Med harpun etter oppdrettslaks

With harpoon after farmed salmon

Farmed salmon threaten the wild salmon population in many salmon rivers in Norway. Once in the river, it will continue its natural instinct to spawn. too many farmed salmon end up in rivers

By Thomas Guldvik, 05/01/2014


A job as a fisherman for many years, keen salmon fisherman and free diver, proved to be a good combination for a test project on harvesting escaped farmed salmon with a harpoon. This can be a good method to limit the damage caused by the genetic pollution farmed salmon is responsible for.


At regular intervals, large quantities of farmed salmon escape, and figures from nina (Norwegian Institute for Natural Research) show that 12-35% of the spawning stock from 1989-2005 has been farmed salmon.

in 2007, 618,000 escaped farmed fish were reported to the authorities. The farming industry works continuously to limit escapes, but with such high numbers this is too bad.

The instinct of the farmed salmon takes it up the rivers to spawn, and it can spawn together with wild salmon. Farmed salmon are created to live a life in captivity. when this mixes with the wild salmon's genetic material, adapted to the conditions in a particular river over thousands of years, it is gradually mixed out. This reduces the salmon's ability to survive and in many rivers the salmon is already extinct


In order to counter the threat from farmed salmon, the fish manager in northern Trøndelag was interested in trying out the idea of ​​harpoon hunting. The trial project was started in Moelva in collaboration with the landowner, a necessity for carrying out such a project. The Moelva is a small river of 1.2 km, with clear water and good visibility. It has holes at a depth of 2-5 metres.

Wedge nets, seines and nets were also used to retrieve escaped farmed salmon from the watercourse.


The main characteristics of farmed salmon are rounded spurs, a worn dorsal fin and sometimes a worn nose. in addition, the shell structure and pattern are different from those of wild salmon. underwater, the salmon's track is fully expanded, which makes it easy to see deformities and scars.

Characteristics that can be difficult to see underwater are shorter gill covers and worn and irregular pectoral and pelvic fins.

Some may have a tendency to behave differently, i.e. they stand in different stands than the wild salmon. You can also get closer to farmed salmon, but this is not a given.

On farmed salmon that have been in the sea for a long time, worn fins have grown back, and the fish may have a partially wild salmon-like pattern on the shell structure. These can be recognized by irregularities along the track and fins.

It is important to have good lighting conditions to see the difference between wild salmon and escaped farmed salmon. If in doubt, don't shoot. Fish that escape as smolts (juveniles) can only be identified by shell samples.

To get at the fish, I chose to dive next to stands or to swim diagonally from behind against the current.


Salmon have different limits for how close you can get. This depends on things like escape routes, whether it feels threatened, whether it will spawn and the behavior of the diver.

It varied greatly how close I got to the fish, some were not frightened until I was half a meter away, others swam away when I was 10 meters away. The ideal distance for shots is 4-6 metres.

Salmon often live in groups and wild salmon and farmed salmon can live together. This increases the risk of misfiring. if you shoot a farmed salmon with a wild salmon in the firing line behind, you can injure both.

I started to position myself after getting an overview of the type of salmon in the river. By swimming in from different angles I saw where they pulled so I could avoid damage shooting. It is important to know your harpoon well so you know where the arrow goes.

When I got too close to the salmon, it moved a few meters and then retreated to the same spot. calm demeanor and cooperation with the current made the job easier.

The salmon is usually right at the bottom of the pools, and shots from above will go straight to the bottom. Therefore, it is an advantage to harpoon horizontally. I dived down to the edge of the pool where the fish was and then swam along the bottom to get the best possible direction for the shot.

With freediving equipment it was fine to swim upstream in the river or at the edge of the river if the current was strong. There were also many backwaters that I could take advantage of on the way up into the cave.

Gradually, as I became familiar, I was able to calculate the dive in relation to current and position, and to go straight into position for shots. down at the bottom there is generally much less current than at the surface.


It is known that salmon establish territories over a spawning area. large salmon have larger territories and can occupy many female salmon. What if this big male is a farmed salmon?

I took out a male salmon of 12.1 kg that had settled in an area with many spawning pits. This salmon had many female salmon in its harem and chased other male salmon.


The harpoon is a weapon and must be treated accordingly. River diving can be risky, and it is important that you respect the forces at play. You have to know rapids, undercurrents, rocks/large rocks etc. Fishing lines that have become tangled can be scary to get lost in, especially if there are hooks hanging from them, which they often do. A control dive is mandatory and you must bring a knife. It may be a good idea to have a helper on land or at the water's edge. I didn't use line as the river had a relatively strong current and was clear.

Because you often shoot close to the bottom, you have to be aware of ricochets, i.e. that the arrow comes back. Fortunately, I was not exposed to this myself.


To get an overview, identify farmed salmon and to fire shots, it is important to have good visibility. In darker conditions, such as in cloudy weather or in gray light, it is more difficult to identify the farmed salmon, even if you can occasionally get closer than in clear weather.

in Moelva the visibility was good, and with sun and little particles the visibility was up to 10 meters and longer.


The current is strongest at the surface (0.5 to 1 m). In order to have good room for action, it pays to go a little deeper. The salmon is also calmer here. It is not impossible to hunt in a strong current, although it is not always as easy to swing the harpoon against the current with one hand.


After 19 dives I shot 21 breeding fish, and I could identify 28 with certainty. This was a sample of 75% of the observations. A dead farmed salmon is a good farmed salmon. Other interesting observations made during freediving are population, sizes, proportion of sea trout and spawning activity.

The project shows that harvesting farmed salmon with a harpoon is entirely possible, and that it can be one of several methods.

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