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Stopping an invasive species of salmon in Norway

(July 2022) At the northernmost tip of Norway in an area of natural beauty on the edge of the Arctic Circle, locals are fighting back against an invasion.

Fishing is in the blood for most of the residents in this part of the world. During the brief summer season, tourists flock to one of the most famous salmon fishing rivers in the world. The Storelva flows into the Barents Sea by the small town of Berlevåg, home to a small fishing fleet and 1,100 people who rely on fishing in one way or another to make a living and survive in this sometimes hostile environment.

William Xu

Northern lights in Norway

However, the prize sought by tourists and locals alike in the streams and lakes in the surrounding mountains is fast disappearing, chased out of their natural habitat by the invasion of a species that doesn’t respect national borders.

The humpback, or pink salmon, is native to the Pacific Ocean. It was released on the Kola peninsula in Russia in the 1960s and began to quickly spread into Norwegian waters. It is a high-risk invasive species and is known to spread disease. It is displacing Atlantic salmon from hundreds of rivers along the Norwegian coast, threatening livelihoods and regional biodiversity. The removal of the uninvited guest was previously done manually by volunteers, a slow and laborious task, until locals decided to fight back with an unusual weapon and Huawei’s help.

In March 2021 Huawei and Berlevåg Jeger- og Fiskerforening (BJFF), a local association of hunters and anglers established a unique partnership to protect the native Atlantic salmon in Norway using machine vision, a type of artificial intelligence technology. The mission was to build an automated fish trap with a built-in camera system utilising AI to recognise and remove the invading humpback salmon.  

When the project was launched, a number of specific challenges needed to be overcome. One was to develop source code which would enable the system to distinguish between the river's native stock of salmon and sea char, and the unwanted humpback salmon.

The second part was to design a computer vision AI to identify the fish, and sort them as they passed through a trap in the river, allowing the fishermen to remove the invading foreign humpback salmon from the local rivers.

William Xu

AI identifying a humpback salmon

The first part of the project was launched in the summer of 2021. Using tens of thousands of images uploaded from a continuous video stream from the river, a model was built and the AI learned how to distinguish between the species in real time with an accuracy of over 90%.

But time was of the essence. While the trap and AI system was being built on site by Troll systems, Vegard Kjenner, technology director at Huawei Norway noted that the spawning season was only weeks away.

“We have seen a sizable number of salmon go up the river while we have worked to put out the installation. The humpback salmon will hardly arrive until one to two weeks from now,” Kjenner says.

“The actual installation of the fishing trap is a demanding job in a powerful river. I am overly impressed with how our partners, the local hunters' and fishermen's association and others in the local community stand up for the project. Here, one is eager to prove what good management is when it comes to saving the river from an environmental disaster.”

Both male and female humpback salmon die after spawning. If humpback salmon breed in the rivers in large numbers, this can result in hundreds of thousands of dead, rotting fish in the rivers throughout the autumn. Humpback salmon have a two-year life cycle, if they start breeding in rivers over larger areas, that increases the chance there will be regular and numerous invasions of pink salmon in Norwegian rivers.

According to Norway's official statistics, 111,700 humpback salmon were caught in Norwegian rivers in 2021. That compares to only 13,900 the previous mating season two years earlier when the Norwegian statistics bureau began to record catches of the species. Norwegian broadcaster NRK quoted biologist Rune Muladal from Naturtjenester, a research and consulting firm working in natural environments in the Barents region, as saying that number could increase by 10 times, to as many as 1 million humpback salmon in Norway by 2023.

After a few days hectic work, the trap was ready and finally installed. Fish swim into a trap and the underwater camera uploads the image to the system, which recognizes whether it is native or not.  Local salmon and sea char pass unhindered, while humpback salmon are stopped and sorted out to a separate area where they can be removed and potentially processed.

By preventing the humpback salmon from swimming up the rivers, the risk of reproduction is eliminated and thus reduce the threat to undesirable biological diversity in rivers.

Geir Kristiansen, manager of the Berlevåg hunters' and fishermen's association, is brilliantly pleased that the installation is in place and working in Storelva and hopes the success can be replicated across the country.

“This is a unique project, both in the Norwegian and international context,” Kristiansen says.  “With this high-tech solution in place, we have secured full control over the river. We are already experiencing great interest in the project from local river-owners along the coast, and both local and central authorities are planning on visiting us to see what all this is about.”

Local spirit and a unique collaboration

The players in this idealistic project are Berlevåg Hunters' and Fishermen's Association (BJFF), Huawei Norway, the Bodø-based company Troll Systems, and Oslo-based Simula Consulting. Troll Systems has developed, produced, and led the testing of the installation, while a research group at Simula Consulting has developed the image vision system that identifies humpback salmon.