Greenpeace have just published a fold-out poster listing how well the British supermarket chains have done with their supposedly “sustainable” Tuna in cans. There are no percentage scores, though some must have been calculated: instead, the supermarkets are ranked from deepest green (presumably near 100% sustainable, i.e. you could go on doing that forever – isn’t that the only plain meaning of the word?) through to brightest red, cheerfully labelled “Unsustainable and harms marine life” (one might say that applies to all scores less than 100%, no?).

In the green corner is Waitrose, “Your go-to #JustTuna brand for 2016”, I guess that hash sign is a snappy little address for some American web gadget or other, maybe a teenager can help me out on that one.

In the red corner (boo! hiss!)  is an old-established brand, John West. According to the poster, “More than 98% of John West’s tuna is caught using destructive fishing methods”. Naughty step: copy out “I must not use enormous nets that catch sharks, turtles and rays” 1000 times neatly without smudging now.

Seriously, it’s disgraceful that a famous old company should be taking so little care of a resource on which its commercial well-being, its very existence as a company, depends. Properly managed – truly sustainably – Tuna fishing will last forever, or until the human race wipes itself out (delete as preferred).  Badly managed – as now – the ocean’s Tuna fisheries will go the way of Cannery Row in Monterey (now the marvellous aquarium there), of the Tonnara of Scopella in Sicily (remembered wonderfully by Gavin Maxwell), indeed of Britain’s long-gone North Sea tuna fishery —and yes, it sounds unimaginable now, doesn’t it? That’s how “canned tuna” will sound in a few years’ time if we don’t sort our ideas on sustainability out.