Dear colleagues,
My co-authors and I are pleased to share our new publication from the
Orca Behavior Institute in Pacific Conservation Biology: "Declining
spring usage of core habitat by endangered fish-eating killer whales
reflects decreased availability of their primary prey."
Abstract:
The salmon-eating Southern Resident killer whales (/Orcinus orca/) of
the north-eastern Pacific Ocean are listed as endangered both in the
United States and Canada. Their critical habitat has been defined as the
region of the inland waters of Washington State and British Columbia
known as the Salish Sea, where they have traditionally spent much of
their time from spring through fall. Using reports from experienced
observers to sightings networks, we tracked the daily presence of the
Southern Residents in these waters from 1 April to 30 June from 1994
through 2016. We found that the escapement estimates of spring Chinook
salmon (/Oncorhynchus tshawytscha/) on the Fraser River in British
Columbia were a significant predictor of the cumulative presence/absence
of the whales throughout the spring season. There was also a difference
in both whale presence and salmon abundance before and after 2005,
suggesting that the crash in Chinook salmon numbers has fallen below
threshold where it is worthwhile for the whales to spend as much time in
the Salish Sea. The use of the Salish Sea by the Southern Residents has
declined in the spring months as they are either foraging for Chinook
salmon elsewhere or are shifting to another prey species. In order to
continue providing necessary protections to this endangered species,
critical habitat designations must be re-evaluated as this population of
killer whales shifts its range in response to prey availability.
Find it online here: https://doi.org/10.1071/PC17041
Or, for a PDF of the article, please contact me at
mon...@orcabehaviorinstitute.org
Best,
Monika Wieland Shields
President, Orca Behavior Institute
San Juan Island, Washington, USA
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