Assessing the Utility of Tributary PIT-Tag Arrays in Monitoring Snake River Salmonid Recovery

Abstract

Passive integrated transponder (PIT) tag technology is used in the Columbia River basin to monitor migration of threatened and endangered salmonid populations. From 2010 to 2018, the number of tag detection arrays installed in tributaries almost tripled, increasing the range of the PIT-tag detection network and its potential use in evaluating mitigation operations for salmonids. This study used PIT-tag arrays in upper Snake River tributaries to assess how adult dam passage and smolt transportation affect upstream migration success and concluded that there is minimal evidence that adult homing success is related to dam passage or juvenile transportation history. This thesis also compared smolt-to-adult return (SAR) ratios calculated with coded wire tags and PIT-tags and concluded that using PIT-tag recovery data to estimate SARs in the basin is preferred given that they capture more of the natural variability.