Archipelagos Marine Mammal Team has been monitoring the population of Sperm Whales (Physeter macrocephalus) in the north Aegean Sea for over 17 years.
Physeter macrocephalus is the biggest species of Odontoceti – toothed whales. A female can reach approximately 12 m and the male 18 m in length. The large head occupies one-third of the whale’s total body length and contains the spermaceti organ, which is involved in sound production and echolocation. During feeding activity, this animal can dive for up to 1 hour (the median diving duration being 45 min) and emits continuously clicks – an echolocating mechanism used to find prey or for social communication. Sperm whales inhabit all the world’s oceans. However, it was proven that the Mediterranean group is agenetically distinct subpopulation. This population is listed on the Red List IUCN (International Union for Conservation of Nature and Natural Resources) 
as an Endangered species category spC2a(ii) based on the assumption that their population size is smaller than 2500 individuals and is continuously decreasing.
During the surveys carried out on September 2017 the Marine Mammal Team crew inspected the area on the north of Samos and Ikaria Island, monitoring the Sperm whale population. Using applied acoustic and visual methods of observation, the team was able to produce great sighting results. 
The main goal of the expedition was to acoustically record Sperm whales as well as the sounds of other cetaceans. Subsequently a social group of approximately three-four whales were found. The crew collected valuable visual and acoustic data.
Archipelagos Marine Mammals Team will continue this important research, whenever the weather conditions allow it, aiming to extend the understanding of this charismatic and important mammal.
Patrizia Marciniak, University of A. Mickiewicz, Poland
