This invasive alien fish is threatening the Guadalquivir ecosystem

Catfish, an exotic and invasive fish Its measurement can be up to two meters and weight can be up to 200 kg. Having been found in 2021 in Alcalá del Río (Seville), about 80 kilometers from the mouth of the river, it has already appeared at several points of the Bajo Guadalquivir.

Their predatory abilities and the indiscriminate nature of their prey –From crabs to ducks – what makes catfish a major threat to the ecosystems where it appears and may even impact the recovery of endangered species such as the gray teal in and around Doñana Park.

As Carlos Fernández Delgado, professor of zoology at the University of Cordoba (UCO), tells EFE, its presence arises from premeditated introduction.With the selfishness of being able to catch them fishing in the reservoir near their city, “A short-sighted mindset that leads to real atrocities.”

Presence in Guadalquivir This vastness of fresh water has been confirmed by a study promoted by the Ministry of Ecological Transition (MITECO), and coordinates the University of Cordoba.

catfish is The largest freshwater fish species in EuropeIt is the third largest on the planet and is characterized by being a high-impact predator, with its native distribution extending from Germany, Poland, Sweden, the Baltic countries, Russia, Turkey and Iran to Kazakhstan and Uzbekistan.

environmental dna

The work conducts acoustic surveys in the water and takes samples to detect catfish DNA. The results are positive in many points, from Lebrija (Seville) to Palma del Río (Córdoba)Without reaching the estuary because the salinity prevents the presence of this fish.

“It is in a quite pronounced expansion phase and we suspect that this is not because of the colonization process of the species, but above all because There is a group of fishermen dedicated to helping the species settle in new areasFernandez Delgado said.

They figured this out because he is overcoming many obstacles with ease. It was first detected downstream of the Alcala del Río Dam. It continued with the verified upstream of the Cantilana and Peñaflor reservoirs.

“Animals do not have such a great capacity for expansion.” By their own means, says the professor, who adds that some photographs of fishermen with captured specimens confirm the sighting.

The scientific project will create an action protocol to control catfish, because “When a population is in the first stages of colonization, this is the only time to attack it, Once established it is almost impossible to eradicate,” Fernandez muses.

donana

At times of heavy water flow, its presence in Doñana Park may be only temporary, “but it is capable of doing a lot of damage,” according to Fernández Delgado, who warns about recovery plans in that environment as endangered. Gray teal may be handicapped by the presence of catfish, Able to eat it and many other birds.

This researcher calls on the board to implement an eradication plan before the problem escalates.

For its part, a working group on Doñana of Ecologists in Action, with the scientific support of the Biological Station, approved requesting the Andalusian Department of Sustainability and Environment for its eradication, as it is an alien and invasive species. it becomes Introduction, possession, transportation of the crime into the natural environment, Transport and commerce.

Iznajar

Iznajar Reservoir, the largest in Andalusia, The catfish population in its glass is limitedAt least since 2011. In this case it is believed that it was introduced to offer fishing to this giant, very attractive due to its size, to fans of the entire region.

Zoology professor indicates that Catfish eat 2% of their weight per day, almost without discrimination, so they fear that if it enters the protected space it could affect the red crab population in the marsh, which supplies the packaging industry, and the birds of Doñana. Due to its salinity in the estuary it is less likely to freeze.

catfish joins Exotic fish brought to the largest Andalusian river, Such as alburnos, gambusias, percasoles, catfish, pike, black bass and others, which have brought native fishes such as colomilija, boga, gypsy barbel and salinate to the brink of extinction.

Professor at the University of Cordoba explains that Fishermen of the Iznajar Reservoir are already warning of the almost disappearance of black bassWhich he attributes to the gluttony of the catfish.

Universities of Seville and Oviedo and the Institute of Agricultural and Fisheries Training and Research of Andalusia (IFAPA) They also participate in a project that studies the impact of catfish, Funded with 190,000 euros, and which will end in December.