Genetische monitoring van de Nederlandse otterpopulatie : ontwikkeling van populatieomvang en genetische status 2017/2018

The Dutch otter population is surveyed each year for the Ministry of Agriculture, Nature and Food Quality to monitor its size, distribution and genetic status. DNA is isolated from spraints and tissue from dead individuals, and data is obtained on the demographic processes of reproduction, mortality, immigration and emigration. The resulting information is also used to detect changes in the spatial distribution and size of the population. Based on the DNA profiles identified during the monitoring of 2017/2018, the population is now estimated to consist of approx. 275 individuals. The population has therefore grown steadily. The success rate of DNA analysis of spraints was relatively high this year and confirmed further population growth. The number of traffic victims increased again in 2017, showing a continuing linear trend with the total population size of previous years. The total amount of genetic variation at the population level seems to be stabilising, as does the average genetic variation within individuals. This underlines the importance of immigration of otters from German populations near the Dutch-German border