How to fight catfish, the monster that rules over large rivers

The Basics It gets a bad rap, but is the catfish the monster often describes deadly to migratory fish?

The Dordogne, “one of the last great rivers in France to enjoy the eight migratory European fish,” is concerned about salmon, eels, shade, lampreys and sturgeon, explains Roland Thieleke, director of the Dordogne Territorial Public Establishment (Epidor). These “biodiversity guardians who are very sensitive are at the forefront of fragility and shit accumulation” between dams, fisheries, pollution and habitat degradation. And that’s why catfish.

In the lower Dordogne, the catfish (Silurus glanis) has a poor source. At the foot of the Mauzac-et-Castang, Tuillières and Bergerac dams, nets, lines and traps have been trying to take as much as possible of this predator from Eastern Europe since 2020 – and for three years – to see if the migrant fish are better off . The hand-to-hand combat is short but vigorous, intense and breaks the peaceful surface of the Dordogne in the early morning. Grabbed by the mouth with both hands, the fish caught on a line is pulled up, “as soon as the heavy head is over, the rest of it tips over …”. And the intimidating mass of 1.75 m for 35 kg lies at the bottom of the boat, still excited at the feet of the fishermen.

Also read: In the Tarn, the catfish is in conquered ground

“Utopian” extermination

The investigation is currently focused on the foot of the dams, where “lifts” or “fish passes” are operated, but incomplete. The less agile fish turn in circles, seek access and are either swallowed by the catfish or, in short, frightened, prevented from going up the river to reproduce.

“It’s not about exterminating or regulating the catfish in the Dordogne. Experience shows that it is utopian to try to remove an introduced and acclimatized species,” says Pascal Verdeyroux, Project Manager at Epidor. “But we want to experiment whether localized management is feasible and relevant.”
On the boat, as soon as the catfish has appeared, a fisherman pushes his arm with mini-teeth like “rasps” on the shoulder in the gaping mouth. A whole young eel emerges from the stomach. A flagrante delicto.

This opportunistic carnivore, which can reach 2.70 m for more than 100 kg, eats fish of all kinds – including its own – but also frogs, rats, small nutrients, even ducks, pigeons surprised on the shore in “Orcas Stranding” mode that adds to the fantasies. “It has a very bad reputation, it has a dirty face, it’s big, it’s sticky (no scales, editor’s note), that’s all we want, it eats everything. It can be a little scary…” , summarizes Jean-Michel Ravailhes, President of the Dordogne Federation for Fisheries and Protection of the Aquatic Environment.

“But it bothers me a little to make the catfish a scapegoat.” It shouldn’t be the tree that hides the forest, ”he says angrily, pointing out the mishap that migrants made while fishing downstream in the Gironde. However, the catfish that humans introduced in the 1970s and 1980s “is here to stay”.

Eat catfish!

This fish, which unleashes passions, has its few fans, amateurs of sport fishing, who sometimes come from far away because at 70-80 kg at the end of the line it is “strong in sensations”.

And recently: “It can be eaten. Local restaurants have started promoting this fish with various recipes. Every year we have more and more inquiries, ”notes Patrick Ceccheto, a licensed professional fisherman.

Vincent Arnould, a Michelin-starred chef in Trémoulat, praises this “interesting” boneless fish with firm meat, reminiscent of monkfish. “It works well in donuts, poached, roasted, with spicy flavors, a little bit spicy, exotic and wonderful with a wine sauce. “”

He predicts a bright future for her in the canteens. “Children are less stuck in certain things than adults. “And if it is also good for biodiversity …

Also read: Philippe Boisneau: “The catfish did not arrive in our rivers by magic”

Is It Dangerous For Humans?

Is catfish a dangerous fish, especially for humans? The question arises when we see the size of the animal. But rest assured there is little risk involved. “The catfish is not a shark. In addition, if you look at a catfish, you will not see any protruding teeth. Rather, it has a very large mouth, it is a fish that swallows greedily, ”explained RTL Philippe Keith, professor at the National Natural History Museum, specializing in ichthyology, the study of fish.

On the other hand, the catfish is a predator that can swallow anything that goes by. Crabs, all kinds of fish including their own congeners, but also ducks and other birds … which can even catch catfish when they come out of the water! This was shown in December 2012 by a scientific study published in the online journal Plos One and carried out in the Tarn River, where catfish has been present since 1983.

From June to October 2011, the scientific team conducted 24 three-hour observation sessions and recorded 54 catfish attacks against birds, 15 of which were successful. During its lightning attacks, the catfish was able to lift half its body out of the water. Samples of catfish tissue then showed that pigeons made up almost 80% of their diet in certain catfish.

The real danger that catfish can pose to humans is more toxicological. The catfish is an organic accumulator fish, meaning it accumulates mercury and other pollutants that can make it unsuitable for consumption. Even if some chefs are interested in the culinary potential of this great fish.

Catfish in Europe, Wikipedia Commons, Cymothoa exigua, Infography DDM – Philippe Rioux

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