Abstract
Sperm whales (Physeter macrocephalus) have been observed but not well studied in the Monterey Bay National Marine Sanctuary (MBNMS). Vessels transiting through MBNMS may pose a threat to sperm whales and modify their behavior. Knowledge of their activity in relation to vessel presence in MBNMS is largely unknown. In this study, passive acoustic monitoring (PAM) data collected at the Sur Ridge, in close proximity to shipping lanes, are used to characterize vocal and foraging behaviors of sperm whales in relation to vessel transits through MBNMS. PAMGuard automated detectors are used to detect sperm whale clicks and measure inter-pulse intervals with feature-based post-processing to reduce false positives. Probability density functions are used to determine distribution of sperm whale size, sex, and presence in relation to vessel transits. Foraging clicks were positively detected in sequences of bouts from June-August, 2020. Sperm whales observed were adult males. Container ship signatures were observed to cover the same frequency bandwidth as sperm whales with a higher amplitude. This study provides insight on the importance of MBNMS to sperm whales and informs policy makers on potential effects that shipping may have on sperm whale behavior, while providing a novel method to analyze PAM data.
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