Giant fish that eat pigeons destroys European ecosystems

Freshwater ecosystems in Western Europe are currently seriously threatened by a giant alien fish that eats pigeons from Eastern Europe.

Frédéric Santoul first witnessed European catfish hunting when he was standing on a medieval bridge in Albi, a town in the south of France.

On a small island below, pigeons roamed, oblivious to the catfish moving nearby. Suddenly, a fish emerged from the water, grabbed the dove and then plunged back into the river, taking the prey in its mouth.

Santoul, a fish ecologist at the University of Toulouse, has spent a lot of time understanding this phenomenon. He said: ‘I know that killer whales can come ashore to catch seals but really can’t imagine that kind of hunting would happen in other fish.

Nearly a decade ago, few people knew about the existence of catfish in Western Europe. This fish that can grow up to 3 meters long and weigh more than 270 kg is native to Eastern Europe but has now appeared in at least 10 countries across Western and Southern Europe.

Giant fish that eat pigeons destroys European ecosystems 

In its native habitat, where this species is both fished and raised for food, European catfish are not considered problematic. There, populations of this species appear to have remained relatively stable for decades, with little evidence of excessive predation with other species.

However, in the rivers where European catfish live, they are considered to be targeting endangered and commercially important fish species, such as the Allis herring and the Atlantic salmon. Positive. These are species whose populations in Europe are in serious decline.

Santoul fears the European catfish could wipe out many native fish species in Western Europe, fundamentally altering river ecosystems that already have to cope with the impacts of dams, water pollution and overfishing. exceed.

Party of ‘Giants’

In 1974, a German fisherman released several thousand baby catfish into Spain’s Ebro River. Other anglers hoping to catch a big fish do the same in rivers in other countries, and the species proliferate from there.

Like many other exotic species, the European catfish thrives in human-altered rivers, where water temperatures are high and oxygen levels are low. Catfish grow fast, have a long life span (up to 80 years), reproduce easily, and the female lays hundreds of thousands of eggs at a time.

However, it is their hunting skills that are terrifying. Like all other catfish, the European catfish has well-developed senses, especially in detecting the movements of its prey. ‘European catfish target fish that swim from the sea into rivers to spawn, such as Atlantic salmon,’ says Santoul .

Giant fish that eat pigeons destroys European ecosystems 

They also adopt new predatory strategies that have never been seen before in their native environment, such as emerging from the water to capture pigeons. In France’s Garonne River, catfish are sometimes waiting inside the tunnels of a hydroelectric power station for salmon to pass.

In the same river, catfish have learned to target the Allis shad herring on the river’s surface at night, when the species is engaged in courtship. ‘European catfish’ has now become a serious threat to important migratory fish species,’ said Santoul.

However, Santoul also added that European catfish are not harmful to humans, although they are famous for their rumors of aggressive attacks, even killing people. He added: ‘They are harmless and very curious to humans, you can swim next to them in the river’.

No attempt has been made to address the threat

Another example of large, invasive fish disrupting freshwater ecosystems is the Nile perch. The species was introduced to Lake Victoria and other lakes in East Africa in the 1960s and subsequently led to a dramatic decline in at least 200 native fish species in the 1980s.

However, freshwater fish species possessing large body sizes are being severely reduced by invasive species, habitat loss, and overfishing. According to a 2019 study, these species known as megafishes (giant fish) have decreased by 94% since the 1970s.

However, European catfish possesses the ability to adapt to the environment and the ability to reproduce well. They are an exception among megafishes.

Giant fish that eat pigeons destroys European ecosystems 

Zeb Hogan, a fish ecologist at the University of Nevada, says freshwater ecosystems are critically endangered, and the introduction of exotic fish species is considered the leading cause.

Scientists say ecological changes caused by climate change, including warming temperatures and shifts in rainfall, could create more favorable conditions for the growth of European catfish. Rob Britton, a fish ecologist at Bournemouth University, said: ‘Climate change affects different species, and some exotic species have a much larger distribution than native species. .

According to Santoul, there is evidence that European catfish, which need water temperatures of at least 20 degrees Celsius to breed, are encroaching on rivers in Belgium and the Netherlands, as the waters in those regions warm. There are indications that European catfish spawn several times a year in France because the rivers there are warmer for longer periods than they used to be.

Current solutions to address the threat of European catfish to native species in Western Europe are still very limited. With fishing and release surging thanks to European catfish, mainly in Spain and Italy, it seems that governments have little interest in getting rid of the fish. This species is commonly used to eat in Eastern Europe, but Western Europeans never actually caught it as a fish.

Santoul stressed that European countries need to work more closely to conserve freshwater ecosystems and address the threats faced by migratory fish species. He said there are currently no efforts underway to eradicate European catfish in Western Europe.

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