Blue mussels (Mytilus spp.) inhabit a wide range of natural and artificial environments and play an important ecological and economic role. Shell size and shape vary across habitats and can influence mussel fitness by affecting protection against predation, wave action, and other environmental pressures. This project aims to explore variation in shell morphology and genetic diversity among populations along the west coast of Sweden. Whole-genome sequencing will be used to identify genetic factors associated with morphological variation in blue mussels.