Why are there no dolphins in the Caspian Sea

The Mystery of the Caspian: Why Are There No Dolphins in the World's Largest Lake?

The Caspian Sea, the largest enclosed body of water on Earth, holds many natural secrets. One of them particularly intrigues scientists and nature enthusiasts — there are no dolphins here. This fact causes bewilderment, considering the richness and diversity of the local aquatic fauna.

The answer lies in the geological history of the basin. The Caspian was once part of the ancient Tethys ocean, but tectonic processes completely cut it off from the world ocean about 5 million years ago. This isolation became a decisive factor in the formation of a unique ecosystem, devoid of many typical marine inhabitants.

The natural conditions of the Caspian are also not favorable for dolphin life. The basin is characterized by significant fluctuations in water salinity and sharp temperature changes. For dolphins accustomed to the stable environment of oceans, such conditions present a serious challenge. Additionally, the salinity of the Caspian Sea is significantly lower than oceanic, creating additional difficulties for marine mammals.

Another critical factor is the absence of migration routes for dolphins. Unlike the Black or Mediterranean seas, the Caspian has no natural straits connecting it to the world ocean, making it impossible for dolphins to naturally enter its waters.

Thus, the unique combination of isolation, specific natural conditions, and lack of migration routes explains the absence of dolphins in the Caspian Sea. However, this does not make the Caspian ecosystem less interesting — it is home to other unique species, including the famous Caspian seal, the only marine mammal of this ancient body of water.