Interannual variability in acoustic detection of blue and fin whale calls in the Northeast Atlantic High Arctic between 2008 and 2018

H Ahonen,Cl Berchok,Km Kovacs,C Lydersen,Km Stafford,Se Moore

doi:10.3354/esr01132

H Ahonen, Cl Berchok + Show 4 more

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https://doi.org/10.3354/esr01132

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Abstract

Northern Hemisphere blue and fin whales are regular summer migrants to Arctic waters. Given the profound changes the Arctic is currently undergoing due to global warming, changes in habitat use and distribution of these migratory species are predicted. In this study, 3 passive acoustic recorders, 2 in Fram Strait about 95 km apart and 1 north of the Svalbard Archipelago (Atwain), were used to investigate the spatial and temporal vocal occurrence of these species in the Northeast Atlantic High Arctic. Acoustic data were available for 7 years for western Fram Strait (WFS), 2.5 years for central Fram Strait (CFS) and 3 years for Atwain. At both Fram Strait locations, most blue whale call detections occurred from August through October, though recently (2015-2018) in WFS a clear increase in blue whale call rates was detected in June/July, suggesting an expansion of the seasonal occurrence of blue whales. In WFS, fin whale calls were detected intermittently, at low levels, almost year-round. In CFS, fin whale calls were more frequent but occurred mainly from July through December. At Atwain, blue whale detections commenced in July, both species were recorded in September/October and fin whale calls extended into November. Results from this study provide novel long-term baseline information about the occurrence of blue and fin whales at extreme northerly locations, where traditional ship-based survey methods are seasonally limited. Continued sampling will support investigation of how environmental change influences cetacean distribution and habitat use.

Highlights

Blue whales Balaenoptera musculus and fin whales B. physalus have worldwide distributions ranging from tropical to polar regions (Cooke 2018a,b)
Visual surveys have been the only source of distribution and abundance information for these northern areas (Moore et al 2019)
A recent study that included 13 yr of cetacean sighting data from around the Svalbard Archipelago suggested an increase in numbers of observations in recent years, it is important to note that tourist operations increased in the region during the study period

Summary

Introduction

Blue whales Balaenoptera musculus and fin whales B. physalus have worldwide distributions ranging from tropical to polar regions (Cooke 2018a,b). These fast-swimming rorqual whales became the focus of commercial exploitation in the 1900s, due to the development of faster vessels and highly effective harpoons. Endang Species Res 45: 209–224, 2021 around Svalbard and along the coast of northern Norway, blue whales continue to be rare and there has been no assessment of their numbers in this region since 1996 (Pike et al 2009). There has been a notable increase in the number of reported sightings of migratory species, such as blue and fin whales, in the Svalbard area over recent decades (Storrie et al 2018)

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