4 – Diversity, Structure, and Status of Salmon Populations

This chapter describes the origin, diversity, genetic structure, and population structure of Pacific salmon and steelhead trout in the Columbia River Basin (CRB). Different species and populations of salmonids exhibit remarkable phenotypic, life history, ecological, behavioral, and genetic diversity. The diversity, which is a hallmark of salmonids in general, arose from differential or local adaptation to the varied and variable environments within the complex landscapes of the Columbia Basin. The diversity has resulted from the plasticity, adaptability, productivity, and long-term persistence of salmonids in the fluctuating geological and environmental landscapes of the Pacific Northwest.. Diversity, within and among salmon populations is critical to the long-term persistence of salmon in the Columbia River ecosystem. Today, salmon populations in the Columbia River can form the base for rebuilding salmon abundance and diversity. The chapter also reviews the current status of salmonids, sturgeon, and lamprey that are native to the Columbia River.