Residence pattern and population size assessment for the short-beaked common dolphin, Delphinus delphis, in Dilek Yarimadasi, Aegean Sea.

Claudia Ascencio


The short-beaked common dolphin Delphinus delphis is one of the most abundant cetaceans with a wide distribution. Despite this, the population in the Mediterranean Sea has experienced declines in recent decades. Historically, studies concentrating on the Aegean Sea have focused on the northern area, leaving a gap of information in the south. The current study focused on creating baseline information of the common dolphin at the Dilek Peninsula. Data collection was gathered during boat surveys from summer and autumn 2019, and summer, autumn, and winter 2020. Results revealed 20 group encounters with a group size from two to 12 (Mode = 3, SE = 0.27) individuals and one to four (Mode = 0, SE = 0.27) subadults. In addition, travelling behaviour was found to be the most common behaviour, and photo analysis determined 40 distinctive individuals. Considering the dominance of travelling behaviour and the fact that Dilek Peninsula is situated between two sardine hotspots, it is possible that the research area may be a biological corridor between foraging grounds. This study presents the first photo identification results of common dolphins in this area; however, results are preliminary and further studies are needed to confirm these results.