TY - JOUR
T1 - Disentangling bottom-up and top-down effects on survival during early ocean residence in a population of Chinook salmon (Oncorhynchus tshawytscha)
AU - Miller, Jessica A.
AU - Teel, David J.
AU - Baptista, Antonio
AU - Morgan, Cheryl A.
PY - 2013/3
Y1 - 2013/3
N2 - We evaluated the relative importance of "bottom-up" (production-limited) and "top-down" (predator-mediated) processes during early marine residence in a population of Chinook salmon (Oncorhynchus tshawytscha) from the upper Columbia River, USA. We examined length, mass, and condition index of age-0 juveniles collected in the ocean during June and September across 11 years in relation to conditions in the river, estuary, and coastal ocean and to future adult returns. Characteristics of juveniles in September, but not June, were related to adult returns. During years when coastal waters were relatively cool and productive, juveniles captured in September displayed relatively low condition and reduced otolith growth compared with years when coastal waters were relatively warm and unproductive; this contrast indicates that top-down effects such as selective mortality or competition are important during early marine residence. Key physical (river plume volume during emigration) and biological (condition) variables and their interaction accounted for >95% of the variation in adult returns. Future research should focus on evaluating predators and competitors and understanding how river plume structure influences survival.
AB - We evaluated the relative importance of "bottom-up" (production-limited) and "top-down" (predator-mediated) processes during early marine residence in a population of Chinook salmon (Oncorhynchus tshawytscha) from the upper Columbia River, USA. We examined length, mass, and condition index of age-0 juveniles collected in the ocean during June and September across 11 years in relation to conditions in the river, estuary, and coastal ocean and to future adult returns. Characteristics of juveniles in September, but not June, were related to adult returns. During years when coastal waters were relatively cool and productive, juveniles captured in September displayed relatively low condition and reduced otolith growth compared with years when coastal waters were relatively warm and unproductive; this contrast indicates that top-down effects such as selective mortality or competition are important during early marine residence. Key physical (river plume volume during emigration) and biological (condition) variables and their interaction accounted for >95% of the variation in adult returns. Future research should focus on evaluating predators and competitors and understanding how river plume structure influences survival.
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U2 - 10.1139/cjfas-2012-0354
DO - 10.1139/cjfas-2012-0354
M3 - Article
AN - SCOPUS:84876328560
SN - 0706-652X
VL - 70
SP - 617
EP - 629
JO - Canadian Journal of Fisheries and Aquatic Sciences
JF - Canadian Journal of Fisheries and Aquatic Sciences
IS - 4
ER -