6 March, 2026

Last week, Waitrose suspended sales of mackerel over overfishing concerns. The move came after a recent international agreement to cut mackerel catches by 48%, a reduction Waitrose judged insufficient to bring stocks back in line with scientific advice. 

Rather than steering shoppers towards “sustainable mackerel”, Waitrose took mackerel off sale and actively substituted it with responsibly sourced alternatives. Behaviourally, that matters. The decision shifts the decision away from the shopper and onto the retailer, signalling not just what to choose, but what no longer meets the bar for being sold. 

Tools like the Marine Conservation Society’s Good Fish Guide have long aimed to influence demand by signalling which species to avoid and which to prefer. As benchmarks go, it’s informative, but relies on consumers noticing, trusting and acting on the information. In this case, Waitrose have applied it to its own range decisions, rather than leaving consumers to interpret and act on it at the shelf.  

There is a risk in relying on substitution alone. When demand simply shifts from one unsustainable species to the next acceptable alternative, pressure may follow. For a while, we were happily eating mackerel believing it was a more sustainable choice than other fish. Without reducing overall demand, sustainability becomes a moving target rather than a destination.  

Drawing a line matters, but pausing demand and redirecting it carries a risk and works best when paired with clear limits and ongoing review. Waitrose have spread that signal, with M&S following, and that direction of travel will be hard to ignore.  

By Bertie Bateman