The Short-beaked common dolphin (Delphinus delphis) hereafter referred to as “the common dolphin” is abundant throughout the continental shelf and pelagic waters of tropical and warm temperate regions in the Atlantic and Pacific Oceans. This species was also found in the Mediterranean and Black Seas, including the Adriatic Sea. Until the early 1970’s this species was one of the most abundant Mediterranean species, but has since experienced a major decline leading to total disappearance from large parts of the previous range. Organised culling campaigns in many Mediterranean countries were the factor leading to their disappearance. The dolphins were perceived as competitors for fish and were considered “pests”. The culling campaign organised in the Yugoslav Adriatic during the mid-1950’s and the beginning of 1960’s significantly affected the population status and, coupled with changes in the environment and overfishing, led to the complete disappearance of the species. In the last three decades, sightings in the northern Adriatic Sea have been very rare. The last sighting in the Cres-Lošinj research area was in 1997, while the last documented sighting in the central Adriatic dates from 2016. Although these animals occasionally occur in the Adriatic, they are considered regionally extinct as a resident breeding population does not exist. Depending on their habitat, common dolphins can feed on a great variety of prey. Their diet includes small schooling fish such as herring, anchovies, sardines and also cephalopods. Common dolphins can be found in schools of up to several thousand animals in the oceans, especially if food is abundant. However, these large schools are composed of smaller family subunits of about 20-30 probably closely related individuals. These individuals usually hunt in smaller groups, splitting away from the large school for foraging but returning for travelling and socializing. In general, they are extremely active, fast moving and engage in spectacular aerial behaviours. Their average life span is estimated to be over 30 years. Habitat degradation from human activities, incidental catch and overfishing is likely to be one of the reasons of common dolphin disappearance in the Mediterranean and Black Seas.
