Scubaism

University of Maryland study in the July issue of the Journal of the Acoustical Society of America reports that high powered sonar, like that used by U.S. Navy ships, did not harm test fish, including their hearing, in a controlled setting.

In a special tank designed for the research, the team conducted “worst case scenario” tests, exposing fish to sound that was far more intense and for longer periods than they would typically receive in the wild when exposed to LFA (Low Frequency Active) sonar.

“The sound level the fish were exposed to is that found only within about 100 meters of a ship using LFA,” Popper said. “And the exposure was for substantially longer than fish would encounter in the wild, where the sonar source is on a moving ship.”

The test results showed no mortality associated with the sound exposure. “All fish appeared healthy and active until the end of our experimental week,” Popper said. “But they had some small behavioral responses to the onset of the LFA signal, including a very short burst of swimming at the onset of the sound.”

The investigators also found that sensory tissue of the fishs’ inner ears did not show damage, even several days after the sound exposure. Examination of other tissues, such as the gills, heart, and brain showed no effect on any tissues as a result of sound exposure.