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Date Permissions Signed

7-1-2010

Date of Award

2010

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Acevedo-Gutiérrez, Alejandro, 1964-

Second Advisor

Donovan, Deborah Anne, 1964-

Third Advisor

Miner, Benjamin G., 1972-

Abstract

The Pacific harbor seal (Phoca vitulina) is a noteworthy omission from the list of predators that aggregate at herring spawning sites, despite strong suggestive evidence that they are likely to respond to herring pulses. Working with the hypothesis that spawning herring aggregations are seasonally important prey for harbor seals, we tested several predictions using an analysis of harbor seal prey remains, GPS telemetry, and satellite-linked time/depth recorder data. Contrary to predictions, herring in harbor seal diet was comprised of 77% juveniles and 23% adults in the spawn season, versus 33% juveniles and 67% adults in the post-spawn season. Seal diving focus peaked at night during the post-spawn season, and seals exhibited less diving effort during the spawn season. Harbor seals did not however appear to alter their foraging behaviors to take advantage of spawning herring aggregations. The lack of response by harbor seals to spawning herring pulses is likely explained by seasonal differences in adult herring profitability, the availability of alternative prey, or a decline in local herring biomass.

Type

Text

Publisher

Western Washington University

OCLC Number

649825369

Digital Format

application/pdf

Geographic Coverage

Puget Sound (Wash.)

Genre/Form

Academic theses

Language

English

Rights

Copying of this thesis in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

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