In the fall of 2013 I was awarded a Marie Curie International Incoming Fellowship to study the potential impact of Eurasian beavers (Castor fiber) on Atlantic salmon and sea trout. Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) are an important economic, recreational, and ecological resource in rural areas of the European Atlantic and Baltic seaboard, from northern Norway to Spain. The Atlantic salmon is listed in annexes II and V of the European Union’s Habitats Directive as a species of European importance. It is important to understand the different factors that can influence the production of salmon because salmon have experienced population declines over much of their range in recent years. Eurasian beavers, once largely extirpated in Europe, are now recolonizing northern and western Europe, which raises concerns for the important salmon and sea trout fisheries of the area. The last three decades have seen both a natural expansion, with beavers returning to many areas from which they were exterminated, and assisted recovery where reintroduction and translocation projects have returned the species to many areas of the EU distant from any surviving populations (Halley et al. 2012). Populations are now established in the wild in all countries in the species’ natural range in Europe apart from Portugal, Italy and the southern Balkans, and in 2008 the species was reclassified as Least Concern, the most favourable conservation status of all, by the IUCN. The return of beavers to rivers holding economically and socially important anadromous salmon and sea trout resources is causing considerable concern in Atlantic and Baltic seaboard regions. Rivers in Norway have both beavers and populations of Atlantic salmon and sea trout, providing the opportunity to determine how beavers may affect these fisheries. I am studying how beavers change habitat quality, how beaver dams may limit Atlantic salmon and sea trout movements, and the potential for beavers to influence the production of juvenile salmon and sea trout. I am using new techniques to monitor the return of adult fish to spawning tributaries and hope to utilize this technology to study how human caused habitat alterations may also affect these fisheries.