batch_auto_20260713 202607131256465730 BOEM ESP geoESPIS ESPIS@boem.gov Bureau of Ocean Energy Management Cook Inlet beluga acoustic monitoring in Lower Cook Inlet (LCI) rivers National Marine Fisheries Service, Alaska Regional Office National Oceanic and Atmospheric Administration Cook Inlet beluga (CIB) have been endangered since 2008 and have failed to recover from the overharvest that led to their drastic decline. Reasons for this lack of recovery are still unclear. Beluga are highly dependent on sound to communicate, navigate, and find prey, and chronic exposure to noise can lead to survival and reproduction impacts. Securing baseline information on habitat use and their soundscape is crucial in evaluating the current and future level of impacts from industry actions. Using passive acoustic monitoring methods, we documented the foraging occurrence and seasonality of CIB, together with orca, harbor porpoise and humpback whale from Sept. 2021-2022 in two historically important but recently overlooked bays and rivers (Chinitna and Tuxedni) on the west coast of lower Cook Inlet (LCI). Results revealed higher presence of harbor porpoise, orca and humpback whale in Chinitna, but lower CIB presence than in Tuxedni perhaps explained by high orca presence. Tuxedni Bay was identified as an important fall and winter foraging ground for CIB. The low level of anthropogenic noise disturbance quantified in both Chinitna Bay and Tuxedni Bay make these areas some of the most pristine and undisturbed sections of their critical habitat, but at the same time highly sensitive to further noise disturbance. Commercial shipping noise was the main anthropogenic noise source identified in both bays. Generating wideband and acute masking within the bays, this noise class is likely to lead to acoustic disturbance. We suggest a seasonal restriction for high sound producing anthropogenic activities, such as seismic surveys and pile driving, in and adjacent to Tuxedni Bay from September 1st to May 15th when CIB are present. 350000 U.S. Department of the Interior, Bureau of Ocean Energy Management, Environmental Studies Program https://doi.org/10.13039/100012475 M20PG00005 10.67297/9A1E5F https://boem.gov/awardpages/100319