Click-Evoked Auditory Brainstem Responses in an Australian Sea Lion (Neophoca cinerea)

Abstract

This otariid species, endemic to Australia, is listed as vulnerable under the Australian Environmental Protection and Biodiversity Conservation Act 1999 (Australian Government, 1999) and as endangered by the International Union for Conservation of Nature (IUCN) (Goldsworthy & Gales, 2015). Breeding colonies of the Australian sea lion can only be found on the south and west coasts of Australia, and numbers are declining. Mother-pup recognition in large breeding colonies is mediated primarily through acoustic cues. Any auditory impairment of a breeding sea lion could have knock-on effects in terms of nursing and, ultimately, breeding success. While by-catch in gill-net and trap fisheries is suspected to be the main threat (Goldsworthy & Gales, 2008), effects induced by excessive exposure to anthropogenic underwater sound (such as seismic exploration, underwater explosions, and pile driving for port construction; see Wyatt, 2008) might also cause changes in the distribution or abundance of this species.