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Date Permissions Signed

8-4-2022

Date of Award

Summer 2022

Document Type

Masters Thesis

Department or Program Affiliation

Biology, Marine and Estuarine Science Program (MESP)

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Acevedo-Gutiérrez, Alejandro, 1964-

Second Advisor

Zinkgraf, Matthew

Third Advisor

Thomas, Austen C.

Abstract

Rebounding pinniped populations have led to conflicts with fisheries over commercially important prey species. Acoustic deterrent devices (ADDs) are used to aid the recovery of depleted fish stocks by mitigating pinniped predation. However, most ADDs use painful sound signals, which can lead to hearing loss and habituation. Alternatively, a new ADD called Targeted Acoustic Startle Technology (TAST) decreases pinniped predation with no evidence of harm or habituation, but effects on the foraging success of individual pinnipeds is unknown. In the Salish Sea, harbor seal (Phoca vitulina) populations have rebounded since the early 1970’s and are suspected of impeding the recovery of Pacific salmon (Oncorhynchus spp.). In fall 2020, TAST was deployed to deter harbor seals that reliably aggregate in the mouth of Whatcom Creek in Bellingham, WA, from preying on fall runs of hatchery chum (O. keta) and Chinook (O. tshawytscha) salmon. Field observations were conducted between 2019-2021 to assess the shortterm (2020 fall salmon run only) and long-term (2019-2021 salmon runs) effectiveness of TAST on mitigating harbor seal predation. Analyses showed that TAST significantly decreased the duration that individuals remained at the creek but had variable effects on the foraging success of individuals in 2020. Generalized Linear Models showed no lingering effect of TAST on the presence or foraging success of seals the following year. I conclude that TAST may be an effective management tool in the short-term, but individual variability must be accounted for when managing predation by pinnipeds on depleted fishery species.

Type

Text

Keywords

harbor seal, Pacific salmon, pinniped management, acoustic deterrents, management tools, hazing devices, conservation conflict

Publisher

Western Washington University

OCLC Number

1341304364

Subject – LCSH

Harbor seal--Food--Washington (State)--Whatcom Creek; Harbor seal--Effect of noise on--Washington (State)--Whatcom Creek; Pacific salmon--Predators of--Control--Washington (State)--Whatcom Creek; Underwater acoustics--Washington (State)--Whatcom Creek

Geographic Coverage

Whatcom Creek (Wash.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

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

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