The flat oyster Ostrea edulis is a native European species whose populations have declined in the past decades, mainly due to the introduction of parasites and overfishing. They are extensively used in aquaculture, involving moving stocks between different countries, which potentially affects wild populations by genetic contamination from escapes. However, Scandinavian populations in Kattegat and Skagerrak are an exception. These can be seen as the last untouched stock of European flat oysters as they have not been subjected to translocations and are not yet infested with parasites. These Scandinavian populations are unique but remain so far understudied. In this project, we want to map variations in genetic diversity in the Swedish populations of Ostrea edulis and investigate for correlations between genetic variations and increased tolerance to environmental changes.  We gathered low coverage whole genome sequencing data from 25 flat oyster populations in Skagerrak and Kattegat that we want to analyse, using a classical genomic pipeline.