Odontocete foraging vocalizations during various Cold Pool states in the Bering Sea

Abstract

The Cold Pool is a subsurface layer (<2°C) that is formed in the summer from stratification and is characterized by previous winter conditions. This bottom layer of relatively cooler temperatures impacts zooplankton dynamics, driving two different energetic pathways. The cold regime pathway favors larger zooplankton species, which increases forage fish biomass while the warm regime pathway favors smaller zooplankton species, which decreases forage fish biomass. Since odontocetes rely on forage fish for survival and use echolocation to find them, tracking foraging vocalizations could lead to a better understanding of the implications of a variable Cold Pool on the Bering Sea’s food web. The Cold Pool was more variable in warm regime years (2014–2017) relative to cold regime years (2007–2013) and was absent in 2018 at this study site. Concurrently, acoustic data with odontocete vocalizations were collected. This presentation will discuss whether odontocete vocal presence is related to Cold Pool dynamics and if odontocete foraging behavior changes as a function of Cold Pool variability. Since a reduced presence of the Cold Pool could occur more often with climate change, it is important to monitor the higher trophic levels’ foraging activities to predict what ecosystem changes could occur in the future.