The migration of fin whales into the southern Chukchi Sea as monitored with passive acoustics

Abstract

Fin whales (Balaenoptera physalus) undergo seasonal migration in the Arctic Sea. Because their migration and distribution is likely affected by changes in global climate, we aimed to examine the migration timing of fin whales, and the relationship with prey availability within the oceanographic environment of the Arctic Sea, using passive and active acoustic monitoring methods. Automatic Underwater Sound Monitoring Systems were deployed in the southern Chukchi Sea from July 2012 to 2014 to determine the acoustic presence of fin whales. Furthermore, water temperature and salinity were recorded by a fixed data logger. An Acoustic Zooplankton Fish Profiler was additionally deployed to estimate prey abundance through backscattering strength. Sea ice concentrations were obtained by remote sensing data. Fin whale calls were automatically detected using a custom-made software, and the per cent of half-hours containing calls were counted. Fin whale calls were detected from 4 August to 20 October 2012 (78 d) and 25 July to 1 November 2013 (100 d). The extended period of acoustic presence of fin whales during 2013 when compared with 2012 is likely related to a longer ice-free period during 2013. Furthermore, generalized linear model analyses showed that half-hour periods containing calls increased with a rise in water temperature and zooplankton abundance during the initial call presence period, while they decreased with a decrease in water temperature and salinity during the end of the call presence period. Our results suggest that the rise in water temperature and zooplankton abundance affect the timing of migration of fin whales in a way that is consistent with the expansion of their suitable habitats and the extension of their presence in the Arctic Sea.

Timing is everything: Drivers of interannual variability in blue whale migration

“…Nishiwaki 29 was the first to suggest that changes in SST might influence the timing of humpback whale (Megaptera novaeangliae) arrival on their wintering grounds. Visser et al 30 tied the timing of peak baleen whale abundance in the Azores to rising SSTs following the spring bloom, and Tsujii et al 31 found that water temperature was a good predictor of fin whale (Balaenoptera physalus) arrival and departure in the southern Chukchi Sea. Our study demonstrates how oceanographic conditions influence migration timing, but also suggests the use of memory.…”

Fin whale (Balaenoptera physalus) migration in Australian waters using passive acoustic monitoring

“…This difference in migration timing between coasts could be due to fin whales leaving Antarctic waters at different times, reflecting variation in the timing of annual sea ice formation in different regions of Antarctica. Fin whales migrate away from polar regions when sea ice increases 22,36,44,46,47 . The origin of the migrating animal could also affect the travel and arrival time of the whales.…”

Acoustic documentation of temperate odontocetes in the Bering and Chukchi Seas

“…, Tsujii et al . ). Corresponding taxonomic names include Megaptera novaeangliae (Borowski 1781), Balaenoptera physalus (Linnaeus 1758), Balaenoptera acutorostrata (Lacépède 1804), and Orcinus orca (Linnaeus 1758), respectively.…”