FISH FARMING TECHNOLOGY
Here comes the sun: Les Poissons du soleil, French RAS farm by Vaughn Entwistle, Managing Editor, International Aquafeed Recycled Aquaculture Systems (RAS) have been around for more than twenty years. Mostly they are used in hatcheries, although the economics are changing and now many RAS systems are used in mainstream fish farms. In 2018, our magazine visited Les Poissons du Soleil (fish of the sun) located at Balaruc Les Bains, France to see their state of the art RAS fish farm facility. We were given a thorough tour of the impressive facility by Mr Dolé Martin, the Production and Logistics Manager for Wellboat Expeditions.
Sur la mer
Upon arriving, one of the first things that struck us about Les Poissons du Soleil was its coastal, “sur la mer” location, as the two main RAS tank buildings are located right on the shore of the Mediterranean. Being located so close to the sea offers a fish farm facility a number of important advantages. “We pump water directly from the Mediterranean,” Martin explained. “All the water is treated. We pump and treat approximately 100 cubic meters of water an hour. Each of our two buildings has its own filter system. The water is first run over the primary sand filters. It is also run through biofilters. “UV filters, supplied by the Marseille company BioUV, and drum filters are supplied by Faivre. The biological filter takes the ammonia out of the water which is recycled and returned to the tanks. The big particles are taken out by the Faivre drum filters.” The ability to have a free supply of water is invaluable, but there are complications, as Martin explained: “The water pumped from the Mediterranean varies in temperature according to the season. In the winter, the water must be heated to at least 18°C to ensure a good growth rate in the fish. We try to maintain a temperature of between 18°C and 25°C throughout the year.”
Martin explained that fish are more active in the warmer summer water, and consequently consume more fish feed. “We have to manage all these parameters in our growth predictions,” Martin added.
Two hall facility
The Poisson du Soleil facility is divided into two buildings, which mirror one another in their layout. Each building houses 12 tanks for a total of 24. Each tank holds 40 cubic metres of water. Martin explained, “Because we are so close to sea level here the tanks are tall, but not very wide. As the water circulating through the tanks passes the pump it is injected with oxygen to around 500ppi.” The Poisson du Soleil facility grows mainly Sea Bass and Sea Bream. They receive stock from their two hatcheries in France and then grow the fish until they reach a specific size/weight. “We receive the sea bass at 1.5 grams,” Martin said, “we grow them to 5-10 grams, and then sell them to fish farms all over Europe. These fish farmers then grow them to around 300 grams—it depends on the market they serve. We send a lot of fish to Tunisia where the fish might be grown to 200 to 250 grams, because the customers there like to buy five fish per kilo to feed the family.”
Money in the tank
“In a tank like this, we put in between 100,000 to 500,000 fishes. Usually we work 20 to 30 kilos per cubic metre. We have the capacity to have 70 kilos per cubic metres with good feeding, good oxygenation, and good water quality, but we don’t reach this biomass by security.” A tankful of fish represents a large capital outlay, so Poisson du
42 | March 2019 - International Aquafeed