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Cetacean Assessment & Ecology Program

Spatio-Temporal Movement Patterns of Two Alaskan Beluga Whale Stocks Based on Acoustic Detections (cont.) (pg 1, 2, 3)

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refer to caption

Figure. 3. Beluga acoustic detections from September 2010 to September 2011 on the four recorders located in the western Beaufort, northeastern Chukchi, and northern Bering Seas. Arrows indicate the stock/population origin(s) of acoustic detections from the current study based on satellite-tagging studies of the eastern Chukchi Sea (ECS) stock (white arrows) and the eastern Beaufort Sea (EBS) stock (black arrows) in the a) Beaufort Sea, b) “inshore” northeastern Chukchi Sea, c) “offshore” northeastern Chukchi Sea, and d) Bering Sea. Colors indicate mooring locations shown in Figure 2.

The peaks in beluga call detections from passive acoustic monitoring presented here agree with the overall understanding of the seasonal migration of two beluga populations in Alaskan Arctic waters (e.g., Hauser et al. 2014).  However, our data provide a finer scale of temporal detail to allow investigation of the population origin of each peak. After overwintering in the Bering Sea, belugas from the EBS and ECS stocks migrated north through the northeastern Chukchi and western Beaufort Seas in multiple waves, which were temporally distinct. Inclusion of all data (100%) into analyses has provided a robust assessment of the fine-scale timing of movements. These results suggest peaks in vocal activity are able to capture fine-scale temporal movements of populations when temporal or spatial differences between detection peaks are large enough to be identified as independent events. Additional studies are already underway to investigate the vocal repertoire of each population to evaluate the feasibility of using differences in dialects to identify each population.

Table 1. Location of each long-term recorder and deployment information.
Location Latitude (N) Longitude (W) Depth (m) Recording date Length (days) Sampling rate (Hz) Duty cycle
Start End
Bering Sea 62.1960000 174.6588333 70 10/03/2010 02/01/2011 120 8,192 8 min/20 min       
“Inshore” Chukchi Sea 70.7983833 163.0811167 43 09/10/2010 06/27/2011 291 16,384 95 min/300 min  
“Offshore” Chukchi Sea 71.8339500 165.9033000 44 09/10/2010 06/08/2011 272 16,384 95 min/300 min  
Western Beaufort Sea 71.6880333 153.1739833 105 09/20/2010 08/22/2011 337 8,192 9 min/20 min      



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