Environmental conditions required for intensive farming of Arctic charr (Salvelinus alpinus (L.))

The Arctic charr (Salvelinus alpinus) is a relatively stenothermal fish that displays a high degree of biological plasticity. Although primarily a freshwater fish, there are anadromous populations at the northernmost limits of the distributional range. Developmental plasticity has both advantages and disadvantages for establishment in culture, with variable growth rates and early onset of sexual maturation at small size being distinctly disadvantageous. In addition, a requirement for water of low temperature for egg production (4-7A degrees C) and early development limits the possibilities of farming Arctic charr outside of its natural distributional range. On the other hand, a tolerance of high stocking density (60-150 kg m(-3)) makes it a candidate for rearing in recirculation systems where effective use of both water and rearing unit volume are at a premium. It is possible to farm some strains of charr in either fresh water or brackish water (20 aEuro degrees) throughout the year, but year-round farming in full-strength seawater (33-35 aEuro degrees) does not seem to be feasible. Photo-thermal manipulation can be used to influence feeding, growth, salinity tolerance and the reproductive cycle. Water quality requirements seem to be similar to those of other salmonids.