First, there was the £2 chicken. Now Asda has attracted the ire of food campaigners by offering shoppers a £2 whole Wild Alaskan salmon.

The retailer, which has a reputation for jaw-droppingly low prices, is selling a 840g frozen salmon for a base price of £2, reduced from £3 last month, and down from £4 in March. The price equates to £2.38/kg [BrandView.co.uk].

The £2 chicken - which rose to notoriety in 2007 - was derided at the time by animal welfare group Compassion in World Farming, which claimed the £2 price devalued life. However, animal welfare groups are unlikely to find fault with Asda’s salmon promotion, because it is sustainably sourced wild Alaskan salmon.

That has not stopped food campaigners from criticising it as unsustainable. The Grocer’s columnist Joanna Blythman said it was hard to fathom how a proper return could be given to fishermen and processors at the price.

Asda said it had been able to sell the salmon so cheaply because of a canny approach to purchasing. “The price is due to us buying early,” a spokeswoman said.

She said it was not the first time Asda had run “great” prices on salmon, citing a Christmas 2011 promotion that saw it selling a 1.2kg whole salmon for £3. At the time, Asda compared the £2.50/kg cost with £14.99 for an organic Duchy Originals farmed salmon at Waitrose, and £12.50/kg for an M&S farmed salmon.

Much of the Wild Alaskan salmon sold in the UK holds MSC certification, although from 29 October most will no longer do so as the eight processors that account for about 70% of the Wild Alaskan harvest have decided not to fund participation beyond then.