Commercial cultivation of shellfish may have less harmful long-term effects on mud-dwelling creatures than previously thought. Tests on the Solway by scientists at the Scottish Office Agriculture, Environment and Fisheries Department suggest that, although initial damage from harvesting is high with many species' numbers plummeting, recovery is relatively fast. Harvested sites can resemble unharvested ones within three months as they are re-colonised by mud-dwellers from undisturbed areas.