Siluros Found in Lebrija Irrigation Pond 12 km from Guadalquivir 2026

The recent discovery of siluros (European catfish) in an irrigation pond in Lebrija, just 12 kilometers from the Guadalquivir River, has raised alarm among researchers and local fishermen. The find, confirmed after a decomposed fish was found near the Melendo pond in December 2023, highlights the growing presence of this invasive species in the region.

But how did these large predators end up in an isolated irrigation pond? And what does their presence mean for the fragile ecosystems of the Guadalquivir and nearby Doñana National Park?

What Happened: Discovery in Lebrija

In December 2023, a team of researchers found a decomposing fish next to the Melendo irrigation pond, northeast of Lebrija. The fish was identified as a siluro, a species not native to the area. This was not entirely unexpected: six months earlier, environmental DNA from one of the irrigation channels connected to the pond had already detected the presence of siluro DNA.

The corpse confirmed that siluros were present in the area. Now, almost three years later, local fishermen have captured several specimens in the agricultural channels near the pond, just at the gates of Doñana National Park. The situation has escalated from a single dead fish to an established population.

Why It Matters: The Threat of an Invasive Predator

The siluro (Silurus glanis) is one of the largest freshwater fish in Europe, capable of reaching over 2 meters in length and weighing more than 100 kilograms. It is a voracious predator that feeds on fish, amphibians, and even birds, posing a significant threat to native species.

Its presence in the Guadalquivir basin has been documented for over a decade. The first confirmed specimen was caught in July 2011 in the Iznájar reservoir. By 2015, siluros were found in the Huelva riverbank, suggesting two independent introductions. In 2021, a 100-kilogram specimen was found at the Alcalá del Río dam, and in May 2025, the Doñana Biological Station (EBD-CSIC) announced the capture of three juveniles of just over 30 centimeters in the Rivera de Huelva.

The discovery in Lebrija, so close to Doñana, is particularly concerning because the park is a UNESCO World Heritage site and a critical stopover for migratory birds. Invasive species like the siluro can disrupt the delicate balance of these ecosystems.

How Did They Get There? Unraveling the Mystery

The exact pathway of introduction to the Lebrija pond remains unknown. However, several possibilities exist. Siluros may have been introduced illegally for sport fishing, a common practice in some regions. Alternatively, they could have escaped from fish farms or been transported via irrigation channels connected to the Guadalquivir.

The fact that environmental DNA was detected in the channels suggests that siluros are moving through the irrigation network. During periods of high water or flooding, fish can swim from the river into the channels and then into the ponds. The Melendo pond is part of an agricultural irrigation system that draws water from the Guadalquivir, providing a direct pathway for aquatic organisms.

Researchers are also investigating whether the siluros in Lebrija are part of the same population as those in the Guadalquivir or represent a separate introduction. Genetic analysis could provide clues, but such studies take time.

What’s Being Done: Management and Monitoring

Authorities and researchers are stepping up monitoring efforts in the area. The EBD-CSIC has been tracking the siluro population in the Guadalquivir for years, and the recent captures in Lebrija have prompted calls for increased surveillance.

Control measures for invasive fish species are challenging. Physical removal, such as electrofishing or netting, can reduce local populations but is unlikely to eradicate them. Public awareness campaigns are also important to prevent further illegal introductions. Fishermen are encouraged to report any catches of siluros to local authorities. Context on how this played out before sits in Siluros Found in Lebrija Irrigation Pond 12 km from Guadalquivir.

In the meantime, the presence of siluros in the irrigation channels near Doñana is a stark reminder of the connectivity between human-modified waterways and natural habitats. Once an invasive species establishes itself, containment becomes a complex and costly endeavor. The background to this story is set out in Invasive Species Cost Australia Billions: How to Respond. A related thread runs through Invasive Species Cost Australia $24.5B: How to Respond.

What to Watch Next

The situation in Lebrija is evolving. Key questions remain: How large is the siluro population in the pond and channels? Are they breeding successfully? And what impact are they having on native fish and amphibians? Earlier coverage in Energy Utilities: latest articles shows how the argument developed. A closer look at the same subject appears in How Rotenone Restored Two Pyrenees Lakes After Fish Removal.

Researchers will continue to monitor the area, and local fishermen will play a crucial role in early detection. The case also underscores the need for stricter regulations on the transport and release of non-native species. As the siluro continues its spread, the challenge of protecting the Guadalquivir and Doñana’s biodiversity grows more urgent. Anyone following the wider picture can start with Invasive Mouflon Sheep in Teide National Park: A Growing Ecological Crisis. The same theme surfaces in Invasive Pheasants Now Dominate Argentina's Victoria Island Forests, which takes a different angle.

FAQ