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

Abstract

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 usingadvanced equipment to collect a large dataset of wideband, continuous recordings. We examinedthe detailed acoustic signals of franciscana dolphins, comparing the sounds from rehabilitateddolphins in captivity with those of wild dolphins near fishing nets. Significant differences in acousticcharacteristics were found between neonates and older dolphins, with juvenile and wild dolphinsshowing 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 feedingand communication. This study emphasizes the need for detecting neonates for species protectionand suggests the potential for developing acoustic classifiers specific to different age groups. Ourfindings offer valuable insights for conservation efforts and the development of protection strategiesfor franciscana dolphins.