But the problem goes far beyond this year’s specific figure.
This is because the French mussel industry was already struggling before the heatwave.
In 2022, France produced around 58,100 tonnes of mussels. By 2023, production had fallen to 54,531 tonnes. By 2024, it had fallen to just 48,775 tonnes – a further 11 per cent drop in a single year. The downward trend was therefore already well established before the exceptional summer we have just experienced. (Agreste)
And the summer of 2026 obviously did nothing to help matters.
Between mid-June and the end of August, mainland France experienced 53 days of heatwaves. This was unprecedented on this scale. July 2026 was even described as the hottest July ever recorded in France since records began in the early 20th century. (INSEE)
Yet a mussel has no parasol, no air conditioning and, above all, very few options for escape.
Attached to its rock, to a rope or in a farming area, it is directly exposed to fluctuations in water temperature, periods of exposure at low tide, lack of oxygen, changes in salinity and the availability of food.
When the water becomes too warm, its metabolism speeds up. It breathes more heavily, expends more energy and eventually becomes exhausted. In shallow waters, the situation can become particularly severe: very warm water, falling oxygen levels, already weakened organisms and a chain reaction of deaths.
The Thau lagoon, in the Hérault department, serves as a real-life laboratory illustrating what might lie in store for part of the French shellfish farming industry.
In early July 2026, in an experiment conducted by researchers at Ifremer, nearly 20 per cent of the mussels placed in tanks fed with lagoon water at ambient temperature had already died. In the ponds that had been deliberately heated to a higher temperature, there were virtually no survivors left. (Le Monde.fr)
Even more worrying: the scientific studies carried out in this area no longer speak merely of a bad year. They quite simply call into question the mussel’s ability to continue to be farmed sustainably in certain Mediterranean areas if water temperatures continue to rise and acidification worsens. (Le Monde.fr)
What was once considered an exceptional occurrence is therefore gradually at risk of becoming a structural problem.
France is all too familiar with this scenario.
Following the 2003 heatwave, a study of mussel farms along the Charente coast had already noted extremely significant declines in stocks: up to 66 per cent in the Marsilly-Esnandes area and 43 per cent in the Bay of Yves and Île d’Aix area. Scientists had identified heat, drought and water temperatures exceeding 25 degrees as factors likely to have pushed the mussels to the limits of their resilience. (OIEau)
Twenty-three years later, the problem has resurfaced with one key difference: extreme events are becoming more frequent.
This is where the real concern for mussel farmers begins.
A farm may be able to weather a bad season. It may sometimes survive two. But a business model becomes much harder to sustain when mortality events, harvesting uncertainties, parasites, diseases, storms and, now, extreme heat begin to occur in succession.
Yet the French mussel represents far more than just a dish served in a seaside restaurant.
It represents an entire industry, comprising often family-run businesses, jobs and a gastronomic and maritime heritage. Northern Brittany and Normandy-North Sea are notably among the main French production areas. The bouchot mussel has also become a product strongly associated with certain regions.
And the French market is already unable to function solely on domestic production.
In 2023, France produced 54,531 tonnes of mussels, whilst its apparent consumption of fresh mussels was estimated at over 93,000 tonnes. Nearly 39,000 tonnes were imported, mainly from Spain, the Netherlands and the United Kingdom. (Observatoire des Prix et Marges)
If French production continues to decline, one of the consequences is therefore fairly easy to predict: we will still be eating mussels, but they will be less and less French.
The future of the sector will probably involve several simultaneous adjustments.
It will be necessary to select strains better suited to withstanding high temperatures, adjust certain rearing periods, monitor water temperature and oxygenation much more closely, possibly relocate some production sites, and rethink techniques on a regional basis.
Above all, we will have to accept a rather unpleasant reality: we cannot expect a species adapted to certain natural conditions to continue in exactly the same way indefinitely when those conditions change.
The question, therefore, is not really whether the French mussel will disappear in five years’ time. It probably will not disappear.
The real question is where we will still be able to produce it, at what cost, in what quantities and with what regularity.
Some regions along the Atlantic coast or in the English Channel could retain more favourable conditions for a long time, whilst conditions in Mediterranean areas would become much more challenging. The map of French mussel farming could thus gradually shift.
And behind this story of mussels lies, ultimately, something much broader.
Climate change is no longer just a projected trend for 2050 or 2100. It is beginning to have a very tangible impact on what ends up on our plates, where we can produce it, and the price at which we will be able to buy it.
The mussel is a rather unassuming little creature.
But when they start dying by the millions because the water is getting too warm, they may be telling us quite precisely what is changing.
And it would be a great shame to wait until the last mussel is cooked before realising that the water was getting warmer.
