Sea trout entering the rivers Adour and Nivelle in south-west France at the start of the 21st century

This dataset aims to supply information on the presence/abundance of sea trout as well as run characteristics (timing, size composition, parasite infestation) in two target rivers draining into the Bay of Biscay from South West France. The runs of sea trout entering the Adour and Nivelle rivers were sampled in trapping devices at seven upstream locations (Puyoo, Baigts-de-Béarn, Sorde-l’Abbaye, Chopolo, Halsou, Uxondoa, Olha). The dataset includes 1257 specimens of Salmo trutta and consists of the date, the location of the catch and some biological data regarding the fish (size and colour of the fish, parasite infestation by the ectoparasite Lepeophtheirus salmonis). When available (600 individuals in total), photographs of sea trout scale have been previously published on INRAE's open access digital repository (https://doi.org/10.15454/SFE2D7 for Nivelle, and https://doi.org/10.15454/5X8L3X for Adour). The present dataset has already been used by Masson et al. (2018) for studying sea trout movement (https://doi.org/10.1111/eff.12349).