Measurements were obtained both in the presence of and the absence of whale watching boats. It was observed that a period of intense boating activity caused the killer whales to adjust their call duration levels to compensate for the background noise. This clearly indicates that anthropogenic noise levels directly interfere with the routine life of the killer whales, which are dependent on vocal communication for successful hunting and survival. [Andrew et.al. 2004]

It is well-known that anthropogenic sounds can even have fatal consequences as evidenced by the recent mass strandings of beaked whales that coincided with the mid frequency sonar exercises by the navy. A recent research by (Holt et.al, 2009) focused on the effects of anthropogenic sounds on the vocal behavior of killer whales. The resident killer whales of the waters of the Puget Sound, Seattle, were the subjects of this study. The southern resident killer whales in three...
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