Sharks are hardy mammals, so it is not problematic for them to overcome the Bosphorus and from the Mediterranean to the Black Sea. There are many sharks in the Mediterranean Sea, although only white and bull sharks are dangerous to humans, but they practically do not swim in the Black Sea. According to scientists, sharks are uncomfortable in the Black Sea, this is facilitated by intensive shipping and lower water temperatures. Also, despite the fact that both seas are connected, the chemical composition in them is different.

Sharks do not like to swim in the Bosphorus, ships constantly ply there, and the Black Sea is in heavy traffic of boats and yachts. Predators do not like it when there is so much noise around them, especially since it scares off prey.

Sharks are accustomed to warm water, if its temperature drops below 18 degrees, they cannot hunt normally, they lose speed. In the Black Sea, the water is cool, it rises above 18 degrees only in summer.

The water of the Black Sea is not salty enough for sharks: 18 ppm versus 38 ppm in the Mediterranean. Previously, the Black Sea was a lake with fresh water, communication between water bodies through the Bosphorus does not allow to compare the indicators. For many marine creatures living in the Mediterranean Sea, the Black Sea is not suitable for food supply, they have no chance to have offspring here. At the same time, the Black Sea developed its own biological diversity.

Even if the shark crosses the Bosphorus, its chances of surviving in the Black Sea are low. Not a single case of attack by these predators on the Black Sea beaches has been recorded. Biologists rejoice when sharks appear in new locations, because many populations of predators are threatened with extinction.