The impact of production intensity on water quality in oxygen enriched, floating enclosures for post-smolt salmon culture

The main aim of the study was to decide the effect of specific water consumption (L/kg/min) and feed load per water flow (g/m3) on the water quality parameters pH, CO2, total ammonia nitrogen (TAN) and suspended solids (SS) in two large semi-closed containment systems (S-CCS). The reported production parameters (range) in the two S-CCS were specific water consumption (q): 0.04-0.47 L/kg/min and feed load per water flow: 9.0-64 g/m3. The study period was split in two sub-periods; January-May (4.4-7.5 °C), and June-September (7.5-13.2 °C) before a regression model was used to determine the relationship between production intensity (q, feed load) and water quality (pH, CO2). With the acceptable level of CO2 defined as ≤10 mg/L, the model predicted a minimum specific water consumption (L/kg/min) between 0.07 (winter) and 0.2 (summer). The predicted maximum feed load per water flow (g/m3) was between 35 (summer) and 45 g/m3 (winter). These calculated limits for production intensity were close to the values earlier reported for smolt or post-smolt production in large, onshore tanks.