocide documentation efforts?

I do not know. But if we look at the official russian discourse, they try to downplay the scale of the deaths and claim nothing is happening, even when a dolphin carcass washes ashore in the center of Sevastopol.

There is a significant difference between their official and unofficial narratives. Their only similarity is that both are lies.

Can we identify an event or series of events that are most likely causing dolphin deaths?

The only cautious conclusion I can make is that the animals are dying for various reasons. It is unlikely we’ll find that all the deaths stem from a single cause. 

To draw an analogy, though it may seem imperfect, let us look at how war affects people. There are direct life-threatening factors, such as bombardment with various weapons. But people also die from heart attacks, strokes, or from not receiving timely medical care, lacking clean water, or from increased infection rates. 

When forensic pathologists examine the deceased, they find various causes of death, but investigators and prosecutors may conclude that the root cause is war.

The same applies to wildlife, including dolphins. There are multiple threats to their lives and health. Missile launches from surface and underwater naval vessels, whether successful or not, pose a danger. A failed missile that crashes into the sea contaminates the dolphins’ environment with rocket fuel. Even a missile that was successfully launched underwater exposes the animals to harmful noise. Speaking of noise pollution, another source is russian radar systems, which also harm marine mammals. Thus, due to the war, animals are suffering from both acoustic trauma and chemical pollution.

Stress is another threat to the animals. And it is not just the dolphins that are stressed; the fish they feed on are too. To put it simply, the fish get scared and move away, and the dolphins follow. This migration into unfamiliar conditions increases the risk of them getting caught in fishing nets.

There is also speculation that dolphins can suffer from concussions even far from combat zones. A recent article in Science suggested that mild concussions might be a possible cause of whale strandings around the world. While we need technologically complex studies to confirm this, it is not something we can rule out as being connected to the war.

The destruction of sewage systems or larger-scale events, such as the russian military’s destruction of the Kakhovka dam, is also dangerous for dolphins. These incidents release large amounts of organic matter into the sea—from agricultural fertilizers to sewage from cities. This raises the risk of infectious diseases and provides the conditions for phenomena like “red tides,” massive algal blooms. Some of these algae release toxins into the sea.

If a dolphin washes ashore in Bulgaria or Georgia, for example, can this also be linked to the war?

Biological and veterinary analyses are needed to confirm that. When we study what is happening to dolphins in the Black Sea, we must consider everything, because there are no state borders for animals. The impact might occur within our economic zone, say, halfway between Snake Island and Crimea, but the aftermath could manifest in Bulgaria or Turkey.

Then, it is important to establish cooperation with other countries to jointly assess the effects of the war on marine animals. Is such cooperation in place, and how does it work?

Yes, cooperation has been established. Colleagues in Romania, Bulgaria, Turkey, and Georgia perform autopsies on dead dolphins, conduct laboratory analyses, and share their data and findings with us. 

However, as in Ukraine, the capabilities for such research are limited in all Black Sea countries: no government funds autopsies or analyses. Scientists carry out these studies only when they can and out of their own initiative. 

Considering that dolphin bodies decompose quickly, very few are suitable for autopsy. As a result, the data we receive is quite scarce.

As far as I know, dolphins are at the top of the food chain. How does their death affect the Black Sea ecosystem?

Yes, dolphins are at the top of the food web. We use the term “web” because it is not a single chain but a network of interconnected chains. 

Dolphins are considered keystone species, meaning that top predators like them stabilize entire ecosystems. In the Black Sea, dolphins regulate fish populations, and in turn, fish control the populations of zooplankton, phytoplankton, crustaceans, etc.

So, if dolphins are absent (or too few), fish begin reproducing uncontrollably. When there are too many fish, they deplete zooplankton, and that leads to the unchecked growth of microalgae. The toxins from these algae can kill both zooplankton and fish. In the end, we end up with a sea overrun by algae where little else can survive. 

Moreover, when dolphins die out, their place is often taken by jellyfish or, even worse, comb jellies. There have been cases in history where the mass death of dolphins led to ecological disasters.

In the 80s and 90s, up to 90% of Black Sea dolphins perished. This was caused by the dolphin hunting industry, which thrived until 1983. Around the same time, a species of comb jelly, Mnemiopsis, entered the Black Sea through ballast water. With no competition, it multiplied rapidly—an aggressive spread of an alien species is known scientifically as a bioinvasion. As a result, in the 1990s, Mnemiopsis consumed the eggs of almost all common fish species, and anchovy catches dropped 100 to 200 times by 1991. It was even said the Black Sea could become a dead one.

