Preliminary analysis of effects of pile driving sounds on fish.

There is continuing concern about the potential effects on fishes of the sounds produced during pile driving activities. Data in the literature are unclear as to physiological and behavioral effects. The earlier studies also generally did not include either experimental controls or control of signal parameters. We have developed a unique laboratory device that permits accurate simulation of impulsive pile driving signals in controlled experiments. Juvenile Chinook salmon were exposed to different combinations of sound levels and number of strikes to achieve various cumulative sound exposure levels. Controls received identical treatment as experimental animals, but without sound. The fish were evaluated by necropsy for assessment of barotrauma. Necropsies were conducted on exposed and control fish with experimenter not knowing the stimulus parameters. Preliminary analysis of results show that the extent of barotrauma rises with increased cumulative sound exposure level (SEL). Future experiments will examin...