ABSTRACT
An overview over several underwater size-grading experiments carried out at the department of agricultural engineering is given. Salmo Salar and Oncorhyncus Mykiss were used in these experiments, and both fingerlings and smolt have been tested. The stimulis used was waterflow velocity and environmental factors like colour. The effect of crowding the fish were also tested out by letting the living space for the fish decrease. A summaryzing conclusion is that both salmon and trout do size-grade voluntary if used specific stimulis. Waterflow, crowding and colours are stimulis showing effect in the conducted studies.
