According to a study published in Nature last month, oceanic shark numbers have declined by 70 per cent since 1970. Three-quarters of ocean-going shark and ray species are now threatened with extinction. Yet we are still more likely to feel that sharks are a threat to us than the other way round. Peter Benchley’s novel Jaws – both symptom and cause of that feeling – was published 46 years ago, in February 1974. Production of the movie version began that summer, filmed in the village of Menemsha on Martha’s Vineyard. A few years ago I went for a swim at the beach there. I had never considered myself afraid of sharks. But with every stroke I glanced backwards over my shoulder towards the open water.