The repeated deaths of Caspian seals along the shores of the Caspian Sea have become a persistent environmental concern, with experts still unable to identify a definitive cause despite years of investigations, according to a report by Iran's Shargh newspaper.
What was once an occasional discovery has turned into a recurring pattern. Seal carcasses continue to wash ashore across the Caspian coastline, prompting authorities and environmental organizations to record the losses while searching for answers.
Researchers increasingly view the deaths as the result of multiple pressures rather than a single cause. Climate change, declining water levels, industrial pollution, overfishing, accidental entanglement in fishing nets and the possible spread of disease have all been cited as contributing factors.
The Caspian seal (Pusa caspica) is the only marine mammal native to the Caspian Sea and one of the region's most distinctive species. Found nowhere else in the world, it plays a key role in maintaining ecological balance by feeding on small fish and other aquatic organisms.
Environmental experts regard the species as an indicator of the sea's overall health. A decline in seal numbers can point to broader problems, including pollution, shrinking fish stocks and disruption of the marine food chain.
The species is also part of the shared natural heritage of the five countries bordering the Caspian Sea — Iran, Russia, Azerbaijan, Kazakhstan and Turkmenistan. Its survival is closely linked to the environmental future of a region where millions depend on fishing, tourism and coastal industries.
Deaths across the Caspian
The crisis attracted international attention in 2022 when around 2,500 dead Caspian seals were found along Russia's Dagestan coast in one of the largest recorded die-offs involving the species.
Scientists examined a range of possible causes, including disease outbreaks, oxygen depletion, environmental contamination and natural gas emissions from the seabed. No definitive explanation emerged.
The event was not isolated. Hundreds of dead seals had previously been recorded along the Dagestan coastline, suggesting that large-scale mortality events are becoming a recurring feature of the Caspian ecosystem.
Researchers also point to climate change as a growing threat. Caspian seals rely on ice in the northern part of the sea to breed and raise their pups. Rising temperatures and shrinking winter ice cover have reduced the availability of suitable breeding habitat, placing additional pressure on an already vulnerable population.
Population in decline
Conservation estimates indicate the Caspian seal population has fallen by more than 90 percent over the past century. Once numbering above one million animals, the population is now believed to have dropped below 100,000.
The species is listed as endangered by the International Union for Conservation of Nature, reflecting concerns about its long-term survival.
Amir Sayad Shirazi, director of Iran's Caspian Seal Conservation Center, told Shargh that pollution remains one of the most significant threats facing the species.
Because the Caspian Sea is shared by five countries and functions as a closed body of water, environmental damage in one area can affect the wider ecosystem, he said.
Russia halted commercial hunting of Caspian seals in 2020, eliminating one source of mortality that had previously resulted in thousands of deaths annually. Yet unexplained die-offs continue to undermine conservation efforts.
For conservationists, the fate of the seal increasingly mirrors the condition of the sea itself, making its survival a test of whether the region can protect one of its most distinctive ecosystems.
