Investigation Into the Potential Effects of Anthropogenic Noise on Sperm Whale Sound Production (Physeter macrocephalus) in the Gulf of Mexico
Date of Award
Doctor of Philosophy (PhD)
Five weeks of continuous acoustic recording were examined to assess the potential impact of vessel noise on sperm whale diving behavior in the summer of 2001. Sperm whale acoustic activity was defined by the number of clicks detected in Ishmael (version 1.0). A noise event was defined as a broadband spectrum noise level of >65dB re: 1mPa, normalized to I Hz bands for an average dB-upper range (2-5.5kHz). Only noise events that were confirmed to be related to vessel traffic were used for analysis. Sign tests revealed that sperm whale acoustic activity decreased after noise events at the EARS 1 site for the 5-minute and 15 minute time samples. There was no difference in sperm whale activity at the EARS 2 and the EARS 3 site for any of the time samples. There was a significant decrease in the perceived number of whales after noise events at the EARS 1 location but not at the EARS 2 or the EARS 3 site. In conclusion, most noise events related to vessels were detected at the EARS 1 location in which they were typically longer in duration. Additionally, EARS 1 had fewer clicks, and whales, detected after a boat event. Further analysis of this data is needed to determine if noise is in fact affecting sperm whale behavior.
Walker, Rachel Thames, "Investigation Into the Potential Effects of Anthropogenic Noise on Sperm Whale Sound Production (Physeter macrocephalus) in the Gulf of Mexico" (2005). Dissertation Archive. 924.