Salmon is dying in France
Audio 02:43
19% of fish species are particularly threatened, like the Atlantic salmon, the wild salmon that comes to reproduce in rivers (photo illustration).
Getty Images / 500px - Mike Bons / 500px
By: Florent Guignard
8 mins
Nearly 20% of animal and plant species risk disappearing in France, according to a study published this week.
19% of fish species are particularly threatened, like the Atlantic salmon, the wild salmon that comes to reproduce in rivers.
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It is a paradise on earth.
A green valley where a river flows in the middle, fresh, limpid water, pollution-free and almost predator-free.
This river, the Allier, is a tributary of the Loire, in the heart of the Massif Central and very deep France, where the last wild salmon in Europe are born, under polished gravel for millions of years, up close. from the source, if possible… This is
Salmo salar
, the wild Atlantic salmon, one of the largest salmon, which can measure over a meter, so abundant in the past in the waters of the Rhine, or from the Elbe, in eastern Europe, where it has completely disappeared.
There are still some in France, but less and less;
the species is threatened with extinction, like many freshwater fish.
According to a study published this week by the French Office for Biodiversity, the Museum of Natural History of Paris and the IUCN, the International Union for the Conservation of Nature, 19% of freshwater fish species present in mainland France risk disappearing.
It's a reality: in the Loire and Allier, we see less and less wild salmon.
“
In the best years, for twenty years, we have been able to count in Vichy, on the Allier, 600 fish,
details Roberto Epple, the president of the environmental association SOS Loire vivante.
The rest of the time, on average, there are 200 salmon.
And higher up, around the Poutès dam, when you go up close, it's a few dozen salmon.
"
When humans stand in the way of salmon
The Poutès hydroelectric dam is located in Haute-Loire.
A dam that bears its name too well for salmon, since it constitutes a major obstacle that must be overcome to reproduce in good conditions, during the run, or to reach the ocean after birth.
Fish passes were indeed installed a few years ago, but they were insufficiently effective.
So, as sometimes happens, human beings agree to take a step back, and concede to nature what they had taken from her.
The Poutès dam is therefore currently under construction.
EDF, under the pressure of a long struggle waged for years, has agreed to “
radically transform
” it, for the well-being of the salmon.
"
We are reducing the height of the dam, which will drop from 20 meters to 7 meters,"
explains Sylvain Lecuna, the New Poutès project manager for EDF.
This will allow us to reduce the size of the reservoir upstream, since we will go from a reservoir 3,500 meters long to a reservoir that will only be 400 meters long.
In doing so, the young fish which go to the sea, and which could take several weeks to find the exit of the dam, will pass in just a few hours.
"
A race against time followed by a marathon
Because their time is running out.
The ocean is nearly 1,000 kilometers away.
You have to descend the Allier, then the Loire, to reach the Atlantic.
And switch from fresh water to salt water.
This is when a salmon's respiratory system, and its gills, change.
A delicate operation which imposes this race against time.
Then begins the salmon marathon: 4000 kilometers to Greenland.
The young fish spend two to three years there, gorging themselves on shrimp, before returning exactly where they were born, "
within a few ten meters
," says Roberto Epple, of SOS Loire vivante.
It's a really great story
!
They use several methods to accomplish this incredible migration.
When salmon are at sea, they are thought to orient themselves by the stars, and probably also by magnetic waves.
When it approaches the coasts, it orientates itself differently
: the salmon will analyze the smell and the composition of the water to find its river.
Finally, on the last kilometers, we think he is orientated visually.
He finally uses several GPS
!
"
These extraordinary capacities remain in part still mysterious.
If it has overcome all the pitfalls encountered along the way, fishing, predators and human constructions, then the salmon, which comes back from where it came, will arrive at its final destination.
After having reproduced, the fish ends up dying, exhausted, arriving at the end of the cycle of a life guided by a single imperative: the safeguard of its species.
The migration of salmon is a miracle of life, increasingly precarious.
QUESTION OF THE WEEK
"Why are salmon flesh pink?"
"
It is for exactly the same reason that flamingos are pink;
because they mainly feed on shrimps, which contain carotenoids, a family of plant pigments, molecules, which also give grapefruit, tomato, corn, and of course carrot its color who, she, gives the pink buttocks!
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