Onset of barotrauma injuries related to number of pile driving strike exposures in hybrid striped bass

Previous studies exploring injury response to pile driving in fishes presented exposure paradigms (>900 strikes) that emulated circumstances where fish would not leave an area being ensonified. Those studies did not, however, address the question of how many strikes are needed before injuries appear. Thus, the number of strikes paired with a constant single strike sound exposure level (SELss) that can cause injuries is not yet clear. In order to examine this question, hybrid striped bass (white bass Morone chrysops × striped bass Morone saxatilis) were exposed to 8–384 strikes in three different SELss treatments that generated different cumulative sound exposure level values. The treatment with the highest SELss values caused swim bladder injuries in fish exposed to as few as eight pile strikes. These results have important implications for pile driving operations where SELss values meet or exceed the exposure levels used in this study.