In-Air Behavioral Audiograms of Two Australian Sea Lions (Neophoca cinerea)

The Australian sea lion (Neophoca cinerea) is an endangered species with threats including bycatch, prey depletion, pollution, and habitat loss. Coastal and offshore industrial development causes disturbance-largely mediated by noise. Yet nothing was known about this species' hearing sensitivity. We present the first in-air audiograms of two adult female Australian sea lions, measured between 100 Hz and 20 kHz via behavioral audiometry. Greatest sensitivity occurred at 3.2 kHz at 13 and 14 dB re 20 µPa in the two individuals. Their 20 dB bandwidth of best sensitivity ranged from 600 Hz to 9 kHz in one and to at least 20 kHz in the other sea lion. While these audiograms were generally comparable to those published for other sea lion species, frequencies of best sensitivity were lower in the Australian sea lions. These results may add to future research on comparative ecology in pinnipeds and inform the management of anthropogenic noise.