Say what? Hearing abilities and subsequent variability for a wild population of Beluga Whales (Delphinapterus leucas)

Odontocetes use sound for vital biological functions and hearing is considered their primary sensory modality. To understand and predict noise impacts, we need to know natural hearing ability at the population-level. Yet we have no wild population-level hearing data for any cetacean. Here, we measured the audiograms (4-150 kHz) of wild beluga whales from 2012-2016 using auditory evoked potential methods. The goal of this work was to establish the mean audiogram and variance of wild beluga whales to define what this population hears. Audiograms were collected from 26 belugas during capture-release events in Bristol Bay, AK. In general, belugas showed excellent sensitivity (u003c60 dB) from 45 to 100 kHz and most (76%) heard up to at least 120 kHz. Hearing thresholds at lower frequencies 4-11 kHz tracked the low environmental noise levels (70 dB/Hz), suggesting that quiet habitats may allow substantial hearing sensitivity. Beluga audiograms show substantial (20-40 dB) variation but less than that of bottlenose ...