Humpback salmon in large schools in 2023. Photo: Malin Solheim Høstmark/State Administrator of Troms and Finnmark

Norway Deploys AI and Expanded Traps in Major Battle Against Humpback Salmon Invasion

NORWAY
Thursday, June 12, 2025, 06:00 (GMT + 9)

Over 60 northern Norwegian rivers will see intensified efforts, doubling state-funded measures from 2023, as authorities leverage technology and local collaboration to protect wild salmon stocks.

OSLO – Norway is gearing up for a significant offensive against the invasive humpback salmon or Pink salmon (Oncorhynchus gorbuscha) this summer, expanding its defense to over 60 rivers across northern regions. This marks a doubling of state-funded traps and mitigation measures compared to two years ago, with new artificial intelligence (AI) prototypes also being deployed to enhance sorting efficiency.

A fish trap is placed near the mouth of the river and it directs all the fish into a structure where they are caught. The humpback salmon are removed, while the wild salmon can continue upstream to spawn. | Photo: Jan Harald Tomassen, State Administrator of Troms and Finnmark

Humpback salmon, an unwanted and alien species, typically arrives in large numbers in Norwegian rivers every two years, with substantial influxes expected this season in northern Norway. After reproduction, the fish die and rot, posing a threat to native wild salmon populations and local biodiversity.

"We have a responsibility to stop humpback salmon from establishing themselves in Norwegian rivers, and to prevent it from spreading further to other countries," stated Minister of Climate and Environment Andreas Bjelland Eriksen. He added that efforts have been significantly strengthened since the last invasion, expressing confidence that combined actions will protect wild salmon and natural diversity.

Doubled Efforts and Strategic Expansion

Following the 2023 invasion, where almost half a million humpback salmon were caught or observed, lessons learned have informed this year's intensified strategy. "Most state-funded traps were effective during the humpback salmon invasion in 2023, and local volunteers stopped close to one hundred percent of the humpback salmon in many of the rivers," said Hilde Singsaas, Director of the Norwegian Environment Agency. "Now we will use the experience from 2023 to make the measures during this year's invasion even more effective."

While 2023 measures focused from Sør-Varanger to Hammerfest, this year's operations will extend to cover Vest-Finnmark and large parts of Troms. Of the 63 rivers receiving state support for equipment and staffing, 53 will feature fish traps. In seven rivers, humpback salmon will be removed with nets, and in three, they will be stopped and sorted using specialized fish ladders. Local associations, the Norwegian Environment Agency, and the State Administrator of Troms and Finnmark have dedicated two years to these preparations.

Tackling Challenges in Major Rivers and Leveraging AI

Authorities acknowledge the unpredictable nature of humpback salmon arrivals and the challenges posed by natural conditions like heavy rain or snowmelt, which can hinder trap installation and maintenance. "The humpback salmon that will arrive this year probably originate from rivers where we were unable to stop the increase in 2023," noted Anders Tandberg, section manager at the State Administrator of Troms and Finnmark. "This summer, we will set traps in new rivers and improve the extraction in the rivers that already have traps. We believe we are well prepared, but it is a large and complex operation."

Lessons from 2023 highlighted the need for better results in larger rivers. Significant efforts are underway in key areas:

• In Tana, a new and improved trap is being installed in a more suitable location to boost catches.
• The Reisa River in Troms, which saw an estimated 10,000 humpback salmon reproduce in 2023 due to the absence of a trap, now boasts the largest floating trap used in Norway to date, approximately 100 meters wide.
• Neiden will see a new fishing cage at the top of its salmon ladder and net removal below Skoltefossen.
• In the Alta River, the Alta Salmon Fishing Partnership (ALI) will use nets that catch fish alive, facilitating the safe release of native Atlantic salmon.

Humpback salmon trap in the Syltefjord River. Photo: Henrik H. Berntsen (NINA)

Crucially, Norway is also piloting artificial intelligence (AI) solutions. At traps in Repparfjordelva, Vestre Jakobselv, and Skallelva, prototypes of machines using image recognition will be tested to automatically sort humpback salmon from Atlantic salmon and other species. "If the technology works, it will be relevant to use such systems in many rivers in 2027," Tandberg confirmed.

Facts about Humpback Salmon:

• An unwanted, alien species arriving in large quantities, particularly in northern Norwegian rivers.
• They die and decompose after reproducing, impacting water quality and native species.
• Norway now has self-producing populations of humpback salmon, with fry emigration to the sea documented in 2024. The survival rate and return numbers for 2025 are unknown.

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