© Tristan Macquet
After years of experimentation with closed-loop systems at the Paul Ricard Oceanographic Institute, Miard made a bold decision. Rather than wait decades for his research to trickle down to the industry, he stepped out of the lab and into… the marshes.
“It usually takes 10 to 20 years for research to move from the lab to real-world application. I wanted to find a way to accelerate that process – and the best way was to get my hands dirty and test it in the field,” he explains.
A living lab in the marshes
Miard now runs Les 4 Marais, a one-hectare multitrophic aquaculture farm nestled in the salt marshes of Île de Ré. The site was a previously abandoned “marais d’affinage” (Oyster refinement ponds) and overgrown, but Miard saw in it a living ecosystem that was already organising itself. Instead of imposing a plan, he started by observing.
“I didn’t begin with a list of species. I began by asking: what functions are already happening here? What’s missing? What can I support or strengthen?” he recalls.
The farm is now divided into four interconnected basins. Each supports a different layer in the ecological chain: shrimp disturb sediments and provide nutrients through faeces, bivalves filter the water to allow for transparency, and macroalgae convert sunshine and nutrients into biomass while oxygenating during the day. Gravity takes water one way, a small pump loops the circuit. Small DIY aerators help maintain oxygen levels at night and avoid phytoplankton blooms caused anoxia.
Over time, the system has become highly productive – especially for its scale. Miard reports harvesting 1.5 tonnes of ulva, 2 tonnes of part-grown oysters, 150 kg of marsh shrimps, and hundreds of kilos of halophyte plants such as salicornia, maceron (marsh pepper) and inula (marketed as marsh thyme). Everything is sold fresh or transformed into value-added products like powders, tartares, or pastes.
A few are set aside to mature longer, for family, friends and the occasional feast. © Tristan Macquet
“At this stage, I’m not a grower – I’m a gatherer. The system takes care of itself. I just intervene to keep the balance and harvest the surplus,” Miard notes.
And surplus can also mean finding value where others would see nothing but nuisance. His leptomysis zooplankton – naturally occurring in the system – now fetch €1,200 per kg from aquariums, making them his highest-value product by weight.
“Everyone focuses on big fish. But sometimes the most overlooked species are the most profitable,” Miard points out.
Rethinking the system: biology first
This low-tech, low-input model is built around biological functions rather than monoculture production.
“I think in terms of roles: filtration, oxygenation, nutrient cycling. Once I know the role, I look for the best local species to fill it.”
This systems-thinking approach was shaped during his years at the Paul Ricard Institute, where he worked on breeding seahorses in semi-autonomous tanks.
“We used to have constant problems with bloom imbalances. The juveniles would eat all the zooplankton, and then the phytoplankton would spike. So I started splitting flows, isolating plankton groups, recycling nutrients - it worked better. That’s where the idea really started.”
He later adapted the same principles to larger systems, testing different species combinations: from ulva and sea urchins to sea bass and mussels. The goal was always to build a web where one species’ output became another’s input.
“1kg of feed allowed us to get 5kg of output biomass. It was insane !”
© Tristan Macquet
Why "permaquaculture"?
While many in the aquaculture world refer to this as integrated multi-trophic aquaculture (IMTA), Miard has coined a different name: permaquaculture.
“IMTA is great, but it tends to scare people away. When I say ‘permaquaculture’, visitors immediately think of permaculture. It’s accessible, intuitive, and that’s exactly the mindset I’m trying to promote,.” he explains.
The comparison is apt. Just as permaculture farms stack crops, animals, and water management into a cohesive whole, permaquaculture builds aquatic polycultures that mimic natural food webs. It’s not just about species - it’s about flows.
Miard sees this approach as particularly well suited to salt marshes.
“We’ve got thousands of hectares of disused or abandoned salt marshes in France, and thousands more to come, with rising sea levels worldwide. They’re often historically compartmentalised, close to the sea, and bursting with ecological potential. All they need is a bit of rethinking," he reflects.
© Tristan Macquet
A one-man operation, with global relevance
What’s perhaps most surprising is how much Miard has achieved with so little. His start-up capital was only €10,000. He rented the land through France’s coastal protection agency and cobbled together equipment from salvaged parts.
He works alone, using gravity-fed systems and low-powered pumps with total energy costs “lower than at home”. There are no heavy machines, no automated feeders, and no external inputs.
Now that the system is running smoothly, generating a more than reasonable income with little to no operating costs, Miard is focused on two things: scale and structure.
He hopes to expand beyond one hectare to test additional species combinations and biogeochemical setups. But more importantly, he wants to turn Les 4 Marais into a training and demonstration farm.
“Current multitrophic aquaculture training is too theroretical. Students need to get their boots wet. They need places to learn by doing and messing up,” MIard observes.
With La Rochelle University focus on marine sciences and the Lycée de la Mer vocational school just across the bridge, he sees Île de Ré as the perfect place to build a permaquaculture hub - complete with on-site education, applied research and open data sharing.
He’s also open to international partnerships, particularly in areas where coastal food production intersects with development goals.
“The less you have, the more permaquaculture makes sense. It’s about doing more with less. Using species that are already there. Building systems that are smart, not expensive," Miard reflects.
He’s currently seeking funding to support research, modelling and replication.
“A doctoral student could easily build a hydrological model of the flows here, run it under different scenarios, and generate real predictive data. That would be a huge step towards scaling this intelligently,” he reflects.
Finally, since establishing the farm, Miard has observed a steady return of biodiversity: more birds nesting nearby, more invertebrates in the ponds, and a richer diversity of indigenous marsh plants taking root along the basin edges. While he hasn’t formally tracked these changes, he’s increasingly interested in whether such ecological co-benefits could be recognised as added value for the farmers who help foster them. With La Rochelle University already studying blue carbon in the local marshes, he sees an opportunity for scientific collaboration to explore how biodiversity or nature credits could one day become part of permaquaculture’s business model.
© Tristan Macquet
A vision beyond the pond
Miard isn’t just building a farm - he’s building a proof of concept. One that demonstrates it’s possible to reconcile food production, biodiversity restoration, and economic resilience.
His vision?
- As many IMTAs as there are farmers.
- Permaquaculture as both a climate and development solution.
- Regenerative aquaculture that grows food, knowledge, and ecosystems - all at once.
“The tides are rising. Permaquaculture is one way to rise with them," Miard concludes.
