Slabs of squeaky-fresh sole, turbot and bass lie on a fish counter in Marylebone High Street, Central London. Above the counter a large TV screen shows a trawler and a blinking dot on a map of the Western Isles of Scotland. “So we can see that the Ranger is on its way back to Stornoway, with skipper Garry Duncan,” says Mitchell Tonks, the owner of the FishWorks restaurant and fishmonger chain. “We know that he has just taken 25kg of langoustine on board and we can see exactly where he caught them. They’ll be dispatched to me within eight hours and on my counter in the morning.

“It’s the ultimate in traceability. Provenance has always been key to selling fish. People really want to have that guarantee of freshness.”

The system is run by Young’s, the seafood people, as a way of managing stocks for its scampi-processing plants in the Hebrides. Equipment on the fishing boats records and transmits live data of the catches as soon as it is brought aboard and sorted, showing location, quality and maturity. This means that if lots of small langoustine or females carrying eggs are landed, they can ensure that other boats avoid the particular field. “With all the concern about diminishing fish stocks, this is one of the first indicators that you can eat these with confidence,” says Tonks. The tracing scheme has been extended to bass and pollock, but Tonks does not believe that any fish should be off-limits.

“Everybody gets confused over the different advice about what we should be eating,” he says. “It’s no good suddenly stopping eating skate, for example, because fishing doesn’t discriminate; we can’t just target specific species. It is much better to make sure that your fishmonger is buying from a well-managed fishery and take a little of everything.” For more information on where your fish has come from visit: www.linecaught.org.uk

FishWorks 89 Marylebone High Street (020-7935 9796; www.fishworks.com).

Times Recommends

• Gordon Brown’s favourite pud
• Five-spice butternut soup
• How to make popcorn and crisps