Dead Cuvier’s beaked whale near Orebić

17.12.2017

Today, 17. 12. 2017. we received the information on dead whale found stranded on Pelješac peninsula near city of Orebić. Animal, about 5 meters in length in a moderate state of decomposition has been washed ashore after strong southern wind. After checking the photographs that mr. Ivica Trojanović published on his FB profile we identified the species as Cuvier’s beaked whale (Ziphius cavirostris). Unfortunately, dead animal has not been taken for autopsy so cause of death was not established.

Cuvier’s beaked whale is the only beaked whale species that inhabits the Mediterranean sea. After analysing the data on strandings and observations and two aerial surveys carried out by Blue World Institute we confirmed the regular presence of Cuvier’s beaked whale in the area of southern Adriatic. Unfortunately, small number of observations did not allow for establishment of more information on abundance and distribution. Recently, with number of colleagues we analysed 24 sets of data collected by different organisations between 1990 and 2016 in Mediterranean and Adriatic Sea. The results confirmed southern Adriatic and Hellenic trench as one of the most important habitat of the species in the Mediterranean.

Cuvier’s beaked whale is a species with deepest dives recorded. Recent surveys in the area of southern California recorded dives to depth of 2992 m lasting 137.5 min. In a group of eight tracked animals, dives on average lasted over one hour and were to the depth of around 1400 m. Such prolonged periods underwater and in great depths makes this species very hard to study, hence our knowledge on their ecology and behaviour is very limited.

Cuvier’s beaked whale is extremely sensitive to acoustic pollution of the sea and especially to loud mid and low frequencies sound. A number of mass strandings of this species caused by military sonar were recorded. In the Mediterranean such strandings have been recorded on several occasions near Valencia (1996), in Kyparissiakos bay (1996), in the area of Ionian islands (1997), along the Algerian coast (2001), near west coast of Corfu (2011) and near south coast of Crete (2014) and have been linked to naval operations of NATO.

Seismic surveying and prospecting for hydrocarbons also produces strong noise and presents a danger for this and many other marine species. Blue World Institute has warned the authorities and public on the need for special caution when issuing permits for such activities in the Adriatic. After environmentally damaging seismic surveying carried out without any environmental impact assessment in Croatian Adriatic from September 2013 to February 2014, currently the largest threat is posed by 3D seismic surveying in Montenegro planned during the winter 2017/2018. In order to raise the public awareness on the negative effects of noise on the marine life a workshop on mitigating the impact of underwater noise on marine biodiversity has been recently organised in Split.