The tides multiply by 70 the habitable area of the Chausey archipelago. A significant tidal range (difference between high and low tide), sometimes more than 46 ft (14 meters), uncovers nearly 12,355 acres (5,000 ha) of sandy-muddy foreshores. Two main channels pass between a multitude of pitfalls and allow the work of seaweed, shellfish (bivalves, abalone), shrimp, and lobster gatherers. The collection is, however, regulated, and controls are carried out by authorities