Event Title

Characterizing juvenile Chinook salmon outmigration timing, size and population origin in the Fraser River estuary

Presentation Abstract

Estuaries connect freshwater and ocean environments for Pacific salmon, providing important habitats during a crucial transition period for juveniles. Juvenile salmon from multiple populations migrate through the Fraser River estuary, British Columbia, annually, but little is known about out-migration timing, migratory pathways, estuary residence, or habitat preferences of different populations. We conducted a spatio-temporally extensive juvenile salmon monitoring program throughout the Fraser River delta over the last two years (2016-17), surveying salmon at 20 sites that span Roberts and Sturgeon Banks and encompass three habitat types using beach and purse seine methods. Our objective was to determine the outmigration timing, size, residency time, and population origin of juvenile Chinook across the estuary and the outmigration season. Over two seasons we have captured 3,240 juvenile Chinook, the majority in brackish marsh habitats, and have collected 838 tissue samples for genetic stock identification. Our initial results demonstrate that in both 2016 and 2017 ocean-type Chinook originating from the Harrison River made up the majority of our genetic samples, arriving the earliest near the end of March, and present the longest until mid-July in 2016 and mid-June in 2017. Harrison Chinook arrive the smallest, with individuals increasing in mean fork length over the season, potentially indicating estuarine growth. Conversely, ocean-type Chinook from the South Thompson were not captured until late June in both years, arriving in the estuary in the 60 – 80 mm fork length range and were last detected in mid-July in both years. Overall we have captured juvenile Chinook from 18 different populations with stream-type populations generally captured in very low numbers. We discuss how this research provides significant insight into several of the key hypotheses of the Salish Sea Marine Survival project including relating stock specific information to recent trends in marine survival.

Session Title

The Lower Fraser River: A Wildlife Hotspot on the Brink

Conference Track

SSE4: Ecosystem Management, Policy, and Protection

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE4-147

Start Date

6-4-2018 11:15 AM

End Date

6-4-2018 11:30 AM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

This document is currently not available here.

Share

COinS
 
Apr 6th, 11:15 AM Apr 6th, 11:30 AM

Characterizing juvenile Chinook salmon outmigration timing, size and population origin in the Fraser River estuary

Estuaries connect freshwater and ocean environments for Pacific salmon, providing important habitats during a crucial transition period for juveniles. Juvenile salmon from multiple populations migrate through the Fraser River estuary, British Columbia, annually, but little is known about out-migration timing, migratory pathways, estuary residence, or habitat preferences of different populations. We conducted a spatio-temporally extensive juvenile salmon monitoring program throughout the Fraser River delta over the last two years (2016-17), surveying salmon at 20 sites that span Roberts and Sturgeon Banks and encompass three habitat types using beach and purse seine methods. Our objective was to determine the outmigration timing, size, residency time, and population origin of juvenile Chinook across the estuary and the outmigration season. Over two seasons we have captured 3,240 juvenile Chinook, the majority in brackish marsh habitats, and have collected 838 tissue samples for genetic stock identification. Our initial results demonstrate that in both 2016 and 2017 ocean-type Chinook originating from the Harrison River made up the majority of our genetic samples, arriving the earliest near the end of March, and present the longest until mid-July in 2016 and mid-June in 2017. Harrison Chinook arrive the smallest, with individuals increasing in mean fork length over the season, potentially indicating estuarine growth. Conversely, ocean-type Chinook from the South Thompson were not captured until late June in both years, arriving in the estuary in the 60 – 80 mm fork length range and were last detected in mid-July in both years. Overall we have captured juvenile Chinook from 18 different populations with stream-type populations generally captured in very low numbers. We discuss how this research provides significant insight into several of the key hypotheses of the Salish Sea Marine Survival project including relating stock specific information to recent trends in marine survival.