A supermarket advertisement featuring Robert Lindsay, the My Family star, has been taken off air because it made unsubstantiated claims about fish sold by the retailer.

Wm Morrison agreed not to show the advertisement after complaints to the Advertising Standards Authority (ASA), The Times has learnt.

In the advertisement, Lindsay is shown pushing a supermarket trolley along a river, asking: “Does it have to cost a fortune every time you want some fresh fish? I just want a decent choice from a sustainable source.”

Morrisons declined to comment.

It is not clear whether the complaints to the advertising watchdog came from members of the public or from rival supermarkets that believed Morrisons could not substantiate its claims of sustainability. The complaint was resolved informally between the ASA and the supermarket.

Relatively upmarket grocers such as Sainsbury’s and Waitrose have tried to distance themselves from cheaper rivals by highlighting the sustainability of the fish that they sell. Waitrose supported the launch of a documentary The End of the Line on the depletion of fish stocks, while Sainsbury’s tins of tuna carry a prominent message that the retailer uses only line-caught fish.

Gwyn Burr, customer director at Sainsbury’s, declined to comment on the Morrisons case, but said: “It is very important that we have integrity in how we communicate with customers. All retailers have to be diligent on this, or it can discredit the industry and cause distrust among customers.”

Conservationists have gone as far as to raise questions over fish certified by the Marine Stewardship Council (MSC), the eco-labelling scheme introduced to encourage consumption of sustainable fish. Critics have said that stocks such as New Zealand hoki and Alaskan pollock have plunged after gaining MSC approval and argue that it sets the bar for certification too low.

The MSC was set up by Unilever, the consumer goods group, and the World Wildlife Federation in 1996.

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