My family eats fish two or three times a week. I have a six-year-old son and it’s important for him to get his oily fish. The only wild-caught fish we eat is Marine Stewardship Council-certified. Sainsbury’s has the largest number of these. We would never buy cod; we choose frozen fillets of Alaskan salmon and white fish such as pollock. Farmed, herbivorous fish are more sustainable still – I would eat basa (pangasius), tilapia and even carp.

The other thing we devour is shellfish. Mussels, oysters and scallops are regarded as sustainable, but I would only eat scallops if they are hand-caught by divers. Prawns are probably the biggest nightmare; we don’t often buy them. Cold-water prawns are trawled, which damages the sea bed, and there are also big environmental issues with tropical prawns. I know the fish buyer from M&S and his company really has done the work on where it sources its tropical prawns.

I don’t eat out often and when I do I steer away from fish, unless the waiter can assure me that he knows about the fishing methods used and the geographical area. Good places will say, for example, if their fish was line-caught in Iceland; I would also choose handline-caught fish. There is a pole and troll method of tuna-fishing that is sustainable, too.

I hardly ever go to a fish and chip shop but went to one recently and bought scampi, as the langoustines were highly sustainable. You don’t know where it’s from, but it’s a better bet than white fish.

There is a handful of MSC-certified restaurants, mostly in London. The Moshi Moshi sushi chain is fanatical about sourcing; I also go to the Duke of Cambridge pub in Islington.

Andrew Purvis is a food journalist

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