Once a plentiful creature in the Humber, overfishing and disease drove oysters to extinction. Now they are back.The results from a trial project earlier this year suggest the species has all the potential to thrive.This project is sourcing new oysters from a Scottish sea loch. Thousands of them are being relocated to the very different surroundings of the Humber mudflats.But why go to this trouble in the first place for the sake of one species? Well, it's all about biodiversity, enriching all marine life in this area.