Columbia River Fisheries Program Office
Pacific Region

Native Trout Program - Bull Trout Age Analysis

Bull Trout Fin Rays for Age AnalysisRecovery of bull trout listed as threatened under the Endangered Species Act will depend on assessing the status of populations. To conduct an adequate assessment, it is necessary to determine the age structure of various populations or metapopulations. The age of most salmonids has been determined using a variety of methods. Scales may be collected non-lethally, analyzed relatively inexpensively, and for many salmonids provide sufficiently accurate age information. However, bull trout are a member of the charr family (Salvelinus spp.). Scale analysis of charr often provides relatively inaccurate age information. Fin rays may be used to determine the age of bull trout, may possibly be collected non-lethally, and are only moderately expensive to analyze. Otolith analysis provides very accurate age information but otoliths are collected through lethal sampling and analysis is relatively expensive.

The purpose of this study is to provide additional guidance toward methods of determining age in bull trout. The primary objective is to compare accuracy of age analysis using scales, fin rays, and otoliths from known age bull trout. The ultimate goal of this project is to determine age structure of bull trout populations using non-lethal means.

Last updated: December 7, 2012
Columbia River Fisheries Program Office
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