Modeling Effectiveness of Gradual Increases in Source Level to Mitigate Effects of Sonar on Marine Mammals |
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Authors: | ALEXANDER M VON BENDA‐BECKMANN PAUL J WENSVEEN PETTER H KVADSHEIM FRANS‐PETER A LAM PATRICK J O MILLER PETER L TYACK MICHAEL A AINSLIE |
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Institution: | 1. Netherlands Organisation for Applied Scientific Research (TNO), , P.O. Box 96864 The Hague, The Netherlands;2. Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, , Fife, KY16 8LB Scotland;3. Maritime Systems Division, Norwegian Defense Research Establishment (FFI), , NO‐3191 11 Horten Norway;4. Biology Department, Woods Hole Oceanographic Institution (WHOI), , Woods Hole, MA 02543, U.S.A. |
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Abstract: | Ramp‐up or soft‐start procedures (i.e., gradual increase in the source level) are used to mitigate the effect of sonar sound on marine mammals, although no one to date has tested whether ramp‐up procedures are effective at reducing the effect of sound on marine mammals. We investigated the effectiveness of ramp‐up procedures in reducing the area within which changes in hearing thresholds can occur. We modeled the level of sound killer whales (Orcinus orca) were exposed to from a generic sonar operation preceded by different ramp‐up schemes. In our model, ramp‐up procedures reduced the risk of killer whales receiving sounds of sufficient intensity to affect their hearing. The effectiveness of the ramp‐up procedure depended strongly on the assumed response threshold and differed with ramp‐up duration, although extending the duration of the ramp up beyond 5 min did not add much to its predicted mitigating effect. The main factors that limited effectiveness of ramp up in a typical antisubmarine warfare scenario were high source level, rapid moving sonar source, and long silences between consecutive sonar transmissions. Our exposure modeling approach can be used to evaluate and optimize mitigation procedures. Modelado de la Efectividad de los Incrementos Graduales en el Nivel de la Fuente para Mitigar Efectos de Sonar sobre Mamíferos Marinos |
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Keywords: | acoustics killer whales marine mammals Ramp‐up procedures soft‐start procedures sound impact acú stica ballenas asesinas impacto de sonido mamí feros marinos procedimientos de arranque suave procedimientos de incremento gradual |
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