[MARMAM] New paper on prey selection by southern resident killer whales

Brad Hanson Brad.Hanson at noaa.gov
Wed Mar 17 15:09:18 PDT 2010

Dear Marmam subscribers

The following paper was recently published online in Endangered Species 

Hanson, M.B., R.W. Baird, J.K.B. Ford, J. Hempelmann-Halos, D.M. Van 
Doornik, J.R. Candy, C. K. Emmons, G. S. Schorr, B. Gisborne,  K.L. 
Ayres, S.K. Wasser, K.C. Balcomb, K. Balcomb-Bartok, J.G. Sneva, and 
M.J. Ford. 2010. Species and stock identification of prey consumed by 
endangered “southern resident” killer whales in their summer range. 
Endangered Species Research 11: 69–82

Available at http://www.int-res.com/abstracts/esr/v11/n1/p69-82/

Please contact Brad Hanson (brad.hanson at noaa.gov) with any questions

ABSTRACT: Recovery plans for endangered southern resident killer whales
/Orcinus orca/ have identified reduced prey availability as a risk to
the population. In order to better assess this risk, we studied prey
selection from 2004 to 2008 in 2 regions of the whales’ summer range:
San Juan Islands, Washington and the western Strait of Juan de Fuca,
British Columbia. Following the whales in a small boat, we collected
fish scales and tissue remains from predation events, and feces, using a
fine mesh net. Visual fish scale analysis and molecular genetic methods
were used to identify the species consumed. Chinook salmon, a relatively
rare species, was by far the most frequent prey item, confirming
previous studies. For Chinook salmon prey, we used genetic
identification methods to estimate the spawning region of origin. Of the
Chinook salmon sampled, 80 to 90% were inferred to have originated from
the Fraser River, and only 6 to 14% were inferred to have originated
from Puget Sound area rivers. Within the Fraser River, the Upper Fraser,
Middle Fraser, South Thompson River and Lower Fraser stocks were
inferred to currently be sequentially important sources of Chinook
salmon prey through the summer. This information will be of significant
value in guiding management actions to recover the southern resident
killer whale population.

M. Bradley Hanson, Ph.D.
NOAA/NMFS/Northwest Fisheries Science Center
2725 Montlake Blvd. E
Seattle, WA 98112

Office phone: 206-860-3220
Fax: 206-860-3400
Cell Phone 206-300-0282

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