Saving Norway's Endangered Atlantic Salmon

Norway is home to 1,190 fjords and boasts the world's second longest coastline as well as countless rivers and lakes. Its extensive river system also represents the world's largest breeding ground for wild Atlantic salmon, a species that is intrinsic to Norwegian culture and a popular catch for recreational anglers.

Starting in early June and continuing into September, the "salmon flood" is a short but exciting time when wild Atlantic salmon migrate between freshwater and seawater. A year after hatching, they migrate to the ocean, spending between one and three winters there before returning to freshwater to spawn.

Salmon fishing in Norway

In troubled waters

However, the population of Norwegian wild Atlantic salmon has declined alarmingly, dropping by 50% since the 1980s.

The major threat to this species comes in the shape of its distant cousin, the humpback salmon (also known as pink salmon). Artificially introduced from the east side of the Pacific Ocean to rivers bordering Norway in the 1960s as a way of boosting food supply, the humpback salmon gradually made it way throughout Norway’s river systems over several decades. It then emerged as an invasive species that began disrupting food chains, introducing disease, and upsetting the natural balance of native ecosystems. Moreover, dead and decaying humpback salmon increase the nitrogen content and cut the oxygen content in rivers, reducing the number of other organisms that rivers can support and causing other marine life to die.

Today, the humpback salmon has proliferated to the extent that it could overwhelm the Atlantic salmon and other wild fish. The invasive species competes - and competes well - with native species for food and spawning grounds. They enjoy the same food as their Atlantic cousins, are aggressive, and have high reproductive rates.

Biennial invader

Due to its biennial (24-month) reproductive cycle, the humpback salmon peaks in odd years. In 2019, the number caught by sports anglers surged to 13,900, which jumped to a record-breaking 111,700 in 2021 – 57% of all salmon caught in Norway.

The most recent invasion took place between June and September 2023.

The humpback salmon's high spawning rates could wipe out the Atlantic salmon in the worst-case scenario
Photo: Knut-Sverre Horn, NRK

Escaped farmed salmon also add to the threat, competing with wild Atlantic salmon for resources and weakening the genome of the species after interbreeding.

Fishing for a smart solution

Traditional methods for protecting wild Atlantic salmon stock are labor-intensive. Volunteers would stand or dive into the river to try and identify humpback salmon by their humps (males) or the spots on their tails (females), and remove them by hand. This made it impossible to accurately monitor and quantify the threat and also risks harming other marine life.

Humpback salmon (male, above; female, below)

Wild Atlantic salmon

Berlevag JFF (BJFF) - a local hunting and angling association - approached Huawei to explore a possible technological solution. The aim was to automatically identify different fish types and filter out the invasive species.

After an extensive developmental process lasting over two years, 2021 saw the completion of two phases: First, an algorithm was developed that could identify different fish species. Then in June, the partners deployed a monitoring station with an underwater camera in Storelva River, which provided a continuous video stream and generated tens of thousands of images to train the algorithm.

In 2022, the partners deployed an automated gate system that, prompted by the AI system, lets wild Atlantic salmon and other fish pass upstream to spawn, but filters the invasive humpback salmon into a holding tank for removal.

Installing the 12-meter filtering system / Photo credit: Bendik Skogli, Huawei

Testing the filtering system / Photo credit: Nils Johan Porsanger, NRK

Progress so far

After two years of development, pilot projects were scheduled two of Norway’s rivers - Kongsfjord and Storelva - ready for the start of the salmon breeding cycle in June 2023. Over the next few months, the efficacy of the solution was put to the test. And the test was passed: with the system

• Detecting and preventing more than 6,000 humpback salmon from proceeding upstream to spawn, achieving an identification accuracy rate of 99%+.
• Cutting manual labor requirements by 90%, with volunteers no longer needing to stand in the river and visually identify the invasive species before catching them with their hands.

So far, the partners have observed that:

• A few Atlantic salmon swam into the filtering system at the same time as humpback salmon, entering the holding tank at the same time. They can be retrieved and returned to the river unharmed by hand.
• Some Atlantic salmon hang back down the river, potentially waiting for days until the waves of humpback salmon have passed before proceeding through the gate.
• Most wild Atlantic salmon wait below the fence at the entrance to the system until the humpback salmon have passed through the tunnel and have been filtered into the holding tank. The Atlantic salmon then swim through the tunnel and proceed upstream.

A world first

The project is the world’s first intelligent AI-based salmon filtering system deployed in a natural river system that has successfully captured a target species. It features several innovations:

• AI: implements a fish recognition algorithm based on underwater images, the accuracy rate of which exceeds 99%+.
• Tech-enabled solution for nature conservation: yields a much higher success rate at catching the invasive species than the manual sorting used in other rivers in Norway this year. It also allows native fish to pass through unharmed, unlike manual solutions that result in an average injury/death rate of 30%. All fish, whether they pass through the automated gate or are diverted to the water tank are neither frightened nor hurt.
• Green and low-carbon: uses a smart PV system installed in the river to power the whole system. The project partners have worked to ensure that the solution is as environmentally friendly as possible.
• Partnership between the private sector and local community: represents the combined efforts of the local community, conservation groups, and technology companies.
• Research insights: collects data 24/7, which can reveal accurate patterns of migratory behavior, monitor different types of fish populations, provide information for further research, and help to prevent overfishing.

What’s next?

It has become increasingly clear that automated solutions are the best way to solve the issue of invasive salmon.

The solution has also been designed to identify and remove escaped farmed salmon. After seeing the results of the TECH4ALL project, the fishing industry is now very interested in investing in the next step.

The success of the pilot project has not just given confidence to fishermen in Berlevag, it also gives hope that the solution can be applied in other similar rivers in Norway and Europe facing the threat of invasive species.

Norway's wild salmon are threatened by other species, including humpback salmon and escaped farmed salmon. The monitoring systems using AI is helping to stop this and enable future-proof river management.Tor Schulstad
Hunting and Fishing Association Administrator, BJFF

This is a unique innovation, both in Norway and globally. With this high-tech solution, we have complete control of the river. Local river managers and local and central administrations along the coast have also shown great interest in the project. Geir Kristiansen
President, BJFF

We hope the technology will help us protect the Atlantic salmon schools here. If this option works here, it will work in other Norwegian waters as well. Liljia Birgitte Huus Lygren
River Supervisor, Storelva

Installing a diversion system in a turbulent river is an extremely challenging task. I was impressed with the efforts of our partners, BJFF, and the local community. Here, people aspire to prove the role that good management has in saving rivers from environmental disasters. Vegard Kjenner
CTO Huawei Norway