The acoustic presence of sperm whales (Physeter macrocephalus) at Ocean Station PAPA in the Gulf of Alaska 2007–2012

Abstract

Sperm whale (Physeter macrocephalus) populations were severely depleted by commercial whaling worldwide in the 18th through the 20th century. Consequently, in 1970, this species was listed in the United States as an endangered species. To date, accurate information on the abundance and distribution of sperm whales in offshore areas of the North Pacific are scant. Sperm whales regularly produce high intensity sounds for navigation, prey detection, and communication. Thus, this species can be very effectively monitored using passive acoustic techniques especially in remote and inaccessible locations such as the Gulf of Alaska (GOA). In this study, a Passive Aquatic Listener (PAL) was deployed at Ocean Station PAPA (50°N, 145°W) in the GOA between 2007 and 2012 to monitor the seasonal occurrence of sperm whales in the area. Preliminary results indicate that within the 5-year deployment period sperm whales were acoustically present year round and that the number of acoustic sperm whale detections showed a seasonal trend with slightly higher numbers during the summer months. We are currently investigating the linkage between the occurrence of sperm whales and environmental conditions (e.g., Pacific Decadal Oscillation index) in the study area. [Funding from the Office of Naval Research.]