Since 2009, researchers from the Institute of Marine Research, Nofima and the University of Oslo have developed new technology to measure the environmental conditions in salmon cages.
Installations at sea measure and continuously send data via the cellular network to a database for analysis. The operator can then see in real time what is happening via the internet.
A measurement buoy is placed in the middle of the cage which travels up and down the cage. This measure temperature, oxygen, salinity, chlorophyll (fluorescence) and particles in the water (turbidity). Another probe measures the flow rate and the quality of the water.
A special sonar also detects fish density at various depths in the cageand researchers have also developed instruments that provide detailed data about salmon breathing patterns.
A separate "speedometer" for welfare makes it easy to read the state of the environment in the cage.
"It is important to know for sure how the water environment is exactly where the fish are. We know that there can be large differences in the aquatic environment at various locations in the pen, which point measurements will not show up. For example, the oxygen level inside the cage be directly harmful to fish, despite the fact that O2 saturation just outside is 100 per cent," says researcher Lars Helge Stien.
The new tools offer far more accurate data than before and make it easier to find the causes of various stress reactions, disease outbreaks, increased mortality and poor appetite.
"This technology will thus make it possible to optimise fish welfare and thus optimise both production and earnings in salmon farming," says Mr Stien.
