The presence of great white sharks (Carcharodon carcharias) in the Mediterranean Sea, though increasingly rare, is not new. Historical records spanning over 150 years document their existence in the region. However, the surprise surrounding recent sightings, such as one filmed between Tunisia and Sicily, underscores the uniqueness of this population, which was thought to be nearly extinct.
Despite the popular belief that these individuals are merely lost from the Atlantic, recent research, including a 2020 genetic study led by the University of Bologna, reveals that Mediterranean great white sharks constitute a unique population. Their DNA has remained isolated for approximately 3.2 million years, making it one of the oldest and most distinctive colonies on the planet, more closely related to Pacific populations than Atlantic ones.
This distinct lineage exhibits extremely low genetic diversity, indicating a small and fragile population classified as critically endangered. The lack of knowledge regarding their distribution, habitat use, and population trends significantly hinders conservation efforts.
Recent evidence reinforces the idea of their persistence. In April 2023, fishermen accidentally caught a juvenile specimen about 20 nautical miles off Alicante. This finding, coupled with the sighting of an adult in the Strait of Sicily, suggests that the species never fully left the Mediterranean and that certain areas might serve as nursery or breeding grounds.
The increase in documented sightings is attributed to improved surveillance (underwater cameras, citizen science) and potentially to the effects of global warming. Climate change is altering marine ecosystems, changing prey distribution and forcing species like the great white shark to modify their movements and habitats. This can lead to them appearing in unusual locations or at unusual times, without necessarily indicating a population recovery.
Satellite tagging studies confirm that shark movements are intrinsically linked to environmental conditions and prey availability. Despite over 150 years of records, scientists still do not know where these animals spend most of their lives, whether breeding grounds still exist, or how many individuals remain. The primary challenge today is to protect this critically endangered apex predator.
