Temporal peaks in beluga whale (Delphinapterus leucas) acoustic detections in the northern Bering, northeastern Chukchi, and western Beaufort Seas: 2010–2011

Abstract

Two populations of beluga whales (Delphinapterus leucas) migrate annually between their summering grounds in the eastern Chukchi and eastern Beaufort Seas, and overwintering areas in the Bering Sea. To contribute to the understanding of migratory streams of this highly vocal species, we investigated temporal peaks in acoustic detections from 4-year-long (2010–2011) recorders located in the northeastern Chukchi (inshore and offshore), western Beaufort, and northern Bering Seas. Beluga calls were detected throughout summer (July–August) in the western Beaufort; other studies suggest these animals are likely from the eastern Chukchi population. In autumn (September–November), calls were detected in the western Beaufort and northeastern Chukchi, which were likely from both the eastern Beaufort and eastern Chukchi populations. A strong peak at the inshore northeastern Chukchi site occurred in late-November; this peak is likely to be from the eastern Chukchi population. During spring, beluga calls were detected in the northeastern Chukchi and western Beaufort in two distinct vocal peaks (early- and late-May). The timing was consistent with the hypothesis that both vocal peaks were caused by the eastern Beaufort population. This suggests that migration of populations can be discriminated when temporal differences between vocal peaks are large enough to be identified as independent events. Our study results complement and support the population identity of peaks suggested by satellite telemetry, aerial surveys, and other acoustical studies. Passive acoustic monitoring improves our understanding of the migratory timing of beluga populations for management and conservation in a region undergoing rapid change.