The festivals celebrate the native Galway oyster or ostrea edulis - also known as wild oysters. Ireland produces over 750 million tonnes of oysters each year and only a small percentage of these are the native oysters making them highly sought after across the globe. September is the start of the native oyster season as the warmer summer months are when they are reproducing and it is advised not to eat them 1. To allow them ensure a future and 2. they are not at their best in terms of flavour and meatiness. The larger, more widely know Rock oysters are available all year round.
The world is your oyster and for September - Galway is the centre of the oyster world.