SCOTTISH EXECUTIVE LOCATIONAL GUIDELINES FOR FISH FARMING: PREDICTED LEVELS OF NUTRIENT ENHANCEMENT AND BENTHIC IMPACT

The assessment of the acceptable level of fish farm development in Scottish coastal areas is strongly dependent on the predicted rate of release of nitrogenous nutrients and particulate organic waste. A simple mass balance model has been used to estimate the rate of production of dissolved and particulate nitrogenous waste by cultivated salmon. The predicted release of dissolved nitrogen is 35-45 kg N/tonne of fish produced, depending upon details of the stocking, feeding and harvesting strategies adopted. Calculations based upon records from a number of Scottish salmon farms indicate that the net waste productions during the cultivation of ‘normal’ S1 and PP1 (photoperiod modified) smolts are similar.