Fishers and poachers along the Black Sea coast often find suffocated dolphins entangled in their nets, They release them by cutting off their fins and dropping them in the sea. Their bodies, with net marks on their skin, are often washed ashore.

Fishing and poaching in littoral Black Sea nations plummeted because of Russia’s 2022 full-scale invasion, as Moscow strove to occupy all of Ukraine’s Black Sea coast.

It failed – but the ongoing hostilities have been killing “hundreds times more” bottlenose and short-beaked dolphins and harbour porpoises, according to Ivan Rusev, head researcher at the Tuzly Lagoons national park in southern Ukraine.

In 2022 alone, some 50,000 dolphins died this way, and by 2026, the number exceeded 120,000, or one in four cetaceans in the Black Sea, Rusev told Al Jazeera.

Dolphins are apex predators, and their decimation further ruins the Black Sea’s ecosystem already affected by chemicals from munitions, spills of oil, fuel and vegetable oils from dozens of sunk or damaged warships, tankers and freighters. Many dead dolphins still have their fins, but look starved.

A dead Black Sea dolphin [Courtesy of Ivan Rusev] Explosions, launches of cruise missiles from warships, and military sonar systems confuse them, deafening their primary survival tool, echolocation, and making them unable to navigate, communicate and hunt.

“If a dolphin can’t fish, it loses weight fast,” said Rusev, whose park covers 280 square kilometres (108 square miles) of salty lagoons that serve as a stopover and breeding site for migratory birds.

The dolphins switch to consuming their blubber that has already accumulated pollutants from wastewater, agricultural runoff, microplastics and antibiotics.

The self-poisoning incapacitates their immune system, and they succumb to lethal respiratory tract infections caused by the so-called morbillivirus.

The Black Sea is one of the world’s youngest – some scholars hypothesise that it was a freshwater lake until about eight millennia ago, when the Bosporus Strait burst open, causing what may have been the biblical Great Flood. The sea’s waters lack oxygen and support no fauna or flora below 50 to 100 metres.

The chronic environmental damage from the war was aggravated by another shock: the 2023 destruction of the giant Kakhovka dam on the Dnipro River, releasing most of its 18 cubic kilometres (4.3 cubic miles) of water contaminated with fertiliser runoff, heavy metals and machine oil.

A water mine explodes during the military exercise Sea Breeze on July 22, 2022, in Burgas, Bulgaria [File: Hristo Rusev/Getty] Fish species such as mullet and bluefish have become scarce, even though fishing in Black Sea nations has been affected by restrictions, bans and naval mines that were spotted near Istanbul. The changes inevitably affect the dolphins.

“With dolphins at the top of the food chain, everything from zooplankton to fish reaches them,” Rusev said.

Environmentalists from other Black Sea nations – Bulgaria, Romania, Turkiye – also reported a spike in dolphin deaths, even though the cause of their death couldn’t always be established.

“Most of the stranded dead cetaceans are usually in an advanced state of decomposition, making detection of net marks and other marks almost impossible,” Dimitar Popov of Green Balkans, Bulgaria’s oldest nature conservation group, told Al Jazeera.

He agrees with Rusev that “sonar systems of warships and submarines definitely affect cetaceans and their echolocation and hearing abilities”.

Meanwhile, Russian environmental monitors blamed the dolphin deaths on “parasites” and “virus infections” without any further explanation.

And even though only a tiny percentage of dead dolphins are washed ashore, their appearance horrifies Ukrainians already unnerved by nearly daily drone and missile attacks.

In August, Tetiana Smolchenko enjoyed a seaside stroll with her eight-year-old son Oleh in the southern city of Odesa – until the child spotted an emaciated, decaying dolphin.

“I nearly threw up,” the 33-year-old, whose husband serves in the military and whose apartment building has been damaged by a Russian drone twice, told Al Jazeera.

“We’re so used to human deaths now, but seeing these creatures die because of the war is no less horrifying,” she said. “We both wept.”What looks like a military triumph could become a heavy blow to the marine ecosystem.

A heavily damaged Russian-flagged cargo ship is seen washed ashore at Alacalı Beach in September 2026 in the Sile district of Istanbul, Turkiye, following a drone attack that struck the vessel in the Black Sea [File: Burak Kara/Getty] Since 2022, Ukrainian sea and airborne drones have sunk two submarines and three dozen Russian warships, including the Black Sea Fleet’s flagship, the Moskva (Moscow) guided missile cruiser. They were all loaded with toxic fuel and other chemicals.

Even though Ukrainian drone operators attacking Russian“shadow fleet” tankers are instructed to specifically target their engines, oil and fuel spills continue to happen.

Oil molecules form a film that coats seaweed, poisoning molluscs and fish, especially sturgeons that die in droves.

Every explosion deafens and kills fish, and the sound, coupled with flying drones, startles birds migrating back and forth between Northern Europe and the Middle East.

“And when a bird can’t find enough food, doesn’t have ‘fuel,’ it can’t reach the destination where it winters or nests,” Rusev said. “It will affect the number of certain bird populations for years.”

Startled by the blasts, flamingoes, who only started nesting in his park years ago, are leaving their hatches, and seagulls immediately eat the eggs, he said.

The war’s only silver lining for wild nature around the sea is that the number of boars, roes, foxes, jackals, hares and badgers has risen because hunting and poaching nearly stopped, he said. And the ecosystem’s post-war recovery is going to be uneven.

While the number of insects and small mammals should return to normal within years, the dolphin population’s recovery will take decades.

“We estimate that it would take 30 to 50 years to renew the population of cetaceans, so that the sea ecosystem becomes more or less normal,” Rusev said.

In 2022 alone, some 50,000 dolphins died because of the war, but by 2026, the number exceeded 120,000, or one in four cetaceans from the Black Sea [Courtesy of Ivan Rusev]