Dan Saladino finds out how Brexit could wreck plans to turn the mussel into a mainstream food. They're good for our health and the environment so why are producers facing ruin? From their base in Lyme Bay in South Devon Nicki and John Holmyard grow mussels out at sea. Their pioneering farm, once completed, will be the largest of its kind in European waters, capable of producing ten thousand tonnes of mussels each year. Since January however, they haven't been able to harvest the shellfish which they mostly sell into to Europe. Following Brexit a dispute between the government and the EU has meant the export of much of the UK's live bivalve molluscs (oysters and cockles as well as mussels) has ground to a halt. Dan explains what lies behind this trade dispute and the devastating impact its having on the industry. Exports into the European Union are essential to mussel farmers in the UK because we eat so little of the shellfish we produce. So why do these bivalves matter? Mary Seddon, a mollusc expert, explains why this source of food was so important to our ancestors and also describes the environmental benefits mussels bring to our coastline. Belgian food writer Regula Ysewin (pictured) reveals why it was Belgium that fell in love with mussels and also provides a guide to cooking them. Produced and presented by Dan Saladino.