Fish and chips off the menu as marine experts warn haddock has become unsustainable 

Families who regularly enjoy regular fish and chip suppers are being advised to scale back, as haddock has joined cod and plaice on a list of fish which should be eaten as a "very occasional treat".

The Marine Conservation Society has today revealed it has relegated haddock from the North Sea and West Scotland from its recommended "green" list of fish to eat.  

Around 80pc of the UK's haddock is caught in the North Sea and West Scotland area, meaning the majority of fish and chip shops and restaurants are likely to be affected by the change. 

Haddock is also one of the UK’s “Big 5” fish species eaten in the UK along with cod, tuna, salmon and prawns. 

It is often chosen by consumers instead of cod and plaice it is thought of by many as the only "sustainable" option left. Haddock fisheries were downgraded because stock numbers in 2016 were below the recommended level and action was needed to increase the number of fish of breeding age, the society said.

Two of the fisheries are now rated "amber" - scoring just four in a scale of one to five, where one is the most sustainable in the Marine Conservation Society's "Good Fish Guide".

The other fishery has seen its fish drop from being a good choice of haddock to buy to one to eat only occasionally, with a "three" rating.

Bernadette Clarke, manager of the Good Fish Guide, said: “These ratings changes have come about because scientific perception of the stock has changed. Compared to 2015, the stock numbers in 2016 were below the recommended level and at the point where action is now needed to increase the number of fish of breeding age.”

According to the Marine Conservation Society 47pc of haddock eaten in the UK now scores an "amber" or "red" in its traffic light system, which indicates that they should be eaten very occasionally or avoided all together. 

Meanwhile some 77pc of cod and 82.5pc of plaice were in these categories. The sustainability of cod fishing appears to have improved, however. 

After being severely depleted by decades of overfishing, the recovery in cod stocks is now strong enough that the fish became eligible to qualify for the Marine Stewardship Council's blue label for certified sustainability for the first time ever last year.

The Marine Conservation Society added that it had seen improvements in the sustainability of scampi fisheries in the west of Scotland, Clyde and Jura catch areas in the latest list from the society.