Detailed Comparison of Acoustic Signals from Rehabilitated and Wild Franciscanas (Pontoporia blainvillei) Dolphins.

Simple Summary: Our research focuses on the franciscana dolphin, the most threatened dolphin in the southwestern Atlantic, mainly due to its frequent entanglement in artisanal gillnets. This has led to their classification as vulnerable. To better understand their sounds and communication, we recorded and analysed the sounds of both wild dolphins and those in a rehabilitation centre. We found that neonate dolphins emit sounds that differ from those of juveniles. Interestingly, the sounds made by juvenile dolphins are similar to those of wild dolphins. We also discovered patterns in the way dolphins produce clicks, sounds which are important for feeding and communication. Our findings highlight the need to protect calf dolphins and suggest that it might be possible to create tools to identify dolphins by their age, based on their sounds. This research is important for conservation efforts and could help in creating better protection strategies for these dolphins. The franciscana dolphin is a small, vulnerable species often caught in artisanal gillnets. This study aims to provide a comprehensive assessment of their acoustic capabilities by using advanced equipment to collect a large dataset of wideband, continuous recordings. We examined the detailed acoustic signals of franciscana dolphins, comparing the sounds from rehabilitated dolphins in captivity with those of wild dolphins near fishing nets. Significant differences in acoustic characteristics were found between neonates and older dolphins, with juvenile and wild dolphins showing similar features. For the first time, repetition patterns in click production were identified, highlighting the importance of understanding the context of these sounds in regards to feeding and communication. This study emphasizes the need for detecting neonates for species protection and suggests the potential for developing acoustic classifiers specific to different age groups. Our findings offer valuable insights for conservation efforts and the development of protection strategies for franciscana dolphins. [ABSTRACT FROM AUTHOR]