The destructive date-mussel fishery and the persistence of barrens in Mediterranean rocky reefs

► Reefs impacted by fishery for an endolithic mollusc host high sea urchin densities. ► Holes left empty after mollusc removal allow juvenile urchins to escape predation. ► The reduced juvenile mortality contributes to locally high sea urchin density. ► This destructive fishery creates a new microhabitat for urchins that maintain barrens.