Hundreds of dead fish float at the Guadaiza river mouth in Marbella

Hundreds of fish have been found dead at the mouth of the Guadaiza river in Marbella. The area carries a conservation designation with the Natura 2000 network due to its ecologically valuable ecosystem.

Animal rights activists raised the alarm on social media, attributing the incident to the closure of the river mouth with a sand dam. Activist Virginia de Nibiru questioned the technical criteria that had authorised the closure and whether its consequences had been adequately assessed.

Marbella town hall has told SUR that the causes of this incident are under investigation. Municipal technicians are considering two possibilities.

"At first glance, it could be due to a school of fish entering the area during a high tide. When the tide went out, they got trapped and died from a lack of oxygen in the freshwater," sources said.

The town hall is not ruling out the possibility of a spill. To confirm or rule out this, water analyses are already under way.

According to activists, there is a sewage discharge upstream from the river mouth. While awaiting the results of the analyses, municipal services have removed all the fish for transport to an authorised incineration plant.

The town hall has used heavy machinery to "widen the opening of the river mouth, reshape the area and move sand", with the aim of "renewing water circulation and completely minimising any possible risk".

"The Guadaiza river has been in the spotlight for years," Virginia de Nibiru said. "A protected area can just be a label."

According to her, protection "must translate into responsible and effective management". "When a river becomes diseased, it's not just fish that die: we lose biodiversity, we lose natural heritage and we lose a part of what we should be conserving for future generations," she stated.

The incident has occurred just seven months after the completion of the renaturalisation and flood risk mitigation project on the Guadaiza, which cost 2.8 million euros.

The project was supported by the biodiversity foundation of the Ministry for Ecological Transition and the Demographic Challenge and was 85 per cent funded by the EU.

During the project, nearly 60,000 square metres of invasive species, mainly reeds, which posed an additional risk in the event of flooding, were removed and more than 8,000 native plants were planted, promoting the recovery of biodiversity and creating refuges for local wildlife.

The renaturalisation project also included cleaning bridges and walkways and removing sediment carried by the river's flow. In addition, a new three-kilometre-long riverside promenade was built in the La Campana area of Nueva Andalucía.

Access environmental monitoring and nature news