Animal migration is a widespread phenomenon. It evolved to maximize survival and reproductive success by stimulating the movement between critical habitats such as reproductive and feeding grounds. Diadromous fish species show extensive migrations, in which they bridge vast distances between foraging and spawning habitats in freshwater and marine environments. Behavioral traits like migration speed and timing likely evolved to reach critical habitats in time under the prevailing environmental conditions, hence, habitat connectivity is an essential feature. Yet, connectivity is often constrained by migration barriers, leading to delays and migration stops, which may affect both the numbers and fitness of spawning individuals. Within the European Tracking Network, a pan-European initiative to integrate fish tracking studies, unique meta-analyses will be conducted on telemetry datasets of diadromous species to better understand their migration behaviour and the impact of barriers hereupon. First, to understand how migration is organized over the wide distribution ranges of the different species, migration speed and timing will be related to the distance between foraging and spawning habitats. Next, the relationship between migration speed and timing and size and sex will be investigated. Finally, the impact of barriers on the migration speed and timing will be investigated by quantifying and qualifying migration delays, and how these affect migration-related traits.