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Date Permissions Signed


Date of Award

Summer 2021

Document Type

Masters Thesis

Department or Program Affiliation

Biology, Marine and Estuarine Program (MESP)

Degree Name

Master of Science (MS)



First Advisor

Acevedo-Gutiérrez, Alejandro, 1964-

Second Advisor

Schwarz, Dietmar, 1974-

Third Advisor

Anderson, Roger A. (Roger Allen)


The complexities of trophic dynamics complicate the management of predator populations. In some cases, targeted culling campaigns are meant to control predator populations. In these campaigns, predators are considered ‘rogue individuals’ based on visitation rates to a site. This definition carries the underlying assumption that all predators impact prey equally, however, individual variability in foraging success may compromise such an assumption. Thus, to test the hypothesis that foraging success varies among individual predators, I studied harbor seals preying on adult Pacific Salmon during the 2014-2019 fall salmon runs. I analyzed individual harbor seal visitation rate and foraging success based on photographs and field observations, and I employed Generalized Linear Mixed-Effects Models to determine individual variability in metrics of foraging success. Individual harbor seal identity better explained both total foraging success and the odds of success of a given foraging event when compared to models based on visitation rate alone. My data suggest that considering intraspecific variability and classifying ‘rogue individuals’ based on foraging success is a more accurate protocol for managing predator populations than relying solely on visitation rate of the predators.




predator, prey, trophic, management, culling, rogue individual, harbor seal, Pacific salmon, Phoca vitulina, Oncorhynchus spp.


Western Washington University

OCLC Number


Subject – LCSH

Harbor seal--Food--Washington (State)--Whatcom Creek; Pacific salmon--Predators of--Control--Washington (State)--Whatcom Creek; Food chains (Ecology)--Washington (State)--Whatcom Creek; Predation (Biology)--Washington (State)--Whatcom Creek

Geographic Coverage

Bellingham (Wash.)




masters theses




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