There was a time when the streets of Edinburgh echoed with cries from fishwives of “caller ou” (“fresh oysters”), and the Firth of Forth swayed with blades of seagrass. That is now long gone.

When we look at the sea, often we think of it as a wild space, rich with life. But it is also an environment with a long history of depletion, as I learned when I talked last year to Celine Gamble, project manager behind the Wild Oysters Project, which is currently restoring oysters in the Firth of Clyde.

Gamble described to me the vanishing of that important mollusc. Across Europe, the European native oyster population has declined by 95%. It has all but disappeared in areas of Scotland in which it once abounded: the Firth of Forth, for instance, was home during the 19th century to the most productive oyster reefs in the country. During its peak production, Gamble notes, 30 million oysters were being landed per year.