All mammals, including marine mammals, lose hearing sensitivity with age (presbycusis), particularly at higher frequencies. Killer whales (Orcinus orca) are one of the most cosmopolitan marine mammal species, and they experience exposure to many anthropogenic noise sources, which makes it important to understand how individuals may be affected by age-related hearing loss. Previous audiograms have been published on this species using both physiological and behavioral methods, but the effects of presbycusis on this species have never been studied. For this study, audiograms from multiple killer whales housed at SeaWorld San Diego were repeated for direct, within-subjects comparison to a study conducted nearly a decade prior (Branstetter et al., 2017). Subjects ranged from 12 to 60 years of age. The results provided evidence of presbycusis in killer whales, which is consistent with other studies in marine mammals. Monitoring these changes is important for ensuring optimal welfare of the whales, providing a better representation for population-level hearing, and benefiting the conservation of wild killer whales.
Nease et al. (Wed,) studied this question.