title: Assessing risk of baleen whale hearing loss from seismic surveys: The effect of uncertainty and individual variation.
abstract: The potential for seismic airgun "shots" to cause acoustic trauma in marine mammals is poorly understood. There are just two empirical measurements of temporary threshold shift (TTS) onset levels from airgun-like sounds in odontocetes. Considering these limited data, a model was developed examining the impact of individual variability and uncertainty on risk assessment of baleen whale TTS from seismic surveys. In each of 100 simulations: 10000 "whales" are assigned TTS onset levels accounting for: inter-individual variation; uncertainty over the population's mean; and uncertainty over weighting of odontocete data to obtain baleen whale onset levels. Randomly distributed whales are exposed to one seismic survey passage with cumulative exposure level calculated. In the base scenario, 29% of whales (5th/95th percentiles of 10%/62%) approached to 1-1.2 km range were exposed to levels sufficient for TTS onset. By comparison, no whales are at risk outside 0.6 km when uncertainty and variability are not considered. Potentially "exposure altering" parameters (movement, avoidance, surfacing, and effective quiet) were also simulated. Until more research refines model inputs, the results suggest a reasonable likelihood that whales at a kilometer or more from seismic surveys could potentially be susceptible to TTS and demonstrate that the large impact uncertainty and variability can have on risk assessment.
authors.affiliation: Australian Marine Mammal Centre, Australian Antarctic Division, 203 Channel Highway, Kingston, Tasmania 7050, Australia. jason.gedamke@noaa.gov
authors.forename: Jason
authors.initials: J
authors.lastname: Gedamke
authors.forename: Nick
authors.initials: N
authors.lastname: Gales
authors.forename: Sascha
authors.initials: S
authors.lastname: Frydman
mesh_terms: D000162:Acoustics; D000818:Animals; D003198:Computer Simulation; D005844:Geology; D006317:Hearing Loss, Noise-Induced / Q000209:etiology / Q000662:veterinary*; D015233:Models, Statistical; D009622:Noise / Q000009:adverse effects*; D018570:Risk Assessment; D012307:Risk Factors; D035501:Uncertainty; D014907:Whales