Q: Is swimming good for your figure? A: If swimming is good for your figure, explain whales to me.
Decadal shifts in autumn migration timing by Pacific Arctic beluga whales are related to delayed annual sea ice formation.
- 1School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA, 98105, USA.
- 2Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA, 98105, USA.
- 3Applied Physics Laboratory, University of Washington, Seattle, WA, 98105, USA.
- 4North Slope Borough, Department of Wildlife Management, PO Box 69, Barrow, AK, 99723, USA.
- 5Freshwater Institute, Fisheries & Oceans Canada, 501 University Crescent, Winnipeg, MB, R3T 2N6, Canada.
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.
© 2016 John Wiley & Sons Ltd.
KEYWORDS:
Beaufort
Sea; Bering Sea; Chukchi Sea; cetacean; climate change; foraging
ecology; marine mammal; passive acoustics; phenology; satellite
telemetry
