According to the journal Marine Environmental Research San Diego sea lions also react to underwater sonar. Younger sea lions react even more heavily to sonar sounds. According to the study, 15 captive sea lions reacted in varying ways. As they were swimming across the pool to hit a paddle the bursts of sonar forced them to change their heart rate, stay deeper underwater or jump out and stay on land. Some simply refused to finish their routes or participate anymore.
The Navy is seeking to collect and understand more about the sparse information available about wildlife as it relates to military activities. In this case, the sonar test is helping them understand both the capabilities as well as the impact of underwater sound waves. So far the use of tactical sonar signal (1 s duration, 3250–3450 Hz) has a noticeable impact on this species.
What is the benefit of this research? Certainly it is nice to know if there is a damaging impact on sea life and if adjusting the frequency lowers the risk. In addition, such research may help us learn about the capabilities of sea life. Robotics is taking special interest in trying to mimic wildlife capabilities in man made equipment. Doing so raises the level of technology available for both civilian and military purposes. At present the study is limited to impact alone.
Houser, et. al. (2013). Behavioral responses of California sea lions to mid frequency (3250–3450 Hz) sonar signals. Marine Environmental Research, 92. http://www.sciencedirect.com/science/article/pii/S0141113613001797