The Namsblanken is a very special Atlantic salmon. It never goes to the sea, but lives its entire life in flowing river water.
There are many threats to this little fish, but luckily there are many things we can do to save it! You can read more about all this here.
What is a relict salmon?
A relict salmon never goes to sea, but lives its entire life in fresh water. The Namsblanken is a relict Atlantic salmon.
Foto: Per Harald Olsen, NTNU
The Namsblanken lives its entire life in the river. It likes it best where the river current is strong. Like other salmon, the Namsblanken spawns in the fall. The females dig a spawning pit and cover the fertilized eggs with gravel.
In early spring, the yolk sac fry emerge from the eggs. When the nutrients in the yolk sac have been used up, the fry emerge from the gravel. Then the hunt for food and the fight for space in the river begins.
The Namsblanken stays largely in the same area where it was hatched - its entire life.
because it is alone in living its entire life in fast-flowing river water. It lives above large waterfalls in Øvre Namsen - and only there. Juvenile, immature and spawning salmon live together throughout their lives.
because there are few left. The Namsblanken has little variation in its genetic material and does not tolerate changes in the environment in which it lives. The Namsblanken has been isolated in the upper Namsen for about 9500 years. It is therefore genetically very different from sea-going salmon - both salmon living further down the Namsen and salmon in other Norwegian rivers.
because over the past 100 years, humans have destroyed large parts of the habitat of the Namsblanken.
because the Namsblanken is unique. No other salmon lives in the same way as the Namsblanken. If the Namsblanken disappears, we cannot replace it with other salmon. There is no other salmon population that lacks the desire to migrate, that lives its entire life in running water, and where both males and females reach sexual maturity when they are only 15-20 cm long.
The Namsblanken lives only in the river Namsen. Its natural habitat is an 85-kilometer-long stretch of the Upper Namsen and some tributaries that flow into it. The Namsblanken does not go anywhere and stays in the same area for most of its life. It prefers fast-flowing water.
Spawning time is late in the fall. The Namsblanken is a small salmon, but the eggs are almost as large as those of sea-going salmon: about 5 mm. Each female has an average of 100 eggs. Fertilized eggs are buried in appropriately sized spawning gravel. A female salmon of only 20 cm is unable to dig deeper than 5-7 cm.
The Namsblanken usually has distinct stripes on its sides throughout its life. These parr marks, or finger marks, are excellent camouflage in flowing river water. With its large, strong pectoral fins, the Namsblanken is adapted to a life in rivers.
Image of the river Namsen. Photo: Eva B. Thorstad, NINA.
Insect larvae are the main food of the Namsblanken. They are not particularly nutritious. Therefore, the little fish has to stand up all the time to catch enough food. As a result, the Namsblanken never grows very big and is only 15-20 cm when it spawns.
Due to its small size, the Namsblanken has little value as food for people. Compared to sea-going Atlantic salmon and farmed salmon, the Namsblanken therefore has no economic value. But the rare little salmon is nevertheless very valuable. It has a unique opportunity to tell us humans how nature works. This is why it has great conservation value.
The Namsblanken and humans have lived together for almost 9500 years. For more than 9,400 years, the Namsblanken was allowed to live undisturbed, but in recent decades we have made major harmful interventions in the fish's habitats. The Namsblanken is therefore critically endangered, and scientists believe it will die out if we don't do something to protect it! Fortunately, researchers have several suggestions for what we can do. You can read more about this below.
Map of the Namsenvassdraget with names of tributaries. The habitat of the Namsblanken is marked in red. The habitat of sea-migrating salmon is marked in green. In addition, power stations, power tunnels, artificial thresholds and the distribution of the alien species Örekyt are marked.
Drawing: Kari Sivertsen.
In 1952, operations began at Skorovas Mines, and acidic water containing metals killed all the fish in the Grøndalselva river from the mine down to the mouth of the Namsen. It is likely that Namsblank lived in parts of this river before mining began.
Hydropower development has been responsible for the biggest detrimental changes to the habitat of the Namsblanken. A lot of water has been removed from the upper parts of the watercourse and used for power generation. This affects a 70-kilometer stretch of river that makes up most of the habitat of the Namsblanken in the main river. In addition, two tributaries are affected.
The wide river Namsen became narrow when much of the water was removed. People did not like the narrow river with its wide, bare beaches. So artificial thresholds were built to raise the water level. Small, still-flowing lakes formed on the upper side of the sills. Trout thrive here, and people like to fish for them. The river looks prettier, but the water here is still flowing. This does not suit the Namsblanken, which thrives in strong currents.
Earwigs are small carp fish that live close together and can form very numerous populations. The mullet does not belong in Namsen. People moved it from lakes in Sweden and released it into a lake far upstream in Namsen. From there, it has spread to large parts of Namsen's habitat. Ørekyt thrives best in still or slow-flowing water, but can eat some of the food of the Namsblanken.
Every year between 1950 and 1976, many thousands of juvenile migrating salmon were released into the Namsblanken habitat above Aunfoss. They may have competed with the Namsblanken for both food and space. In addition, some of the small males may have spawned together with the Namsblanken. The researchers have found that the offspring of both salmon and migratory salmon become migratory.
The 300 meter long fish ladder in Nedre Fiskumfoss was opened in 1976. The purpose was to expand the nursery areas for migrating salmon. In a 14-kilometer-long area above the waterfall, researchers have found many young sea-run salmon. In the same area, the number of Namsblanker has been greatly reduced.
Picture of the fish ladder in lower Fiskumfoss. This is used by sea-run salmon to migrate up and into the habitat of the Namsblanken. Photo: Eva B. Thorstad.
Photo of river fish in the Frøyningselva, a tributary of the upper Namsen, which is home to the Namsblank. Photo: Tone Løvold.
The Namsblanken lives in several tributaries of the Namsen. We must not make any more interventions that could harm the Namsblanken in the most important tributaries.
Today, the Namsblanken lives in the lowest kilometer of the Grøndalselva river. It probably lived further upstream before mining pollution from Skorova's mines wiped out the fish in the river. Today, toxic emissions are much lower and the river is once again liveable for fish. It is possible to move the Namsblank up past waterfalls and back to areas where it used to live.
Tributaries that do not contain Namsblank may be good habitats. It may be relevant to move Namsblank up several of the tributaries.
The hydropower plants in the Namsen river will be subject to new operating rules. They will probably have to release more water in the upper parts of the Namsen and in an important tributary. When and how much has not been decided. Researchers can find out how much more water the Namsen and other animals need to thrive. They call it environment-based water flow. The power plants prefer to discharge as little as possible and use the water for power generation.
The Namsblanken thrives best on stretches of river with high water velocity. To bring back such stretches of river, some of the artificial thresholds can be demolished. Other thresholds can be improved to create short rapids.
Researchers believe that the fish ladder in Fiskumfoss should be closed to migrating salmon. Within a few years, the Namsblanken will reclaim important habitats and increase in number. This is the easiest way to help the Namsblanken.
Namsblank can be secured in a live gene bank. This usually means keeping male and female fish in tanks of water and feeding them there. Sea migrating salmon have been kept in such facilities for generations, and the offspring have been used to build up salmon stocks. Moving the Namsblank to new habitats will act as a kind of living gene bank where the Namsblank live in natural conditions.
