Austen Thomas

PhD Candidate
Tel: 604.822.8181
Fax: 604.822.8180
E-mail: a.thomas@fisheries.ubc.ca

Education:

BSc – Biology (Western Washington University);  MSc – Marine and Estuarine Sciences (Western Washington University)

Research Interests: Foraging/Spatial ecology of top predators in marine ecosystems

Research Area: The Salish Sea

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Foraging behaviour and prey consumption of harbour seals (Phoca vitulina) in the Salish Sea.

Problem

For many decades harbour seals have been perceived to compete with fisheries for economically valuable fish resources.  This perception resulted in a population management strategy in both British Columbia and Washington that substantially reduced the number of harbour seals in the region’s inland waters (The Salish Sea).  Since their protection in the early 1970’s, harbour seal populations in the Salish Sea have rebounded vigorously and are once again under scrutiny for their consumption of valuable fish stocks, some of which are ESA/SARA listed species.

Research direction

Making informed decisions regarding harbour seal management requires understaning 1) the population structure and dynamics of harbour seals in the Salish Sea, 2) the quantities of prey consumed by harbour seals and where they acquire these resources, and 3) the seasonal foraging strategies used by harbour seals to meet their energetic demands.

 

 

Approach

We intend to employ a variety of techniques to further our understanding of harbour seal foraging ecology.  Aerial surveys will be conducted throughout the year to monitor the seasonal distribution and abundance of harbour seals in the region.  These data will be used to infer how seals respond to seasonal changes in fish distribution, and will provide an overall seal abundance estimate.  We will also analyze harbour seal prey remains (Hard parts and DNA) to reconstruct their diets.  Lastly, seal-mounted data loggers will be used to assess where and how harbour seals acquire their prey.

Previous work in the region

Click on the image below to see how harbour seals forage in 3D!

This video represents one month of foraging movements of a satellite tagged harbour seal from Protection Island, Washington.  The data are from my MSc project at Western Washington University, in collaboration with the Washington Department of Natural Resources.

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Publications:

Thomas AC, Lance MM, Jeffries SJ, Miner BG, Acevedo-Gutiérrez A (2011) Harbor seal foraging response to a seasonal resource pulse, spawning Pacific herring. Mar Ecol Prog Ser 441:225-239

Thomas AC (2010) The behavioral response of Harbor seals to seasonal prey pulses of spawning Pacific herring. M.S. Thesis, Western Washington University.

Haman KH, Norton TM, Thomas AC, Dove ADM, Tseng F (2012) Baseline health parameters and species comparisons among free-ranging Atlantic sharpnose (Rhyzoprionodon terraenovea), bonnethead (Sphyrna tiburo), and spiny dogfish (Squalus acanthias) sharks in Georgia, Florida, and Washington, USA.  Journal of Wildlife Diseases 48, 295-306.

Presentations:

Thomas, A. C., M. Lance, S. Jeffries, A. Acevedo-Gutiérrez (2010). The behavioral response of Harbor seals to seasonal prey pulses of spawning Pacific herring. AGU, 91(26), Ocean Sciences Meeting, Abstract BO45G-17

Thomas, A. C., M. Lance, S. Jeffries, A. Acevedo-Gutiérrez (2009). Selective foraging by harbor seals (Phoca vitulina): The importance of herring spawning and holding aggregations. 18th Biennial Conference on the Biology of Marine Mammals, 12 – 16 October, Quebec City, Canada.