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ESR 41:225-243 (2020)  -  DOI: https://doi.org/10.3354/esr01023

Seasonal distribution and foraging occurrence of Cook Inlet beluga whales based on passive acoustic monitoring

Manuel Castellote1,2,*, Robert J. Small3, Marc O. Lammers4, Justin Jenniges5, Jeffrey Mondragon3, Christopher D. Garner6, Shannon Atkinson7, Jade M. S. Delevaux4, Richard Graham8, Delmar Westerholt9

1Joint Institute for the Study of the Atmosphere and Ocean (JISAO), University of Washington, Seattle, WA 98105, USA
2Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, Seattle, WA 98115, USA
3Alaska Department of Fish and Game, Juneau, AK 99811, USA
4Oceanwide Science Institute, Honolulu, HI 96839, USA
5Alaska Department of Fish and Game, Douglas, AK 99824, USA
6Joint Base Elmendorf Richardson, US Air Force Conservation Department, 673 CES CEIEC, JBER, Anchorage, AK 99506, USA
7School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Juneau, AK 99801, USA
8Colorado State University, Fort Collins, CO 80523-1490, USA
9Off The Bottom, Anchorage, AK 99508, USA
*Corresponding author:

ABSTRACT: A paucity of information on the basic biology and ecology of Cook Inlet beluga whales Delphinapterus leucas remains a decade after the species was listed as endangered in 2008. The causes of its continued decline remain unclear. This lack of knowledge limits our understanding of, and ability to manage, potential threats impeding the recovery of this endangered population. Seasonal distribution and foraging ecology, particularly during winter, are currently among the most basic gaps in knowledge. Therefore, we conducted a year-round passive acoustic monitoring program from 2008-2013, monitoring 13 locations within the belugas’ critical habitat. We identified seasonal occurrence patterns across years at most locations. Detections were higher in the upper inlet during summer, peaking in known concentration areas. The occurrence of whales in the upper inlet when ice coverage peaked during winter was more prevalent than previously suggested. We documented seasonal differences in foraging habitat preference, with foraging behavior more prevalent during summer, particularly near upper inlet rivers, than during winter. Foraging peaks coincided with the presence of different anadromous fish runs from spring to fall. Low levels of feeding activity in winter suggest a lack of feeding aggregation areas, feeding in non-monitored offshore waters, or increased effort on benthic prey. These results represent a substantial contribution to our knowledge of Cook Inlet beluga seasonal distribution and foraging ecology, which will strengthen conservation and management strategies and thus more effectively promote recovery of this endangered population.


KEY WORDS: Cook Inlet beluga · Passive acoustic monitoring · Seasonal distribution · Foraging behavior


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Cite this article as: Castellote M, Small RJ, Lammers MO, Jenniges J and others (2020) Seasonal distribution and foraging occurrence of Cook Inlet beluga whales based on passive acoustic monitoring. Endang Species Res 41:225-243. https://doi.org/10.3354/esr01023

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