Turbot (Scopthalmus maximus) grow-out in Europe: Practices,results, and prospects

Turbot farming is an emerging industry with a total production of 5,500 metric tonnes in Europe in 2000 (only 5% of sea bream and sea bass production). The market situation at the moment is favourable for turbot. This paper provides an overview of the major features of turbot grow-out methods that are in the public domain and describes the results of rearing studies done with an Atlantic strain of turbot, both in the laboratory and by the industry. Turbot farming has developed mostly in land-based systems supplied with sea water at ambient temperature, or most often heated. Rearing methods are highly diversified among sites. Under the most intensive rearing conditions, stocking densities average 45-50 kg $m{-2}$ and fish are fed dry pellets manually. Growth results are highly dependent on environmental conditions, mainly the average annual temperature. The best growth rates are obtained at about 14-19°C. To reduce heating costs, there is now great interest in re-circulation systems in several countries. This paper also discusses the gap between the observed growth potential and the usual growth results in the light of recent applied scientific research. Major growth improvements may be obtained by using the optimal thermal regime, by increasing oxygen concentration to near saturation and by feeding fish correctly near apparent satiety. Since efficient commercial diets are now available, dietary composition is the main determinant of flesh quality. Selection of fast-growing and late-maturing fish is another way to improve growth of turbot.

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