Body morphology differs in wild juvenile Chinook salmon Oncorhynchus tshawytscha in the Willamette River, Oregon, USA

Journal of Fish Biology
By: , and 

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Abstract

Body morphology of juvenile Chinook salmon Oncorhynchus tshawytscha in the upper Willamette River, Oregon, U.S.A., was analysed to determine if variation in body shape is correlated with migratory life-history tactics followed by juveniles. Body shape was compared between migrating juveniles that expressed different life-history tactics, i.e. autumn migrants and yearling smolts, and among parr sampled at three sites along a longitudinal river gradient. In the upper Willamette River, the expression of life-history tactics is associated with where juveniles rear in the basin with fish rearing in downstream locations generally completing ocean ward migrations earlier in life than fish rearing in upstream locations. The morphological differences that were apparent between autumn migrants and yearling smolts were similar to differences between parr rearing in downstream and upstream reaches, indicating that body morphology is correlated with life-history tactics. Autumn migrants and parr from downstream sampling sites had deeper bodies, shorter heads and deeper caudal peduncles compared with yearling smolts and parr from the upstream sampling site. This study did not distinguish between genetic and environmental effects on morphology; however, the results suggest that downstream movement of juveniles soon after emergence is associated with differentiation in morphology and with the expression of life-history variation.

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Publication type Article
Publication Subtype Journal Article
Title Body morphology differs in wild juvenile Chinook salmon Oncorhynchus tshawytscha in the Willamette River, Oregon, USA
Series title Journal of Fish Biology
DOI 10.1111/jfb.12482
Volume 85
Issue 4
Year Published 2014
Language English
Publisher Academic Press
Publisher location London, England
Contributing office(s) Coop Res Unit Seattle
Description 14 p.
First page 1097
Last page 1110
Country United States
State Oregon
Online Only (Y/N) N
Additional Online Files (Y/N) N
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