Airgun Effects On Arctic Seals: Auditory Detection, Masking And TTS In Pinnipeds

Arctic environments are changing rapidly as a result of ice retreat and industrialisation. Subsequently, increased human noise in the Arctic, absence of data on hearing in Arctic seals, and the recent listing of some Arctic species as threatened have increased the need for data on hearing in Arctic pinnipeds. Assessing the risk of hearing effects from shipping and E&P sound and developing appropriate mitigation measures depend on acquiring good baseline hearing data.

This ongoing collaborative project between the University of California Santa Cruz and SEA Inc. will provide information on the auditory capabilities of three species of Arctic seals.

Objectives and methods

• Train captive ringed, spotted and bearded seals for voluntary participation in behavioural hearing tests
• Measure hearing thresholds under different conditions to assess auditory performance in the absence of noise, the presence of simultaneous (masking) noise, in order to determine critical ratios, and before and after exposure to impulsive sound (single air gun shots), in order to examine the sound levels that cause a temporary shift in hearing threshold. 

Importance

When completed, this research will describe the auditory capabilities of Arctic seals and should improve our ability to predict the effects of sound exposure on these species. The type of data to be provided by this project will serve to fill critical data gaps for some Arctic pinnipeds and enable decision-making based on best available science. The results published thus far provide the first description of the auditory biology of spotted seals (Phoca largha).