Passive Acoustic Monitoring of Cook Inlet Beluga Whales

The endangered beluga whale (Delphinapterus leucas) population in Cook Inlet, Alaska faces threats from a variety of anthropogenic factors, including coastal development, oil and gas exploration, vessel traffic, and military activities. To address existing gaps in understanding about the occurrence of belugas in Cook Inlet, a project using passive acoustic monitoring was developed to document the year-round distribution of belugas, as well as killer whales (Orcinus orca), which prey on belugas. Beginning in June 2009, ten moorings were deployed throughout the Inlet and refurbished every two to eight months. Despite challenging conditions consisting of strong tidal currents carrying debris and seasonal ice cover, 83 percent of mooring deployments were successfully recovered. Noise from water flow, vessel traffic, and/or industrial activities was present at several sites, potentially masking some signals. However, belugas were successfully detected at multiple locations. Detections were relatively common in the upper inlet and less common or absent at middle and lower inlet locations. Killer whale signals were also recorded. Some seasonal variability in the occurrence of both belugas and killer whales was evident.

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Marc O. Lammers, Manuel Castellote, Robert J. Small, Shannon Atkinson, Justin Jenniges, Anne Rosinski, Julie N. Oswald, and Chris Garner. Published in Acoustical Society of America, September 2013.