A Risso’s dolphin has been spotted in the open waters of the Aegean Sea, between the islands of Ikaria and Chios, during a research mission aboard the vessel Nautilus, operated by the Archipelagos Institute of Marine Conservation.
The sighting, shared by the institute on social media, took place on a calm spring day — just before the northerly winds known as meltemi returned to sweep across the Aegean.
An Elusive Giant of the Greek Seas
The Risso’s dolphin — known in Greek as stachtodelfino, or “ash-gray dolphin,” a nod to its distinctive pale, scarred coloring — holds a unique place in the marine ecology of Greece. It is the largest dolphin species found in Greek waters and the only one known to exhibit migratory behavior.
Despite this distinction, Risso’s dolphins remain among the least-studied and least-known cetaceans in the Mediterranean. Their highly mobile lifestyle makes them difficult to track: groups typically consist of three to 20 individuals, and they cover vast distances across the open sea, rarely staying in one area long enough for researchers to study them systematically.
Deep Divers of the Aegean
What makes Risso’s dolphins particularly remarkable is their extraordinary diving ability. They can plunge to depths of up to 300 meters (nearly 1,000 feet) and remain submerged for more than 30 minutes, a feat that sets them apart from most other dolphin species in the region and points to a highly specialized ecological role in the deep-water ecosystems of the Aegean.
