With fish, the solution is even simpler and more straightforward than with the other ecological crises ensnaring us. The scientific experts say we need to follow two steps. First, expand the 0.6 per cent of the area of the world's oceans in which fishing is banned to 30 per cent. In these protected areas, fish can slowly recover. Second, in the remaining 70 per cent, impose strict quotas on fishermen and police it properly, as they do in Alaska, New Zealand and Iceland.

The cost of this programme? $14bn a year – precisely the sum we currently spend on subsidising fishermen. At no extra cost, we could turn them from the rapists of the oceans into their guardians.