Yes, the Black Sea does have sharks, but they are not the large, predatory species often associated with open oceans. This semi-enclosed sea is a unique environment, connected to the Mediterranean only by the narrow and shallow Bosphorus Strait. This geographical bottleneck and the sea’s distinct internal chemistry severely restrict the types of marine life that can thrive in its waters. The sharks that inhabit the Black Sea are specialized for this particular ecosystem.
Identifying the Shark Species of the Black Sea
The primary and most common shark species in the Black Sea is the Spiny Dogfish (Squalus acanthias). This relatively small shark reaches an average adult size between 80 and 110 centimeters, with a maximum length of about 160 centimeters.
The Spiny Dogfish is a slow-swimming shark that lives closer to the bottom on the continental shelf, though it can also be found near the surface in coastal areas. Its diet consists mainly of small schooling fishes, invertebrates, crustaceans, and cephalopods. The Small-Spotted Catshark (Scyliorhinus canicula) is another species occasionally noted in the Black Sea. This transient visitor from the Mediterranean is even smaller, preferring to hunt at night among rocky crevices.
Unique Environmental Factors Limiting Large Sharks
The geographical and chemical characteristics of the Black Sea create a barrier to large, oceanic shark species. The connection to the Mediterranean Sea through the Turkish Straits System is restrictive, acting as a natural filter. The Bosphorus Strait is shallow and narrow, limiting the migration of large pelagic sharks like Great Whites or Tiger Sharks into the basin.
A more profound limitation is the severe stratification of the water column, making the Black Sea the world’s largest meromictic basin. Freshwater runoff from major rivers creates a less saline surface layer, which rests atop a much saltier layer flowing in from the Bosphorus. This density difference prevents the waters from mixing, resulting in a vast, deep anoxic layer.
This deep zone begins at about 150 to 200 meters and is completely devoid of oxygen, containing high concentrations of hydrogen sulfide. This chemical environment is toxic and uninhabitable for almost all complex marine life, including large predatory sharks that require access to deep waters. Only the upper 10 percent of the water column is oxygenated and capable of supporting fish populations. The lower salinity of the surface waters, compared to the open ocean, further affects the physiology of most large, marine-adapted shark species.
Assessing the Risk of Human Encounters
Given the species that inhabit the Black Sea, the risk of a dangerous human encounter is extremely low. The resident Spiny Dogfish and the occasional Catshark are small, shy, and non-aggressive towards people. They are not considered a threat to swimmers or beachgoers.
The Spiny Dogfish possesses two sharp, ungrooved spines, one in front of each dorsal fin. These spines secrete a mild venom and are used as a defensive mechanism, primarily posing a risk to fishermen handling the fish. The potential for injury is limited to accidental handling or stepping on a fish in very shallow water. Throughout history, there has never been a single recorded shark attack on a human in the Black Sea.