Institute of Marine Research
APB Feeding [x]
Automatic profiling buoy (APB505) inside a sea cage


The Welfaremeter is an expert system for assessing fish welfare in aquaculture. The system consists of a buoy (APB 505) with profiling probe (CTD,SD204) placed in the centre of a sea cage, a reference probe (CTD, SD204) placed at a distance from the fish farm, a database, an expert software program and an internet webpage. The profiling probe measures temperature, oxygen, salinity, fluorescence and turbidity for each half meter downwards in the cage. The buoy's control unit determines how often the probe profiles the water column and present data on an internal webpage. The Welfaremeter polls these data via the mobile phone network (GPRS) and stores it in the database. The data are then analysed by the expert software which gives an evaluation of the environmental conditions in the cage as either very good, fair or potentially harmful for the fish. The software also calculates a welfare index from 0 (terrible welfare) to 100 (excellent welfare). This index is based on modelling of metabolic scope (the salmon’s capacity to extract oxygen beyond its basic needs from the water under the current environmental conditions) and factorial scope which reflects the salmon’s robustness for stress and environmental perturbations under the current environmental conditions). The results are shown on the internet webpage (requires login).


Tore S. Kristiansen
Research group leader
+47 92069918

Lars H. Stien
+47 47291029

Research group

Animal welfare

Institute of Marine Research University of Oslo Nofima ARGUS | Remote Systems AS SAIV AS Plastinvent AS