Gordon Johnson is director of Shetland Select, the company that provides some of the best mussels in Scotland. Based in Basta Voe on the island of Yell, they have also recently started harvesting in Vementry off the west mainland of Shetland. The water depth, tidal flow and shelter are optimum in Shetland’s ‘voes’ (small fjords). Water depth is important for mussels as the ropes must not touch die sea-bed or starfish climb up and feast! The tidal flow and shelter are crucial as the water is clean and unpolluted and there is just enough ebb and flow to ensure water purity, but the mussels can still cling on to the ropes without being carried away by the tide. What sets these mussels apart, Gordon told me, is the fact they are seasonal. When they are spawning, from the end of May or early June through to mid-August, they stop harvesting the mussels, to avoid them being contaminated with toxins in the water as temperatures increase during the summer.