Seals and sound in a changing Arctic: Ongoing psychoacoustic studies of spotted and ringed seals

Abstract

Arctic environments are changing rapidly as a result of climate warming and industrialization, and as sea ice recedes, activity associated with transportation and oil and gas production increases. Among the many concerns for ice-living seals in the region is the potential for behavioral or auditory effects resulting from noise exposure. Currently there are limited data available concerning the hearing sensitivity of arctic seals - some data exist for harp and ringed seals, while the most comprehensive data are for harbor seals. As the phylogenetic relationships among northern seals are not well resolved, extrapolation across species for management purposes is difficult. To this end, we are working to describe the species-typical hearing of spotted (Phoca largha) and ringed seals (Pusa hispida). Thus far, measurements of the underwater hearing sensitivity of spotted seals show best sensitivity between 3.2–25.6 kHz and peak sensitivity of 51 dB re 1 μPa at 25.6 kHz. Absolute thresholds for airborne tonal signals indicate acute sensitivity of <10 dB re 20 μPa from 0.80–12.8 kHz. Audiometric testing for ringed seals is ongoing, as are critical ratio measurements for both species. These studies will provide valuable insight into how arctic seals perceive acoustic signals, as well as inform management practices for these vulnerable species.