Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 7426
Title: Correspondence between scale morphometrics and scale and otolith chemistry for interpreting juvenile salmon life histories
Author: Lance A. Campbell, Daniel L. Bottom, E. C. Volk, I. A. Fleming
Publication Year: 2014
Journal: Transactions of the American Fisheries Society
Volume: 144
Issue: 1
Pages: 55-67
Keywords: Chinook salmon, life history, otolith chemistry, scale chemistry, scale morphometrics ,

Fish scales have long been used to reconstruct fine-scale habitat transitions such as the movement of juvenile fish
from freshwater, estuary, and ocean environments. Despite the importance of life history information to fisheries
management and conservation, few studies have validated that scale morphology accurately describes fish
movement between these habitats. Therefore, we tested the accuracy of using scale morphometric criteria to
identify the movement of juvenile Chinook Salmon Oncorhynchus tshawytscha from freshwater to marine portions
of the Columbia River estuary by comparing scale morphometric classification, scale chemistry, and otolith
chemistry. Nearly one-half of all fish collected in the saline portion of the estuary and approximately one-quarter in
the freshwater portion exhibited morphometric patterns (i.e., scale checks and intermediate growth) often
associated with periods of estuary rearing. Depending upon the criteria used to define scale checks, otolith chemical
results indicated that 33–53% of fish would have been misclassified as estuary residents based solely on their scale
patterns. Moreover, many individuals who had resided in strontium-rich estuary water did not form a visible check
(37%) on their scales to coincide with estuary entry. We estimated from otolith chemistry that these fish had either
entered at or near the size at which scale formation occurs (35–42 mm) or had recently migrated to the saline
portion of the estuary (<30 d) before new scale material could be formed and calcified. Scale chemistry alone was a
good indicator of entrance into the saline portion of the estuary. Scale chemistry responded to the strontiumenriched
salt water, and explained 86% of the variation found in otolith chemistry. Scale morphometric
classification did not provide the fine-scale resolution that scale and, even more so, otolith chemistry provided for
describing the proportion of juvenile Chinook salmon using the saline portion of the Columbia River estuary.

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Notes: 10.1080/00028487.2014.963253 Published online Dec 2014 but publication date is 2015 (January)
Theme: Habitats to Support Sustainable Fisheries and Recovered Populations
Foci: Characterize relationships between habitat and ecosystem processes, climate variation, and the viability of organisms.