Fishing practices affect the behavioural budget of bottlenose dolphins off the coast of Montenegro, South Adriatic Sea
The spatio-temporal distribution of cetacean species often overlaps with fishing practices in the Mediterranean, having direct and indirect negative consequences. The present study is the first long-term study focusing on the effects of commercial and artisanal fisheries on the behaviour of T. truncatus in Montenegro. Focal group scan sampling was used during boat and land surveys between September 2016 and August 2020 to create transition probability matrices using first-order Markov chains for behavioural states in both control (absence of fishery practices) and impact chains (presence of fishery practices). Despite the low number of dolphin-fishery interactions in Montenegro, results revealed that the behavioural budgets of T. truncatus were significantly altered both for commercial and artisanal fisheries. However, the magnitude of the threat differed between practices, with commercial fisheries altering three out of the four behaviours in the behavioural budget compared to artisanal fisheries which just altered one. Significant behavioural alterations due to disturbance can have negative consequences on the energy accumulation of individuals. Whilst the Montenegrin fishing fleet is currently limited to 128 vessels, the significant effects already witnessed are concerning for Montenegrin bottlenose dolphins. To develop in-situ mitigation strategies, there is a clear need to better understand the impact that fishery interactions have on these individuals.