Abstract
Over the last century, wild populations of salmonids in the Columbia River basin have significantly declined. Several of these populations have been listed as “threatened” under the Endangered Species Act and collaborative multi-state, multi-agency efforts have been established to manage and restore at-risk populations. A thorough understanding of a species’ life history is necessary for effective conservation. A tool widely implemented to collect information during juvenile salmonid life stages is a rotary screw trap. Rotary screw traps sample juvenile salmonids as they migrate to the ocean but environmental conditions, low species abundances, and complex life histories can lead to sparse data. In this study I implemented a hierarchical Bayesian model to obtain abundance estimates from rotary screw traps with large periods of missing data and utilized this information to explore two predominant life history assemblages of juvenile Chinook salmon that have strong implications on survival and reproductive success.