The ideal weather conditions allowed the Archipelagos Marine Mammal Team to carry out an extensive survey in the waters north of Samos and Ikaria Islands during the past week.
The Team spent several days in the sea with the aim to have an updated census of the cetacean species present in the study area.
At the beginning of the boat survey from the South of Samos Island, Bottlenose dolphins (Tursiops truncatus) were monitored in their typical habitat close to the coast. During the transect, Common dolphins (Delphinus delphis) confirmed their presence also in the North part of the island. That was an incredible sighting, confirming the presence of this species all around Samos Island, on the contrary to the rest of the Mediterranean Sea where they are slowly disappearing.
Hydrophone-based monitoring
A large pod of Striped dolphins (Stenella coeruleoalba), the most abundant Mediterranean species, showed all their energetic surface behaviour when the 2 Archipelagos research boats arrived in the deep pelagic area.
A big pod of 30 individuals of Risso’s dolphin (Grampus griseus) surprised the Archipelagos crew inspecting the boat and showing their particular skin patterning full of scars. This species is considered Least Concerning in the IUCN (International Union for Conservation of Nature) red list of Threatened Species. The sightings of the species are increasingly rare in the rest of the Mediterranean Sea and Archipelagos Institute will improve the research effort in order to collect more data about the status of this dolphin in the eastern Aegean waters.
Risso’s dolphin (Grampus griseus)
Another incredible sighting was of two Cuvier’s beaked whales (Ziphius cavirostris), a solitary species that rarely brings attention (as it is not displaying acrobatic behaviours). They usually spend most of the time taking advantage of their unique diving ability searching for prey and are then calmly resting on the surface. This small population of Cuvier’s beaked whale has been monitored by Archipelagos Institute for the past 17 years. The flat sea helped the Archipelagos Marine Mammal Team Members to spot and identify these rare species from far away.
After many days using hydrophones to record the underwater sound and listening to the typical clicks of the Sperm whales (Physeter macrocephalus), finally, a social group was spotted between Samos and Ikaria Islands. A family of mothers with a calf and some juveniles were resting on the surface in the typical behaviour called logging. The researchers who monitored these amazing animals collected a lot of video-photographic material of some animals performing spectacular breaches but also 
flucking (showing their large tales prior to diving) which is most useful for the Photo-Identification of the individuals.
Six of the eight species of whales and dolphins habitually living in the Mediterranean Sea were recorded during the last boat-based surveys of Archipelagos Marine Mammal Team around Samos, Ikaria and Fourni Islands. Bioacoustics, photo-ID, video, behaviours and other many data were collected in order to maximize the knowledge about these extraordinary inhabitants of the sea, but also of the threats that human activity poses on their survival.
Dr. Guido Pietroluongo, Marine Mammal Researcher and Conservation Team Supervisor,
DVM, University of Teramo, Italy
