LONG-TERM TEMPORAL PATTERNS OF BOTTLENOSE DOLPHIN (TURSIOPS TRUNCATUS) ECHOLOCATION ACTIVITY IN THE SICILY STRAIT

Understanding temporal variations in the occurrence of cetacean species is critical for the design and application of successful conservation and management measures. In this study we used passive acoustic monitoring to investigate bottlenose dolphins (Tursiops truncatus) acoustic presence through the detection of their echolocation clicks. We deployed a single sensor on an elastic beacon fixed to the seabed at 3 miles from the coast, in the shallow waters of the Sicily Strait (Italy). Data were collected continuously for 8 months, from January to August 2016. About 3800 hours of recording were processed with an automatic detection algorithm. We calculated click detection rates (CDRs) as number of clicks on recording time. In order to identify and describe temporal patterns in the echolocation activity, we analysed the CDRs in relation to temporal variables (season, time and diel phase), by using General Additive Models. The results are discussed in the light of previous information about this bottlenose dolphin resident population. Further studies will be essential to estimate the density of the population that uses this coastal area.