Can you hear me? Impacts of underwater noise on communication space of adult, sub-adult and calf contact calls of endangered St. Lawrence belugas (Delphinapterus leucas)

Noise and anthropogenic disturbances from vessel traffic are an important threat to the recovery of endangered St. Lawrence Estuary (SLE) beluga population. The consequences acoustic masking could be particularly adverse in case critical vocalizations that maintain contact between mothers their dependent but mobile calves. This study models communication range adults, sub-adults newborn calls presence absence vessels summering area for this Ambient noise measurements, a composite audiogram apparent source levels adult/sub-adult calls, informed model. Apparent were estimated received produced by four individuals carrying digital tags SLE, Canada, recorded two adults calf at aquarium, known distances calibrated hydrophone. median ranges over 18 times larger SLE adult sub-adult than with 57 53% reduction noise, respectively. For results 170 m noise. These first estimates function suggest quiet newborns impair mother–calf contact.