Design and Analysis of Salmonid Tagging Studies in the Columbia Basin, Volume V; Analysis of In-River Growth for PIT-Tagged Spring Chinook Smolt, 1999 Technical Report.

摘要

The length of tagged fish is often measured at the release site and at least one downstream detection site for many PIT-tagged releases, enabling the study of growth of a particular salmonid species, run, year-class and rearing type, during their downstream migration. The purpose of this report is to suggest an approach to analyze the in-river growth of PIT-tagged salmonid yearlings. Since the age of the tagged fish is unknown, its growth must be assessed by means of the relationships between the release and recovery sizes of tagged fish, and between those and the time elapsed between release and recovery. Analyses of this type require adequate samples. A simple three-step protocol for selecting adequate data for unbiased samples is provided. Three methods: Walford's lines, Kolmogorov-Smirnov tests and one-tail paired t-tests, are suggested as analytical tools and applied to detect in-river growth from selected samples of PIT-tagged spring chinook yearlings. Finally, the between-sample comparison of growth rates by means of a simple linear model is discussed.