title: Decadal shifts in autumn migration timing by Pacific Arctic beluga whales are related to delayed annual sea ice formation.
abstract: Migrations are often influenced by seasonal environmental gradients that are increasingly being altered by climate change. The consequences of rapid changes in Arctic sea ice have the potential to affect migrations of a number of marine species whose timing is temporally matched to seasonal sea ice cover. This topic has not been investigated for Pacific Arctic beluga whales (Delphinapterus leucas) that follow matrilineally maintained autumn migrations in the waters around Alaska and Russia. For the sympatric Eastern Chukchi Sea ('Chukchi') and Eastern Beaufort Sea ('Beaufort') beluga populations, we examined changes in autumn migration timing as related to delayed regional sea ice freeze-up since the 1990s, using two independent data sources (satellite telemetry data and passive acoustics) for both populations. We compared dates of migration between 'early' (1993-2002) and 'late' (2004-2012) tagging periods. During the late tagging period, Chukchi belugas had significantly delayed migrations (by 2 to >4 weeks, depending on location) from the Beaufort and Chukchi seas. Spatial analyses also revealed that departure from Beaufort Sea foraging regions by Chukchi whales was postponed in the late period. Chukchi beluga autumn migration timing occurred significantly later as regional sea ice freeze-up timing became later in the Beaufort, Chukchi, and Bering seas. In contrast, Beaufort belugas did not shift migration timing between periods, nor was migration timing related to freeze-up timing, other than for southward migration at the Bering Strait. Passive acoustic data from 2008 to 2014 provided independent and supplementary support for delayed migration from the Beaufort Sea (4 day yr-1) by Chukchi belugas. Here, we report the first phenological study examining beluga whale migrations within the context of their rapidly transforming Pacific Arctic ecosystem, suggesting flexible responses that may enable their persistence yet also complicate predictions of how belugas may fare in the future.
authors.affiliation: School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA, 98105, USA.|Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA, 98105, USA.
authors.forename: Donna D W
authors.initials: DDW
authors.lastname: Hauser
authors.affiliation: School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA, 98105, USA.|Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA, 98105, USA.
authors.forename: Kristin L
authors.initials: KL
authors.lastname: Laidre
authors.affiliation: Applied Physics Laboratory, University of Washington, Seattle, WA, 98105, USA.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Stafford
authors.affiliation: Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA, 98105, USA.
authors.forename: Harry L
authors.initials: HL
authors.lastname: Stern
authors.affiliation: North Slope Borough, Department of Wildlife Management, PO Box 69, Barrow, AK, 99723, USA.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Suydam
authors.affiliation: Freshwater Institute, Fisheries & Oceans Canada, 501 University Crescent, Winnipeg, MB, R3T 2N6, Canada.
authors.forename: Pierre R
authors.initials: PR
authors.lastname: Richard
mesh_terms: D000413:Alaska; D025041:Animal Migration; D000818:Animals; D001110:Arctic Regions; D050643:Beluga Whale; D057231:Climate Change; D046448:Ice Cover; D009792:Oceans and Seas; D012426:Russia; D014907:Whales
keywords: Beaufort Sea; Bering Sea; Chukchi Sea; cetacean; climate change; foraging ecology; marine mammal; passive acoustics; phenology; satellite telemetry