Bowhead and beluga whale acoustic detections in the western Beaufort Sea 2008-2018.

Kathleen M Stafford,John J Citta,Jinlun Zhang,Stephen R Okkonen,William David Halliday

doi:10.1371/journal.pone.0253929

Abstract

The Distributed Biological Observatory (DBO) was established to detect environmental changes in the Pacific Arctic by regular monitoring of biophysical responses in each of 8 DBO regions. Here we examine the occurrence of bowhead and beluga whale vocalizations in the western Beaufort Sea acquired by acoustic instruments deployed from September 2008-July 2014 and September 2016-October 2018 to examine inter-annual variability of these Arctic endemic species in DBO Region 6. Acoustic data were collected on an oceanographic mooring deployed in the Beaufort shelfbreak jet at ~71.4°N, 152.0°W. Spectrograms of acoustic data files were visually examined for the presence or absence of known signals of bowhead and beluga whales. Weekly averages of whale occurrence were compared with outputs of zooplankton, temperature and sea ice from the BIOMAS model to determine if any of these variables influenced whale occurrence. In addition, the dates of acoustic whale passage in the spring and fall were compared to annual sea ice melt-out and freeze-up dates to examine changes in phenology. Neither bowhead nor beluga whale migration times changed significantly in spring, but bowhead whales migrated significantly later in fall from 2008–2018. There were no clear relationships between bowhead whales and the environmental variables, suggesting that the DBO 6 region is a migratory corridor, but not a feeding hotspot, for this species. Surprisingly, beluga whale acoustic presence was related to zooplankton biomass near the mooring, but this is unlikely to be a direct relationship: there are likely interactions of environmental drivers that result in higher occurrence of both modeled zooplankton and belugas in the DBO 6 region. The environmental triggers that drive the migratory phenology of the two Arctic endemic cetacean species likely extend from Bering Sea transport of heat, nutrients and plankton through the Chukchi and into the Beaufort Sea.

Highlights

The Arctic, the Pacific Arctic, is where climate change is having the most dramatic effect on the environment [1]
We examined whether environmental drivers that appear to drive the occurrence of bowhead and beluga whales near Barrow Canyon [22,23,24,25,26] function in a similar manner in Distributed Biological Observatory (DBO) region 6
In the late fall and winter of 2016–2017 bowhead whales were in the region into January, suggesting that they were only absent from the Beaufort Sea for 2 months before returning in April

Summary

Introduction

The Arctic, the Pacific Arctic, is where climate change is having the most dramatic effect on the environment [1]. First in 2007 and in 2012, sea ice extent in the Arctic. Agreement M07RG13317 with the U.S Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, as part of the BOEM Alaska Environmental Studies Program. Funding was provided to JZ by the National Science Foundation PLR-1602985 NNA-1927785

Methods

Results

Conclusion