Correspondence between Scale Morphometrics and Scale and Otolith Chemistry for Interpreting Juvenile Salmon Life Histories

• Published in: Transactions of the American Fisheries Society (1900) Vol. 144; no. 1; pp. 55 - 67
• Main Authors: Campbell, Lance A, Bottom, Daniel L, Volk, Eric C, Fleming, Ian A
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 01-01-2015
• Subjects: Brackish; brackish water; estuaries; fish; fisheries management; freshwater; habitats; juveniles; life history; morphometry; Oncorhynchus tshawytscha; otoliths; rearing; saline water; Columbia River; USA, Columbia R
• ISSN: 1548-8659; 0002-8487; 1548-8659
• DOI: 10.1080/00028487.2014.963253

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 strontium-enriched 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. Received December 26, 2013; accepted August 28, 2014