Ironically, the dolphin population recovered partly due to another bioinvasion, an accidental one at that. In 1997–1999, another species of comb jelly, Beroe, was introduced into the Black Sea, and it fed on Mnemiopsis.

In your opinion, how difficult will it be to restore the dolphin population after the war?

Ukraine is home to various dolphin populations. We have three species: the harbor porpoise, the common dolphin, and the bottlenose dolphin. Each species has its own life cycle, lifespan, reproduction rate, and so forth.

As of now, the common dolphin, is doing relatively well. This species is mostly found in the open sea and stays away from the coast.

On the other hand, the harbor porpoise suffers greatly due to human activity. Although no one hunts it intentionally, it often gets accidentally caught in fishing nets. Each year, 12,000–16,000 porpoises die this way, one of the highest rates in the world. Due to this constant pressure, porpoises reproduce quickly: females give birth almost every year and reach sexual maturity at just three years of age, or perhaps even earlier now.

In contrast, the Black Sea bottlenose dolphin reproduces much more slowly, giving birth only once every three years, and reaching sexual maturity at 5–6 years, sometimes even later. This species is listed as endangered and is the largest dolphin in our waters with the smallest population.

Bottlenose dolphins are divided into several local groups. Some groups can be large, numbering in the hundreds, while others are much smaller. For example, near Dzharylhach Island, between 2016 and 2020, we studied a group of fewer than 50 bottlenose dolphins.

Bottlenose dolphins have strong cultural traditions and sophisticated social relationships—they are highly attached to their home territory. If some russian soldiers were to shoot them near Dzharylhach, the dolphins would simply disappear from that area, leaving it desolate for decades.

Therefore, even if we assume that the overall dolphin population in the Black Sea recovers, it does not mean that each small group of bottlenose dolphins will survive. It is entirely possible that while things may look fine in the center of the sea, the situation near the shores—particularly near our shores—will be much worse. And it is crucial to understand this: the bottlenose dolphin population cannot be replenished in captivity. Second-generation offspring simply do not get born in captivity.

Thus, bottlenose dolphins are the most at risk, especially in peripheral areas where fighting occurs, and even in areas without direct combat.

What non-combat measures negatively affect them?

The russians are distorting nature. They do not just destroy dams—they build new ones, and that is bad.

They constructed a causeway between Dzharylhach Island and the occupied mainland of Ukraine. Fortunately, nature took care of it: in 2023, a massive storm washed it away. But that causeway posed a threat to the Dzharylhach Bay ecosystem by blocking the water exchange with the open sea.

As for the Kerch Bridge, it does not just threaten nature—it has already caused harm. 

Firstly, its construction generated severe acoustic pollution, harmful to dolphins.

Secondly, there is now a dam between Tuzla Island and the Caucasian shore, damaging the ecosystem of the Taman Bay and the Kerch Strait, where small herds of bottlenose dolphins live. It also endangers the entire ecosystem of the Sea of Azov, home to a unique population of harbor porpoises.

What can Ukraine do to protect Black Sea marine mammals? How can we at least reduce our own negative impact on them?

Scientists propose three main areas of work, which align with the international convention that came into force in Ukraine back in 2003.

• The first is to reduce accidental dolphin deaths. We can learn from the experience of Romania and Bulgaria, where special devices are installed on fishing nets to deter harbor porpoises.
• The second is to expand the network of protected areas. This requires political will since it requires legislative changes. It is crucial to start this process now, even during the war, and especially to create these protected marine areas in Crimean waters.
• The third area is to strengthen government control over pollution sources—biological, chemical, and acoustic. This is not about punishment but about systemic recommendations. In other words, experts should be present to say, “Do not operate here right now because fish are coming,” or “This area is clear for operations.”

Will the abolition of dolphinariums affect the dolphin population? 

It will, and significantly. We do not have large herds of bottlenose dolphins like in the Pacific, where they number in the thousands. Our groups are small, each with its own routes and feeding grounds. When a dolphinarium poacher catches five bottlenose dolphins, it can have fatal consequences for the entire group.

For our country, dolphinariums are evil. Public pressure is key here—going to dolphinariums should become bad taste.

This publication was compiled with the support of the European Union and the International Renaissance Foundation within the framework «European Renaissance of Ukraine» project. Its content is the exclusive responsibility of the authors and does not necessarily reflect the views of the European Union and the International Renaissance Foundation.

Main photo: NGL media. Photographer: Maxym Kozmenko