Event Title

Identifying Critical Periods of Growth and Mortality in Pacific Salmon and Deciphering Underlying Mechanisms

Presentation Abstract

Size-selective mortality (SSM) is a significant force regulating recruitment of salmon. The life stage(s) and habitat(s) in which SSM occurs can vary among species, stocks, and life history strategies. Moreover, the relationship between juvenile growth and survival is unclear for most salmon stocks. The first marine growth season is commonly regarded as a critical period for growth and survival. For ESA-listed Puget Sound Chinook salmon, preliminary studies suggest that: at least one critical period occurs during the first marine growth season; growth is limited more by food supply than energetic quality of prey or thermal regime; and higher growth and survival rates correspond with higher contributions of key prey like crab larvae.

We can identify critical periods using scales to create growth histories of a juvenile cohort sampled serially at successive life stages throughout its first marine growth season. Divergences in growth trajectories indicate reduced contributions of smaller members to subsequent life stages. These divergences indicate critical periods of growth and survival and the magnitude of SSM. We can diagnose factors affecting growth during critical periods through bioenergetics modeling simulations linked to directed sampling of diet, growth and environmental conditions. This approach could improve run forecasting and focus restoration efforts.

Session Title

The Salish Sea Marine Survival Project- Novel Approaches, Project Status and Key Findings

Conference Track

Species and Food Webs

Conference Name

Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)

Document Type

Event

Location

2016SSEC

Type of Presentation

Oral

Contributing Repository

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

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Type

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Language

English

Format

application/pdf

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Identifying Critical Periods of Growth and Mortality in Pacific Salmon and Deciphering Underlying Mechanisms

2016SSEC

Size-selective mortality (SSM) is a significant force regulating recruitment of salmon. The life stage(s) and habitat(s) in which SSM occurs can vary among species, stocks, and life history strategies. Moreover, the relationship between juvenile growth and survival is unclear for most salmon stocks. The first marine growth season is commonly regarded as a critical period for growth and survival. For ESA-listed Puget Sound Chinook salmon, preliminary studies suggest that: at least one critical period occurs during the first marine growth season; growth is limited more by food supply than energetic quality of prey or thermal regime; and higher growth and survival rates correspond with higher contributions of key prey like crab larvae.

We can identify critical periods using scales to create growth histories of a juvenile cohort sampled serially at successive life stages throughout its first marine growth season. Divergences in growth trajectories indicate reduced contributions of smaller members to subsequent life stages. These divergences indicate critical periods of growth and survival and the magnitude of SSM. We can diagnose factors affecting growth during critical periods through bioenergetics modeling simulations linked to directed sampling of diet, growth and environmental conditions. This approach could improve run forecasting and focus restoration efforts.