Boat anchoring impacts coastal populations of the pen shell, the largest bivalve in the Mediterranean

► We use a Bayesian formulation of individual covariate models to estimate population size of P. nobilis. ► Population density of the pen shell is highly variable around Mallorca. ► Differences in population density cannot be attributed to structural parameters of the habitat (seagrass meadows) nor storm occurrence. ► Density at sites were boat anchoring was prohibited was much higher than in sites without this restriction. ► Permanent mooring buoys would be an effective conservation measure to reduce damage by anchoring.