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The Traditional system
Artificial environment, created from as early as the 11th century, the ponds are characterised, in principle, by the presence of a dam fitted with an outlet, by a range of surface areas (from some hundreds of m2 to 180 ha) with average depths from some tens of cms to 2.5 m.
- The exploited or non-exploited traditional pond
These tanks are exploited or not exploited for aquacultural purposes according to their inherent characteristics (unable to be emptied, very difficult access...), or their owners, or the competition of otheractivities (hunting, leisure activities...).
- The traditional pond with natural and random production
The operation is limited to fishing by emptying every 1 to 3 years. Production therefore depends exclusively on the natural production of the waters which vary according to the region from 25 kg to 150 kg/ha/year.
- The traditional pond with planned production
These ponds are exploited via polyculture with an annual winter emptying. The production relies on natural productivity enhanced by the addition of organic or mineral fertilisers and, if necessary an artificial feeding supplement (cereals in particular), the production varies from 150 - 500 kg/ha/year.
- The traditional pond with intensive production
This system of rearing results from a development in management of the pond by reprofiling and reworking of the banks with access to the periphery and the presence of an energy source on the site. Production depends on the supply of exogenous food (cereals and especially protein foods). The extent of intensification varies from 500 - 3000 kg/ha.
The basin system
Of recent creation, this consists of more geometric shapes with sloping banks around its periphery, a water depth from the foot of the bank of at least 0.8 m, and permanent access possible at all points. It requires management of the water and the energy. The size varies from 250 m2 to more than 5 hectares, it must be possible to empty it and it must have a harvesting equipment.
The basin system with water which is not renewed
This has a characteristic rectangular shape and an average depth of 1 to 1.2 m, the surface aera varies from 500 m² to 7 hectares. The continuous production lies between 1 and 10 tonnes/hectare/year inclusive. The water requirements are therefore limited to potential renewal in the event of yearly emptying and the compensation for evaporation wich is around 3000 m3/ha/year on average. However, the water control must be able to supply, at any point, clear or good quality water in the event of problems (especially climatic). The aeration power per hectare is around 2.5 to 3 kW. The feeding is done either by the distribution of the food along the length of the bank using towed hoppers, or by programmable dispersion feeders (disk, worm screw, compressed air) at a fixed point.
The basin system with renewed water by recycling
The principle of this system is to raise the fish in an intensive way in mono-culture, in basins with small dimensions where the water is constantly renewed by recycling from a natural pond, acting as a lagoon, prurifying the waters (biofilter).
The rearing of cyprinoids, which require a water temperature between 20 and 27°C for growth, is perfectly adapted to this system.
The key point of this system is the homogeneity of the water mass, hence the shape of the pond and the arrangement of the aerators.
Indeed, for a pond of 500m3 with a recycling volume of 100m3/h (given a theorical renewal water rate of 4 - 8 times/day) the rate of actual recycling of all the water in the entirety of the pond is only once a day.
Current investigations which have been carried out on the technical improvement of these systems, with the aim of a better control of the quality of the water, include : use of pure oxygen for aeration, microfiltration of the water imported from the pond, use of zeolites for control of NH4, addition of a complementary simple biological filter in the basins, etc...
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To contact AQUALOG |
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Aqualog
Bouée Borha
Corniche du Bois Sacré
Marépolis Est
83500 La Seyne sur Mer
Tél. : 04 94 10 26 26
Fax : 04 94 10 26 30
