Genetische monitoring van de Nederlandse otterpopulatie : Ontwikkeling van populatieomvang en genetische status 2019/2020

Summary

The Dutch otter population is surveyed each year for the Ministry of Agriculture, Nature and Food Quality to closely monitor trends in the genetic status of the population and in the demographic processes of reproduction, mortality, immigration and emigration. This form of monitoring, which uses DNA isolated from spraints and tissue from dead individuals, also allows changes in the spatial range and population size to be detected. From the DNA profiles identified during the 2019/2020 round of monitoring the population size is estimated at approx. 450 individuals, indicating steady growth of the population. The number of traffic victims increased strongly again in 2019 and roadkill hotspots have been identified in each province. Thetotal amount of genetic variation at the population level appears stable, as does the average genetic variation within individuals. Immigration of otters from German populations near the Dutch-German border therefore remains significant. Although this occurs only incidentally, it has been more frequent than in previous years. A hopeful sign is that there appear to be various immigration routes through the provinces of Overijssel and Gelderland.