It can go towards complete collapse. Rune Aslaksen, from Tanavær, fears that, who sits on the board of the Tanavassdragets Fiskefforvaltning. In a month’s time, the recovery of humpback salmon will begin in earnest. The solution to catch it has not been tested in practice, and the trap has not been fully built. The professionals behind it also cannot say how large a capacity it has. Two years ago, up to 7,000 humpback salmon a day came up in the Tanaelva. But the species is increasing violently; this year there may be five or ten times as many. The calculations are not encouraging: – If we multiply that by five, there are 35,000 salmon a day. It only takes two days, then we have as much as the entire season two years ago, says Aslaksen. – They are unable to say whether the traps are sized for this. It’s terrifying. It’s terrifying. Then you suddenly have humpback salmon in the entire watercourse. Here at Seidaholmen, directly below the Tana bridge, the salmon trap will be placed. Photo: Knut-Sverre Horn / news Fears for the ecosystem in the river The dreaded humpback salmon belongs in the Pacific Ocean. Nobody really knows what will happen if it really establishes itself in Norwegian salmon rivers. In the worst case, it can spread diseases, change the entire balance in the rivers and take food from the wild salmon. The large Tanae river presents completely different challenges than in the smaller salmon rivers in Eastern Finnmark, where large quantities of humpback salmon have been successfully caught. Roar Sandodden from the Veterinary Institute is the project manager for the trap, which is still under production. At a public meeting in Tana on Wednesday, he explained how it should work. Project manager Roar Sandodden is honest that the humpback salmon trap can have its limitations during floods or heat waves. Photo: Knut-Sverre Horn / news A 600-metre long barrier fence will lock all salmon into one side of an islet in the river. There is a fleet with a facility to monitor and sort the fish. The humpback salmon must be stunned with electricity, drained of blood and sent straight to a fish reception. The wild Tana salmon – which was in crisis even before humpback salmon became so numerous – will be sent on. 30 people will work on sorting and handling the salmon. Open about the challenges – Can something go wrong? Yes, it can. We must be honest about that, said Sandodden. The problems arise if there is very much or very little water in the river. – If the fish start to die because the river is low and warm, we may end up in a situation where we have to tear up the trap and let the fish go, said Sandodden. – If we get a summer flood, we may have to lead the entire fleet ashore. Sandodden was asked about the capacity of the fella, but had to say that he had no good answer. – Hopefully it will increase over the summer, when the crews gain more experience, he said. Sandodden wished they were better prepared before the expected invasion. – This is the best thing we could do with the time and money we had, he said at the public meeting. Sturla Brørs in the Norwegian Environment Agency emphasizes that the wild Atlantic salmon must not suffer when fighting humpback salmon. Photo: Knut-Sverre Horn / news Tolerating a little humpback salmon The aim of the catch is to take out the humpback salmon in a way that affects local fish as little as possible. This is emphasized by Sturla Brørs from the Norwegian Environment Agency. – We will not take out the last humpback salmon at any cost. We can tolerate some humpback salmon in the river; this is not like fighting gyro. (Gyro or Gyrodactylus salaris is a salmon parasite that is eradicated by killing all fish in affected waterways with rotenone.) Brørs believes it is not necessarily a disaster if some of the humpback salmon are allowed to pass: – If they are talking about one day out of twenty-thirty days with an extremely high total number, then it may not be dramatic in the big picture. There must be a plan to catch fish that have made it past the trap and further up the river. According to Brørs, it is best to have ice in the stomach and wait until it collects on the spawning grounds. There you have good opportunities to take it with a seine, without catching wild salmon and sea trout. Humpback salmon die after spawning, and tons of rotting humpback salmon can become a problem in rivers. Photo: Knut-Sverre Horn / news Concerned about the tributaries About 90 people in the audience at the public meeting in Tana had many questions and comments for the professionals from the Veterinary Institute and the Norwegian Environment Agency. After the meeting, Marit Broch Johansen is still puzzled by one thing: – I wonder how much humpback salmon goes up the various tributaries, she says to news. There are several tributaries below the fella. Only the Masjo river gets its own trap. – But Luftjokelva has not been mentioned in a single word, says Johansen. Hege Persen is more worried about escaped farmed salmon than about humpback salmon in the Tanavassdraget. Photo: Knut-Sverre Horn / news Hege Persen is a daily adviser at the National Wild Salmon Center in Tana. She is happy that a large-scale fight is finally in place. – I hope there will be enough money now for follow-up research, and that we will get enough monitoring of both water quality and the other species that live in the river.
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Fears the humpback salmon trap in Tanaelva will collapse – news Troms and Finnmark
