Novel diet profile of coastal Washington Steller sea lion (Eumetopias jubatus) stocks: Investigating predation impacts on the iconic Chinook salmon (Oncorhynchus tshawytscha)
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Presentation Abstract
Novel diet profile of coastal Washington Steller sea lion (Eumetopias jubatus) stocks: Investigating predation impacts on the iconic Chinook salmon (Oncorhynchus tshawytscha) Chinook salmon are an iconic species in the Pacific Northwest and fulfill critical cultural, economic and ecosystem functions. Despite decreasing numbers taken by commercial and recreational fishing, coastal Chinook salmon populations continue to decline. These salmon migrate through the Strait of Juan de Fuca from their spawning rivers to the ocean, where they reside along the northwest coast of Washington State and mature before returning to the Salish Sea during the winter and spring months. Previous research shows that recovering pinniped populations are consuming large amounts of Chinook salmon. However, this research has focused on the predation impacts of pinniped species near estuarine environments located within the Salish Sea. Consequently, there are spatial gaps in diet data, particularly along the coast of Washington, leading to an incomplete understanding of Chinook salmon mortality in this area. In this study, we collected 300 Steller sea lion scats between December 2020-August 2021 within the Usual and Accustomed fishing grounds of the Makah Tribe. We profiled the diet of Steller sea lions using molecular scatology and hard parts analysis to describe number and species of salmonids and other prey items consumed. Further, we used qPCR methods to determine sex of the pinniped depositor and investigated differential impacts of sex-biased predation. These diet proportion data will be used to estimate the amount of Chinook biomass consumed by Steller sea lions on the Washington coast to help inform management of coastal pinniped populations.
Session Title
Marine Mammals
Conference Track
SSE3: The Circle of Life
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-traditionals-265
Start Date
26-4-2022 11:30 AM
End Date
26-4-2022 1:00 PM
Type of Presentation
Oral
Genre/Form
conference proceedings; presentations (communicative events)
Subjects – Topical (LCSH)
Steller's sea lion--Control--Salish Sea (B.C. and Wash.); Pacific salmon--Predators of--Control--Salish Sea (B.C. and Wash.); Pacific salmon--Conservation--Salish Sea (B.C. and Wash.)
Geographic Coverage
Salish Sea (B.C. and Wash.)
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.
Type
Text
Language
English
Format
application/pdf
Novel diet profile of coastal Washington Steller sea lion (Eumetopias jubatus) stocks: Investigating predation impacts on the iconic Chinook salmon (Oncorhynchus tshawytscha)
Novel diet profile of coastal Washington Steller sea lion (Eumetopias jubatus) stocks: Investigating predation impacts on the iconic Chinook salmon (Oncorhynchus tshawytscha) Chinook salmon are an iconic species in the Pacific Northwest and fulfill critical cultural, economic and ecosystem functions. Despite decreasing numbers taken by commercial and recreational fishing, coastal Chinook salmon populations continue to decline. These salmon migrate through the Strait of Juan de Fuca from their spawning rivers to the ocean, where they reside along the northwest coast of Washington State and mature before returning to the Salish Sea during the winter and spring months. Previous research shows that recovering pinniped populations are consuming large amounts of Chinook salmon. However, this research has focused on the predation impacts of pinniped species near estuarine environments located within the Salish Sea. Consequently, there are spatial gaps in diet data, particularly along the coast of Washington, leading to an incomplete understanding of Chinook salmon mortality in this area. In this study, we collected 300 Steller sea lion scats between December 2020-August 2021 within the Usual and Accustomed fishing grounds of the Makah Tribe. We profiled the diet of Steller sea lions using molecular scatology and hard parts analysis to describe number and species of salmonids and other prey items consumed. Further, we used qPCR methods to determine sex of the pinniped depositor and investigated differential impacts of sex-biased predation. These diet proportion data will be used to estimate the amount of Chinook biomass consumed by Steller sea lions on the Washington coast to help inform management of coastal pinniped populations.
