The first carcass of a great white, a small female, washed up in South Africa on 9 February 2017. The 2.6-metre-long body had no hook or net marks, ruling out human involvement. Whatever had killed her had vanished. So too had all the other great white sharks in Gansbaai on the Western Cape, Dr Alison Towner noticed.

“We had several sharks acoustically tagged, and later realised three had moved as far as Plettenberg Bay and Algoa Bay, more than 500km [300 miles] east,” says the Rhodes University marine biologist.

It was not until May that sightings of the sharks returned to their peak. Then three more carcasses were found over five days, followed by a fifth in June. For eight eerie weeks, not one great white shark was sighted.