Norway is facing an invasion of humpback salmon, informally known as “Russian salmon”, Norwegian researchers have warned. According to them, the intrusion is gaining momentum, and Norway is yet to see the worst of it.
“This year we fear that there will be more Russian salmon than local fish in many rivers, especially in the north”, freshwater biologist Rune Muladal and general manager of the company Naturtjenster i Nord told the daily newspaper Dagbladet.
According to locals and researchers alike, the much-dreaded “invasion” may turn into a prolonged “occupation”.
“They are invading the rivers up here. This morning I was out and took around 20 'Russians'”, Øystein Hansen from Kirkenes told Dagbladet. The country's northernmost Finnmark County has been described as the “front line”.
Elevated populations of the humpback salmon, which is the invader's official name, first baffled Norwegian researchers in 2017. This year, the “Russians” are coming in record numbers. The experts already fear another offensive in 2021, due to the salmon's two-year circle.
“In 2017, we were unsure whether it was just a fluke. Now we have two seasons in succession and we can already say that we will probably witness something similar in the future”, Henrik Berntsen, a researcher at he Norwegian Institute for Nature Research (NINA), told Dagbladet.
Whether the 2017 “humpback onslaught” has had an actual impact on local fish, such as the Altantic salmon and sea trout, Bernsen cannot say for sure. In theory, though, the “Russians” may outperform local fish. Hence they are “blacklisted” as an invasive alien species.
Eva Thorstad, NINA researcher and professor at the University of Tromsø, described “Russian salmon” as a risk to Norwegian biodiversity, urging the local fishermen to “eradicate” them. In Karpelva, Finnmark County, fishing traps against the invader were already set up by volunteers.
According to Berntsen, the “Russian fish occupation” may still be prevented, as the invaders have not yet begun to spawn. Spawning usually takes place from the beginning to mid-August.
Regardless of the efforts, the humpback salmon will still haunt Norway, especially its northern part, researchers predict.
“In the worst case, alleviating the symptoms is the only thing we can do on the Norwegian side. Although we can prevent the salmon from spawning in Norwegian rivers, they will still coming to Norway from large rivers in northwestern Russia, where the humpback grows in huge quantities”, Berntsen said.
The humpback salmon (also known as the pink salmon) originates from the Pacific Ocean, but was released in the White Sea and Kola Peninsula by the Soviet Union from the 1950s onwards. It derives its name from a characteristic bump that males grow in adult age. It averages 2.2 kilograms in weight and is a valuable commercial fish.