Sound discrimination of two sympatric, threatened fish species allows for their <i>in situ</i> mapping

Human impacts on marine ecosystems are increasing and the number of fish species listed in Red List is constantly growing. In Mediterranean Sea, seven 10 bony fishes defined as Threatened by IUCN known to be vocal, including target this study: shi drum (Umbrina cirrosa Linnaeus, 1758) brown meagre (Sciaena umbra 1758). As a result, non-invasive passive acoustic monitoring (PAM) can used pinpoint their distribution at sea. However, for PAM effective, reliable discrimination required because sounds they emit during reproduction remarkably similar (i.e. short broadband pulsed sounds). The closely related, elusive, vocal sciaenids, partially overlapping ecological niche. During summer 2019, three surveys were conducted along tidal inlets Venice lagoon (Italy). Here, calls both have been recognized according temporal features: made up lower longer pulses with different envelope, repeated rate than those meagre. Further, origins (aquaculture semi-natural conditions) analysed compared collected survey study area order validate field data. Call allowed fine-scale mapping, showing two inlets. This first case which sciaenids documented share reproductive habitat Sea. demonstrates that it feasible acoustically monitor even parts Sea where co-exist. This, its turn, could provide managers data effective conservation measures implemented.