Native salmonid populations in the inland West are often restricted to small isolated habitats at risk from invasion by nonnative salmonids. However, further isolating these populations using barriers to prevent invasions can increase their extinction risk. This monograph reviews the state of knowledge about this tradeoff between invasion and isolation. We present a conceptual framework to guide analysis, focusing on four main questions concerning conservation value, vulnerability to invasion, persistence given isolation, and priorities when conserving multiple populations. Two examples illustrate use of the framework, and a final section discusses opportunities for making strategic decisions when faced with the invasion-isolation tradeoff.

Native salmonid populations in the inland West are often restricted to small isolated habitats at risk from invasion by nonnative salmonids. However, further isolating these populations using barriers to prevent invasions can increase their extinction risk. This monograph reviews the state of knowledge about this tradeoff between invasion and isolation. We present a conceptual framework to guide analysis, focusing on four main questions concerning conservation value, vulnerability to invasion, persistence given isolation, and priorities when conserving multiple populations. Two examples illustrate use of the framework, and a final section discusses opportunities for making strategic decisions when faced with the invasion-isolation tradeoff.

Native salmonid populations in the inland West are often restricted to small isolated habitats at risk from invasion by nonnative salmonids. However, further isolating these populations using barriers to prevent invasions can increase their extinction risk. This monograph reviews the state of knowledge about this tradeoff between invasion and isolation. We present a conceptual framework to guide analysis, focusing on four main questions concerning conservation value, vulnerability to invasion, persistence given isolation, and priorities when conserving multiple populations. Two examples illustrate use of the framework, and a final section discusses opportunities for making strategic decisions when faced with the invasion-isolation tradeoff.

Wild salmon, trout, char, grayling, and whitefish (collectively salmonids) have been a significant local food and cultural resource for Pacific Northwest peoples for millennia. The location, size, and distribution of urban areas along streams, rivers, estuaries, and coasts directly and indirectly alter and degrade wild salmonid populations and their habitats. Although urban and exurban areas typically cover a smaller fraction of the landscape than other land uses combined, they have profound consequences for local ecosystems, aquatic and terrestrial populations, and water quality and quantity.​