More than 700 dolphins in the Black Sea have died since the war in Ukraine began. Scientists believe the fighting cripples their ability to navigate, find food, and talk to each other.

• There's been an increase in dolphin strandings around the Black Sea since the war in Ukraine began.
• Dolphins and porpoises talk and navigate via sound, which may be disrupted by the loud noises of war.

Along with the thousands of men, women, and children who have died since Russia invaded Ukraine in February, there have been hundreds of casualties in the Black Sea among the resident dolphin and porpoise populations.

Scientists who study the region reported an "unusual increase" in strandings and bycatch — when animals are unintentionally caught by fishermen — of dolphins, porpoises, and whales, in the spring and summer of 2022, according to a recent report from ACCOBAMS, or the Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea, and Contiguous Atlantic Area.

"Russia's war against Ukraine escalated in February 2022 puts the entire Black Sea basin under a huge threat. Military activities in the marine and coastal areas may affect the marine biota in the region, including cetaceans," the report said.

More than 700 deaths, primarily in dolphins and harbor porpoises, have been recorded on the coasts of countries that border the sea, including Bulgaria, Romania, Turkey, and Ukraine, according to Erich Hoyt, a research fellow at the UK-based Whale and Dolphin Conservation who consulted with the ACCOBAMS scientists.

Researchers are working to determine the cause of the deaths that have been observed, but the ongoing war — and the potential threat posed by drifting mines — make data collection and boat surveys difficult.

There have been reports of dolphins washing ashore with physical injuries, like burns, which could be a direct result of being caught in the crossfire. Ivan Rusev, research director at Ukraine's Tuzla Estuaries National Nature Park, said earlier this year dolphins were washing ashore with burn marks from bombs or mines, while others appeared unable to navigate or like they had not eaten in days.

But the increase in strandings and dolphins caught in bycatch could be a direct consequence of the loud noises associated with warfare.

"Dolphins and porpoises rely on sound to navigate, find their food, and communicate with each other," Hoyt told Insider. "Noise from increased ship traffic can have some impact but the sounds of explosions at the surface or underwater could disorient, wound, or kill dolphins and porpoises within a few mile range or cause increased numbers of strandings or bycatch."

Dolphins, porpoises, and whales have an acute sense of hearing and use echolocation to map out their environment. They emit short, pulsing "clicks," similar to a finger snapping, which travel through the water until they encounter an object and bounce back to the dolphin. But the dolphin's uncanny ability to interpret the returning sound to identify food and understand their environment can be disrupted by loud noises.

Dolphins also use sound, similar to a whistle, to communicate with each other, and have even been documented using verbal labels to address one another — in a word: names.

Sounds also travel much further and about four and half times faster through water than air, making the impact of explosions in the sea all the more damaging.

Though scientists are working to confirm the reasons for the increased deaths, Hoyt said the noise disruptions could be disorienting the dolphins, leading to an increase in them getting stranded on shore or caught in a fisherman's net.

Another factor could be that the fighting is driving the mammals away from familiar Ukrainian waters and bringing them to unfamiliar areas in search of food, where they may be more likely to end up in a net or stranded onshore.

The situation is also worsened by the fact that experts have identified coastal areas near Ukraine as vital for some dolphin and porpoise populations. Hoyt co-chairs the International Union for Conservation of Nature's Marine Mammal Protected Areas Task Force, which seeks to identify areas that are important to marine mammal conservation.

Several locations around Ukraine — including some that have been subject to fighting — have previously been designated as important habitats, including areas around the Crimean peninsula, the Kerch Strait, and the Sea of Azov, as shown in this interactive map.

The areas were identified as important habitats for three species that the IUCN classifies as threatened or endangered: the Black Sea common dolphin, the Black Sea harbor porpoise, and the Black Sea bottlenose dolphin.

"Of course, there are fears that the dolphins and porpoises known to use these areas year-round will have been killed or driven out," Hoyt said. "But because no research can take place there now, we simply will not know until after the war ends."

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