Phenology and biological traits of migrating river lamprey (Lampetra fluviatilis) sampled by trapping in the Bresle river (France).

Since 1982, migratory river lampreys have been captured on the Bresle basin, first as a bycatch from salmonid trapping, then to observe migration phenology and quantify their abundance. 15 km from the river estuary a trapping system controls adult river lampreys migration for a period of 6 months per year (3-6 months per year historically). On the occasion of the capture, biometric characteristics are taken to characterize the population in order to feed this data set.