Reintroduction success of brook lamprey (

Brook lamprey (Lampetra planeri) disappeared in half of its former range in the Netherlands. A reintroduction effort from 2014 to 2018 aimed at re-establishing a population in the Reusel Stream. About 1000 individuals (96% larvae, 4% adults) were translocated yearly from the nearest population. The donor population was not put at risk, and the reintroduced population has successfully established. The new population survives, reproduces, larvae densities increased to >2 individuals per square meter in (sub) optimal habitat, larvae occur in different length classes, and the distribution range expanded to 5 km. In 2024, the population was assessed to be self-sustaining. Due to the impact of droughts and therefore an increased local extinction risk, the best available status estimate of the reintroduced population would be ‘Endangered’. The Reusel Stream showed to be highly sensitive to progressive impacts from climate change and intensive land use. Further restoration of the watershed and sustainable land use are crucial for both the ecosystem and agriculture.