Data and code from: River barriers as a driver of elevated mortality rates in an iteroparous anadromous fish

This dataset contains acoustic telemetry–derived survival and spatial mortality data for twaite shad (Alosa fallax) tracked over seven spawning migrations in the River Severn basin, UK. The data constitute the base for analyses described in "River barriers as a driver of elevated mortality rates in an iteroparous anadromous fish". The repository includes .csv data files and annotated R scripts required to reproduce all analyses. Files are organized into three analysis folders (“Survival_Analysis”, “Weir_Effects”, and “Other_Tests”), plus a receiver metadata file. The data include individual-level survival records (start/end times, censoring, and mortality events), biological variables (fork length, sex, spawning history, tagging status, return year), and spatial summaries of observed mortalities and time spent at acoustic receiver stations. Receiver stations are classified by position relative to weirs (downstream, upstream, unimpeded), and detection efficiencies (2018–2024) are provided. The dataset can be reused for survival analyses, spatial mortality assessments, and studies of migratory fish in fragmented river systems. The data contain no personal information and raise no privacy concerns.