Just eight months ago, Alcollarín dressed in gala. This small town of Cáceres, with just over 300 neighbors, was presented at the International Tourism Fair of Madrid as a privileged corner to observe birds, throw the cane or walk next to its reservoir, blue mirror in the middle of the pasture.
Today, the postcard has completely changed. Where the water was shone before, now a lodazal splashed from dead fish is extended. The air, loaded with a sour smell, reaches the streets of the town. The neighbors speak of “ecological disaster” and look unbelieved towards the dam, while from the Guadiana Hydrographic Confederation defend that the operation was “of vital importance” to protect the future of the basin.
The operation that changed everything. The Ministry for Ecological Transition, through the CHG, He started a plan To eradicate the invasive species Pseudorasbora Parva —An known as Chinese fish or Gobio de Boca Túpe -, present at the reservoir and in the Alcollarín River since 2010. Included in the Spanish catalog of invading exotic species and in the European regulation of worrying species for the EU, its control is a legal obligation to prevent its propagation.
The plan included months of bearsques with specialized ships and, as a final phase, a “controlled” emptying of the dam to facilitate the capture of specimens. As reported by the CHGthe reservoir was 100 % of its capacity – 50 cubic hectometers, equivalent to 50,000 million liters – before starting the operation. The problem, like They have denounced neighbors and associations to the newspaper Extremadurais that the emptying caused the downstream release of thousands of copies, expanding the species towards the Ruecas and Guadiana rivers.
The enemy in the waters of Alcollarín. The Pseudorasbora Parva He arrived in Europe around 1960 and has expanded to more than 30 countries, mainly by introductions linked to aquaculture. In Spain, it was first detected in the Ebro basin in 2002 and, since then, it has colonized sections of Catalonia, Andalusia, Madrid and Extremadura.
In the case of Alcollarín, the species was detected in 2010 and, According to the mitecoits density in the reservoir had reached levels that made its complete eradication technically. Even so, the CHG He defended that it was urgent Reduce its population to avoid dispersion towards new channels, especially before the connection planned with the Orellana Canal, and ensure that the reservoir could be used for irrigation and recreational activities “in accordance with current legislation.”
Of the catastrophe control. The contract, awarded in June 2024 to the engineering company and technical designs SAU for 787,861.99 euros (without taxes), included several phases of analysis of the pisco fauna, installation of metal containment barriers to avoid leaks, extraction of native species and elimination of invasors, and the controlled emptying of the reservoir.
However, According to neighbors and groups such as the Fund for the Defense of Natural and Cultural Heritage of Extremadura (Fondenex)the procedure did not come out as planned. The Captured downstreams overflowed in the critical and “hundreds of thousands” phases of invading specimens escaped towards the wheel and the Guadiana.
The drastic drop of the water level, added to the high temperatures, also caused the death of numerous native species, including the barbo, cataloged as vulnerable. The shores were filled with decomposition fish, aquatic birds abandoned the area and the local economy lost, suddenly, a key resource for nature tourism.
Crossing accusations. The CHG argues that the operation was planned and executed under the supervision of a “multidisciplinary team of biologists, ambientologists and highly qualified engineers”, As the newspaper has detailedand recognize only a “punctual mortality of Barbos.” He affirms that most native specimens were rescued during previous beings.
On the other hand, Fondenex has described in the same medium the action of “ecological nonsense” and accuses the CHG of “manifest negligence” for emptying the reservoir in the middle of summer, without providing urgent uses of water, such as fire extinguishing, and without assessing the impact on protected birds in the Zepa Llanos de Zorita. The group has requested environmental reports and does not rule out file a complaint with the courts. In addition, the neighbors have denounced that “the only positive aspects that a reservoir” have been charged and question the use of “massive and non -selective” methods prohibited by the Nature Conservation Law.
Forecasts Once the presence of Pseudorasbora Parvathe CHG plans to reintroduce native species with the collaboration of the Board of Extremadura and maintain barriers and controls in future unwins.
However, environmental groups warn that the ecological and tourist recovery of the reservoir will take years, and that the invading fish is already present in sections of the wheels and the Guadiana where it had not arrived before.
An open question. In Alcollarín, official versions and citizen perceptions diverge radically: for administration, it is a necessary technical operation; For many neighbors, of an “environmental catastrophe” that has multiplied the problem.
Beyond the specific case, the episode raises a dilemma that transcends Extremadura: what environmental and social cost are we willing to assume to stop a biological invasion when total eradication is practically impossible?
Image | Chgguadiana and B. Schoenmakers
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