Dear colleagues,
My co-authors and I are pleased to announce the publication of the
following article:
Endangered predators and endangered prey: seasonal diet of Southern
Resident killer whales. Hanson, M.B., C.K. Emmons, M.J. Ford, M.
Everett, K. Parsons, L.K. Park, J. Hempelmann, D.M. Van Doornik, G.S.
Schorr, J.K. Jacobsen, M.F. Sears, M.S. Sears, J.G. Sneva, R.W. Baird,
L. Barre. 2021. PLoS ONE 16(3): e0247031.
doi:10.1371/journal.pone.0247031
ABSTRACT
Understanding diet is critical for conservation of endangered predators.
Southern Resident killer whales (SRKW) (/Orcinus orca/) are an
endangered population occurring primarily along the outer coast and
inland waters of Washington and British Columbia. Insufficient prey has
been identified as a factor limiting their recovery, so a clear
understanding of their seasonal diet is a high conservation priority.
Previous studies have shown that their summer diet in inland waters
consists primarily of Chinook salmon (/Oncorhynchus tshawytscha/),
despite that species’ rarity compared to some other salmonids. During
other times of the year, when occurrence patterns include other portions
of their range, their diet remains largely unknown. To address this data
gap, we collected feces and prey remains from October to May 2004-2017
in both the Salish Sea and outer coast waters. Using visual and genetic
species identification for prey remains and genetic approaches for fecal
samples, we characterized the diet of the SRKWs in fall, winter, and
spring. Chinook salmon were identified as an important prey item
year-round, averaging ~50% of their diet in the fall, increasing to
70-80% in the mid-winter/early spring, and increasing to nearly 100% in
the spring. Other salmon species and non-salmonid fishes, also made
substantial dietary contributions. The relatively high species diversity
in winter suggested a possible lack of Chinook salmon, probably due to
seasonally lower densities, based on SRKW’s proclivity to selectively
consume this species in other seasons. A wide diversity of Chinook
salmon stocks were consumed, many of which are also at risk. Although
outer coast Chinook samples included 14 stocks, four rivers systems
accounted for over 90% of samples, predominantly the Columbia River.
Increasing the abundance of Chinook salmon stocks that inhabit the
whales’ winter range may be an effective conservation strategy for this
population.
The open-access article can be downloaded from
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0247031
<https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0247031>
Any additional questions can be directed to me via email at
[email protected] <mailto:[email protected]>
Sincerely,
Brad Hanson
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M. Bradley Hanson, Ph.D.
NOAA/NMFS/Northwest Fisheries Science Center
2725 Montlake Blvd. E
Seattle, WA 98112
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