The ultimate goal is for artificial intelligence and machine vision to be an accurate tool for the industry: Fish welfare is of course a critical topic in salmon farming. It is therefore important to see the fish as individuals, rather than just a group. Researchers have used camera technology combined with artificial intelligence to monitor and analyse the breathing rates of individual fish.
“The breathing rate of the fish is important because it provides us with valuable information about their wellbeing,” says SINTEF researcher Christian Schellewald.
It is hoped that the technology will be able to contribute to the more humane treatment of salmon, reduced handling, fewer interventions and lower mortality rates. The research was recently published in two scientific articles.
Camera meets algorithms
In the Biorelevans research project, the researchers have developed a way of analysing signs of stress and other welfare factors.
“Using algorithms, we can recognise the fish and analyse their respiratory movements at the same time,” said Schellewald.
He explains that the camera technology is able to observe the breath of a fish if it can see its mouth. The fish are therefore filmed horizontally i.e. from the side.
The main focus is on the snout of the fish, which moves as the upper and lower jaws open and close.
Each individual can be observed using the new technology. It can provide information on the wellbeing of the fish long before any signs of disease become visible. Photo: Espen Berntzen Høgstedt
The technique gives the researchers a “digital eye” which makes it possible to monitor numerous fish simultaneously. This is important because it gives the researchers more data to work with.
Satisfied researchers
The researchers have conducted trials where they monitored nine fish tubs, each containing seven fish. The breathing rates of all the fish were then analysed under three different temperature regimes, as well as with different oxygen levels in the water.
“We could see with great accuracy how the breathing of the fish changed in stressful situations or in the event of changes in oxygen levels or water temperature. This helps us to give us a detailed understanding of how the fish are affected by the environmental conditions around them,” says Schellewald.
SINTEF researcher Christian Schellewald in the field. Photo: Private
Researchers at the Norwegian University of Life Sciences (NMBU) were responsible for the biological analyses and project management.
“We found that lower oxygen levels caused the salmon to breathe more rapidly. We saw the same response when we increased the water temperature. Stress also led to an increase in breathing rate,” says Judit Vas, a behavioural biologist at NMBU.
Warning signs can be seen early
Vas says that the study has contributed to a new understanding of the breathing rates that can be regarded as normal and those that can be regarded as indicating that something may be wrong.
“However, we also found that the breathing rates of the individual fish vary. Some of them breathe more slowly or faster than others. The newly developed camera technology, which monitors each salmon individually, is therefore of great help. It enables us to see whether the breathing rate of some fish changes, while that of others does not,” says Vas.
She says that the industry currently mainly uses external signs as welfare indicators.
“The fish may have visible wounds or other injuries, but the fish is already injured in this case. The ability to identify warning signs at an earlier stage would therefore represent a major advance for the industry. In turn, this will probably lead to a reduction in medicine use, fewer interventions and lower mortality rates,” says Vas, whose work has attracted considerable interest from within the industry.
She predicts that the breathing rate of fish will be a widely used technique in fish monitoring in a few years’ time.
Contributing to more humane treatment
The aim of the research project is to improve our understanding of fish welfare under different environmental conditions.
“By enabling breeders and researchers to monitor and analyse the breathing rate of fish at individual level, technology can help to improve the quality of farmed salmon,” says Schellewald.
He is therefore confident that the technology will be adopted by the sector.
“It will obviously be able to provide insights that will lead to the more humane treatment of salmon,” concludes the SINTEF researcher.
In addition to researching fish breathing, researchers have also studied the link between weight loss, stress management and fish behaviour in groups in this project.
Mouth Opening Frequency of Salmon from Underwater Video Exploiting Computer Vision
