The businessman behind France’s only sea salmon farm plans to use fish waste to grow strawberries, tomatoes and salad leaves.
Pascal Goumain claims a world first in developing a way to combine fish farming and hydroponic agriculture.
Hydroponic agriculture is the name given to a system in which plants are grown in nutrient-rich flowing water.
It is usually used for year-round cultivation of tomatoes and salad crops but Mr Goumain said his system relies on unheated greenhouses so the crops will be more seasonal.
Summer crops will be mainly soft fruit such as strawberries and raspberries, along with tomatoes, cucumbers and aromatic herbs, and in winter this will shift to cabbages, salad leaf vegetables and herbs.
“We have called it an aquaponic system to show that this is something new,” he said.
Three small prototype farms have been established so far, with planning permission requested for a larger unit in an old grain silo near Chartres.
It took three years of research and another three years’ development on the prototype farms to convince him the idea could work financially. Plants are grown next to tanks where trout are raised.
The droppings and other excretions from the fish form nutrients for the hydroponic fluid used for the plants.
“Our big success has been finding a method of converting the liquid excretions from the fish into soluble fertiliser using bacteria,” he said.
“It is the key, because without this stage, plants cannot benefit from the fish nutrients.” Water from the trout tanks is pumped through two filters.
The first is a mechanical one to remove solid matter, and the second a bacterial one which separates the nutrients for the hydroponic liquid.
After being filtered, the water is used again in the fish tanks.
Nothing goes to waste. The solid matter is composted, dried and sold as fertiliser.
“This has proved to be very effective in trials and we are confident that it will work as we scale up production,” Mr Goumain said.
A key part of the prototypes and of the full-scale farms will be on-site shops selling both the produce and the trout, as well as salmon from Mr Goumain’s salmon-farming business in Cherbourg.
The trout will be sold as fresh whole fish, fillets or smoked, with fillets sent to Cherbourg, where Mr Goumain has a smoking factory for his salmon operation.
Mr Goumain said: “There are, and have been, systems combining fish farming and agriculture, especially in Asia, but my system is the first to develop it further and use hydroponic growing principles.
“At the moment, it is imposs-ible to build and operate new fish farms in France so the choice is to either buy up existing ones, as I have done, with all the problems that often come with them, or to go off and do something different.”
He opened his first fish farming business in the early 1990s, raising carp and other fish, mainly for angling lakes.
“My parents had a fish farm and it is something which fascinated me from a young age,” he said.
“I studied various systems and began to see the potential to develop new systems.” Located at in the bay of Cherbourg-en-Cotentin, Normandie, in second largest artificial harbour in the world, the farm is protected by a sea-dike. It has 15 hectares of concession and an operating license of 3,000 tons (France’s maximum) per year.
Expansion planned for unique sea site
Pascal Goumain runs the only sea salmon farm in France, and sells his produce under the Saumon de France label in supermarkets or via the internet.
He plans to expand its operation in France from a “couple of hundred” tonnes of fish a year to 1,500 tonnes.
The farm benefits from a unique situation behind the first sea wall protecting Cherbourg harbour.
Passengers on ferries leaving or entering the harbour can see the farm if they look at the interior of the sea wall, “but we are quite discreet, there is not a lot to see unless you know what to look for”.
The site has 15 hectares of water and strong tidal and coastal currents.
“We decided to rely on a high-quality product and found our standards were actually far higher than those required for a bio label, which has rule books drawn up by the large groups,” he said. “We have never had a problem with sea lice because of our low stocking numbers in each cage and the strong tides and currents we have, and so have never had to use the pesticides which are common almost everywhere else.”
The number of salmon farms in France is limited to the one in Cherbourg because of a lack of suitable sheltered spots and rules which prevent buildings within 100 metres of the coast.
Prices of Saumon de France fish are around 30% higher than quality salmon in supermarkets from Norway or Scotland, but Mr Goumain said this is justified by the quality of the fish and the artisan production methods used to smoke it.
“Our market is made up of people who are prepared to eat less but to eat better,” he said. “Fortunately, it is something which French people understand.”