Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 4427
Title: Environmental and geospatial factors drive juvenile Chinook salmon distribution during early ocean migration
Author: Brian J. Burke, Martin Liermann, David J. Teel, J. J. Anderson
Publication Year: 2013
Journal: Canadian Journal of Fisheries and Aquatic Sciences
Volume: 70
Issue: 8
Pages: 1167-1177
Keywords: Chinook salmon,migration,behavior,spatial distribution
Abstract:

Migrating animals rely on a variety of cues to guide them, but the relative importance of those signals may vary with size, life stage, or location.  During their initial ocean migration, yearling Chinook salmon (Oncorhynchus tshawytcha) from the Columbia River have stock-specific spatial distributions that shift through time.  We used a two-process mixture model to examine how the distribution of yearling migrants from three Chinook salmon stocks varies as a function of geospatial (e.g., latitude and distance from shore) and environmental (e.g., chlorophyll a and temperature) covariates.  In this framework, one process described the probability of being inside the spatial, temporal, and environmental boundaries of the migration route, and one process described the patchy distribution of salmon abundance within that route.  We found that both environmental and geospatial covariates explained substantial portions of observed spatial patterns in abundance, suggesting that these stocks responded to multiple cues during migration.  However, model selection criteria indicated that fish distributions were more affected by geospatial than by environmental covariates.  We conclude that during migration, behavioral responses to environmental variation are secondary to responses to geospatial variation, sometimes resulting in suboptimal environmental conditions.  This may have sublethal effects on growth and could ultimately influence stock-specific responses to broad-scale climate changes.

Description:

We used a two-process mixture model to understand the relationship between distribution of yearling migrants from three Chinook salmon stocks and various geospatial (e.g., latitude and distance from shore) and environmental (e.g., chlorophyll a and temperature) covariates.  Both environmental and geospatial covariates explained a significant portion of observed spatial patterns in abundance for all three stocks, suggesting that fish are responding to multiple types of cues during migration. 

URL1: The next link will exit from NWFSC web site http://dx.doi.org/10.1139/cjfas-2012-0505
Theme: Ecosystem Approach to Management for the California Current Large Marine Ecosystem
Foci: Characterize ecological interactions (e.g. predation, competition, parasitism, disease, etc.) within and among species to support ecosystem approach to management.
Characterize linkages between climatic conditions and biotic responses.