6 minute read
Technology
BY VINCE MCDONAGH
Face value
Machines are learning to identify individual fi sh out of thousands
If you believe all salmon have the same facial expression, then it could be � me to think again, according to new research.
A recent study by SINTEF, one of Europe’s largest independent research organisa� ons, and the Norwegian University of Science and Technology (NTNU), suggests it is possible to dis� nguish one face from another.
They are basing their results on ar� fi cial intelligence (AI) technology which has helped them carry out much of the work. By adap� ng the type of exis� ng AI technology that recognises human faces, the researchers believe they can learn more about farmed fi sh and how they feel at a par� cular � me.
Picking out 100 random salmon from a cage that contained more than 100,000 individuals, the iden� fi ca� on success rate was just over 96, which is extremely high.
NTNU research fellow and SINTEF researcher Bjørn Magnus Mathisen says it is diffi cult to explain why the technology has been so accurate, but he has been working with machine learning and ar� fi cial intelligence for 10 years and it seems to work.
He said: “We are not sure how they actually recognise the salmon, but actually recognise the salmon, but we have a theory it is through the pigment spots on the face. They have a dis� nc� ve pigment, in the same way as with the cheetah or giraff e.”
One of the things Mathisen found par� cularly interesting about the research is whether they can iden� fy the same salmon throughout their life cycle. He said: “I am really looking forward to tes� ng if this looking forward to tes� ng if this works on smolts and see if the machine works on smolts and see if the machine is able to recognize the fi sh as it gets bigger.
What adds a li� le to the mystery is that machines can also see things that humans do not, he suggests.
In order to study the images of salmon taken by underwater cameras Mathisen uses a type of machine called a deep neural network which is modelled on the way cells in the brain are organised.
A SINTEF report on his work says these neural networks are able to iden� fy animals, people and objects through sound and images in a way that was previously diffi cult to do mathema� cally.
SINTEF says: “You cannot tell a machine how to see the diff erence in each fi sh. Like us humans, it must learn by itself.
Mathisen adds: “Methodologically, machines learn a bit in the same way as humans. We learn by seeing diff erences.”
The research is also being supported by SINTEF’s aquaculture innova� on centre, SFI Exposed, and was started as a master’s project by Espen Meidell and Edvard Schreiner Sjøblom, supervised by Kers� n Bach, Håkon Måløy and Mathisen. To train the so� ware to iden� fy fi sh,
Above: Bjorn Mathisen Left: A Sco� sh salmon Top right: Salmon underwater
the group had to carry out signifi cant manual work fi rst. The researchers were sent a video fi le with thousands of pictures of the salmon in a cage.
Then the task of marking the fi sh heads by hand began, with 500 salmon heads manually iden� fi ed and stored in a database. This collec� on taught the neural network to cut salmon heads from the images themselves, and in a short � me the network had done the same job thousands of � mes.
The work also gave the team a new and larger database which was used to train new neural networks to recognise each individual salmon throughout the cage.
Facial recogni� on is now becoming increasingly common in human commerce, but its use for applica� ons like law enforcement has led to intense ethical debates.
Anders Bryhni, a business developer at SINTEF says: “By using facial recogni� on on fi sh we of course avoid such privacy-related issues. We are like everyone else, concerned with making good ethical assessment when we build a system based on ar� fi cial intelligence.
“At the same � me, we want the business community in Norway to take advantage of the great opportuni� es that lie in technology as quickly as possible.”
Mathisen says the system has a number of benefi ts for aquaculture: “By learning more about each individual salmon, we get to know more about what makes them sick or why they are healthy and why they are happy or sad. The technology makes it possible to know with confi dence about how an individual salmon feels at a par� cular � me.
He adds: “I’m pre� y sure this is going to be a goldmine for biologists. By following individuals through life we can fi nd even more about the ea� ng habits of fi sh, their social hierarchies, general welfare and their tendency to a� ract lice.
“Also we do not have to take random samples by manual methods which are not only expensive and inaccurate, but are also harmful to the fi sh.
“It can also create a new business model because if we know the life cycle of the fi sh it may be possible to diff eren� ate the price of a fi llet based on how a salmon lived.” FF
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