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	Hatchery Technologies/Larviculture A high priority research area is the mastery of fry production, which is still the most important limiting feature in industrial development. Research integrates experiments with the main rearing techniques (extensive, mesocosm and intensive in open or recirculated systems), and methods (in clear, green or pseudo-green water) in order to investigate optimum conditions necessary to maximise the biological performances (survival and growth), and the quality of the larvae. The so-called "mesocosm" technique is a major emphasis in the Department because of its suitability for the Mediterranean region and for SMEs. Mastery of larval food chain technologies is also an important area of research, because live prey remains an essential element in marine finfish mariculture, and its production has not yet been completely mastered. Research is directed towards either speed or intensity of culture, for quick restoration of production (in case of breakdowns in intensive culture), or towards the maintenance of diversity equilibrium and culture stability in mesocosms. There are two hatcheries (capacity 1 million fry/year) each with an integrated zone of phyto- and zooplankton production. The first has 12 larval rearing 500 litre rearing tanks, and 4 pre-weaning 2 m3 tanks, organised as 6 independent recirculated systems with regulated light and temperature, aimed towards research in pilot scale production under hyperintensive conditions. The second has ten large tanks (40 - 60m3) and is used for research into extensive and semi-extensive (mesocosm technology) conditions, and the use of solar energy for SMEs operating in temperate to hot countries. Intensive techniques The "green water" technique attempts to create a semblance of natural conditions in large cylindrical tanks of 10 to 50 m, with an average density of 30 to 50 larvae/l.The "clean water" technique, used for sea-bass, operates in cylindroconical tanks (0.5 to 2 m3), with a very high larval density of 100 to 200 litre. The methods used are very precise and based on natural processes. Antibiotics are not used as they are responsible for a lower subsequent growth rate and survival performance of the larvae. The "pseudo-green" technique is a method which integrates principles of intensive and extensive aquaculture, and is based on the addition of phytoplankton in closed water systems under light-intensity conditions that do not allow their proliferation. This addition of phytoplankton (a feature of the extensive method) occurs at the most critical time in the rearing procedure, when the tiny fish larvae are still extremely weak, sensitive to the intensive environment, easily stressed and difficult to feed. Intensive methods are then put into operation when the larvae can be easily reared according to classic procedures. This technique is mostly used for sparids. Extensive techniques The extensive technique is based on the use of physical blooms of phytoplankton and zooplankton. Large tanks, or mesocosms, capable of holding from 60 - 100 m3 are filled with sea water pumped direct from the sea. The larvae are introduced into the mesocosms at the appropriate time in the natural food chain, after the rotifer bloom, without the need for additional food. Studies are also undertaken involving closed hydraulic systems, with mechanical filtration (on sand or by a revolving shifter) and types of biological filtration. The quantitative needs of the larvae, in respect of energetic value and quality of prey, are also studied.
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