The autumn of 2021 was a gloomy record year for the number of humpback salmon that invaded the rivers of northern Norway.
Now 2023 could be disastrous if nothing is done.
– There may be hundreds of thousands of humpback salmon in some rivers, and potentially millions in the largest rivers, warns Eirik Frøiland, senior adviser at the Norwegian Environment Agency.
Before he continues:
– The problem spreads to more southern rivers. Norway’s rivers act as a bridgehead for further spread to other countries such as Iceland, Greenland and Scotland. Norway is responsible for prevention, says Frøiland.
Humpback salmon were recorded last year in almost all rivers of Finnmark, as well as in the western and southern rivers.
Bigger than expected
As far south as Lofoten, anglers caught large numbers of humpback salmon from land and boats.
“We think we will get more growth in 2023, but it depends on the growth and survival of the humpback salmon in the sea for the next 12 months,” says Frøiland.
This winter, Finnish researchers took several samples from the Vetsijok River, a tributary of the Tana River in Finnmark. The survey revealed large numbers of live fry under the ice.
Research has also been done elsewhere.
– Survival has been good. In 2021, Frøiland says, there was more spawning the further east you went, and smolt volumes are naturally related to spawning in individual rivers.
Local hunting and fishing associations worked hard all autumn to get rid of the alien species.
– Totally awesome
A tremendous amount of voluntary work was done, but in several places it was to no avail.
Some of those who tried to fight back were local fishermen associated with the Repparfjordelva in the municipality of Kvaldsund in Finnmark.
– It’s just absolutely fantastic. Humpback salmon are huge and we have been fighting all summer, said Geir Skogheim, board member of Vest-Finnmark Hunting and Fishing Association, to the TV 2 program last fall.
Humpback salmon is an unwanted alien fish species in Norwegian nature.
It belongs to rivers that flow into the Pacific Ocean and has also spread to Norway after being released in northwestern Russia.
– What are the consequences of the humpback whale’s huge volumes?
– It has been little studied. We know that humpback salmon can displace Atlantic salmon, sea trout and char. Then we know that the water quality becomes poor when many humpback salmon die and rot in the fall. According to the risk assessment of the Scientific Committee for Food and the Environment, there are other possible negative consequences, says Frøiland.
The Norwegian Environment Agency has now formed a national expert group that will investigate different trapping methods. In addition, they must advise on which waterways efforts should be directed.
One of the companies that wants to help stop the humpback whale invasion is Troll Systems, a limited company in Bodø.
They are working with global Huawei to build a fish trap that uses artificial intelligence to stop humpback salmon.
– A camera that stands inside a fish trap has been developed. It differentiates between different types of fish within a nanosecond. The species that belong to the river are passed through. This means that unwanted hump cracks are closed off by means of resistance, says Rune Rørstad, CEO of Troll Systems.
The first artificial intelligence (AI) tests were conducted in Berlevåg last year.
They are now building on last summer’s encouraging test results.
– We are looking forward to the second phase of the project. Based on the results achieved last year, I have no doubt that it will be successful. Last year the fish was not separated, we will do it this year. Last year, the artificial intelligence module learned to recognize past species in milliseconds with more than 90 percent accuracy, says Geir Kristiansen, head of the BJFF.
Never before has the Norwegian Environment Agency invested so much in getting rid of the humpback whale than now.
An investment of time
The state administrator of Troms and Finnmark has received NOK 10 million to buy and test different traps that stop humpback salmon from spawning.
– Our goal is to build different types of fish traps in as many rivers as possible, based on the resources obtained. Estuary sorting of humpback salmon is the most important measure to limit the species, but there is much more going on. We want to gain more knowledge about the humpback salmon and the consequences of the invasion, says Eirik Frøiland, senior advisor at the Norwegian Environment Agency.
– Is this a lost battle?
– They can become violent if we don’t succeed, but we believe we can control it. We know what is needed, but it requires resources, says Frøiland.
Humpback salmon live only two years and weigh a few kilos around.
It is only when the Pacific rift enters the rivers that a massive transformation begins. The fish becomes hunched over and becomes very aggressive.
Eventually it looks like a monster, rots and dies.
As long as the humpback salmon is caught in the sea or in the mouth of water bodies, it is a good food fish. Therefore, various measures are being taken to make fish a food resource.
The aforementioned Repparfjordelva in Finnmark is one of several rivers in which the Norwegian Environment Agency will now start testing new salmon traps.
– A new float trap will be installed there this year. It will be tested for a few weeks and then stored on land over the winter for use in 2023. If successful, it is an appropriate trap type for several rivers of the same size, says Frøiland.
It’s a race against the clock that’s going on right now.
It was bad in 2021, and 2023 and 2025 could be disastrous in terms of humpback numbers.
– What if you don’t succeed?
– Humpback salmon will then very quickly become the most abundant salmon species in Norway and possibly in other countries along the Atlantic Ocean. This adds to the serious threats to the Atlantic salmon, which already has major problems, says Eirik Frøiland, senior researcher at the Norwegian Environment Agency.