Dispersal has consequences for individual fitness but can also influence local dynamics, stability, and adaptation in interconnected populations. Anadromous salmonid fishes are famed for their precise homing and adaptations to local aquatic environments, whilst navigating between multiple connected habitats. However, recent studies have instead demonstrated considerable straying among connected systems, forming metapopulation dynamics among sub-populations or demes. Salmonids constitute valuable economic and ecological resources, yet many populations are declining due to multifaceted anthropogenic-induced disturbances. This context of reduced populations inhabiting altered environments may impact both population viability and dispersal.

To explore if metapopulation processes are present among impacted neighbouring populations of anadromous brown trout (Salmo trutta), a four-year study of individual dispersal behaviour (biotelemetry, N = 84) and genetic analysis (N = 142) was conducted in four populations, connected by an extensive (> 200 km), semi-enclosed fjord system, Sognefjorden, Norway. To estimate the demographic status of each study population life-table matrices were built, from which a potential source-sink structure among demes could be identified.

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