August 11, 2009
Atlantic Salmon Make Their Comeback In France
Atlantic salmon have returned to France's Seine River with gusto, after disappearing for the past hundred years.
This year has seen hundreds of these salmon swimming past the Eiffel Tower and Notre Dame cathedral, researchers told AFP.It is remarkable that salmon and other species, which had previously been chased away by dams and pollution, are now popping up again without any human effort to bring them back.
"There are more and more fish swimming up the Seine," said Bernard Breton, a top official at France's National Federation for Fishing.
"This year the numbers have exceeded anything we could have imagined: I would not be surprised if we had passed the 1,000 mark," he told AFP over the phone.
With at least 260 salmon counted on a video system in the fish passage of the Poses dam above Rouen - a city roughly half way between Paris and the Atlantic Ocean - had already broken records.
The Seine has historically hosted a thriving population of salmon, a migratory species that come back from the sea between December and June to their freshwater birth place in order to reproduce.
However, between WWI and WWII, the building of dams, along with the more harmful pollution of the Seine from chemical runoff from industry and agriculture along with organic pollution, led to their demise.
Now, the Salmo salar, or Atlantic salmon, is listed as a threatened species throughout Europe.
This made it even more shocking when a weekend angler dragged in the 13 pound fish downstream from Paris at the end of last month, and when fisherman downstream of the city caught an even larger one last October. This was the first catch of its kind in over seven decades.
Other fish are also returning to Seine. In 1995, there were only four species known to its waters. They were eels, redeye, bream and carp - and at least one of these is known to be invasive.
According to the water purification authority for the larger Paris region, there are now at least 32. The lamprey eel, sea trout and shad have returned to the Seine over the last few years.
Scientists are saying that simple clean water was all it took.
In the mid-1990s, "between 300 and 500 tons (600,000 - one-million pounds) of fish died in the Seine up river from Paris every year because of pollution," said Breton.
Over the last 15 years, massive efforts, including a new water purification plant, have effectively cleansed the river of post of its pollutants.
There is now reason to believe that conservation would be better served by restoring the ecosystem than merely restocking depleted waters, says Breton.
According to Scientists at France's National Institute for Agricultural Research who track salmon, it is a "bellwether species". They are a living indication of the health of their habitat.
In order to discover more about how Atlantic salmon are re-colonizing their ancient river home, seven adults have recently been captured and released in the Seine.
Of the seven, four had spent less than two years at sea before returning to fresh waters, two had returned in the Spring after two years in open waters, and one did not leave the ocean for three years.
An analysis of their DNA revealed that the fish came from several different rivers, in France and elsewhere in Europe.
The DNA also indicated that a new "embryo" population specific to the Seine might be in the process of forming, probably southeast of Paris at the headwaters of the Yonne River in the region of Morvan.
These Atlantic salmon were once plentiful throughout the north Atlantic, from Quebec to New England in the west, and from the Arctic Circle to Portugal to the east.
However, the last thirty years have been hard on them and their populations have taken a nose dive, as commercial catches dropped by more than 80 percent.
The full grown salmon spend the majority of their lives in small groups traveling great distances at sea in search of food, mainly squid, shrimp and small fish such as herring.
Salmon do not eat during the grueling upstream journey to their birth place, where the females lay eggs to be fertilized by the males before dying.
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